I have heard that Macromedia Fireworks [macromedia.com], Jasc Paint Shop Pro [jasc.com], and Gimp [gimp.org] have excellent PNG support. Apparently gimp has a windows version now and is free software. I have not used any of these in a long time so I can't tell you for sure if it does what you need. Fireworks has been using PNG since the beginning. It was where I first heard of PNGs. I would try some demo and see which ones work. Let me know if anyone of them does.
Wavelet compression is finally making it into some products (have seen it in ViewPoint Scene Builder). Don't know if it's in anything you could use yet, but keep an eye out, as it introduces superior compression algos.
Have heard good things about GIMP, but have not used it myself. Didn't realize it was freeware - guess I'll get a copy, lol
I'm still waiting to find a good PNG plug-in for Photoshop. Their PNG compression is really weak. Biggest weak point I've found in the program lately.
thanks for the replies!
i tried gimp, 9 compression levels plus
still larger files than the gif version
but i suppose that's because the images
are pretty small (20x22px), in that range
gif still seems to be ahead.
for 27 images i got a ratio of 1:1.455 (gif:png)
PSP 7 has a PNG export feature, so you can preview it, while adjusting the file size...
I love that export feature in PSP... Has it for gif and jpeg too!
I've never used any of the others mentioned here, being a Free software snob, but GIMP does very well for me, and the Windows version is every bit as nice as the Linux one, and looks to be pixel-perfectly the same except for the window decorations. (provided by the OS or windowsing system, not the app itself) When you save an image as a particular format the first time, GIMP will prompt for format-specific settings. With PNG, there is a checkbox for interlacing and a slider for compression. It runs 0-9, with a default of 6. (Standard zlib range and default, for people familiar with zlib.) I've never had a complaint with any of the images GIMP has produced for me.
Idea to get very good compression via Photoshop!
Well i recently discovered PNG and it's power. I am an avid user of Photoshop and am using verion 7 of it, but unfortunately Photoshop has a poor compression algo for PNG.
But i got a better, infact much better way out. Has anybody here tried pngcrush? Its a cool command line utility built for linux, but has a windows exe too.
Use photoshop to your hearts content, save as png from photoshop, then run the photoshop's png throught pngcrush.
pngcrush does a lossless compression and tries all possible filters to get the best possible cmopression.
I tried it myself. I made a image in photoshop with solid colors. Saving it to png gave me about 9.5 kb file....saving it to gif i got about 8 kb file..then i ran the 9.5 kb png via pngcrush and i got a file about 7 kb in size! thats about a 20% reduction insize. pngcrush has a LOT of options to tweak, so maybe i can get better..but i didnt have time to study it. Search for it on google. its on sourceforge i think.
I just found..pngcrush also does:
-Checks different filter and compression methods to determine smallest size
-Fixes bad sRGB chunks produced by Photoshop 5.5
-Removes opaque alpha channels, sets all-gray images to grayscale
-Can fix bad CRC's, or remove unwanted anciallary chunks
-Can add gamma, transparency chunks, or resize color palletes
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I will have to check it out. It seems to be a free utility and open source. I found it at pmt.sourceforge.net/pngcrush.
Thanks you for the welcome. Yes, it is free. If you pass a image, with no switches just 'pngcrush.exe in.png out.png' it does a great job.
I found a freeware Mac plugin called "SuperPNG" which seems to get images within 1/2K of the equivalent GIF size... you just replace the original Photoshop PNG support filter with SuperPNG, and you've got it almost as good as GIF. :)
Maybe I'll switch formats for my personal site... I keep thinking it's time.
Ok, I suggested pngcrush above, but I myself am not too comfortable firing up the dos prompt to optimize a PNG each time.
More research made me discover [members.lycos.co.uk...]
Its a GUI to the pngcrush command line! It is used WITH the actual pngcrush.exe to easily compress PNGs. I mailed the developer and he said it has just been made, so will improve in future. It is in Alpha right now, but worked well for me. Any reports?
As far as i know, its freeware too, and for Windows.