A false-color image is an image that depicts a subject in colors that differ from those a full-color photograph would show.

A true-color image of a subject is an image that appears to the human eye just like the original subject would: a green tree appears green in the image, a red apple red, a blue sky blue, etc. When applied to black-and-white images, true-color means that the perceived lightness of a subject is preserved in its depiction. Absolute true-color is impossible to achieve due to the differences between the chemistry of the display medium and the materials in the original scene.

In a false-color set, human visual perception is limited to three independent coordinates (combination of red, green, and blue); at most, three measurements can be depicted in such a way.

A pseudo-color image is derived from a greyscale image by mapping each pixel value to a color according to a table or function. A familiar example is the encoding of altitude using hypsometric tints in physical relief maps, where negative values (below sea level) are usually represented by shades of blue, and positive values by greens and browns. Pseudo-coloring can make some details more visible, by increasing the distance in color space between successive gray levels. Pseudo-coloring can be used to store the results of image elaboration; that is, changing the colors in order to ease understanding the image. Alternatively, depending on the table or function used, pseudo-coloring may increase the information contents of the original image, for example adding geographic information, combining information obtained from infra-red or ultra-violet light, or MRI scans.