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i would like to calculate difference of two images. Then, histogram of difference of two images. So I can plot a histogram but I am not sure whether it is true or not? Also, I am not sure about what should be second parameter of built-in histogramfunction.

My two images are original_result and output_image. And difference of two image is image_of_dif. my result: 

image_of_dif = double(original_result) - double(output_image);
figure; histogram(image_of_dif(:), 511);

enter image description here

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Let us suppose that images are coded on uint8, hence integers in $[0,\ldots,255]$. For the difference image, values can range from $0-255$ or $255-0$, the maximum span. So I would keep the negative differences by computing the histogram over all $511=255-(-255)+1$ integers in $[-255,\ldots,255]$.

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    $\begingroup$ i changed second parameter of histogram to 511. is it okay now? $\endgroup$ – beyblade41 Dec 17 '19 at 13:51
  • $\begingroup$ This looks ok to me. This way, you get an histogram of all possible values in the difference. $\endgroup$ – Laurent Duval Dec 20 '19 at 19:24
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In your second line, casting with uint8() will change a negative value to 0. Avoid casting or change to another type that supports negative values.

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  • $\begingroup$ i changed my code. is it ok now? $\endgroup$ – beyblade41 Dec 17 '19 at 8:26

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