rgb2lab color conversion

Question

Foram Sanghavi 2017-10-31

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/364308-rgb2lab-color-conversion

评论： Image Analyst 2017-10-31

采纳的回答： Stephen23

Hi, I am using rgb2lab color space conversion and am receiving values in the range of e+03, are these values correct?

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Stephen23 2017-10-31

@Foram Sanghavi: please show us the input values that produce that output.

Foram Sanghavi 2017-10-31

If RGB values are 253,244,245 the Lab values I am getting is 6.5651e+03, 249.1664 and 58.4119 respectively similarly for RGB 242,205,220 i a getting values 6.0022e+03,1.1819e+03 and -225.2120 respectively.

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Answer 1

Stephen23 2017-10-31

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/364308-rgb2lab-color-conversion#answer_288716

编辑：Stephen23 2017-10-31

Either convert the input argument to uint8 or divide it by 255 and you will get the correct output. Many MATLAB color/image functions assume that a double input is in the range 0-1, which clearly your data is not.

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Foram Sanghavi 2017-10-31

Thank you so much this has helped me a lot. Should I do same while converting back lab2rgb? because I am getting negative values in the RGB plane especially in G plane.

Image Analyst 2017-10-31

在 MATLAB Online 中打开

I think this will explain everything. Write back if it doesn't.

rgb = uint8([253,244,245])
lab = rgb2lab(rgb)
rgb = lab2rgb(lab) % Doubles in the range 0-1
rgb = uint8(255 * rgb) % Integers in the range 0-255

You'll see

rgb =
  1×3 uint8 row vector
   253   244   245
lab =
          96.8926628404762          3.17508673704292         0.590818112564628
rgb =
         0.992156862745098         0.956862745098039          0.96078431372549
rgb =
  1×3 uint8 row vector
   253   244   245