Color space conversion xyz2srgb, using makecform function

Question

Jo 2015-6-4

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/222467-color-space-conversion-xyz2srgb-using-makecform-function

编辑： Walter Roberson 2015-6-9

Hi

I have an image and try to convert it from XYZ to sRGB in order to display the image on the screen and be able to draw a ROI. I used the makecform function but it seems that it doesn't work well as I get a black image instead!

RGB=zeros(size(XYZ2));    
cform=makecform('xyz2srgb');
RGB=applycform(XYZ2,cform);

Here are the max values of the XYZ and RGB matrices I get, respectively

   max(max(XYZ2))                       
  ans(:,:,1) = 31.6600,   ans(:,:,2) =33.5200,     ans(:,:,3) = 40.6900
   max(max(RGB))
  ans(:,:,1) = 1,     ans(:,:,2) = 1,    ans(:,:,3) = 1

Do you may have an idea? Did I use the cform function wrongly?

Many thanks in advance

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Answer 1

Radha Krishna Maddukuri 2015-6-9

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/222467-color-space-conversion-xyz2srgb-using-makecform-function#answer_182066

在 MATLAB Online 中打开

This issue is happening because of scaling of the input data. The function 'xyz2srgb' expects input values in the range of 0 to 1.

Therefore, the input data can be scaled by dividing it with a standard value or the maximum value for the data.

clear
XYZ2 = [10 20 30; 40 50 60; 70 80 90; 100 110 120; 130 140 150; 160 170 180];
RGB=zeros(size(XYZ2));
cform=makecform('xyz2srgb');
RGB=applycform(XYZ2/180,cform);

I hope this helps you with the issue that you are facing.