about jpeg2k compress rate

[Ivan_C_]

Hello,

Is there some doc to analyze the compress rate of Jpeg2k ?

I have a source .jp2 file that is about 58KB. I use UIC to transfer it to the .raw file, and the .raw file is about 11.3MB. At last, I use UIC to transfer the .raw file to .jp2 file again. It is surprised that the last .jp2 file is about 1.59MB.

The follow is command arguments: 

1, source .jp2 to .raw: uic_transcoder_con -i a.jp2 -o a.raw

2, .raw to .jp2: uic_transcoder_con -i a.raw -r -W 2208 -H 2688 -C gray -P 16s -o aa.jp2 -l 1

Dose anybody know why?? And I upload the file a.jp2.

[Sergey_K_Intel]

Hi Ivan,

Raw file size is ~11 MB, because 2208 * 2688 * 2 (component depth = 16 bit in source file) = 11,870,208.

Then, "-l 1" equal to "lossless". Lossless image encoding produces lengthy files. Though, even if you set "-l 0" UIC JPEG2000 encoder enforces lossless encoding because the pixel size is 16 bits (I don't know why).

In the "EncodeImage" function you can comment a couple lines:

        //if(image.Precision() > 8)
        //    cmdOpt.lossless = 1;

And, finally, the command line:
uic_transcoder_con -i a.raw -r -W 2208 -H 2688 -C gray -P 16s -o aa.jp2 -l 0 -q 1

(-q 1 means quality = 1%) will give you aa.jp2 of 118 KB. It's bigger than original JP2 file, but something near.

Regards,
Sergey