Modern web browsers and content management systems optimize images to display in any environment. However, it is best to prepare images that are optimized for every possible form factor and location where an image might appear. Focus on three things: image resolution, size, and color space.

Graphic designers rely on two primary color spaces. A color space is a method of combining primary colors to form complex rainbows of color.

Use RGB mode when preparing images for mobile devices. Displays on computer monitors and smartphones rely on a combination of red, blue, and green pixels. This RGB image is optimized to accurately reproduce the intended colors on a screen.

For printing, designers use a four-color process, where each color is distilled into a combination of cyan, magenta, yellow, and black. Sometimes four-color images are called CMYK images for this reason.