![]() ![]() Uncorrected scenes will appear dark on such displays. The first occurs when working with older graphics cards that do not provide gamma correction on framebuffer display. There are two problems that typically arise with gamma correction: not enough correction and too much correction. If the image data has already been gamma corrected for a particular display device, then the linear computations performed in the pipeline and a second application of gamma correction may result in poorer quality images. Care must be taken when importing image data into OpenGL applications, such as texture maps. Even though gamma correction isn't part of OpenGL, it is essential to understand that the OpenGL pipeline computations work best in a linear color space, and that gamma correction typically takes place between the framebuffer and the display device. Gamma correction is not directly addressed by the OpenGL specification it is usually part of the native windowing system in which OpenGL is embedded. #Dynamic gamma control driverApplication or driver software uses these profiles to appropriately adjust image color values as part of the display process. They are controlled by a system of profiles that describes the characteristics of a device. Color management systems (CMS) attempt to solve problems with variation using transfer functions. Printers and other devices also have non-linear characteristics and these may or may not include compensation circuitry to make them compatible with monitor displays. Other types of display devices have non-linear display characteristics as well, but the manufacturers typically include compensation circuits so that they appear to have a gamma of 2.5. The sRGB space represents color values in an approximate gamma 2.2 space. Thus, the well-known 2.2 gamma value has a built-in dim viewing environment assumption. To provide a correct subjective response in this environment, video signals are typically precompensated, treating the CRT as if it has a gamma value of 2.2. CRTs are frequently used for viewing video in a dim environment. The story is somewhat more complicated though, as there is a subjective aspect to the human perception of brightness (actually lightness), that is influenced by the viewing environment. The gamma value for a CRT display is somewhat dependent on the exact characteristics of the device, but the nominal value is 2.5. Displayed ramp intensity with gamma correction. ![]()
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