Whats the Difference Between Dots and Pixels?
How do I preserve the size that I select for my photos when I e-mail them to others? For example, suppose I take a picture and re-size it in Photoshop to a 4-by-6-inch photo at 72 dots per inch, then e-mail it to a few people. When one person opens it, their application displays it as a poster-size image. But another person opens it and sees the correct size. I’ve always been puzzled by this. Can I lock in my selected photo size so it opens the same everywhere in all applications? –John Olszewski, Trenton, New Jersey Good question, John. A lot of people are confused about resolution, dots per inch, print size, and pixels. It all stems from a fundamental misunderstanding of what an image size–like 4 by 6 inches, 72 dpi–is actually telling you. The important thing to understand is that measurements like “4 by 6 inches” are meaningless while the image is still on screen. A computer deals only in pixels. An image can be 640 by 480, 1280 by 1024, or 2240 by 1680 pixels, for instance. And
