Java LZW Compresss & Decompress with Image -


i've checked many sources lzw compression didn't work image file.

here resources have checked far:

https://www.codemiles.com/java/lzw-data-compression-decompression-algorithm-java-code-t99.html

this 1 compress file bigger original file

https://codereview.stackexchange.com/questions/122080/simplifying-lzw-compression-decompression

could please give resource work image compression? thanks!!!

compressing compressed image not idea, because first compression removes statistical hints second compressor can use. that's @ least true contemporary compression algorithms, used in jpeg, png, gif, tiff, , webp image formats. typically, compressed file, viewed in hex editor, looks quite stream of random bytes, , random data (or non-random data statistical properties similar random data) cannot compressed. result bigger original, due overhead in storage format. clever compressors detect condition , revert storing original data, rather compressing it.

so if think image might compressed further, you'll have decompress first. can try different compressor might yield better results. however, doubt lzw variant give significant gain on jpeg. while it's clever enhancement of lempel-ziv family of compression algorithms, lzw purely lossless technique, , hence has innate limitation of attainable compression ratio, rooted in statistical distribution of image data. jpeg , other lossy image formats trade image quality size, , can outperform lossless techniques.

note gif format special case. while uses lossless lzw compression, requires color palette of 256 entries. encode colorful image photograph gif, you'll have quantize color space first 256-color palette. once again lossy technique, albeit quite different algorithms used jpeg , webp lossy. quantized gif images of photos compress excellently due reduction of rgb information in image, expose noticeable deteriorations of color gradients, found in human faces, flower leaves, , cloudy heaven.

as aside: if gif allow larger color palettes (say, 1024), might become real killer format photographic images. maybe it's time gif17a format update?!


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