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Thread: Greetings, Questions, and Benchmarks

  1. #1
    Member musicdemon's Avatar
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    Greetings, Questions, and Benchmarks

    Hello, everyone It seems like this is the most knowledgeable and up-to-date community as far as data compression is concerned. I was very excited to see that the authors of some of my favorite archival programs frequent these forums, and the rest of the community seems extremely intelligent. Without further ado, I have a few questions about compression, if someone would be so kind as to enlighten me:

    1) Is Peazip the only non-command line program that offers ZPAQ support? I would use Peazip, but I don't think it has folder support with its outdated zpaq build, and I'm hesitant to replace the executable. I'm curious as to whether Bulat Ziganshin is going to integrate support for ZPAQ in FreeARC
    2) What is your lossless image format of choice? Mine is PGF, but there's near-zero implementation in image editors/readers
    3) Functionality-wise, I'm slowly starting to convert my .png files to JPEG-XR (.wdr) files with Paint.NET and a batch converter plugin, in the absence of .pgf support for other image viewers. Has anyone seen a JPEG-XR implementation using the newer, ISO-approved .jxr extension? It's my understanding that the original format was improved upon during conformance testing.
    4) This is obscure, but has anyone had any experience coding a plugin for Irfanview? I'm just trying to get a gauge on how difficult it would be using something like libPGF. I have experience with C#, Java, XML, Oracle, HTML, & Javascript (strong-suit).
    5) ^I assume Visual Studio would be used for a project like this? I wish there was an SDK or something I could play around with, and I don't want to email Irfanview's developer until I have some sort of gauge on whether this will take hours, days, or weeks.
    6) What is the best, non-commerical compression program (with a GUI) & format to use when compressing JPEGs (besides PAQ variants)? I've had the most success with FreeARC so far, but I know little about which combination of switches will get me the best results for JPEGs, specifically.

    Here are a few (very) small pieces of knowledge I've acquired that I have to share in return, and to keep this post on-topic for the "Data Compression" subforum:
    -SHIFT+right-click in Windows 7/Vista adds "Open command window here" to the context menu.
    -Irfanview's JPEGs at max quality are ~13% smaller than Photoshop CS5's JPEGs (at max quality), according to my results. I doubt many of you use JPEGs (do you?), but it's just a fun-fact (not set in stone).
    -Also, PNGs compressed with Irfanview (max compression) + PNGOut (default settings) are ~5.5% smaller than those compressed with Photoshop CS5. This isn't set in stone, as I was using a small dataset in the interest of time. I'm sure there are command-line options out there that will beat both of these programs, but I like to stick with GUIs whenever possible.
    -My lossless image format testing results (using TreeSize Free):

    Click image for larger version. 

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    I look forward to hearing from you!

  2. #2
    Administrator Shelwien's Avatar
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    > It seems like this is the most knowledgeable and up-to-date community as
    > far as data compression is concerned.

    So it seems, though there're some other places, like
    http://www.maximumcompression.com/gb/gb.php
    http://groups.google.com/group/comp.compression

    > I was very excited to see that the authors of some of my favorite archival
    > programs frequent these forums, and the rest of the community seems
    > extremely intelligent.

    Unfortunately most of them rarely post anything

    > 1) Is Peazip the only non-command line program that offers ZPAQ support? I
    > would use Peazip, but I don't think it has folder support with its outdated
    > zpaq build, and I'm hesitant to replace the executable. I'm curious as to
    > whether Bulat Ziganshin is going to integrate support for ZPAQ in FreeARC

    And why would you use zpaq? paq8 compression is better and if speed matters
    for you, you'd not use any *paq* anyway.

    > 2) What is your lossless image format of choice? Mine is PGF, but there's
    > near-zero implementation in image editors/readers

    Why, png? How many TBs of images do you have?
    I mean, does it really matter anymore, comparing to video/music?
    Well, comparing to pngs, it might be better to use .bmp + good archivers:
    http://compressionratings.com/sort.cgi?img1.full+6n
    But that's already inconvenient.

    However, it'd be interesting if you could evaluate that:
    http://encode.su/threads/1099-New-lo...ts-per-channel)

    > 4) This is obscure, but has anyone had any experience coding a plugin for
    > Irfanview? I'm just trying to get a gauge on how difficult it would be
    > using something like libPGF. I have experience with C#, Java, XML, Oracle,
    > HTML, & Javascript (strong-suit).

    Well, it shouldn't be a problem with C/C++, but java/C# might be troublesome
    There're also some plugin sources on the net, like this one:
    http://code.google.com/p/irfanpaint/

    > 6) What is the best, non-commerical compression program (with a GUI) &
    > format to use when compressing JPEGs (besides PAQ variants)? I've had the
    > most success with FreeARC so far, but I know little about which combination
    > of switches will get me the best results for JPEGs, specifically.

    http://schnaader.info/precomp.php
    or directly http://www.elektronik.htw-aalen.de/packjpg/
    I guess you can use these with freearc:
    http://freearc.sourceforge.net/rus/F...#_Toc185595018

    > -Irfanview's JPEGs at max quality are ~13% smaller than Photoshop CS5's
    > JPEGs (at max quality), according to my results. I doubt many of you use
    > JPEGs (do you?), but it's just a fun-fact (not set in stone).

    We browse the web, so we can't avoid using jpegs.
    As to jpeg size, "max quality" doesn't mean anything specific.
    I'd use console tools and something like
    http://imq.vt.tpu.ru/indexeng.html
    for metrics.

    > -Also, PNGs compressed with Irfanview (max compression) + PNGOut (default
    > settings) are ~5.5% smaller than those compressed with Photoshop CS5.

    There's also pngcrush which is faster than pngout (though not so optimal),
    and deflopt tool (http://www.walbeehm.com/download/) which can further improve
    pngout's results.

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    Yeah JPEGs can be tweaked and optimised in so so many ways. PS JPEGs will normally be bigger than other editors due to the fact they add buckets of useless junk to the file. And the PS/IrfanView JPEG implementation differ massively in quality depending on picture type, ie PS is great at handling gradients for smaller file sizes. PS also uses separate quality levels on the luminance and chromiance quantisation tables. Whereas those based on the IJG JPEG implementation always use the same quality level for both. And we haven't even got onto subsampling, restart markers, multi-scan JPEGs(some nice size saving here)

    And the same goes for PNGs, at the link below you can find a handy little tool i put together that will squeeze them down even more than you'd expect.
    http://encode.su/threads/534-Compari...ll=1#post21544

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    Member musicdemon's Avatar
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    Thanks for the detailed answers, Shelwien and Intrinsic. Those links have been helpful, although I think I'll wait on the plugin at least until I finish my semester. That image quality tool looks like it would be decent, but the GUI is in Russian :X

    Also, the majority of my image storage isn't even close to a TB; it's more like 15 gigs or so. I mainly just enjoy participating in lossless compression tests for the fun of it.

    I'd like to get back into lossless audio converting and formats, but I haven't made the time to organize my music library properly and convert FLAC to HE-AAC v2 so I can fit them on my phone. Plus, there's not that much going on in lossless audio right now, anyway (I think). Anyway, thanks for the warm welcome, and I look forward to learning about compression and participating in the forums

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    Member Karhunen's Avatar
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    I was looking at the PGF format recently when I found this thread. http://sourceforge.net/projects/libpgf/ I have not tried the command line tool yet. Also for people who are interested, per Matt's discussion http://mattmahoney.net/dc/dce.html#Section_615 one can zero most or all of a JPEG Y AC coefficients and get better compression winth PAQ or PJG format, based on how much data you want to throw away and how good your eyeballs are I use a niave jpegtran script, using the "scans" parameter, here is a "minimal" matrix attached. You then invoke jpegtran -opt -scans 001.sca [input].jpeg [output].jpeg You then get a lossy compressed progressive jpeg, generally smaller than with what you started. You can of course make it an inline jpeg with jpegtran again or other such tools, but it will "grow". However, PackJPG and PAQ will compress it much better than usual, given a "better than baseline" jpeg.
    Attached Files Attached Files

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