background
Understanding color space for audio and video play a role in development aid to understanding; as a basis for the concept, we should understand the requirements of
Outline
Color space is usually described by three separate attribute, the combined effect of three independent variables, constituting a natural coordinate space, which is the color space (color model). And the color can be described by three different angles with different properties, it produces a different color space. But the color of the object being described is an objective in itself, but a different color space to measure the same object from different angles.
Common color space:
1, :: RGB color model is the most common for hardware devices, it is a model of the human visual system is closely linked, according to the human eye structure, all colors can be seen as the three basic colors - red r, green g, and blue b varying proportions of. Red, green and blue three basic colors of illumination wavelengths International Committee of CIE provisions were 700nm, 546.1nm, 435.8nm.
RGB is a cube model space, as shown below:
herein described write image
is written here described image
origin corresponding to black, the farthest vertex from the origin corresponds to white, gray distribution value from black to white on a body diagonal.
Generally For convenience, normalized to the cube unit cube, so that all the RGB values are in the interval [0,1] into. According to this model, each image comprising three separate color plane, the brightness of each color is represented by 0-255 superimposed color change between the three types of channels can be obtained as well as their mutual than 1670 million colors (2563 = 16,777,216) .
2, HSV: HSV color space is a simplified version of the Munsell color space, a color model based on perception. It chrominance signal into three attributes: hue (Hue, H), saturation (Saturation, S), Brightness (Value, V). It represents a hue reflected from an object or transmitted through the optical wavelength over an object, that is, the name of the color hue is to identify, such as red, yellow, blue; the degree of brightness is the brightness of the color; depth of color saturation is such as dark red, light red.
HSV color space reflects the way people observe the color, two notable features:
independent color information of the luminance component of the image
"Hue" and "Saturation" component of the human experience of color is closely linked to the way
here to write picture description
3, YCbCr: YCbCr were sub-sampled image, video images and digital images commonly used color space. Y represents the luminance, Cb, and Cr for blue and red components. The model may be the data type double, but the storage space is 8-bit unsigned integer data space. Y ranges from 16 to 235, the red and blue components in the range of 16 to 240. In a general image compression algorithms (e.g., the JPEG algorithm), the first step is to convert the color space YCbCr image space.
4, Lab: Lab color space is a color mode developed by the CIE (International Commission on Illumination). Any color in nature that can be expressed in the Lab space, it's bigger than the RGB color space space. It is a device independent color system is a color system based on physiological characteristics. This means that it is a digital way to describe the human visual sense. So it makes up for RGB and CMYK color models must rely on the device characteristics deficiencies. Since the Lab color space than large color space RGB mode and CMYK mode. This means that RGB color information can be described in CMYK and Lab space can be alluding to. Lab Lab color space coordinates to take, wherein the luminance L; a is a positive number for red, for green negative terminal; b represent positive numbers yellow, blue representative of the negative terminal (a, b) have L = 116f (y) -16, a = 500 [f (x / 0.982) -f (y)], b = 200 [f (y) -f (z / 1.183)]; where: f (x) = 7.787x + 0.138, x <0.008856; f (x) = (x) 1/3, x> 0.008856
herein described write image
5, YUV: color television, with the Y, C1, C2 respectively represent the color representation meanings luminance signal and two chrominance signals, C1, C2 with the particular application related. In the NTSC color television system, C1, C2 represent two color difference signals I, Q; in the PAL color system, C1, C2 respectively, U, V two color difference signals; the CCIR 601 digital television standard, C1, C2 represent two color difference signals Cr, Cb. The so-called three color component signal refers to a difference (i.e., R, G, B) primary color signals and the luminance signals. According to the National Television System Committee, NTSC format standards, when white luminance represented by Y, the relationship between it and the red, green, and blue light can be used in the equation described by the following formula: Y = 0.3R + 0.59G + 0.11B this is the usual formula brightness. Chrominance U, V is B-Y, R-Y compressed at different proportions. If the space to be transformed from YUV to RGB space, as long as an inverse operation to the reverse. Similar YUV color space and Lab color space as well, it is also used to describe the luminance and chrominance color component, wherein L is lightness, a and b are the respective color difference components.