CHAPTER 5
78
Resizing, Cropping, and Laying Out Images
Keep in mind that resampling can result in poorer
image quality. For example, when you resample an
image to larger pixel dimensions, the image will
lose some detail and sharpness.
Applying the Unsharp Mask filter to a
resampled image can help refocus the image’s
details. (See “Using the focus tools” on page 73.)
To avoid the need for resampling, scan or create
the image at a high resolution. If you want to
preview the effects of changing pixel dimensions
on-screen or print proofs at different resolutions,
resample a duplicate of your file.
Resampling affects not only the size of an image
on-screen but also its image quality and its printed
output—either its printed dimensions or its image
resolution. (See “About image size and resolution”
on page 75.)
If you’re preparing images for the Web, it’s
useful to specify image size in terms of the pixel
dimensions.
To resample an image:
1 Choose Image > Resize > Image Size.
2 Make sure that Resample Image is selected, and
choose an interpolation method:
• Bicubic is the slowest but most precise method,
resulting in the smoothest tonal gradations.
• Nearest Neighbor is the fastest but least precise
method.This method can result in jagged
effects, which become apparent when distorting
or scaling an image or performing multiple
manipulations on a selection.
• Bilinear is the medium-quality method.
3 To maintain the current proportions of pixel
width to pixel height, select Constrain Propor-
tions. This option automatically updates the width
as you change the height, and vice versa.
4 In Pixel Dimensions, enter values for Width and
Height. To enter values as percentages of the
current dimensions, choose Percent as the unit of
measurement.
The new file size for the image appears at the top
of the Image Size dialog box, with the old file size
in parentheses.
5 Click OK to change the pixel dimensions and
resample the image.
For best results in producing a smaller image,
downsample and apply the Unsharp Mask
filter. To produce a larger image, rescan the image at
a higher resolution.
Changing the print dimensions and
resolution of an image
When creating an image for print media, it’s useful
to specify image size in terms of the printed
dimensions and the image resolution. These two
measurements, referred to as the document size,
determine the total pixel count and therefore
the file size of the image; document size also
determines the base size at which an image is
placed into another application. You can further
manipulate the scale of the printed image in the
Print Options dialog box; however, changes you
make in the Print Options dialog box affect only
the printed image, not the document size of the
image file. (See “Positioning and scaling images”
on page 238.)
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