RGB color space

Color Constancy M. Ebner 2007 John Wiley Sons, Ltd 

Wide Web. In order to achieve accurate color reproduction on different systems, a color profile (International Color Consortium 2003) of the generating system has to be attached to every image. However, the associated color profile of the system that was used, when the image was created, is not always stored with the image. Also, sometimes it may be more convenient not to save this information if the this profile can be inferred in some way. 

For older images, the data may simply be not available. The sRGB standard was created to fill this void. 

Tristimulus sRGB values that lie outside the range [0, 1] are clipped to the range [0, 1]. Gamma correction is performed linearly for values smaller than or equal to 0.0031308 and nonlinearly for values larger than 0.0031308 (Poynton 2003). 

This function closely fits the standard gamma function of gamma(x) =xZ3. The two sections (one linear and the other nonlinear) were introduced to allow for invertability using integer arithmetic. Finally the gamma-corrected RGB values are mapped to the range [0, 255]. 

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Color in the HSI color space is represented as three components hue, saturation, and intensity (Gonzalez and Woods 1992 Jain et al. 1995 Smith 1978). Any point in the RGB color space can also be specified using the HSI color model. The attribute hue defines the color of the point. Saturation specifies the amount of white added to the pure color. Finally, intensity specifies the brightness of the point. It is not clear if the HSI components are defined for linear RGB or nonlinear RGB space (Poynton 1997, 1998). Therefore, it is not possible to determine whether the components of the HSI color space refer to a physical... 

The transformation from RGB color space to HSV color space is given by... 

Figure 7.29 A circle of colors in RGB color space is shown in (a). When we transform data points that are sampled along the circle to log-chromaticity difference space, we obtain the graph in (b).

Let us now have a different look on the use of local space average color for color constancy using color shifts. Consider the standard RGB color space. A unit cube is spanned by the... 

Gunbas, G.E., Durmus, A., Toppare, L., 2008. Could green be greener Novel donor-acceptor-type electrochromic polymers towards excellent neutral green materials with exceptional transmissive oxidized states for completion of RGB color space. Adv. Mater. 20,691-695. 

The color of the conveyer belt was chosen blue for two reasons. First, blue does not occur naturally in mangoes. Second, blue is one of the three channels in the RGB color space, making it easier to separate the background from the image of mango. 

The HSV model was created in 1978 by Alvy Ray Smith. It is a nonlinear transformation of the RGB color space and may be used in color progressions. 

The RGB color space uses additive color mixing. It is based on what kind of light needs to be emitted to produce a given color. In contrast, CMYK uses subtractive color mixing. It is used for inks or coatings and it is based on the light reflected from the substrate by which the surfaces produce a certain color. 

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