The range of colors a computer monitor can display is known as the gamut and the monitor’s gamut has a different range of colors than is possible to output with a printer. The Photoshop Gamut Warning feature (View > Gamut Warning) shows when the colors on screen are outside of the printer’s capabilities by coloring the problem areas.

The Gamut Warning’s job is to prevent disappointment when you work in RGB mode. It does so by highlighting all the pixels that are out of gamut or beyond the capabilities of the printer. With the feature turned on you can adjust the colors in the photo until no warning appears and therefore be assured that the colors you see on screen will print.

To adjust the color used for the warning go to Edit > Preferences > Transparency & Gamut.

The Gaussian Blur filter, as one of the group of Blur filters, softens the look of photos, producing a blur effect that is similar to out of focus pictures.

This filter is often used to blur the background of photographs, producing an artificially shallow depth of field effect. To reproduce these results select the area to be blurred first and then apply the filter.

Unlike the Blur and Blur More options, the Gaussian Blur filter provides a slider control that governs the strength of the effect (1).

In recent editions of Photoshop the more sophisticated Lens Blur is more frequently used for depth of field focus effects.

Bridge 2.0 (which ships with Photoshop CS3) now provides options for you to control how the program builds the thumbnails that are displayed in the content area. Rather than build the same level of thumbnail quality for all pictures, the Bridge creates lower quality, but fast to generate and display, thumbnails by default. These ‘Quick Thumbnails’ are based on exiting previews that are embedded in the source file. In the General section of the Preferences (1) you can select between the creation of these Quick Thumbnails, High Quality Thumbnails or even an option that instructs the program to convert the thumbnails to high quality when first previewed.

Bridge is set to Quick Thumbnails by default but for those who are willing to wait a little longer for higher resolution displays, select the High Quality Thumbnails option in the Preferences dialog. Choosing this option instructs Bridge to generate high quality, color managed, thumbnails from the source file.

As an alternative to Bridge generating Quick or High Quality Thumbnails, you can also choose for the program to use Quick thumbnails until the image is previewed. At this time Bridge will create a high quality thumbnail of the image. To use this option select the Convert to High Quality When Previewed entry in the Thumbnails section of Bridge Preferences.

When first pointing Bridge 2.0 at a folder or directory, the program generates quick thumbnails based on the existing embedded thumbnails in the source file. These thumbnails are low resolution and aren’t color managed by Bridge.

To change this so that Bridge generates better quality thumbnails choose the High Quality Thumbnails entry from the Thumbnails section of the Preferences dialog.

Bridge 2.0 ships with a new file transfer utility designed for downloading pictures from cameras or card readers. Called the Adobe Photo Downloader (APD), the utility is accessed by via the Get Photos from Camera option in the File menu.

APD can be used in two different modes - Standard or Advanced - and contains options for nominating the folder where the transferred files will be saved, how they will be named, converting to DNG format whilst downloading and applying metadata templates on the fly.

The GIF format is used to optimize logos and graphics for use on web pages. The format supports up to 256 colors (8-bit), transparency (2), LZW compression and simple animation. When converting a full color picture to GIF the number of colors is reduced and mixed using one of four options - Selective, Perceptual, Adaptive and Restrictive or Web (1).

The Dither option (4) helps simulate continuous tone by mixing patterns of dots. The total number of colors (3) used in the final file can also be set in the dialog. Save images in the GIF format by selecting the GIF option in the Save for Web feature (1) or via the Compuserve GIF format option in the Save As option.

The Glass filter, as one of the group of Distort filters, simulates the texture of a picture when it is viewed through rippled glass.

The look and style of the ripple is determined by the various controls in the filter dialog. The Distortion slider (1) alters the amount of the image that is affected by the glass ripple.

The Smoothness control (2) adjusts the sharpness of the ripple detail and the Texture menu (3) contains a series of options for the style of glass used in the filter.

The Scaling slider (4) controls the size of the glass elements used to distort the picture and the Invert setting (5) switches the way that the effect is applied.

The Drop Shadow, Inner Shadow and Bevel and Emboss layer styles use a light source to help define the look of the effect. The direction of the source can be altered via the dialog for each style (1).

The Use Global Light setting forces all layer styles to use the same light source and direction. Using this option gives your styles a more consistent appearance as all shadows and embossing effects are lit in the same way.

To apply the same light settings to all layer styles in a single document select Layer > Layer Style > Global Light and adjust the values in the dialog that pops up (2).

There are two Glow styles available in the Layer Styles menu of Photoshop - Inner Glow and Outer Glow (1). These options add a glow to a selection or the contents of a layer.

Glow styles look particularly effective when produced around type and can be made to appear from inside or outside the selection in any color. The effect is great for creating fancy headlines for websites or newsletters.

The Structure, Elements and Quality settings in the Glow dialogs (2) control the look, size and strength of the glow effect.

The Glowing Edges filter, as one of the group of Stylize filters, searches for and draws neon-like colored lines around the edges of picture elements.

The edges in the picture are used as the basis for the effect, with the three settings in the dialog providing control over how these are located and the style of the drawn neon line.

The Edge Width slider (1) alters the size and dominance of the lines drawn around the edges.

The Edge Brightness control (2) alters the brightness of the lines and the balance of light and dark in the picture, and the Smoothness slider (3) adjusts the amount of fine detail in the end result.

A Gradient adjustment layer can be added to your picture by selecting the Gradient option from the Layer > New Fill Layer menu (1) or by choosing Gradient from the pop-up menu that appears after pressing the New Fill Layer button at the bottom of the Layers palette. After selecting the option a Gradient Fill dialog appears. Here you can select the gradient colors (2), style

(3), angle (4) and scale (5). Clicking OK creates a new layer and fills it with the Gradient type, color and style that you set in the previous dialog.

The example shows the results of adding a Gradient adjustment layer whilst a selection (of the white background) is active.

The Gradient Editor dialog is used to adjust the existing gradient options found in the Gradient Picker palette or create and save completely new choices to the feature.

To create a new gradient start by displaying the dialog by clicking on the gradient preview (6) in the options bar. Select a preset option (1) to base the new gradient upon. Change colors by double-clicking the color stop (5) and choosing a new color from the Color Picker dialog. Alter the new color’s position in the gradient by click-dragging the stop.

Adjust the position of the opacity by click-dragging the opacity stops (2, 3) along the gradient. Change the midpoint of color or opacity changes by click-dragging the midpoint control (4).

To add new color or opacity stops click on the upper or lower side of the gradient. To delete existing stops drag them into the middle of the gradient.

Save the finished gradient by entering a name and pressing the New button. The gradient will be displayed as a new option in the Gradient Picker palette.

The Gradient Map adjustment layer works in a similar way to the Gradient Map filter in that it swaps the tone of the picture with the colors of the selected gradient.

Applying the changes via an adjustment layer means that the results are always editable later and the original photograph remains untouched. By double-clicking the layer thumbnail (left side) the Gradient Map dialog opens and displays the original settings that were used in the adjustment layer. These settings can be altered and the adjustment layer reapplied.

The Gradient Map feature in either the filter or adjustment layer form is often used to create a custom conversion of a color image to grayscale. By selecting a simple black to white gradient (1) in the feature, the tones in the original image are mapped evenly to the grayscale gradient.

The Gradient Map filter, as one of the group of Adjustment filters, converts the underlying tones (grayscale information) of the photo to the colors and tones of the selected gradient. The dialog contains options for selecting the gradient to use as the basis of the mapping (1) as well as two checkbox controls.

Dither - For applying a Dither to the gradient to help smooth out changes in color and tone.

Reverse - Switches the mapping process so that dark tones are converted to light tones and light tones to dark.

Adding a gradient mask to a layer makes the image take on the gradient when blending with other layers. This is useful for complex image creation and composition. The mask can then be edited to change the shape of the gradation by adding or subtracting from it.

To show how the Gradient Mask can be put to use I’ve merged three photographs - a portrait, sculpture and metal girder. The metal girder was first rotated to suit the angle of the neck on the sculpture, then a black to transparent mask was added to the sculpture layer so that the image fades to transparent. This was repeated on the girl layer and now you can’t see the joins.

Photoshop has five different gradient types. All the options are used to gradually change color and tone from one point in the picture to another. The choices are:

Linear (1) - Changes color from starting to end point in a straight line.

Radial (2) - Radiates the gradient from the center outwards in a circular form.

Angle gradient (3) - Changes the color in a counter-clockwise direction around the starting point.

Reflection (4) - Mirrors a linear gradient on either side of the drawn line.

Diamond (5) - Changes color from the center outwards in a diamond shape.

To create a gradient start by selecting the tool and then adjusting the controls in the Options palette. Choose the colors from the Gradient Picker drop-down menu (6) and the style from the five buttons to the right (1-5). Click and drag the mouse pointer on the canvas surface to stretch out a line that marks the start and end points of the gradient. Release the button to fill the layer with the selected gradient.

The Grain filter, as one of the group of Texture filters, simulates the look of the grain of high-speed film.

The look of the effect is adjusted by three settings in the dialog. The Intensity slider (1) alters the density of the grain effect and the Contrast control (2) adjusts the underlying contrast of the whole picture. The Grain Type menu (3) provides a variety of texture options (4) that can be used for filtering. Film grain or Regular is one of the entries but the look of the end result differs greatly with different selections. With some grain types the current foreground and background colors are used for the grain and background hues. Changing these colors often results in dramatically different results.

The Graphic Pen filter is one of the group of Sketch filters. The feature simulates the effect of making a drawing of the photograph with a thin graphic arts pen. Close overlapping strokes are used for the shadow areas, midtones are represented by balancing strokes with the paper color showing through, and highlight details are drawn with a few sparse strokes.

The filter dialog gives you control over the balance of light and dark - paper and stroke (2) and the length of the pen stroke (1) used to draw the picture. There is also a dropdown menu for selecting the direction of the pen strokes (3).

Grayscale images, in computer terms, are those photos that contain no color. These pictures contain a series of gray tones from pure black through to white. The more tones that exist between the black and white points the smoother any graduations in the picture will be. The photographic equivalent of a grayscale picture is a black and white photograph.

Sometimes the term monochrome is used to describe grayscale photos because they only contain a single (mono) color (chrome) - black on a white background. However, monochrome can also refer to photos that use a color other than black for the tones.

It is possible to change the color mode of your picture by selecting a different mode from the Image > Mode menu (1).

A picture that is in Grayscale mode contains no color at all and supports a total of256 levels of gray, with a value of 0 being black and 256 being white.

When converting a color photograph to Grayscale mode in Photoshop you may need to confirm that you wish to lose all the color in the photo. Clicking OK to this request will lose the picture’s three color channels (RGB) and retain tone and detail in a single gray channel (2).

Though converting a colored image to grayscale using a mode change is a simple process most photographers prefer to employ techniques that allow them to determine how specific colors are mapped to gray. The Channel Mixer and Black & White features provide such options. Both Lightroom and Adobe Camera Raw provide options for creating grayscale images, but keep in mind that changes made with these programs don’t alter the basic color nature of the original file.

A visual non-printing grid is available for display in the Photoshop workspace. With the grid displayed and the Snap to Grid option (View > Snap to > Grid) selected objects will automatically align with grid lines and intersections when being moved or sized.

The grid is often used in conjunction with the Rulers (View > Rulers) feature to help align and size objects and picture parts.

The color, style and spacing of the grid can be adjusted via the Guides, Grids & Slices section of the Edit > Preferences dialog (1).

Grouping layers is a new way of combining individual layers into a common layer folder or Layer Set as it was known in CS. In CS2 it is possible to multi-select layers and then create a new layer group (set) by choosing the Group Layers option (1) from the Layers menu or pressing Ctrl/Cmd G.

To remove layers from a group and restore their place in the Layers palette simply select Layer > Ungroup Layer.

To create an empty Layer Group click on the Create a new group button at the bottom of the Layers palette (2).

The Group with Previous command from CS becomes the Create Clipping Mask in CS2. The feature still combines the contents of two layers using a clipping group. The command is often used to insert the contents of one layer into the non-transparent areas of another. The example shows the winter image, top layer, being clipped by the letter shapes (nontransparent areas) of the bottom layer.

This occurs because all the layers in the clipping group have the opacity attributes and blend mode of the bottom-most layer.

You can create a clipping mask in two different ways:

1. Select the top layer and then choose Layer > Create Clipping Mask (previously Group with Previous).

2. Hold down the Alt/Opt key whilst you click on the boundaries between the two layers that you wish to group.

As well as the options listed under the Select > Modify menu, an active selection can also be altered and adjusted using the Grow and Similar commands.

The Select > Grow feature increases the size of an existing selection by incorporating pixels of similar color and tone to those already in the selection. For a pixel to be included in the ‘grown’ selection it must be adjacent to the existing selection and fall within the current Tolerance settings located in the options bar (1).

For the most part, it is recommended to now use this feature in the Refine Edge dialog as this approach provides a live preview of the changes made to the selection using the Grow option.

These are horizontal or vertical lines that can be pulled out from the edge rulers to appear over the image. If the rulers aren’t visible go to View > Rulers (Ctrl/Cmd R).

Guides can be used to align text or for laying out parts of the image in a symmetrical pattern. Go to Edit > Preferences > Guides, Grids & Slices (1) to choose the guides’ color and style (straight or dotted line). The guides will not print and can be removed or repositioned using the Pointer tool.

As with the Grid, Paint tools will snap to the guides if the Snap to Guides option is selected from the View menu.

The new Vanishing Point filter provides the option of exporting the perspctive grids created in the feature as separate layers. The layers can then be dragged onto a new document and used as a set of custom perspective guides.

New for CS2 was the Smart Guides feature that automatically aligns different layer contents with other elements in a Photoshop document. When moving layer content Photoshop will automatically snap contents to align with edges or centers of other picture parts (1).

To display the Smart Guides as you arrange picture parts select Smart Guides from the View > Show menu (2).

The color of the Smart Guide display lines can be altered via the Edit > Preferences > Guides, Grid & Slices dialog (3).