This is information on Color Depths provided in Help file of MGI Photo Suite:
An image can be represented in many forms, such as a painting, picture, etc. In the computer world an image is made up of a collection of dots called “pixels” arranged in a rectangular grid of rows and columns. Each pixel is a specific color. The number of possible colors in an entire image can vary from two to 16.7 million. The simplest type of image has only black and white pixels and is referred to as a “monochrome” image. “True Color” images can contain any of 16.7 million colors and offer the widest range of colors available using MGI PhotoSuite.
Image sizes can vary from a single pixel to as large an image as system memory and resources can accommodate.
Color Depths
The type of image data determines the range of colors that the image may contain. “Color Depth” is a term that is used to specify the maximum number of colors available. In the simplest type of image, each pixel can be either black or white. Since each pixel can have only two different states, only one “bit” of information is required to store each image. However, an image with 8 bits of color information per pixel allows 256 possible colors (2 to the power of 8 equals 256).
MGI PhotoSuite supports the following color depths; Black and White (1 bit per pixel), 16 color (4 bits per pixel), 256 color (8 bits per pixel) and 16.7 million color (true color, 24 bits per pixel). In addition, MGI PhotoSuite allows you to work with grayscale images containing either 16 or 256 colors. The actual number of colors you will see on your monitor depends on the type of video hardware and video drivers you are using.
MGI PhotoSuite allows for the conversion, from one to another, of the following data types.
Monochrome
One-bit data type. Each pixel can be either black or white.
Grayscale
Grayscale images can contain black, white and a range of grays. 16-color (4 bits per pixel) grayscale images contain 16 shades of gray ranging from pure white to pure black. 256-color (8 bits per pixel) grayscale images contain 256 shades of gray ranging evenly from pure white to pure black.
Indexed 16 and 256-color
Indexed, or color-mapped, images contain colors specified by a table of color values. The color values may be chosen from a larger range of available colors, but only the colors actually in the table are displayed in the image. For example, your system may be able to display 256 colors simultaneously, but if you load a 16-color image, you can only draw in the image using the 16 colors contained in the color table for that image.
Indexed 16-color images use 4 bits per pixel to represent the image while indexed 256-color images use 8 bits per pixel.
True Color (16.7 Million)
True color images use values of red, green and blue to represent colors. Each pixel can contain 256 different intensities of red, green and blue which are combined to obtain the final color. For example, if red, green and blue all have a value of zero, the final color is pure black. If red, green and blue all have a value of 255 (the maximum intensity), the final color is pure white. If red and green have a value of 255 but blue is zero, then the final color is pure yellow, since red and green combine to produce yellow when displayed on a computer monitor.
True color images use 24 bits per pixel to represent the image, divided into 8 bits for each primary color (red, green and blue). Certain file formats store true color images as 32-bit images, which have an extra 8 bits to store transparency or overlay information. MGI PhotoSuite will load these files, but ignores the extra data.
See File Formats.