- Without compression, each pixel in a True Color image uses 3 bytes of storage. An image with a resolution of 1024x768 will use about 2.5 MB of storage space.

- Image compression can help make the file size smaller, while retaining the overall dimensions of the image.

- Compression can be done using one of two formats, either lossless, or lossy.

Lossless

files, like TIFF, BMP and PNG formats retain their data, while

lossy files

, like JPG, lose data.

- Higher compression rates will produce lower quality images and smaller file sizes. Lower compression will preserve image quality and has a larger file size.

- When an image has been compressed too many times, or with a high compression ratio, the image may become pixelated. That's because the pixel data is trashed and when the image is reopened, the computer fills in the missing data by borrowing from neighboring pixels.

- It's usually best to choose a compression ratio that is somewhere in the middle. Make sure to save the image as a copy rather than writing over the original, that way if you don't like the results, you can go back to the original file and try different compression settings.