Changing image and canvas size

You probably know that image dimensions are given in pixels ("dots of paint" that comprise a screen image). In PhotoPlus there are options to change the image size and to change the canvas size, but what's the difference and how do you perform each resize?

Changing image size

Changing the image size means scaling the whole image (or just a selected region) up or down. Resizing is actually a kind of distortion because the image content is being stretched or squashed.

You will change the image size when:

The Image Size dialog lets you specify a new size for the whole image, in terms of its screen dimensions and/or printed dimensions.

To resize the image for on-screen display:

  1. Choose Image Size from the Image menu.

  2. Select the Resize layers option to link the Pixel Size (screen) settings to the Print Size or Resolution settings.

  3. To retain the current image proportions, check Maintain aspect ratio. Uncheck the box to alter the dimensions independently.

  4. Select a preferred scale (either "Pixels" or "Percent") in the drop-down list.

  5. Select a resampling method. As a rule, use Nearest Pixel for hard-edge images, Bilinear Interpolation when shrinking photos, Bicubic Interpolation when enlarging photos, and Lanczos3 Window when best quality results are expected.

  6. Enter new Width, Height or Resolution values.

  7. Click OK.

To resize the image for print:

  1. Choose Image Size from the Image menu.

  2. Uncheck Resize layers.

  3. To retain the current image proportions, check Maintain aspect ratio. Uncheck the box to alter the dimensions independently.

  4. Select your preferred units of measurement and resolution. The pixel size will automatically alter with print size adjustment.

  1. Click OK.

Changing canvas size

Changing the canvas size just involves adding or taking away pixels around the edges of the image. It's like adding to the neutral border around a mounted photo, or taking a pair of scissors and cropping the photo to a smaller size. In either case, the remaining image pixels are undisturbed so there's no distortion.

You will change the canvas size when:

There are several ways of changing the image's native canvas size. You can use the Crop Tool (see Cropping an image) or the Crop to Selection command. For more accurate canvas resizing (both enlargements or reductions), the Canvas Size dialog that lets you specify where pixels should be added or subtracted.

To change canvas size:

  1. Choose Canvas Size from the Image menu.

  2. Enter New Width and/or New Height values (the current values are also shown for comparison). Alternatively, select the Relative check box to enter the number of units you want to add to the existing width and height values—for example, 5 pixels, 1 cm, 100 points, 10 percent, and so on.

  3. In the Anchor box, click to position the image thumbnail with respect to edges where pixels should be added or subtracted. For example, if you want to extend the canvas from all sides of the image, click the centre anchor point.

  4. Click OK.

  1. If the canvas size is increased, the new canvas area is filled (on the Background layer) with the current background colour and (on standard layers) with transparency.