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chenlewis / Chromaticity-Map-Adapter-for-DPAD

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Question regarding extraction of the chromaticity map #1

Open ge38fuy opened 2 months ago

ge38fuy commented 2 months ago

Hi,

after reading the paper I tried to calculate the chromaticity map in Figure 3 where I subtracted the mean value of the rgb channels from each channel and then divided each channel by the standard deviation across the rgb channels. However, I couldn't get the results as shown in the Figure 3. Is the zscore normalization implemented somehow differently? I'm posing this question since the code is not available yet. Any illustration would be much appreciated!

chenlewis commented 2 months ago

Hi,  Thank you for your question! When performing Z-score normalization, it's important to calculate the mean and standard deviation across all three channels together, rather than separately for each channel. This approach is taken because the goal of the chromaticity map is to amplify the imbalance among the RGB channels for each pixel.  Specifically, you need to calculate the overall mean and standard deviation of all pixels across the RGB channels. Then, for each pixel, subtract this overall mean from its RGB values and divide by the overall standard deviation.

ge38fuy commented 2 months ago

Hi Lewis,

thanks for the explanation! Now it makes more sense to me. But when looking into the pixel x3 and x4 in the Figure 3, they both have value 255 for channel g and b. If we subtract the same overall mean from them and divide by the global std of the entire image, why does the chromaticity map have 0 for x3 and 0.984 for x4 in the g and b channel? Did I misunderstand something here?

chenlewis commented 2 months ago

Hi,

Thank you for carefully reading our work. Actually, the g and b channels of x3 and x4, both being 255, should indeed result in the same values in the final chromaticity map. We realized after submitting the paper that some values in Figure 3 were not correctly updated in different versions.

ge38fuy commented 2 months ago

Hi Lewis,

I really appreciate the clarification. If I may ask when could we expect the code to be released?

chenlewis commented 1 month ago

Hi,

Our code has been uploaded. Please check the repository for the latest updates.