# How to calculate PSNR gain?

3 views (last 30 days)
tina jain on 29 Nov 2015
Commented: Walter Roberson on 30 Nov 2015
I want to calculate averge percentage gain for the PSNR values given in the table
*s.no PSNR at column 1 PSNR a column 2*
1 18.61 21.88
2 18.61 22.68
3 18.61 23.72

Walter Roberson on 29 Nov 2015
mean(column2 - column1)
?
tina jain on 30 Nov 2015
It should be mean (column 2- column 1)/mean(column 1)??
Walter Roberson on 30 Nov 2015
PSNR is usually stated in dB, and gain is usually stated in dB, so I would expect you to just be using a subtraction like I show. If you use the ratio like you show then the units would be lost. Also since PSNR is based upon log10 you would need to ask whether you should really be dividing the log values as that would correspond mathematically to taking an n-th root of the original values.

Image Analyst on 30 Nov 2015
meanPsnrCol1 = mean(t{:,2});
meanPsnrCol2 = mean(t{:,3});
where t is your table. Not sure how you're defining gain after that. Maybe
psnrGain = meanPsnrCol2 / meanPsnrCol1;
???
Image Analyst on 30 Nov 2015
Or
psnrGain = (meanPsnrCol2 - meanPsnrCol1) / meanPsnrCol1;
Did my code give you the mean of your table columns?