opencv - Histogram Normalization

Question

I am trying to apply histogram normalization to create a dense color histogram.

1. Split the channels into R, G, B
2. Normalize the individual histogram
3. Merge

I think that this is the normal step perhaps if I am wrong please let me know. Now,

for a rainbow image as shown below I get I get max of 255 for all 3 channel and 0 as min. Using the formula for

Pixel - Min / (Max - min) * 255

I will get the same image as the original one back. What is the critical step that I am missing. Please advise me.Thank you! REf: http://www.roborealm.com/help/Normalize.php.. I used this reference

Answer 1

White = (255,255,255). Black = (0,0,0). So your program finds the white background, and the black line in the bottom right.

Remove the white and change it to black. Then make your program ignore black.