RE: [WM]: Lossless compression of Binary images..

["mohammad awrangjeb bin nurul alam" <awrangjeb@hotmail.com>]

Dear Karthik,
I think you can try with run-length, LZW or JBIG codecs. These are available at

http://datacompression.info/SourceCode.shtml

You may have to try with 2 or more codecs, as I faced problems too to face the best one. For run-length codec you may need to have
1D array before compression to have better performance.

-awrangjeb

>From: "Kannan Karthik" <karthik@comm.utoronto.ca>
>To: <watermarking@watermarkingworld.org>
>Subject: [WM]: Lossless compression of Binary images..
>Date: Sun, 15 Jan 2006 10:20:56 -0500 (EST)
>
>Dear Watermarkers,
>
>I am searching for an efficient way to compress small binary images (32 
>x 32; 64 x 64;) losslessly. The information content in these binary 
>images is used to decide which blocks within a particular encrypted 
>JPEG image must be decrypted. So the binary image provides the 
>necessary side information for decrypting another image.
>
>- Compression efficiency is important because this binary image will be 
>embedded in another image as a watermark and then transmitted.
>- Compression has to be lossless to facilitate synchronization.
>
>These binary images are likely to exhibit high spatial correlation. 
>Hence I would like to know if wavelet based techniques can be used to 
>compress the image losslessly. If so, can anyone suggest a few 
>references.
>
>Can approaches such as runlength coding and minterm reduction be used 
>for lossless compression of these images? How do they compare with 
>wavelet based approaches?
>
>I would also like to know if the MATLAB code for any of the compression 
>techniques are available on the web.
>
>Thanks in advance.
>Karthik
>
>---------------------------
>Kannan Karthik (PhD Candidate)
>Dept. of Elec and Computer Engg.
>University of Toronto
>Communications research group
>Bahen 4154, 40 St. George Street.
>Toronto
>
>Not everything that can be counted counts and not everything that 
>counts can be counted.
>- Albert Einstein


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