Relationship between PSNR and parameter qf in JPEG quantization

The parameter qf multiplying the JPEG quantization step-size matrix was varied with a step of 0.1 from 0.1 to 3.0 and PSNR between the original and the quantized image was computed and plotted for the image Barbara. MATLAB m-file.

The quantized image with qf = 3.0 and PSNR = 27.7 dB

Relationship between PSNR and parameter ‘quality’ in MATLAB JPEG compression

The ‘quality’ parameter in JPEG compression used by MATLAB was varied with a step of 3 from 10 to 100 and PSNR between the original and the reconstructed image was computed and plotted for the image Barbara. MATLAB m-file

Compare these reconstructed images:

‘quality’ = 10, PSNR = 25.7 dB

‘quality’ = 30, PSNR = 30.3 dB

‘quality’ = 70, PSNR = 35.4 dB

‘quality’ = 90, PSNR = 40.7 dB