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#22
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What program is best at JPEG compression?
In rec.photo.digital Fed-Up-With-Corel wrote:
Unless you use an editor that is able to edit JPEG files without recompressing the whole image every time you save it. PhotoLine 32 www.pl32.com is the only one I know of that allows you to edit a JPG file where the only data that gets put through the compression routine again when you save it is that which you specifically edit or change from the original. JPEG Wizard also did/does this to a certain extent. Is PhotoLine32 almost equivalent to Photoshop in functionality? It has 32-bit and LAB/CMYK support, but only costs 59 Euros. The online tutorial does not seem complete. |
#23
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What program is best at JPEG compression?
On Mon, 23 Jul 2007 14:40:31 GMT, "CSM1"
wrote: "imbsysop" wrote in message .. . On Thu, 19 Jul 2007 09:57:39 -0500, "CSM1" wrote: wrote in message egroups.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 yes I did but did you ? quote "... JPEG Compression Although any JPEG process is supported by the syntax of the JPEG File Interchange Format (JFIF) it is strongly recommended that the JPEG baseline process be used for the purposes of file interchange. This ensures maximum compatibility with all applications supporting JPEG. JFIF conforms to the JPEG Draft International Standard (ISO DIS 10918-1). The JPEG File Interchange Format is entirely compatible with the standard JPEG interchange format; the only additional requirement is the mandatory presence of the APP0 marker right after the SOI marker. Note that JPEG interchange format requires (as does JFIF) that all table specifications used in the encoding process be coded in the bitstream prior to their use...." unquote |
#24
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What program is best at JPEG compression?
David J Taylor wrote:
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. Ultimately, I think that's the key: "different programs will better suit DIFFERENT IMAGES". There is no one "best" or "worst" implementation because how "well" a particular encoding scheme works will depend on the specific image it's dealing with. |
#25
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What program is best at JPEG compression?
Matt wrote on Tue, 24 Jul 2007 14:46:19 GMT:
MI David J Taylor wrote: ?? 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. It is an interesting question as to which is the best general method since *most* people won't want to use more than one technique. It does beg the question of what is wanted. Is the "best" method that which produces the smallest result or some sort of compromise among size, resolution and color resolution etc.? James Silverton Potomac, Maryland E-mail, with obvious alterations: not.jim.silverton.at.verizon.not |
#26
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What program is best at JPEG compression?
In article , Bill Tuthill wrote: In rec.photo.digital Fed-Up-With-Corel wrote: Unless you use an editor that is able to edit JPEG files without recompressing the whole image every time you save it. PhotoLine 32 www.pl32.com is the only one I know of that allows you to edit a JPG file where the only data that gets put through the compression routine again when you save it is that which you specifically edit or change from the original. JPEG Wizard also did/does this to a certain extent. AFAIK only on selective compression areas, or limited area processing such as red-eye removal. Then again, it really isn't an editor, per se; more of an image manipulator and processor. I'd imagine if you were to make any global change, such as color balance adjustment, that would require reprocessing in order to save the modified image. |
#27
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What program is best at JPEG compression?
Mike S. added these comments in the current discussion du jour
.... Unless you use an editor that is able to edit JPEG files without recompressing the whole image every time you save it. PhotoLine 32 www.pl32.com is the only one I know of that allows you to edit a JPG file where the only data that gets put through the compression routine again when you save it is that which you specifically edit or change from the original. JPEG Wizard also did/does this to a certain extent. AFAIK only on selective compression areas, or limited area processing such as red-eye removal. Then again, it really isn't an editor, per se; more of an image manipulator and processor. I'd imagine if you were to make any global change, such as color balance adjustment, that would require reprocessing in order to save the modified image. Until I started reading posts in this thread, I was unaware that there are ANY programs that can alter a JPEG without having to recompress the entire image. I can see your point about a localized change like the small parts of an image that had red eye removed, but I would think that you are right that any change that affects literally every pixel in the image, which would happen in your example of changing colors, would require a complete recompress. I've stayed out of this discussion because it doesn't really apply to my work, but I would like to just offer a comment. Like most people, I save the unedited images files from my camera should the need arise to completely redo a picture. One reason to do that for me, since I print very little, would be to create one with more PPI. But, if I discover a minor defect in one of my finished JPEGs, I will re-edit it, but save it with the 1-100 compression set one lower than the first time, as judged by the real-time file size. Then, as always, I inspect the final compressed image on my HD by looking at it full size to see if I've accidently introduced any damage at all from the re-edit. Luckily, or maybe I just have low standards, I fine very, very few that have enough damage that I can't fix it by altering the compression, Chroma subsampling, or maybe rubbing some blotches with a mild soften brush. -- HP, aka Jerry |
#28
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What program is best at JPEG compression?
In article , HEMI-Powered wrote: Until I started reading posts in this thread, I was unaware that there are ANY programs that can alter a JPEG without having to recompress the entire image. I can see your point about a localized change like the small parts of an image that had red eye removed, but I would think that you are right that any change that affects literally every pixel in the image, which would happen in your example of changing colors, would require a complete recompress. Well, they _claim_ that they do so, but I have not been obsessive enough to try to verify it. Conceptually, though, I don't understand how Huffman encoding would even allow you to change _any_ pixel values in a bitmap and not have it require changing the rest of the compressed data. |
#29
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What program is best at JPEG compression?
In rec.photo.digital HEMI-Powered wrote:
Until I started reading posts in this thread, I was unaware that there are ANY programs that can alter a JPEG without having to recompress the entire image. I can see your point about a localized change like the small parts of an image that had red eye removed, but I would think that you are right that any change that affects literally every pixel in the image, which would happen in your example of changing colors, would require a So I guess you know that Irfanview, among other applications, can do lossless rotation and flip, although it truncates to 8-pixel boundaries so it's only truly lossless with 8x pixel dimensions. To guess JPEG parameters, you can obtain the "jpegdump" program by Allan N. Hessenflow. When saving an edited JPEG, the destruction is minimal if you save with the same quality and chroma subsampling. As the JPEG FAQ says, destruction is worst when resaving with slightly different parameters at the higher quality values, counterintuitively. P.S. Thanks for your comments in the PaintShopPro thread. |
#30
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What program is best at JPEG compression?
Mike S. added these comments in the current discussion du jour
.... In article , HEMI-Powered wrote: Until I started reading posts in this thread, I was unaware that there are ANY programs that can alter a JPEG without having to recompress the entire image. I can see your point about a localized change like the small parts of an image that had red eye removed, but I would think that you are right that any change that affects literally every pixel in the image, which would happen in your example of changing colors, would require a complete recompress. Well, they _claim_ that they do so, but I have not been obsessive enough to try to verify it. Conceptually, though, I don't understand how Huffman encoding would even allow you to change _any_ pixel values in a bitmap and not have it require changing the rest of the compressed data. That's what I always thought, until I read about these magic programs in this thread. I'm no expert and not interested in trying to verify the veracity of the claims because my work isn't such that would be helped. But, in keeping with my general philosophy that learning is a life-long endeavor, if somebody has invented a better mouse trap, I'm interested enough to at least listem. Prevailing wisdom, and we all know the limitations to that, says that the way the JPEG standard is actually implemented in software always results in the entire pixel map being considered in a re-compress/re-save. That said, it doesn't necessarily follow that every damn pixel gets mangled by the process, which is why - I think - that my personal experience is that minor edits/re-saves done judicially can avoid the usual hysterical "you're going to damage the image!" claims. But, like your comments, I've not done scientific tests of my belief nor have I done the pathological examples of half dozen edits/resaves. -- HP, aka Jerry |
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