SRGB color space: Meaning (information, definition, explanation, facts)

sRGB color space is an RGB color space created cooperatively by Hewlett-Packard and Microsoft Corporation, and has been endorsed by the W3C, EXIF, Intel, Pantone, Corel, and many other industry players. It is also well accepted by Open Source software such as the Gimp and the PNG image file format.

The relative luminance of an sRGB image is defined by the following function, after scaling the values in the image to the 0-1 range:

v < .04045 ? v / 12.92 : pow((v+.055)/1.055, 2.4)

The linear portion is designed so that the function is invertable without an infinite slope at zero. There is no need to replicate it in actual hardware as this is hidden by reflected internal and ambient light on even the highest-contrast devices.

sRGB also defines the whitepoint, which is the exact color you get when all three channels have the same number in them. However most monitors ignore this and often have the ability to change the whitepoint (often called the color temperature).

It is important to realize that sRGB is designed to match what current (in 1996) CRT monitors do. Vast amounts of software, both professional and personal computer software, assumme an 8-bit image file placed unchanged into a 8-bit/channel display buffer will display correctly. For this reason you can assumme any 8-bit file found on the Internet is in the sRGB color space. Also all non-CRT hardware, such as LCD screens, digital cameras, and printers, although they don't naturally produce an sRGB curve, are built with compensating circuitry or software so that in the end the also obey this standard. For this reason you can also assumme almost any other image file I/O you find with 8 bits per channel is in sRGB.

Reference

[http://www.w3.org/Graphics/Color/sRGB A Standard Default Color Space for the Internet - sRGB Michael Stokes (Hewlett-Packard), Matthew Anderson (Microsoft), Srinivasan Chandrasekar (Microsoft), Ricardo Motta (Hewlett-Packard) Version 1.10, November 5, 1996]