User Guide

631
Resolution and bit depth
Resolution is the measure of how many
dots or pixels are in a given unit of mea-
sure. One way of expressing bitmap
resolution is in pixels per inch (ppi).
Note: Many textbooks and manuals
refer to image resolution in dots per
inch (dpi). Used in the context of image
resolution, dpi means the same thing as
ppi.
Scanning, paint, and image-editing soft-
ware determine the resolution of bitmap
images. With scanning software, you
select the resolution before scanning
the image. Paint programs usually cre-
ate bitmap images with a fixed resolu-
tion. The original MacPaint® program,
for example, creates 72-ppi images.
With image-editing software, such as
Adobe Photoshop, you can change the
resolution of images by either combin-
ing pixels to make larger pixels, or by
dividing pixels into smaller pixels.