Grayscale Image

Black and white means here as grayscale gradient. For the transformation of an image into black or white binary, see the binary image tool.

Each color pixel of an image is generally defined by a triplet of values of red, green and blue, but can also be defined by a triplet hue, saturation, brightness. This brightness value is the position of the pixel between black and white.

To calculate this brightness, several algorithms / color references are possible, like the recommendations 709, 601 or 2100 used as standard in photography or video (and from the CIE International Commission of Lighting).

If an error is returned, it may be an altered file, a bad image, or the file format does not match its extension.

Recommendation 709 is used as a standard for HDTV. The luminance is calculated as Gray = 0.2125 * Red + 0.7154 * Green + 0.0721 * Blue

Example: A color representing the color Orange consisting of Red = 255, Green = 127, Blue = 0. Then the value of gray is 255*0.2125+127*0.7154+0*0.0721=145

Recommendation 601 was used as a standard for analogic terrestrial television. Luminance is calculated as Gray = 0.299 * Red + 0.587 * Green + 0.114 * Blue

Example: A color representing the color Orange consisting of Red = 255, Green = 127, Blue = 0. Then the value of gray is 255*0.299+127*0.587+0*0.0114=151