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#11
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What program is best at JPEG compression?
On Thu, 19 Jul 2007 22:38:17 -0400, Jonathan wrote:
What is xv? I think I must have missed something somewhere. Like another poster related. I only use Jpeg for uploading to usenet and I am not that concerned much beyond that point. X-Newsreader: Microsoft Outlook Express 6.00.2900.3028 Jon, Don't worry your pretty little head about it. :-) |
#12
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What program is best at JPEG compression?
In article , Scott W wrote: wrote: Are some graphics programs better than others for compressing JPEG? A friend swears that Image Ready is the best for getting the smallest file with same quality. But I see a few companies have made utilities purely for compressing pictures, and claim they obtain better compression than the top tier graphics programs. I presume there are different numerical routines used by different companies in their software, but I would guess maybe 5% variation in file size at best. I know there was a comparison done several years ago, but the website with the pictures seems to be kaput. (www.imagecompress.com ?) Is there a recent comparison of different programs to see who offers the best compression? That is, best quality for same size, or smallest size for same quality. I have a program called Advanced JPEG Compressor, it gives you far more control in how the compression is does and allow you to use different amounts of compression in different areas of the image. It can do a better job, but takes a fair bit of use to use and the gains are fairly small. I only use it when posting to the web and where I am really trying to limit the file size of the photo. The xat.com Image Optimizer, and JPEG Wizard (Pegasus Systems) are two similar products that work somewhat differently, and have differing additional feature sets - but also allow direct visual manipulation of the trade-off between file size and image quality on a per-area basis within the image. As you say, mainly for web posting of where size is of absolute importance (like when we email photos to relatives using dial-up connections). |
#13
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What program is best at JPEG compression?
Gordon Freeman wrote:
I like Irfanview too -- it is a great image and slideshow viewer -- but it does not control chroma subsampling. You can turn subsampling off in Irfanview by ticking an option during saving. Do you mean "Disable color subsampling" option in the JPEG/GIF dialog? I had not noticed it before, but upon testing, it only switches between 2x2 (default) and 1x1 chroma subsampling. It can't set 4:2:2 like GIMP. I would agree with the person who said that Photoshop is amongst the worst - I find I can always shrink a Photoshop-saved JPEG significantly by running it through a lossless optimiser (such as Irfanview's) afterwards. And Photoshop's Save For Web produces remarkably lousy quality, allowing (if I'm not mistaken) quality 99-100 with 2x2 chroma subsampling, which is just stupid. Anything above about Q 85 should use 1x1 or 4:2:2. |
#14
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What program is best at JPEG compression?
Jonathan wrote:
Xnview is available for Linux, apparently. Do you prefer it to xv? What is xv? I think I must have missed something somewhere. XV is an old Unix/X11 program by Jon Bradley that's much like Irfanview, though obviously not as modern. For example, xv 3.10 lacks EXIF support. Irfanview is better in some ways, worse in others. I use xv on Linux because Irfanview runs only on Windows, and GIMP (like Photoshop) is more an editor than a viewer. Like another poster related. I only use Jpeg for uploading to Usenet and I am not that concerned much beyond that point. In theory that is the best plan, but my friends are often sending me JPEG files from digital cameras incapable of producing RAW. So I have learned how to edit JPEG with minimal damage. |
#15
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What program is best at JPEG compression?
On 20 Jul 2007 15:44:07 -0700, Bill Tuthill wrote:
I use xv on Linux because Irfanview runs only on Windows, ......... Irfanview runs just fine under wine. |
#16
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What program is best at JPEG compression?
On Thu, 19 Jul 2007 09:57:39 -0500, "CSM1"
wrote: wrote in message roups.com... Are some graphics programs better than others for compressing JPEG? A friend swears that Image Ready is the best for getting the smallest file with same quality. But I see a few companies have made utilities purely for compressing pictures, and claim they obtain better compression than the top tier graphics programs. I presume there are different numerical routines used by different companies in their software, but I would guess maybe 5% variation in file size at best. I know there was a comparison done several years ago, but the website with the pictures seems to be kaput. (www.imagecompress.com ?) Is there a recent comparison of different programs to see who offers the best compression? That is, best quality for same size, or smallest size for same quality. Jpeg compression is a big subject, since JPEG is a lossy compression scheme, there are always trade offs. File size vs. amount of compression and artifacts. The better Graphic programs give you a choice of the amount of compression used. The de facto best Photo editor it Adobe Photoshop. The full version is about $650 or $150 for the upgrade. Photoshop Elements is a consumer grade Photo editor that costs much less money ($100) and does most of what Photoshop CS does. http://www.adobe.com/products/photoshopelwin/ I've always thought jpeg and its compression algorithm were subject to a general standard and not to any program makers' fantasy ..???? |
#17
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What program is best at JPEG compression?
imbsysop wrote:
[] I've always thought jpeg and its compression algorithm were subject to a general standard and not to any program makers' fantasy ..???? There is a standard, but with a large number of different choices. For example, you can change the colour resolution relative to the luminance resolution. How different programmers interpret "95% quality" is up to them, so it's entirely possible that different programs will better suit different images. Cheers, David |
#18
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What program is best at JPEG compression?
"imbsysop" wrote in message ... I've always thought jpeg and its compression algorithm were subject to a general standard and not to any program makers' fantasy ..???? As with MPEG, JPEG decoders are deterministic (given the same input, they all produce the same output), but the encoders are not. Choices can be made during encoding even for algorithms that produce the same output file size. MPEG encoding has even more variance and there can be enormous quality differences in the decoded output of a given average bit rate. Coders for DVDs do a good job because the encoding does not have to be done in real time and multipass encoding and larger GOP sizes are used. David |
#19
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What program is best at JPEG compression?
On Jul 23, 1:47 pm, "David" wrote:
"imbsysop" wrote in message ... I've always thought jpeg and its compression algorithm were subject to a general standard and not to any program makers' fantasy ..???? The standard has a large number of free parameters in it. And although many applications use a scaled version of the original canonical quantisation table given in the standard other encoders have made different choices. And in some cases an encoder with all the time in the world can find an optimised quantisation table for a specific target image. This helps encode physically small dimensioned images in a more compact JPEG file. As with MPEG, JPEG decoders are deterministic (given the same input, they all produce the same output), but the encoders are not. Choices can be made during encoding even for algorithms that produce the same output file size. Sadly even though the specification of JPEG is fairly precise there is still enough latitude for the decoder that there is plenty of scope for different decoders producing different images from the same JPEG encoded file. The most commonly noticeable implementation differences are in the chroma subsampling treatment (seriously broken in PSPro 9's encoder). And where for example the IJG codec uses interpolation whereas Adobe uses pixel replication - both of these methods have their merits and demerits. There are other options dating from the bad old days when computing a DCT was still hard work that permit various speed for accuracy trade- offs (much less of an issue these days with fast hardware floating point support). Regards, Martin Brown |
#20
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What program is best at JPEG compression?
"imbsysop" wrote in message
... On Thu, 19 Jul 2007 09:57:39 -0500, "CSM1" wrote: wrote in message groups.com... Are some graphics programs better than others for compressing JPEG? A friend swears that Image Ready is the best for getting the smallest file with same quality. But I see a few companies have made utilities purely for compressing pictures, and claim they obtain better compression than the top tier graphics programs. I presume there are different numerical routines used by different companies in their software, but I would guess maybe 5% variation in file size at best. I know there was a comparison done several years ago, but the website with the pictures seems to be kaput. (www.imagecompress.com ?) Is there a recent comparison of different programs to see who offers the best compression? That is, best quality for same size, or smallest size for same quality. Jpeg compression is a big subject, since JPEG is a lossy compression scheme, there are always trade offs. File size vs. amount of compression and artifacts. The better Graphic programs give you a choice of the amount of compression used. The de facto best Photo editor it Adobe Photoshop. The full version is about $650 or $150 for the upgrade. Photoshop Elements is a consumer grade Photo editor that costs much less money ($100) and does most of what Photoshop CS does. http://www.adobe.com/products/photoshopelwin/ I've always thought jpeg and its compression algorithm were subject to a general standard and not to any program makers' fantasy ..???? Have you read the JPEG specification? http://www.w3.org/Graphics/JPEG/jfif3.pdf If you are talking about Digital cameras, you use the EXIF 2.2 spec. http://www.exif.org/Exif2-2.PDF There is a lot of room for interpolation of the application of JPEG compression. Many factors that have to be balanced for the best result. Since Jpeg is lossy, it throws away a lot of important information that is gone forever, if you choose wrong. -- CSM1 http://www.carlmcmillan.com -- |
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