Signal to noise ratio color image (code) for dB

Question

Dadhichi 2013-2-3

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https://ww2.mathworks.cn/matlabcentral/answers/61982-signal-to-noise-ratio-color-image-code-for-db

回答： Toqeer Mahmood 2015-10-9

I am trying to compute signal to noise ratio (dB) in color images as follows:

 noisydata = imnoise(original,'gaussian',0.0,0.1); % mean = 0.0, variance = 0.1
 [var_orgR, var_noiseR] = snr(noisydata(:,:,1),original(:,:,1));
 [var_orgR, var_noiseR] = snr(noisydata(:,:,2),original(:,:,2));
 [var_orgR, var_noiseR] = snr(noisydata(:,:,3),original(:,:,3));
 SNR= 10*log10((var_orgR + var_orgG + var_orgB)/(var_noiseR + var_noiseG +   var_noiseB));
 function [var_original, var_noise] = snr(noisydata, original)
   mean_original = mean(original(:));
   tmp           = original - mean_original;
   var_original  = sum(tmp(:).^2);
   noise      = noisydata - original;
   mean_noise = mean(noise(:));
   tmp        = noise - mean_noise;
   var_noise  = sum(tmp(:).^2);    
 end

The problem is I get value of SNR = 0.0330, I would like to get SNR in dB like 1 dB, 5 dB, etc.

Could any one please guide/suggest how to obtain SNR in dB?

Thank you. Dbs

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Answer 1

Image Analyst 2013-2-3

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Where did you get these formulas? I'm not sure I agree with them. In fact I don't, unless you can show me some reference that say otherwise.

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Image Analyst 2013-2-3

I don't think that would fix it. I would need proof. Anyway, I don't know what a "fix" is. Like I said, you asked how to get the number in decibels and I told you that it's already in decibels.

Dadhichi 2013-2-4

What proof do you need? If you have access to papers you'll agree. The code is correct, uint8 was programming error, it is not required. Anyways, 'noisydata' and 'original' should have values in same range i.e. between 0 to 1 (was another programming error) :D .

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Answer 2

Toqeer Mahmood 2015-10-9

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Dear Dadhichi

I am also confused in the same problem, I also want to find SNR with the whole number as 5dB, 10db, 15dB etc. Please send me the working code to find it, if possible for you (my email is toqeer.mahmood@yahoo.com).

Thanks in advance, waiting for your kind reply.