Cropping is the process of removing portions
of an image to create focus or strengthen the composition. You can
crop an image using the Crop tool and the
Crop command. You can also trim pixels using the Crop And Straighten
and the Trim commands.
The Trim command crops an image by removing unwanted image data in different ways than the Crop command. You can crop an image by trimming surrounding transparent pixels, or background pixels of the color you specify.
Transparent Pixels to trim away transparency at the edges of the image, leaving the smallest image containing nontransparent pixels.
Top Left Pixel Color to remove an area the color of the upper left pixel from the image.
Bottom Right Pixel Color to remove an area the color of the lower right pixel from the image.