compare two components with their colors

Question

i want to compare to components with their filled colors if they are equal or not i do the following algorithm , i do averaging for the rgb as following

                double avg1 =(comp[0].Red+comp[0].Blue+comp[0].Green)/3;
                double avg2 =(comp[1].Red+comp[1].Blue+comp[1].Green)/3;

then compare them as following

                      double ratio  = avg1/avg2 ;
                      if(ratio > 0.8 && ratio < 1.2){} //then they are supposed to be equal

but this way isn't accurate at all

after searching i found that the best way is converting the image to HSL space and compare but i can't get how i compare 2 colors ?!! here

in other words after converting the image into HSL space what can i do ?!

help please !!

modification to the question for more clarification i mean with component (sequence of points) so in the averaging step actually i revisit all the points calculating the sum of the average of rgb for each pixel , then do averaging over the total number of the points

What kind of comparison are you looking to do, exactly? "Close enough"? What's your use case? — Michael Petrotta, Jul 14 '11 at 01:23
actually i want to get if two components are having the same color ?! then group them together etc.,, — user690069, Jul 14 '11 at 01:30

score 1 · Answer 1 · answered Jul 14 '11 at 02:29

1

Convert to HSL and use the difference in H (hue) to group colors.

answered Jul 14 '11 at 02:29

Jacob

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score 1 · Answer 2 · answered Jul 15 '11 at 01:05

So if your question is "after converting the image into HSL space what can i do ?!" then here goes:

convert the RGB image you've loaded to HSL using cvCvtColor() with the CV_RGB2HLS flag (the HSL image should be 3-channel, naturally)
make three single-channel images (of same size) for the H, L, S channels to be separated into
cvSplit( hls, h, l, s, 0 ) to separate the HSL image into channels
Now the h_image will be just like any single-channel grayscale image. So after extracting components (do this from thresholding the RGB image, sometimes Hue channel image looks weird :P) simply compare the colors in the hue image that correspond to their co-ordinates.

Hope this helps.

compare two components with their colors

2 Answers2