Comprehensive color normalization

The influence of the scene geometry can be removed by normalizing all pixel values. Let [ri, gi, b ]T and [ 2, g2, 2lr be two image pixels. If the pixels actually represent the 

The influence of the illuminant can be removed by using the gray world assumption. 

Notice the scaling factor of. Let I0 be the input image. Then, the comprehensive color normalization iteratively applies the two algorithms 4llorm and 4gray to compute a new output image. 

This process continues until the termination condition 

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Figure 6.26 Comprehensive color normalization iteratively normalizes all pixels and then rescales the color channels using the gray world assumption. Therefore, intensity information is lost. Since it is based on the gray world assumption, it does not work if we have a nonuniform illumination.

Figure 6.27 Results of comprehensive color normalization when the lightness of the pixels from the input image is used to rescale the output pixels.

Comprehensive color normalization, developed by Finlayson et al. (1998), which is described in detail in Section 6.7, interleaves color normalization and normalization based on the gray world assumption. First, the image pixels are normalized by dividing each channel by the sum over all channels. This algorithm is denoted by Aiorm- Next, the image pixels are normalized by dividing each channel independently by the sum over all pixels. 

Comprehensive color normalization based on local space average color was discussed in Section 6.7. As we have already seen earlier, after the first step of the algorithm, when the colors are normalized, the reflectance of either the sample or the background drops out of the equation. After normalization, we obtain the output o ... 

Now all pixels have the same color. Computation of local space average color instead of global space average color will not make a difference. Since comprehensive color normalization does not correspond to the results obtained by Helson, neither will comprehensive color normalization based on local space average color. 

Comprehensive color normalization, colors with original lightness. 

Comprehensive color normalization using local space average color. 

Klein AL, Burstow DJ, Tajik AJ, Zachariah PK, TaUercio CP, Taylor CL, Bailey KR, Seward JB. Age-related prevalence of valvular regurgitation in normal subjects a comprehensive color flow examination of 118 volunteers. J Am Soc Echocardiogr 1990 3(l) 54-63. 

Random recognition rate Full range per band White patch retinex Gray world assumption Simplified hom Gamut constraint 3D Gamut constraint 2D Color cluster rotation Comprehensive normalization Risson (2003)... 

Comprehensive normalization Described in Section 6.7. The lightness of the colors in the original image is used to scale the output colors to add back information about shading. 

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