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  #1  
Old 03-May-2003, 09:22
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PNG transparency works in Mozilla but not in internet explorer


Sometimes I think most browsers are very similar, but when you fall across something like this: http://entropymine.com/jason/testbed/pngtrans/ you realise it is not the case.

I like PNG because of the zlib compliance that it has. Just have a look at this: http://www.schaik.com/pngsuite/pngsuite_zlb_png.html I think that's really impressive stuff especially if you compare it to GIF compression: http://www.schaik.com/pngsuite/pngsuite_zlb_gif.html

I don't really know how to have a png compressed so if someone can fill me in on this I'll appreciate it a lot.

Rob
  #2  
Old 03-May-2003, 09:37
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Re: PNG transparency works in Mozilla but not in internet explorer


Quote:
Originally posted by jrobbio
I like PNG because of the zlib compliance that it has. Just have a look at this: http://www.schaik.com/pngsuite/pngsuite_zlb_png.html I think that's really impressive stuff especially if you compare it to GIF compression: http://www.schaik.com/pngsuite/pngsuite_zlb_gif.html

Rob


So basically what you're saying is that having .png graphics in your compressed web pages translate into compressed .pngs as well???

I DIDN'T know that!

If it's true, that's fantastic...
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Old 03-May-2003, 11:03
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I'm pretty sure what I'm saying is correct. In the past I have been confused when saving a png file from a site and looking at it on my computer to see that the size has increased dramatically. I hadn't saved it in a different way or anything and maybe this is a possible explanation for it.
I decided to do some research and I found this site:
http://pmt.sourceforge.net/pngcrush/ and I tried it on some large png files and managed to get a 50% reduction with my first effort.
Whether it is actually possible to do it on the fly from a server using zlib compression is a different question.

I decided to have a play with the GIDForums image, which comes in at 4kb which is pretty good all being said and I managed to get it down to 3.4kb, which you can see at http://www.topfunwebsites.com/gidforum.png. That is 85% of the original file size with no loss seen although I wouldn't recommend it for transparent files because of what I posted earlier.

Rob
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Old 03-May-2003, 12:38
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I'm currently using a browser from 1998 (by the now defunct Acorn Computers), and even it does PNG transparancy. I am really supprised that IE doesn't!
PNG Crush is a great tool, I have found in the past when creating PNGs for the web. I have intergrated it into BannerCreate to compess the images it makes.
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Old 03-May-2003, 15:08
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So the big questions are, how did you do it and is it easy enough to do?

I tried converting some photos to png in my art program, but when using 8bit the quality isn't good enough and 24 bit is just too bigger file size. PNG seems to be best for images with less than 256 colours.

Rob
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Old 03-May-2003, 18:48
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How to compress .png files?


I don't know how they do it but I am going to try a few things to see what I can discover (using PHP and gzip).
  #7  
Old 04-May-2003, 01:21
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Quote:
Originally posted by jrobbio
So the big questions are, how did you do it and is it easy enough to do?


Well as the images are being created by a PHP script I just get the script so save the image to disc and then:

PHP Code:

system("pngcrush sourcefile.png destinationfile.png"); 



Then I unlink the uncompressed image.
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Old 04-May-2003, 01:40
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Where can I download pngcrush from?


This program pngcrush, but you need it on the server right? Where did you get (download) it from? Or is this a RISC OS thingy?
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Old 04-May-2003, 01:55
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Quote:
Originally posted by JdS
This program pngcrush, but you need it on the server right? Where did you get (download) it from? Or is this a RISC OS thingy?


Works on most OSes, I just downloaded it and got the server admin to install it.

http://sourceforge.net/project/showf...?group_id=1689
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  #10  
Old 04-May-2003, 02:04
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Bookmarked it... when we move to the VDS, I will install and try it out.
 
 

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