Color Values Used during Display

Although an image's color palette (or in the case of a 24-bit image, each pixel's 24-bit RGB value) normally determines the color to display at each pixel location, there are cases when this is not so. ImageGear maintains a set of Red, Green, and Blue "Look Up Tables" (LUTs), which are used to determine whether the colors to actually display are different from those in the image's palette. These LUTs can be modified, for example, by setting display attributes using properties DisplayContrast or DisplayBrightness, for example. When the LUTs are modified, the colors displayed may no longer correspond directly to the colors in the Image's palette.

If your display monitor determines colors by using a single 256-color palette, then you can have ImageGear automatically "dither" your image's colors, allowing all images on the screen to display using a single 256-color palette. The display attribute properties (including DitherMode) are described in Using ImageGear.

The colors displayed for an image may also be modified due to constraints imposed by the display monitor being used. Some display monitors use a single 256-color hardware palette. ImageGear can reload this hardware palette each time an image is to be displayed, but since all images on the screen are being displayed using this one hardware palette, all other images on the screen at the same time will change to reflect the colors of this new palette. For such cases, you can instruct ImageGear as to which image or images are to have precedence in establishing the device's hardware palette. In addition, ImageGear can also inform you when the colors of an image may have changed due to the loading of another image's palette.