Is the IJG supporting lossless JPEG Compression?

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sivasankari
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Is the IJG supporting lossless JPEG Compression?

#1 Post by sivasankari »

Hello,
I am using the IJG library released on 27-Mar-1998.
The version is 6b.
I walked through the code of dcmcjpeg of dcmtk-3.5.4, where we have many options for compression(lossy,lossless,etc). It seems that you have used IJG lib.
I tried +e1 (encode-lossless-sv1).But the output compressed image is distracted and blurred.
with option "+el (encode-lossless) ", it showed the error "Unsupported JPEG Process:SOF type 0xc3"
Why such errors in lossless?

I tried to read a normal bmp file using an example code given in IJG and converted it into Jpeg file.
when i tried with lossy it is working perfectly.A valid Jpeg file created with good compression ratio and a good quality.
But for lossless, it is not working.It is creating an invalid JPEG file.

Now I have 3 questions
Do we have to make any patches in IJG library for lossless?
If so what type of work to be done for it?
Or Is IJG not supporting lossless ?

Expecting for reply asap.
Thank you in advance :-)
Shanks

Jörg Riesmeier
ICSMED DICOM Services
ICSMED DICOM Services
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#2 Post by Jörg Riesmeier »

IJG does not support JPEG lossless by default. DCMTK uses a patched version of the IJG implementation. See discussion in comp.protocols.dicom for details.

sivasankari
Posts: 20
Joined: Thu, 2005-03-10, 11:28
Location: India
Contact:

#3 Post by sivasankari »

Thank you very much

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