DLI v1.2 introduces the visual quality option '-plc'. It forces DLI to preserve low contrast
details which would be smoothed out when optimizing for minimal MSE. The option
takes a numerical parameter indicating the MSE threshold for when to use the different
compression. Through experimentation this parameter has been found to be image
dependent, with an optimal value varying with the type of image. However, for ease of use,
the value of 500 can be used as it performs fairly well across all images.
The following is a comparison of DLI with the -plc feature on and off.
The original image can be found at http://r0k.us/graphics/kodak/kodim24.html
 DLI without -plc (23490 Bytes)
 DLI with -plc 500 (23568 Bytes)
The following graphs illustrate the effect '-plc 500' has on objective measures.
 As shown, '-plc 500' causes PSNR to drop 1.6-2.4 dB, but produces higher MS-SSIM results.
More MS-SSIM results comparing DLI with other codecs are available here.
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DLI v1.2 Details |