Re: [Gimp-user] png compression
On Thursday 14 April 2005 18:51, Jim Clark wrote: > I no-dithered and I crushed and I reduced my 10 images from 165084 > to 113479 without using any thumbnails. 50K isn't 100K, but it is a > significant reduction, and with no visible loss of image quality. > > Worked well--thanks for the pointers. > Well...so good for the PNG's..but if trading space for quality is what you want, than, just check the old JPGs ... > Jim Clark Regards, JS -><- ___ Gimp-user mailing list Gimp-user@lists.xcf.berkeley.edu http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-user
Re: [Gimp-user] png compression
On Thu, Apr 14, 2005 at 03:16:30PM -0500, Jim Clark wrote: > > Is there something I should be doing to get a smaller file size? a not so obvious file size issue is whether or not your image has an alpha channel. if your png needs transparent areas then this is a needed channel. if your png does not need transparency, it can still be saved with the channel. an example being the screenshots on my web site. if they are screen shots of menu's stepping out, those images needed transparent areas and are really big compared to the simpler screen shots of dialogs. if you do not have transparent areas in your screenshot, Image -->Flatten will reduce the file size by an amount that i was able to see. carol ___ Gimp-user mailing list Gimp-user@lists.xcf.berkeley.edu http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-user
Re: [Gimp-user] png compression
I no-dithered and I crushed and I reduced my 10 images from 165084 to 113479 without using any thumbnails. 50K isn't 100K, but it is a significant reduction, and with no visible loss of image quality. Worked well--thanks for the pointers. Jim Clark
Re: [Gimp-user] png compression
Hi, "Kalle Ounapuu" <[EMAIL PROTECTED]> writes: > So now I have 4 images which all look about the same, ranging > in size from 19419 to 30705. Quite a hit or miss process. One > would think indexing and crushing would yield the smallest > image, but it did not. There are lots of options when indexing. If your goal is smaller file-size, you should avoid dithering, or at least do positioned dithering. Sven ___ Gimp-user mailing list Gimp-user@lists.xcf.berkeley.edu http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-user
Re: [Gimp-user] png compression
Jim Clark ([EMAIL PROTECTED]) wrote: > Things get odder and odder. > > I need to put 10 screen shots on a web page and was hoping to shave 100K > from the final page. > > So I took one of my images and indexed it. > Before index: 27004 > After index:30705. > > It got larger? This can happen when dithering is enabled. PNG compression deals quite good with large areas of uniform color, dithering can spoil this by effectively creating areas with lot of differently colored pixels. You can choose the dithering method when you convert to indexed. "None" yields smaller PNG files but might have stronger impact on the image quality. Hope this helps, Simon -- [EMAIL PROTECTED] http://simon.budig.de/ ___ Gimp-user mailing list Gimp-user@lists.xcf.berkeley.edu http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-user
RE: [Gimp-user] png compression
Crushers shouldn't give you larger filesize... by default all of them have the overwrite_if_bigger function set to off. Another PNG tool that is handy: TweakPNG This displays all the PNG chunks being used, and allows you to see what is changing in a PNG file exactly. -Original Message-From: Jim Clark [mailto:[EMAIL PROTECTED]Sent: Thursday, April 14, 2005 5:05 PMTo: Kalle OunapuuCc: gimp-user@lists.xcf.berkeley.eduSubject: RE: [Gimp-user] png compression Things get odder and odder.I need to put 10 screen shots on a web page and was hoping to shave 100K from the final page. So I took one of my images and indexed it.Before index: 27004After index: 30705.It got larger? I downloaded and installed a png crusher and ran it against both files:27004 after crush became: 19419 or a 28% reduction30705 did not change--all the crushed versions were larger.So now I have 4 images which all look about the same, ranging in size from 19419 to 30705. Quite a hit or miss process. One would think indexing and crushing would yield the smallest image, but it did not. Thanks again-Jim Clark
RE: [Gimp-user] png compression
Things get odder and odder. I need to put 10 screen shots on a web page and was hoping to shave 100K from the final page. So I took one of my images and indexed it. Before index: 27004 After index:30705. It got larger? I downloaded and installed a png crusher and ran it against both files: 27004 after crush became: 19419 or a 28% reduction 30705 did not change--all the crushed versions were larger. So now I have 4 images which all look about the same, ranging in size from 19419 to 30705. Quite a hit or miss process. One would think indexing and crushing would yield the smallest image, but it did not. Thanks again- Jim Clark
RE: [Gimp-user] png compression
There's lots of things you can do to make PNG's smaller. If you save them as Indexed PNG's and reduce the colours, you may end up with smaller filesizes. Change the image mode to Indexed and it should prompt you for number of colours and other options. After exporting the PNG, it still isn't very efficient... most apps like Gimp, Photoshop, Paintshop... they don't do a good job optimizing the PNG export. You may want to try PNG crushing programs that will optimize the PNG much more. Personally I use something called Megaopt: http://www.hydrogenaudio.org/forums/index.php?showtopic=16167 ... it's a DOS script that uses 5 PNG crushers and compares the results. Also, a WIndows GUI program called "PNG Gauntlet" does pretty good too (same as Megaopt almost). Search the net for that. There's other tricks and things you can do... but they only save a matter of 100's of bytes. Kalle -Original Message-From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]On Behalf Of Jim ClarkSent: Thursday, April 14, 2005 4:17 PMTo: gimp-user@lists.xcf.berkeley.eduSubject: [Gimp-user] png compression H...I have a couple of pngs that I have scaled to make smaller but still visible thumbnails. Image 1 (install1.png) was 799 X 598, I scaled it to 300 X 225. install10.png was 765 X 538, scaled to 450 X 317. Here's an ls:10725 Apr 14 13:54 install10.png24020 Apr 14 15:01 install10_tn.png35217 Apr 14 13:54 install1.png32378 Apr 14 15:01 install1_tn.pnginstall1.png was reduced significantly and yet the file size reduction is less than 10% (hardly worth the bother to make a smaller version) and install10.png, reduced in size by a much smaller proportion, was reduced a useful (and much greater) amount. These were png screenshots sent to me from a Win box...I cropped them to the useful area and saved them as pngs using the default settings. Then for the thumbnails I just scaled the image and saved again.Is there something I should be doing to get a smaller file size? I have only recently started using pngs as my users are all MS/IE folks and have not really thought about file compression much. But this seems weird to me.I realize what I don't know about file compression (or pngs, or GIMP, or most other things discussed on this list) could fill a few books, but same source same process same tools yielded very different results. Why?Thanks-Jim Clark
[Gimp-user] png compression
H... I have a couple of pngs that I have scaled to make smaller but still visible thumbnails. Image 1 (install1.png) was 799 X 598, I scaled it to 300 X 225. install10.png was 765 X 538, scaled to 450 X 317. Here's an ls: 10725 Apr 14 13:54 install10.png 24020 Apr 14 15:01 install10_tn.png 35217 Apr 14 13:54 install1.png 32378 Apr 14 15:01 install1_tn.png install1.png was reduced significantly and yet the file size reduction is less than 10% (hardly worth the bother to make a smaller version) and install10.png, reduced in size by a much smaller proportion, was reduced a useful (and much greater) amount. These were png screenshots sent to me from a Win box...I cropped them to the useful area and saved them as pngs using the default settings. Then for the thumbnails I just scaled the image and saved again. Is there something I should be doing to get a smaller file size? I have only recently started using pngs as my users are all MS/IE folks and have not really thought about file compression much. But this seems weird to me. I realize what I don't know about file compression (or pngs, or GIMP, or most other things discussed on this list) could fill a few books, but same source same process same tools yielded very different results. Why? Thanks- Jim Clark
Re: [Gimp-user] PNG compression level 6 or 9 ?
Daniel Carrera wrote: On Wed, Jun 04, 2003 at 09:31:05PM +0100, David selby wrote: When saving PNGs gimp defaults to compression level 6. Is there any reason why I should not use compression level 9 ... Is there a reason why this is not the default ? Dave I understand that the higher the compression the longer it takes to compress/decompress. So a file compressed more will download faster, but it would take longer to if you were to open them up on a viewer. I could be wrong though. This is what I thought, though my (pre-historic) 700MHz PIII, de-compresses in a trice ... Many thanks Dave ___ Gimp-user mailing list [EMAIL PROTECTED] http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-user
Re: [Gimp-user] PNG compression level 6 or 9 ?
On Wed, Jun 04, 2003 at 09:31:05PM +0100, David selby wrote: > When saving PNGs gimp defaults to compression level 6. Is there any > reason why I should not use compression level 9 ... Is there a reason > why this is not the default ? > > Dave I understand that the higher the compression the longer it takes to compress/decompress. So a file compressed more will download faster, but it would take longer to if you were to open them up on a viewer. I could be wrong though. -- Daniel Carrera | OpenPGP fingerprint: Graduate TA, Math Dept | 6643 8C8B 3522 66CB D16C D779 2FDD 7DAC 9AF7 7A88 UMD (301) 405-5137| http://www.math.umd.edu/~dcarrera/pgp.html pgp0.pgp Description: PGP signature
[Gimp-user] PNG compression level 6 or 9 ?
When saving PNGs gimp defaults to compression level 6. Is there any reason why I should not use compression level 9 ... Is there a reason why this is not the default ? Dave ___ Gimp-user mailing list [EMAIL PROTECTED] http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-user
