how to calculate pixel value differences?

Question

Rezaur Rahman 2016-2-23

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/269580-how-to-calculate-pixel-value-differences

评论： Rezaur Rahman 2016-2-23

let my image be

temp=
[5 10;
10 15]

if i want to calculate temp(1,1)-temp(1,2) or temp(1,1)-temp(2,1) it always shows 0. how can i store the value?? i have also tried abs(temp(1,1)-temp(1,2)); bt failed. thanx in advance

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Answer 1

Guillaume 2016-2-23

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在 MATLAB Online 中打开

In your example, it actually works the way you want. The most likely reason why it does not work with your real image is that your image is of type uint8 (or uint16). The range of uint8 is limited to [0, 255], any value below or above these values are clamped to 0 or 255.

The fix is simple, convert your image to double:

temp = uint8([5 10; 10 15]) %demo image
temp(1,1) - temp(1, 2)    %output 0, since -5 is not allowed for uint8
temp = double(temp);      %convert to double
temp(1,1) - temp(1, 2)    %output -5 as it should