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4

PNG is always compressed by DEFLATE algorithm, as mandated by PNG specification. This is same algorithm used by zip compressor, among others. There are no lossy compression algorithms for PNGs. PNG is always loseless. Disclaimer: There are methods of "optimizing" PNG size by decreasing quality (color depth) of an image before saving it as PNG. This has ...


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I doubt that the different schemes would make a lot of difference to be honest since the compression algorithms typically only look forward a limited amount in order to control memory use. The exception is S3 which would end up larger most likely since compressing a compressed file adds overheads but cannot compress. If you want better compression, look ...


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I have just conducted a test using a 4.2G ISO of a PS2 game and there is negligible difference in decompression times (and size too) between the default 7zip compression and ultra: Default: Size: 4411064320 Compressed: 3135355831 real 4m55.908s user 3m46.838s sys 0m5.811s Ultra: Size: 4411064320 Compressed: 3118958337 real ...


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unsquashfs -s did not have the capability of displaying the compression type used until this commit on 07 August 2009. This means that if you are running squashfs-tools 4.0 or older, you wouldn't be able to see the compression method used. From this information, I derived a way to read the SquashFS 4.0 superblock to determine the compression method used ...


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Estimating compression ratio of any image file is actually pretty simple. You have to know the width, height and bit depth of the image. To calculate how much data would be needed by uncompressed raw image data you have to do this simple thing: raw data size = image width * image heigth * (bits per pixel / 8). Then just divide raw data size by your PNG's ...


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It's the JPEG. The keyword here is visible. The entire reason for JPEG working so well is that you can quantize away lots of high frequencies before the human visual system can even perceive any artifacts. Also note that before artifacts (like ringing) become present, the picture will simply lose high frequencies. Without a reference picture to compare ...


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A file that has already been compressed by a reasonably good compression algorithm will typically not compress well if you try to compress it again with another. In fact, in the worst case, “compressing” a compressed file can sometimes even make it bigger. Many files that you use every day are already compressed. Typically audio, video, and image formats are ...


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So you are accessing the remote server shares via standard windows sharing (doesn't matter if it is over LAN or VPN). Windows threats it as another local disk. Everything you do with files stored there is done by the CPU on your PC. So the unzipping will be done on your CPU. If you have enough RAM, it won't download the zip file from remote server again as ...


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A really simple solution to reduce the file size just for the purpose of mailing it would be to compress it using any popular archiving utility.


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lrztar is a wrapper around tar and lrzip, the file it produces is a lrzip'd tarball. Knowing this we can view a listing of the files within the tarball via: lrzcat file.tar.lrz | tar -tv This will perform a streaming decompression of the lrz tarball and then use the tar command to print the contents.



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