Tutor: ALAN BURCH B.Sc.Hons
St. Lawrence
Isle of Wight.
Course Overview
The course will cover the use of Adobe Photoshop techniques applied to compliment traditional photography and will include:
General introduction to Adobe Photoshop 6.
Overview of techniques available.
Photographic correction. [Levels, Colour, Sharpening etc.]
Selection tools. [Marquee, Lasso, Magic Wand, Feather etc.]
Layers. [Copy, Paste, Effects, Opacity, Transform etc.]
Retouching and restoration. [Cloning, Erasing, Toning etc.]
Advanced techniques. [History Brush/Palette, Text, Filters etc.]
Summary of techniques used in exhibition quality printing.
Photoshop Course Notes
Toolbox
The tools in the toolbox let you select, paint, edit, and view images. Other controls choose foreground and background colours, create quick masks, and change the screen display mode. Most tools have associated Brushes and Options palettes, which let you define the tools’ painting and editing effects.
To change the viewing mode and magnification of image windows:
Click a window control at the bottom of the toolbox:
• The left window control to display the default window with a menu bar at the top and scroll bars on the sides.
• The centre window control to display a full-screen window with a menu bar but no title bar or scroll bars.
• The right window control to display a full-screen window with no title bar, menu bar, or scroll bars.
The hand tool or [SPACE BAR] & Mouse or the Navigator palette can be used for scrolling.
You can magnify or reduce your view using various methods, normally either the Zoom Tool or using [CTRL] + [+] or [-] keys on the keyboard. The window’s title bar displays the zoom percentage at all times.
Note: The 100% view of an image displays an image based on the monitor resolution [72 dpi] and the image resolution, not on the actual image dimensions.
Photoshop Window
The above is a screenshot from a Macintosh, Photoshop 6.01 window showing most of the palettes open with the Cropping Tool selected.
To open a file
1 Choose File > Open.
2 Specify a file format:
• In Windows, for Files of Type, choose All Formats to display all the files in the selected directory. Choose an individual format to display only files saved in that format.
• In Mac OS, select Show All Files to display all files in the selected folder. To locate files in other folders, click Find and type the filename.
3 In Mac OS, select Show Thumbnail to preview files before opening them (if a preview has been saved with the image). This option requires the Apple QuickTime extension.
4 Select the file.
5 Click Open. In some cases, a dialog box appears, letting you set the open options.
In some cases (such as when first opening a file that was saved in an older version of Photoshop), a status bar appears indicating the file is being converted to a specified color space. If the Profile Mismatch dialog box appears, specify whether to convert the file’s color profile.
To save files:
• The Save command saves the file in its current file format.
• The Save As command lets you save an alternate version of the file in a different format.
• The Save a Copy command lets you save a copy of the file, leaving the original file intact. You can optionally flatten the file copy and exclude non-image data or alpha channels.
File Formats
You can use various file formats to get images into and out of Adobe Photoshop. Graphic file formats differ in the way they represent graphic information— either as vector drawings or as bitmap images. The most common formats are;
PSD – For internal Photoshop use
The Photoshop document is Photoshop’s native file format, it is the most flexible for pure Photoshop use as it is the only format that supports layers*[Except TIFF-7 Below] so an image can be re-opened and worked on again from where you left off. Unfortunately very few other programs will accept PSD format and it takes up the most hard disk space, but the file can always be converted to another format by flattening the image and “Saving As” so that the file can be exported to another application.
TIFF – Practically universal print format
The Tagged-Image File Format (TIFF) is used to exchange files between applications and computer platforms. TIFF is a flexible bitmap image format supported by virtually all paint, image-editing, and page-layout applications. Also, virtually all desktop scanners can produce TIFF images.
The TIFF format supports CMYK, RGB, and grayscale files with alpha channels, and Lab, indexed-color, and Bitmap files without alpha channels. TIFF also supports LZW compression.
When you save an Adobe Photoshop image in TIFF, you can choose to save in a format that can be read either by IBM PC-compatible or Macintosh computers. To compress the file automatically, click the LZW Compression check box; compressing a TIFF file decreases its file size but increases the time required to open and save the file. Adobe Photoshop also reads and saves captions in TIFF files.
*TIFF-7 – New format to PS 6.0 with similar properties to PSD, Photo CD, Jpeg and EPS Formats combined, backwards compatible as composite image is also saved. Will probably become the new universal standard high quality format, but is slower than PSD. Can only be accessed if Enable Advanced TIFF Save Options is checked in “Saving Files Preferences”
EPS – For exporting to DTP applications
The Encapsulated PostScript (EPS) language file format can contain both vector and bitmap graphics and is supported by virtually all graphic, illustration, and page-layout programs. The EPS format is used to transfer PostScript language artwork between applications. When you open an EPS file containing vector graphics created in another application, Photoshop rasterizes the file, converting the vector graphics to pixels.
The EPS format supports Lab, CMYK, RGB, indexed-color, duotone, grayscale, and Bitmap color modes, and does not support alpha channels. EPS does support clipping paths.
JPEG – Compressed format for photographic images
The Joint Photographic Experts Group (JPEG) format is commonly used to display photographs and other continuous-tone images in hypertext markup language (HTML) documents over the World Wide Web and other online services. The JPEG format supports CMYK, RGB, and grayscale colour modes, and does not support alpha channels. Unlike the GIF format, JPEG retains all color information in an RGB image but compresses file size by selectively discarding data.
A JPEG image is automatically decompressed when opened. A higher level of compression results in lower image quality, and a lower level of compression results in better image quality. In most cases, the Maximum quality option produces a result indistinguishable from the original.
GIF - Compressed format for flat graphic images
The Graphics Interchange Format (GIF) is the file format commonly used to display indexed-color graphics and images in hypertext markup language (HTML) documents over the World Wide Web and other online services. GIF is a LZW-compressed format designed to minimize file size and electronic transfer time. The GIF format does not support alpha channels.
You can convert files to GIF format using one of the following methods:
• The File > Save As command lets you save a Bitmap-mode, grayscale, or indexed-color image in GIF format and specify an interlaced display. An interlaced image appears gradually in increasing detail as it is downloaded from the Web but can increase the file size. You cannot save alpha channels with the image.
• The GIF89a Export command lets you convert an RGB or indexed-color image to GIF89a format, specify interlacing, and define background transparency.
Colour Mode - RGB OR CMYK
Whether you work in RGB or CMYK depends again on the ultimate destination of the image. CMYK is industry standard for all print work, whereas RGB is the standard for Web use, however most domestic Inkjet printers automatically convert RGB to CMYK. As most domestic scanners use RGB sensors and RGB uses 25% less information it allows quicker work when on the computer it is normally best to work in RGB and convert to CMYK when necessary by changing modes;
Choose Image > Mode > CMYK
This command can also be used to change to other modes e.g. Greyscale or from CMYK to RGB
Image Size & Resolution
When preparing images for print, it’s useful to specify image size in terms of the printed dimensions and the image resolution. These two measurements determine the total pixel count and therefore the file size of the image.
If you turn on resampling for the image, you can change print dimensions and resolution independently. If you turn resampling off, you can change either the dimensions or the resolution—Photoshop adjusts the other value automatically to preserve the total pixel count. For the highest print quality, it’s generally best to change the dimensions and resolution first without resampling. Then resample only as necessary.
The file size of an image refers to the total amount of pixel information in the image. For example, a 1-inch-by-2-inch high-resolution image has more pixels, and thus a larger file size, than a 1-inch-by-2-inch low-resolution image. In print, a high-resolution image has more detail than the same image at low resolution. On-screen, a high-resolution image appears larger (see Image resolution). The enlarged on-screen display does not affect the dimensions of the printed image.
To change the print dimensions and resolution of an image:
1 Choose Image > Image Size.
2 Change the print dimensions or image resolution or both:
• To change only the print dimensions or only the resolution and adjust the total number of pixels in the image proportionately, make sure that Resample Image is selected. Then choose an interpolation method, as described in Choosing an interpolation method.
• To change the print dimensions and resolution without changing the total number of pixels in the image, deselect Resample Image.
3 To maintain the current proportions of image width to image height, select Constrain Proportions. This option automatically updates the width as you change the height, and vice versa.
4 Under Print Size, enter new values for the height and width. If desired, choose a new unit of measurement.
5 For Resolution, enter a new value. If desired, choose a new unit of measurement.
6 Click OK.
Common Resolutions;
Computer Screen Resolution [web use] – 72 dpi
Print Resolution – 180 to 360 dpi [Ignore Inkjet Printer manufacturer’s 1440 dpi etc., these refer to ink dots not pixel dots. Each pixel being made up of four colour dots; Cyan, Magenta, Yellow and Black(K).]
E.g. Epson 1440dpi Printers print best at 360dpi [1440/4 = 360dpi] regardless of whether 4 or 6 ink colours are available as the extra 2 light Cyan and Magenta toned inks are used instead of the standard Cyan and Magenta inks keeping the total no. of inks used to 4.
Cropping the image
To crop an image using the Crop Tool:
1 Select the crop tool.
2 Press and hold mouse button Drag over the part of the image you want to keep.
When you release the mouse button, the crop marquee appears as a bounding box with handles at the corners and sides.
3 Adjust the crop marquee:
• To move the marquee to another position, position the pointer inside the bounding box and drag.
• To scale the marquee, drag a handle. To constrain the proportions, hold down Shift as you drag a corner handle.
• To rotate the marquee, position the pointer outside the bounding box (the pointer turns into a curved arrow), and drag. To adjust the point around which the marquee is rotated, drag the circle at the center of the bounding box.
Drag handle to scale; drag outside bounding box to rotate.
Note: You can’t rotate the crop tool marquee for an image in Bitmap mode.
4 To crop the image, press Enter (Windows) or Return (Mac OS). To cancel the cropping operation, press Esc.
Basic Copy & Paste
1 Select area you want to copy
2 Press [CTRL] + [C] to copy selected area or “Copy” from EDIT Menu
3 Click on image you want to copy into
4 Press [CTRL] + [V] to paste selected area into image or “Paste” from EDIT Menu
If you want to copy a composite layered image use “Copy Merged” from EDIT Menu at 2. above
SELECTION TOOLS
The selected area will always be highlighted by a dotted line of “marching ants” unless you select “Hide Edges” from the VIEW drop down menu
Some tool boxes have several tools within them, clicking and holding down your mouse will show all the tools available, whilst still holding down your mouse button, slide your mouse to the tool required. E.g.
As with all tools on the tool bar, double clicking on the tool required brings up the specific tool option palette, in Photoshop 6.0 the options for each tool selected automatically appear in a moveable toolbar with only a single click on the tool icon in the toolbar with the corresponding icon for the tool displayed far left [see below].
PS 6.0
PS 5.5
Marquee
Rectangular, elliptical or single row tools (+ Cropping tool)
Click, hold and drag to select.
Lasso
Freehand, polygonal or magnetic lasso tools
Using Magnetic Lasso tool;
1 Select and double-click the magnetic lasso tool to display its Options palette, and select options as described in the procedure To set options for the lasso, polygon lasso, and magnetic lasso tools.
2 Click in the image to set the first fastening point.
Fastening points anchor the selection border in place.
3 To draw a freehand segment, move the pointer along the edge you want to trace. (You can also drag with the mouse button depressed.)
The most recent segment of the selection border remains active. As you move the pointer, the active segment snaps to the strongest edge in the image. Periodically, the magnetic lasso tool adds fastening points to the selection border to anchor previous segments.
4 If the border doesn’t snap to the desired edge, click once to add a fastening point manually. Continue to trace the edge and add fastening points as needed.
Fastening points anchor selection border to edges.
5 To switch temporarily to the other lasso tools, do one of the following:
• To activate the lasso tool, hold down Alt (Windows) or Option (Mac OS) and drag with the mouse button depressed.
• To activate the polygon lasso tool, hold down Alt/Option and click.
6 To erase recently drawn segments and fastening points, press Delete.
7 Close the selection border:
• To close the border with a freehand magnetic segment, double-click, or press Enter (Windows) or Return (Mac OS).
• To close the border with a straight segment, hold down Alt (Windows) or Option (Mac OS), and double-click.
Magic Wand
The magic wand tool lets you select a consistently coloured area (for example, a red flower) without having to trace its outline. You specify the colour range, or tolerance, for the magic wand tool’s selection.
Note: You cannot use the magic wand tool on an image in Bitmap mode.
To use the magic wand tool:
1 Double-click the magic wand tool to display its Options palette.
2 For Tolerance, enter a value in pixels, ranging from 0 to 255. Enter a low value to select colours very similar to the pixel you click or a higher value to select a broader range of colours.
3 To define a smooth edge, select Anti-aliased.
4 To select colours using data from all the visible layers, select Use All Layers. Otherwise, the magic wand tool selects colours from the active layer only.
5 In the image, click the colour you want to select.
All adjacent pixels within the tolerance range are selected.
Feathering
Feathering blurs edges by building a transition boundary between the selection and its surrounding pixels. This blurring can cause some loss of detail at the edge of the selection.
You can define feathering for the marquee, lasso, polygon lasso, or magnetic lasso tool as you use the tool using the tool’s Option Palette or Options Bar, or you can add feathering to an existing selection using the “Feather” command from the “Select” drop down menu. Feathering effects become apparent when you move, cut, or copy the selection.
With, as above, a figure of 20 pixels set, 10 pixels outside the selection are gradually added to the selection and 10 pixels inside are gradually subtracted from the selection giving a softer edge.
Adding/Subtracting and modifying selections
You can use the selection tools to add to or subtract from existing selections.
Before manually adding to or subtracting from a selection, set the feather and anti-aliased values in the Options palette to the same settings used for the original selection.
To add to, subtract from, or intersect a selection:
1 Make a selection.
2 Using any selection tool, modify the selection:
• To add to the selection or select an additional area in the image, hold down Shift (a plus sign appears next to the pointer), and select the area or areas you want to add.
• To subtract an area from a selection, hold down Alt (Windows) or Option (Mac OS) (a minus sign appears next to the pointer), and select the area or areas you want to subtract.
In PS 6.0 selection tools have options in the options toolbar displayed that allow normal, adding, subtracting or intersect selection. [see below for Lasso with “adding” option selected]
PS 6.0
To Expand or Contract a selection by a specific number of pixels:
1 Choose Select > Modify > Expand or Contract.
2 For Expand By or Contract By, enter a pixel value between 1 and 16, and click OK.
The border is increased or decreased by the specified number of pixels. Any portion of the selection border running along the image’s edge is unaffected.
Stroking and Filling
Photoshop provides a variety of ways to fill a selection or a layer with colours, images, or patterns. You can also paint a border around a selection or a layer using the Stroke command:
1 Specify a foreground colour as described in Choosing the foreground and background colours.
2 Select the area or layer you want to stroke.
3 Choose Edit > Stroke.
4 Specify the width of the hard-edged border. Values can range from 1 to 16 pixels.
5 For Location, specify whether to place the border inside, outside, or directly over the selection or layer boundaries.
6 Specify an opacity and a blending mode
7 If you’re working in a layer and want to stroke only areas containing pixels, select the Preserve Transparency option.
8 Click OK to stroke the selection or layer.
Alternatively to fill a selection completely: at 3 above Choose Edit > Fill.
To fill with a Pattern or Texture: at 1 above select an area to copy texture or pattern from, then: Choose Edit > Define Pattern
2 Select the area or layer you want to fill.
3 Choose Edit > fill. Specify Use “Pattern” as contents
Paste Into
The “Paste Into” command constrains a pasted image to a selected area on an image, which as with all pasted images can be moved using the “Move” tool.
Paste Onto New Document
Select then Copy Image to be Pasted
Create a “New Document” by: Choose File > New
Set Image Size, Resolution and Colour Mode as required. (Setting Image Size to your Paper size e.g.A4= 29.7cm x 21.0cm is very useful)
Paste onto New Document, use “Move” tool as required, and Paste again to produce two or more identical images on same page.
This is a very useful way of producing a document with images and text exactly were you want them to appear on the printed page [e.g. Greetings Cards], obviously you have to account for the unprintable border areas of your individual printer.
LAYERS
Think of layers as sheets of acetate stacked one on top of the other. Where there is no image on a layer, you can see through to the layers below. Behind all of the layers is the background. All layers in a file share the same resolution, the same number of channels, and the same image mode (RGB, CMYK, or Greyscale). The main advantage of using Layers is that work can be done on an image without changing pixels on the original, if the work on a new layer goes horribly wrong, the whole layer can be discarded, leaving the original image untouched.
The Layers palette lists all layers in an image, starting with the topmost layer. A thumbnail of layer contents appears to the left of the layer name. It is updated as you edit. Use the scroll bars or resize the palette to see additional layers.
You use the Layers palette to create, hide, display, copy, merge, and delete layers. (Additional commands appear in the menu.) Changes to an image affect only the highlighted or active layer. You select a layer to make it active, and only one layer can be active at a time. The active layer’s name appears in the image window’s title bar, and a paintbrush icon appears next to the layer in the Layers palette, indicating that the layer can be modified.
To display the Layers palette:
Choose Window > Show Layers.
To select a layer:
In the Layers palette, click a layer to make it active. Click the layer to make it visible/invisible
Note: Images created using the Transparent option in the New dialog box are created without a background. Images with no background, as well as images with layers, can be saved only in the Photoshop format.
Newly added layers appear above the selected layer in the Layers palette. You can add layers to an image in a variety of ways:
• By creating new layers or turning selections into layers.
• By converting a background to a regular layer or adding a background to an image.
• By pasting selections into the image.
• By creating type using the horizontal type tool or vertical type tool.
To create a new layer using default options:
Click the New Layer button at the bottom of the Layers palette. The layer uses Normal mode with 100% opacity and is named according to its order of creation.
To delete a layer, drag the layer name in the Layers palette to the Trash button.
To turn a selection into a new layer:
1 Make a selection.
2 Choose Layer > New, and choose a command from the submenu:
• To copy the selection into a new layer, choose Layer Via Copy.
• To cut the selection and paste it into a new layer, choose Layer > New > Layer Via Cut.
The selection contents appear in the same position relative to the image boundaries.
Note: When pasting a selection into an image, a new layer is automatically created except in multichannel, Bitmap, or indexed-colour mode, because these modes do not support layers.
Using adjustment layers
An adjustment layer lets you experiment with colour and tonal adjustments to an image without permanently modifying the pixels in the image. The colour and tonal changes reside within the adjustment layer filter, which acts as a veil through which the underlying image layers appear.
When you create an adjustment layer, its effect appears on all the layers below it. This lets you correct multiple layers by making a single adjustment, rather than making the adjustment to each layer separately.
Opacity options
You can change the opacity of each layer using either the Opacity option in the Layer Options dialog box or the Opacity slider in the Layers palette. A layer with 1% opacity appears nearly transparent, one with 100% opacity completely opaque.
Layer blending modes
You use layer blending modes to determine how the pixels in a layer are blended with underlying pixels on other layers. By applying modes to individual layers, you can create a variety of special effects.
Specify a blending range
The sliders in the Layer Options dialog box let you control which pixels from the active layer and which from the underlying visible layers blend and appear in the final image. For example, you can drop dark pixels out of the active layer or force bright pixels from the underlying layers to show through. You can also define a range of partially blended pixels to produce a smooth transition between blended and unblended areas. This can be useful when pasting a complicated subject that is difficult to select by other means, e.g. Spiky Hair, onto a background. It works especially well with well-lit studio portraits against a white backdrop, which can be dropped into another background image very easily without using selection tools.
To define a range for the blending operation:
1 In the Layer Options dialog box, select a Blend If option:
• Grey to specify a blending range for all channels.
• An individual colour channel (for example, red, green, or blue in an RGB image) to specify blending in that channel.
2 Use the This Layer and Underlying sliders to set the brightness range of the blended pixels—measured on a scale from 0 (black) to 255 (white). Drag the white slider to set the high value of the range. Drag the black slider to set the low value of the range.
3 To define a range of partially blended pixels, hold down Alt (Windows) or Option (Mac OS), and drag one half of a slider triangle. The two values that appear above the divided slider indicate the partial blending range.
Layer effects
Photoshop has numerous different effects that you can apply in any combination to a layer.
• The Drop Shadow effect lets you add a shadow that falls behind the contents on the layer.
• The Inner Shadow effect lets you add a shadow that falls just inside the edges of the layer contents, giving the layer a recessed appearance.
• The Outer Glow and Inner Glow effects let you add glows that emanate from the outside or inside edges of the layer contents.
• The Bevel and Emboss effect lets you add various combinations of highlights and shadows to a layer.
Transform Command
The commands under the Edit>Transform submenu let you apply specific transformations to a selection, layer, path, or selection border. Photoshop previews the effect and surrounds the selected area with a bounding border that lets you manipulate the selection, layer, or path.
You can apply several commands in succession before applying the cumulative transformation. For example, you can choose Scale, drag a handle to scale, and then choose Distort, drag a handle to distort, and press Enter (Windows) or Return (Mac OS) to apply both transformations.
The Free Transform command lets you use the Scale, Rotate, Skew, Distort, and Perspective commands without having to select them from the menu. To access the various transformation modes, you use different shortcut keys as you drag the handles of the transform bounding box.
1 Specify what to transform:
• To transform part or all of the layer, select it. Then choose Edit > Free Transform.
2 Transform as follows:
• To move, position the pointer inside the bounding border (it turns into a black arrowhead), and drag.
• To scale, drag a handle. Press Shift as you drag a corner handle to scale proportionately. When positioned over a handle, the pointer turns into a double arrow.
• To rotate, move the pointer outside of the bounding border (it turns into a curved, two-sided arrow), and then drag. Press Shift to constrain the rotation to 15° increments.
• To distort freely, press Control (Windows) or Command (Mac OS), and drag a handle.
• To distort relative to the center point of the bounding border, press Alt (Windows) or Option (Mac OS), and drag a handle.
• To skew, press Control+Shift (Windows) or Command+Shift (Mac OS), and drag a side handle. When positioned over a side handle, the pointer turns into a white arrowhead with a small double arrow.
• To apply perspective, press Control+Alt+Shift (Windows) or Command+Option +Shift (Mac OS), and drag a corner handle. When positioned over a corner handle, the pointer turns into a grey arrowhead.
To undo the last handle adjustment, choose Edit > Undo.
3 Press Enter (Windows) or Return (Mac OS) to apply the transformation. To cancel the transformation, press Esc.
Photographic Correction
Import scanned images
You can import scanned images directly from any scanner that has an Adobe Photoshop-compatible plug-in module or supports the TWAIN interface. To import the scan, choose the scanner name from the File > Import submenu.
To import an image using the TWAIN interface:
1 If you’re using the TWAIN device for the first time with Adobe Photoshop, choose File >Import > Select TWAIN_32 Source. Then select the device you’re using. You do not need to repeat this step for subsequent uses of the TWAIN module.
If more than one TWAIN device is installed in your system and you want to switch devices, use the Select Source command.
2 To import the image, choose TWAIN_32 (Windows) or TWAIN Acquire (Mac OS) from the File > Import submenu.
Note: Remember to close down the scanner’s TWAIN device after scanning, Photoshop will not function with the TWAIN device on or minimized.
To estimate scan resolution:
To estimate scan resolution you have to know the final destination resolution of the image, most high quality print work is printed at 180-360dpi, whereas most web work will be seen at 72dpi. If you have a 10cm x 15cm original and it is going to be printed the same size by a high quality printer at 360dpi, then you must scan at 360 dpi at least. If it’s to be printed to 20cm x 30cm then you must scan at least 720 dpi. If it’s for same size web use then 72 dpi is sufficient. If the final destination is not known scan at the highest resolution you are ever likely to need, bearing in mind the limitations of your equipment, as the resolution can be reduced in Photoshop’s “Image Size” consequently reducing the file size. Even though you can resample up an image size by interpolation, original detail can never be added to a scan and is best avoided.
Name and Save image once scanned and open in Photoshop!!
Levels
You begin professional tonal correction by assigning values to the extreme highlight and shadow pixels in the image, setting an overall tonal range that allows for the sharpest detail possible throughout the image. This process is known as setting the highlights and shadows or setting the white and black points and ensures blacks are black and whites are white. This is normally done using the Levels command. The Brightness/Contrast command is very basic and not recommended.
To set the highlights and shadows using the Levels sliders:
1 Open the Levels dialog box
The Levels dialog box displays a histogram of the image.
2 If the image has more than one colour channel, choose the channel (or channels) you want to adjust from the Channel menu.
To edit a combination of colour channels at the same time, Shift-select the channels in the Channels palette before choosing the Levels command. The Channel menu then displays the abbreviations for the target channels—for example, CM for cyan and magenta. The menu also contains the individual channels for the selected combination.
3 Drag the Input Levels sliders to the edge of the first group of pixels on either end of the histogram.
For example, suppose you want to increase the contrast in an image with pixels that currently cover a range of only 0–233. If you drag the Input Levels white triangle to 233, pixels with brightness values of 233 and higher (in each channel of the image) are mapped to 255, pixels with lower brightness values are mapped to corresponding lighter values. This remapping lightens the image, increasing the contrast in highlight areas.
Suppose instead you want to decrease the contrast in the image. If you drag the Output Levels white triangle to 220, pixels with brightness values of 255 are remapped to 220, and pixels with lower brightness values are mapped to corresponding darker values. This darkens the image, decreasing the contrast in highlight areas.
You can also enter values directly into the Output Levels text boxes.
4 If your image also needs midtone corrections, you can set them now with the Levels dialog box. Do this before applying the levels changes.
5 Click OK.
Curves
Like Levels, Curves lets you adjust the tonal range of an image. However, instead of making the adjustments using just three variables (highlights, shadows, and midtones), you can adjust any point along the 0–255 scale while keeping up to 15 other values constant.
You can also use the Arbitrary Map option in the Curves dialog box to draw a tonal curve by dragging. This feature lets you create a variety of interesting tonal and colour effects.
Colour Balance
The Colour Balance command lets you change the mixture of colours in a colour image.
To adjust the levels of a particular colour in an image:
1 Open the Colour Balance dialog box.
2 Choose Shadows, Midtones, or Highlights to select the tonal range on which you want to focus the changes.
3 With RGB images, select Preserve Luminosity to prevent changing the luminosity values in the image while changing the colour. This option maintains the tonal balance in the image.
4 Drag a triangle toward a colour you want to increase in the image; drag a triangle away from a colour you want to decrease in the image.
The values above the colour bars show the colour changes for the red, green, and blue channels.
Hue/Saturation
The Hue/Saturation command lets you adjust the hue, saturation, and lightness of individual colour components in an image. Like the Colour Balance command, this command relies on the colour wheel. Adjusting the hue, or colour, represents a move around the colour wheel. Adjusting the saturation, or purity of the colour, represents a move across its radius.
Adjusting the Hue/Saturation of individual colours can be used for very precise colour balance compensation
You can also use the Colorize option to add colour to a greyscale image converted to RGB, or to an RGB image—for example, to make it look like a duotone image by reducing its colour values to one hue.
For Sepia Effect; Select “Colorize” and set Hue to approx. 31 and saturation to approx. 25
Variations
The Variations command lets you visually adjust the colour balance, contrast, and saturation of an image or selection. This command is most useful for average-key images that don’t require precise colour adjustments.
Rubber stamp tool and pattern stamp tool:
The rubber stamp tool takes a sample of the image, which you can then apply over another image or part of the same image. Each stroke of the tool paints on more of the sampled image. Cross hairs mark the original sampling point. The pattern stamp tool lets you select part of an image and paint with the selection as a pattern.
1 Double-click the rubber stamp tool or pattern stamp tool to display its Options palette.
2 • Specify the blending mode and opacity.
• Choose a brush size
3 If you are using the rubber stamp tool, select Use All Layers to sample data from all visible layers. If left deselected, the tool samples only from the active layer.
4 Do one of the following:
• With the rubber stamp tool, select Aligned to apply the entire sampled area once, regardless of how many times you stop and resume painting. This option is useful when you want to use different sized brushes to paint an image. You can also use the Aligned option to duplicate two halves of a single image and place them at different locations.
• With the rubber stamp tool, deselect Aligned to apply the sampled area from the initial sampling point each time you stop and resume painting. Because the rubber stamp tool samples the entire image, this option is useful for applying multiple copies of the same part of an image to different images.
• With the pattern stamp tool, select Aligned to repeat the pattern as contiguous, uniform tiles, even when you stop and resume painting in different parts of the image.
• With the pattern stamp tool, deselect Aligned to centre the pattern on the pointer each time you stop and resume painting.
5 Set the sampling point or pattern:
• For the rubber stamp tool, position the pointer on the part of any open image you want to sample, and Alt-click (Windows) or Option-click (Mac OS). This sample point is the location from which the image is duplicated as you paint.
• For the pattern stamp tool, use the rectangle marquee tool on any open image to select an area to use as a pattern. Then choose Edit > Define Pattern. Reselect the pattern stamp tool.
Note: If you are sampling or using a pattern from one image and applying to another, both images must be in the same colour mode.
6 Drag to paint with the tool.
Cloning onto a new layer
Using the Rubber Stamp Tool, it is possible to clone pixels from one layer to another. In the “Layers palette” create a new layer and make sure this stays the active layer, use the “Use All Layers” option in the “Rubber Stamp Options” palette, then use the tool as normal making sure all layers are visible. Again the main advantage is you are not altering the original underlying layers, the new layer consists only the cloned parts against a transparent background, any changes such as using the Erase Tool can be made to the cloned layer without affecting the original.
Filters
To use a filter, choose the appropriate submenu command from the Filter menu. These guidelines can help you in choosing filters:
• The last filter chosen appears at the top of the menu.
• Filters are applied to the active, visible layer.
• Filters cannot be applied to Bitmap-mode, indexed-color.
• Some filters only work on RGB images and 8 bit per channel colour.
• Some filters are processed entirely in RAM.
• Applying filters—especially to large images—can be time-consuming. Previewing effects can save time and prevent unintended results. Depending on the filter, you may have a preview window or the option to preview effects on the entire layer.
Unsharp masking
Unsharp masking, or USM, is a traditional film compositing technique used to sharpen edges in an image. The Unsharp Mask filter corrects blurring introduced during photographing, scanning, resampling, or printing. It is useful for images intended both for print and online.
The Unsharp Mask filter locates pixels that differ from surrounding pixels by the threshold you specify and increases the pixels’ contrast by the amount you specify. In addition, you specify the radius of the region to which each pixel is compared.
The effects of the Unsharp Mask filter are far more pronounced on-screen than in high-resolution output. If your final destination is print, experiment to determine what dialog box settings work best for your image.
To sharpen an image using the Unsharp Mask filter:
1 Choose Filter > Sharpen > Unsharp Mask.
• For Amount, drag the slider or enter a value to determine how much to increase the contrast of pixels. For high-resolution printed images, an amount between 150% and 200% is recommended.
• For Radius, drag the slider or enter a value to determine the number of pixels surrounding the edge pixels that affects the sharpening. For high-resolution images, a Radius between 1 and 2 is recommended.
A lower value sharpens only the edge pixels, whereas a higher value sharpens a wider band of pixels. This effect is much less noticeable in print than on-screen, because a 2-pixel radius represents a smaller area in a high-resolution printed image.
• For Threshold, drag the slider or enter a value to determine how different the sharpened pixels must be from the surrounding area before they are considered edge pixels and sharpened by the filter. To avoid introducing noise (in images with fleshtones, for example), experiment with Threshold values between 2 and 20. The default Threshold value (0) sharpens all pixels in the image.
If applying the Unsharp Mask filter makes already bright colours appear overly saturated, convert the image to Lab mode and apply the filter to the L channel only. This technique sharpens the image without affecting the colour components.
Gaussian Blur
Quickly blurs a selection by an adjustable amount. Gaussian refers to the bell-shaped curve that is generated when Adobe Photoshop applies a weighted average to the pixels. This filter adds low-frequency detail and can produce a hazy effect.
Smart Blur
Precisely blurs an image. You can specify a radius, to determine how far the filter searches for dissimilar pixels to blur; a threshold, to determine how different the pixels’ values should be before they are eliminated; and a blur quality. You also can set a mode for the entire selection (Normal), or for the edges of colour transitions (Edge Only and Overlay). Where significant contrast occurs, Edge Only applies black-and-white edges and Overlay Edge applies white.
Add Noise
Applies random pixels to an image, simulating the effect of shooting pictures on high-speed film. The Add Noise filter can also be used to reduce banding in feathered selections or graduated fills or to give a more realistic look to heavily retouched areas. Options include noise distribution: Uniform distributes colour values of noise using random numbers between 0 and plus or minus the specified value, for a subtle effect; Gaussian distributes colour values of noise along a bell-shaped curve for a speckled effect. The Monochromatic option applies the filter to only the tonal elements in the image without changing the colours.
Dust & Scratches
Reduces noise by changing dissimilar pixels. To achieve a balance between sharpening the image and hiding defects, try various combinations of radius and threshold settings. Or apply the filter on selected areas in the image.
Advanced Techniques
History Palette
The History palette lets you jump to any recent state of the image created during the current working session. Each time you apply a change to an image, the new state of that image is added to the palette.
For example, if you select, paint, and rotate part of an image, each of those states is listed separately in the palette. You can then select any of these states, and the image will revert to how it looked when that change was first applied. You can then work from that state.
The following guidelines can help you with the History palette:
• Program-wide changes, such as changes to palettes, colour settings, actions, and preferences, are not changes to a particular image and so are not added to the History palette.
• By default, the History palette lists the previous 20 states. Older states are automatically deleted to free more memory for Photoshop. To keep a particular state throughout your work session, make a snapshot of the state.
• Once you close and reopen the document, all states and snapshots from the last working session are cleared from the palette.
• By default, a snapshot of the initial state of the document is displayed at the top of the palette.
• States are added from the top down. That is, the oldest state is at the top of the list, the most recent one at the bottom.
• Each state is listed with the name of the tool or command used to change the image.
• By default, selecting a state dims those below. This way you can easily see which changes will be discarded if you continue working from the selected state.
• By default, selecting a state and then changing the image eliminates all states that come after.
• If you select a state and then change the image, eliminating the states that came after, you can use the Undo command to undo the last change and restore the eliminated states. By default, deleting a state deletes that state and those that came after it. If you choose the Allow Non-Linear History option, deleting a state deletes just that state.
Snapshot command
The Snapshot command lets you make a temporary copy (or snapshot) of any state of the image. The new snapshot is added to the list of snapshots at the top of the History palette. Selecting the snapshot lets you work from that version of the image.
1 Select a state.
2 Click the New Snapshot button on the History palette, or choose New Snapshot from the History palette pop-up menu.
3 Enter the name of the Snapshot in the Name text box.
4 For From, select the snapshot contents:
• Full Document to make a snapshot of all layers in the image at that state.
• Merged Layers to make a snapshot that merges all layers in the image at that state.
• Current Layer to make a snapshot of only the currently selected layer at that state.
5 Click OK.
History Brush
The history brush tool lets you paint a copy of one state or snapshot of an image into the current image window. This tool makes a copy, or sample, of the image and then paints with it.
For example, you might make a snapshot of a change you made with a painting tool or filter. After undoing the change to the image, you could use the history brush tool to apply the change selectively to areas of the image. Unless you select a merged snapshot, the history brush tool paints from a layer in the selected state to the same layer in another state.
The history brush tool works similarly to the rubber stamp tool, but on any state or snapshot of the image, not just the current one.
To paint with a state or snapshot of an image:
1 Double-click the history brush tool to display its Options palette.
2 Specify the opacity and blending mode as explained in Using the Options palette for painting and editing tools.
3 Choose a brush size, as explained in Using the Brushes palette.
4 If desired, select Impressionist to paint with an “impressionistic” copy of the source state or snapshot. This option drags and smears the pixels as you paint.
5 In the History palette, click the left column of the state or snapshot to use as the source for the history brush tool.
6 Drag to paint with the history brush tool.
Bitmap type
Paint and image-editing programs such as Adobe Photoshop 5.5 create bitmap type composed of pixels. The sharpness of bitmap type depends on the type size and the resolution of the image. For example, type that has been scaled up in size may show jagged edges. High-resolution images can display higher-resolution (and therefore smoother) type than low-resolution images.
Photoshop 6.0 creates scaleable Vector type or text that remains editable in a separate layer until Rendered.
Important: A type layer is normally created except for images in multichannel, Bitmap, or indexed-colour mode, because these modes do not support layers. In these image modes, type appears on the background and cannot be edited.
To create type in PS6.0
Click in Toolbar, then click I-Beam in image area were you w ant text to appear, then simply enter text directly onto image using options in the Options Toolbar for Font size, colour and style, Paragraph Style and Text Warping etc. similar to Word processing programs. To change any parameter such as Font style after text has been typed, just highlight the text, then change the settings on the Options Toolbar, then click again in the highlighted area to view the effect.
When finished entering text do not use shortcuts to select another tool as the character will be added to the text.
Creating type in PS 7.0
1 Select the type or vertical type tool. The pointer changes to an I-beam pointer.
The small line through the I-beam marks the position of the type baseline. For horizontal type, the baseline marks the line on which the type rests; for vertical type, the baseline marks the centre axis of the type characters.
2 Click in the image to set an insertion point for the type.
3 To display a preview of the type in the image, select Preview. (This option is not available for images in multichannel, Bitmap, or indexed-colour mode.)
4 Specify type attributes, as described in Setting type attributes.
5 To change the colour of the type, click the colour box, choose a colour as described in Using the Adobe Photoshop Colour Picker, and click OK.
6 Click inside the text area at the bottom of the dialog box, and enter your text. To create a line break, press Enter (Windows) or Return (Mac OS) while the cursor is in the text area.
7 To control the display of type in the text area, do any of the following:
• To resize the text area, drag the lower right corner of the dialog box.
• To change the view magnification, click the zoom buttons at the bottom of the dialog box. Click the percentage value to specify a 100% view.
• To scale the magnification so that the type always fits in the text area, select Fit in Window. Selecting this option makes the zoom buttons unavailable.
8 To adjust the placement of the type, drag the type preview in the image. This option is only available if you have selected Preview.
9 Click OK. The type appears in the image on a new type layer, and a type icon appears next to the layer name.
To create type selection border
The type mask and vertical type mask tools let you create selection borders in the shape of type. Type selections appear on the active layer, and can be moved, copied, filled, or stroked just like any other selection.
1 Select the type mask tool or the vertical type mask tool .
2 Click where you want the type selection border to appear.
For best results, create the type selection border on a regular image layer, not a type layer.
3 Specify type attributes, as described in Setting type attributes.
4 Click inside the text area at the bottom of the dialog box, and enter the text you want. To create a line break, press Enter (Windows) or Return (Mac OS) while the cursor is in the text area.
To control the display of type in the text area, see the instructions in step 7 of the procedure To enter text.
5 Click OK. The type selection border appears in the image on the active layer.
Editing type layers
Once you have created type, you can edit the contents, attributes, and orientation at any time by using its type layer. Type layers save with the image. You can move, restack, copy, and change the layer options of a type layer just as for a regular layer. You can also apply these commands to a type layer and still be able to edit the text:
• Transformation commands under the Edit menu, except for Perspective and Distort. (To transform just part of the type layer, you must convert the type layer to a regular layer.)
• Layer effects
• Fill shortcuts
To apply the full range of Photoshop effects (such as filters) to a type layer, you can convert the type layer to a regular layer. Converting a type layer makes its contents uneditable as text.
To convert a type layer to a regular layer:
1 Select the type layer in the Layers palette.
2 Choose Layer > Type > Render Layer.
Channels and Masks
In Adobe Photoshop, channels store an image’s colour information. In addition, channels and masks store selections that let you manipulate and control specific parts of an image in sophisticated ways.
Colour information channels are created automatically when you open a new image. The image’s colour mode (and not its number of layers) determines the number of colour channels created. For example, an RGB image has three default channels: one for each of the red, green, and blue colours plus a composite channel used for editing the image.
Alpha channels store selections as 8-bit greyscale images and are added to the colour channels in an image. You use alpha channels to create and store masks, which let you manipulate, isolate, and protect specific parts of an image. An image can have up to 24 channels, including all colour and alpha channels.
In addition, spot colour channels can be added to an image to let you specify additional plates for printing with spot colour inks.
Quick Mask mode
Quick Mask mode lets you edit any selection as a mask without using the Channels palette and while viewing your image. The advantage of editing your selection as a mask is that you can use almost any Photoshop tool or filter to modify the mask. For example, if you create a rectangular selection with the marquee tool, you can enter Quick Mask mode and use the paintbrush to extend or contract the selection, or use a filter to distort the edges of the selection. You can also use selection tools, because the quick mask is not a selection.
Start with a selected area and use Quick Mask mode to add to or subtract from it to make the mask, or create the mask entirely in Quick Mask mode. Colour differentiates the protected and unprotected areas. When you leave Quick Mask mode, the unprotected areas become a selection.
A temporary Quick Mask channel appears in the Channels palette while you work in Quick Mask mode. However, you do all mask editing in the image window.
To create a quick mask:
1 Using any selection tool, select the part of the image you want to change.
2 Click the Quick Mask mode button in the toolbox.
A colour overlay (similar to a piece of rubylith) covers and protects the area outside the selection. The original selection is left unprotected by this mask. By default, Quick Mask mode colours the protected area using a red, 50% opaque overlay.
3 To edit the mask, select a painting or editing tool from the toolbox, or select a filter or adjustment command from the menu bar. By default, painting with black adds to the mask, shrinking the selection. Painting with white removes areas from the mask, expanding the selection. Painting with grey or another colour creates a semitransparent area, useful for feathering or anti-aliased effects.
4 Click the Standard mode button in the toolbox to turn off the quick mask and return to your original image. A selection border now surrounds the unprotected area of the quick mask.
The selection boundary indicates where 50% of the pixels are selected. That is, if a feathered mask is converted into a selection, the boundary line runs halfway between the black pixels and the white pixels of the mask gradient.
5 Apply the desired changes to the image. Changes affect only the selected area.
6 Choose Select > None to deselect the selection, or Choose > Select >Save Selection to save as an alpha channel, which can be saved along with the image data.
Paths
Paths provide an effective way to draw precise selection borders. A path is any line or shape you draw using the pen, magnetic pen, or freeform pen tool. Unlike the bitmap shapes drawn by the pencil or other painting tools, paths are vector objects that contain no pixels. As a result, paths remain separate from the bitmap image and do not print, with the exception of clipping paths.
Once you have created a path, you can save it in the Paths palette, convert it to a selection border, or fill or stroke the path outline with colour. In addition, you can convert a selection to a path. Because they take up less disk space than pixel-based data, paths can be used for long-term storage of simple masks. Paths can also be used to clip sections of your image for export to an illustration or page-layout application. As opposed to selections paths can be open ended, easily readjusted and saved with the image data.
Because of their smooth outlines, paths can be converted into precise selection borders. You also can convert selection borders into paths, using the direct-selection tool for fine-tuning.
To save a path as a clipping path
When printing a Photoshop image or placing it in another application, you may want only part of the image to appear. For example, you may want to print or show a foreground object and exclude its rectangular background. A clipping path lets you isolate the foreground object and make everything outside the object transparent when the image is printed or placed in another application. Use the following methods to export and print files containing clipping paths:
To save a path as a clipping path:
1 Draw and save a path or convert an existing selection into a path.
2 Choose Clipping Path from the Paths palette menu.
3 For Path, choose the path you want to save.
4 For good results with most images, leave the flatness value blank to print the image using the printer’s default value. If you experience printing errors, enter a new flatness value.
5 Click OK.
If you plan to print the file using process colours, convert the file to CMYK mode.
6 Save the file:
• To print the file using a PostScript printer, save in Photoshop EPS format and export to a page-layout application such Quark or Pagemaker.
Gradient fills
The gradient tools create a gradual blend between multiple colours. You can choose from existing gradient fills or create your own. You draw a gradient by dragging in the image from a starting point (where the mouse is pressed) to an ending point (where the mouse is released). The starting and ending points affect the gradient appearance according to the gradient tool used.
To Save a Selection
If you want to use a selection size or shape to use again you can save it as a mask in the Channels palette by;
Select> Save Selection then name the selection.
Re-activate selection by:
Select> Load Selection then choose the required named selection.
ALAN BURCH B.Sc.Hons
St. Lawrence, Ventnor,
Isle of Wight.