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LZW + Predict. is lossy?

Posted: Wed Jan 07, 2009 1:25 am
by gregory
What is lzw+predict.? Particularly the "predict" part. I'm assuming it's not lossless.

Thanks

Re: lzw+predict.

Posted: Wed Jan 07, 2009 8:14 am
by xnview
gregory wrote:What is lzw+predict.? Particularly the "predict" part. I'm assuming it's not lossless.
It's always lossless, LZW compression + predictor method (difference between pixel)

Posted: Wed Jan 07, 2009 8:26 am
by gregory
I assumed it was not because;

5.04MB Bitmap -> LZW = 4.52MB Tiff

and

5.04MB Bitmap -> LZW + Predictor = 1.99MB Tiff

It was such a big difference.
Thanks for clarifying.