BEFORE YOU BEGIN
86 About Size and Resolution
107 Change Image Size or Resolution
Each image has a canvas essentially the image background. The benefit of thinking of an image's background layer as a canvas is that it helps you conceive how that layer can be stretched to change the size of the area on which you can paint, draw objects, and insert text. For a newly imported digital photo, the image is " painted ," if you will, to fill the canvas. You can expand the background layer (the canvas) of an image such as a photograph, for example, to make room for a frame, and fill the new area with color and apply a filter, style, or effect. Or you might simply want to expand the canvas to create more room in which to add a clip from another image, an object, or some text.
Canvas The working area of an image, as defined by the image's outer dimensions.
When you expand the canvas of an image, you add new pixels around its edges. Every photo imported from a digital camera or scanner has a background layer. When you use the Canvas Size command, the extra pixels are given the color you select. If an image has no background layerfor example, if you created the image using the File, New command and made the bottom layer transparent, or you converted the original Background layer to a regular layer using the Layer, New, Layer from Background commandthen the new pixels are made transparent. Every layer above the base layerwhether it's a background layer or a regular layeris expanded by the same amount.
If you shrink the canvas, data on the lowest layer outside the canvas area is discarded. However, data in the upper layers is simply hidden and not removed. Because this data on upper layers is only hidden, you can reposition that data as needed to display what you want.
Choose Image, Resize, Canvas Size
In the Editor , open the image whose canvas size you want to adjust, and save it in Photoshop (*.psd) format. Choose Image, Resize, Canvas Size from the menu bar. The Canvas Size dialog box is displayed.
Enter New Dimensions
The current dimensions of the image are displayed at the top of the Canvas Size dialog box. If you want to simply add a certain amount to the outer dimensions of the image, enable the Relative option. If the option is disabled, the dimensions you enter reflect the total width and height of the image.
You can reduce the canvas size of an image. If you do, although all the layers are reduced in size, data is not removed from the upper layersit's just placed off the canvas where it is not seen in the final image. You can then use the Move tool to move the data on these nonbackground layers to display exactly the portion you want. Data from the bottom layer is clipped and cannot be retrieved. But if you increase the canvas size later on (even after saving and closing the image), you'll see that the data on upper layers is now visible again.
108. Change the Working Area Without Affecting Image Size
In the New Size pane, select a unit of measure such as inches or pixels from one of the drop-down lists next to the Width and Height boxes (the other will change automatically). Then type values in the Width and Height boxes.
Select Anchor Point
Normally, the anchor point is in the center of the Anchor pad. This means that the added canvas is placed equally around the image. If you want to add canvas to just one side of the image, you can tell the Editor where to position the image in relation to the canvas by clicking the appropriate arrow on the Anchor pad. For example, to add canvas only on the left side of the image, click the arrow, located to the right of the center white button.This action tells the Editor to position the image in the right-center positionand to place the additional canvas width to the left. To add space to the leftand below the image, click the arrow (located in the upper-right corner of the Anchor pad) instead.
Choose a Fill Color and Click OK
If the bottom layer of the image is not a Background layer, the added canvas will be transparent. If the bottom layer is the Background layer, the added canvas will be opaque . You can choose a color to fill the extra canvas space. Open the Canvas Extension Color list and select an option such as Background (which applies the current background color ). If you choose Other , the Color Picker appears, and you can choose a color from it. With the Color Picker displayed, you can also click anywhere in the image to pick up that color with the dropper.
To display the Color Picker without choosing Other from the Canvas Extension Color list, just click the box to the right of the list.
View the Result
After expanding the image canvas, make any other changes you want and then save the final image in JPEG or TIFF format, leaving your PSD image with its layers (if any) intact so that you can return at a later time and make different adjustments if you want.
In the sample figure, the canvas was expanded around the central image, text was added, and several new images were pasted into the new space, creating a photo collage of a snowy day. Look for this image in the Color Gallery.