been reading a little about the thing going on with the gif patents etc. it has also become noticeable that more and more open source content sites use this format. now i have to admit that i am not very familiar with graphics stuff, but is converting from GIF/JPG to PNG lossless?

and to add to that.. i have been looking for a possible converter. there are lots of them, but is there also a freeware application for this?

thanks in advance

Conversion from lossy formats (supposing gif is one, cause it reduces the color number, ok, I thought about it, I'm quite unsure so I won't point that out...) to png does not make much sense. It's like transcoding MP3, heehee(.ogg)

the reason i am thinking about converting from one to the other is not because of quality, but because of the fact that the PNG format is patent free (like ogg).

You could use IrfanView. It's a image viewer with a lot of features (batch converting/renaming of images, ...)

GIF, per se, is not a lossy format, as long as you consider 256 colors as the standard number of colors. You can convert from Gif to BMP, back to Gif, back to BMP, back to Gif again, etc, and it will remain the same.

GIF to PNG is lossless, unless you introduce some pointless and unneeded color conversion from 8 bits to 16 or 24 bits, and then back.

JPG to PNG is pointless. JPG copyright issues are not being ran after, as far as I know, and you will end up with way bigger files. And since JPG is lossy, you shouldn't do a JPG to PNG to JPG to PNG to JPG conversion process, because that IS transcoding.

thanks all

userXYZ: will definitely have a look at it

Kblood: thanks for the info

The LZW algorithms will expire on June 20th. Less than three months from now. So, I wouldn´t be too concerned about using GIF or not.

so png is lossless?! When saving a picture as png I can choose somewhat; there are different quality modes. Do I influence the compression rate by changing the quality setting or mode?

PNG is lossless.

The compression setting is a time/space tradeoff. Just like gzip/bzip2/pkzip/winzip/rar/7z/etc have compression settings.

To bring the analogy back to the audio world, FLAC has a lot of compression settings. It's lossless with any of the settings. Some of the settings just take (much) longer and you wind up using (a bit) less disk space.

Converting non animated GIFs to PNG is a smarter idea. PNGs are usually smaller (I converted all the GIFs that I had to PNG). On some rare occassions there'll be files that are smaller in GIF, but most of the times PNG beats GIF with a decent margin.

Don't listen to GIF supporters(rjamorim? ), PNG IS the superior format. It's been widely supported in browsers in 1997(Netscape 4.04, IE4), so don't listen to BS about it not being widely supported. This is 2003, not 1995.

PNG is LOSSLESS.

http://www.libpng.com/pub/png/



For a great website:

http://burnallgifs.org

I agree with Wish: if you can, and I don't see why you not (Irfanview is free, after all, and it's a damn nice piece of software, free for NON-COMMERCIAL use, which could be a relevant detail), you should convert ALL your GIFs to PNG right away. All modern browsers support PNG. And the older browsers should disappear from the face of Earth already!!!!! Come on!

This post has been edited by Kblood: Apr 1 2003, 23:10

Try the "Office" suite 602 Pro(freeware), wich includes the "602 Photo".
It has nice features and supports saving and converting between several image formats, including .png.
Give a shot. I recommend.
Here is the link

This post has been edited by LIF: Apr 2 2003, 00:58

On top of that, there are many advantages to using PNG, such as support for 32bit colour and alpha transparency channel (GIF only does 256 colour. or 255 and 1 transparent)

There is a slight flaw in what you say. To which the next post will shead some light.



PNG support in IE has not improved since the release of IE 4.x back in 95 or 96. IE support for PNG alpha transparency is in a word non-existant unless you are running IE 5.5 on Mac. IE supports only 1 bit gif style transparency. It will not do pallated transparency or alpha transparency at all. Neither will it do embedded color profiles. And don't dare to try and feed IE a MNG image. It's just not going to happen.

Now because I know someone will bring it up there is a way to get alpha transparent PNG to work in IE. But you have to use (of course) a proprietary Microsoft extension that breaks the page for all non-Microsoft browsers. So it is not an option. There is also the possibility to embed gecko inside IE but you may as well just use Mozilla in that case.

PNG will beat GIF hands down in almost any instance. And there are even instances in which it blows JPEG out of the water completely. You have to understand what each format was designed for. Gif is for 256 color non-photographic images. JPEG is designed for photographic images and supports 16 million colors, but it is lossy. And on things like cartoons or large solid colored areas JPEG artifacts are easy to see. PNG like GIF is lossless but it supports 16Million+ colors IIRC. So as a rule of thumb if it is a photographic image use JPEG or JNG. For everything else PNG. Though from time to time you "WILL" find photographic images that PNG will handle best.

I just did a small test, slightly OT, but interesting for image compression. 60 1024x768 TGA images (screenshots from a 3d game) compressed to different formats:

TGA originals: 138mb
PNG q=9: 53mb
JPG q=100: 25mb
JPEG2000 lossless: 43mb
JPEG2000 q=95 (default): 4mb !!
JPEG2000 q=100 : 21mb

Quality: jpg is noticeably different from the original sitting a reasonable distance from the display. Blurs certain objects, and seemingly the colour red more often than others.

jp2 at q=95 is not noticeably different unless you either zoom or move very close to the display, where you notice everything is very slightly blurred/altered.

jp2 at q=100 I couldn't tell the difference even at close distance, and eyestrain made me quit trying. I would say virtually lossless, at least on the pics I tried. The filesize difference between q=95 and q=100 is very strange though... I would use q=95 or even lower myself as the artifacts aren't ugly like jpg produces and the filesizes are great.

As for speed jpg and png are extremely fast to encode, whereas jp2 lossless is very, very slow to encode and jp2 lossy is somewhere inbetween.

Overall jp2 is very impressive. Hopefully it gets natively supported by browsers sometime soon. (though I easily grabbed a Mozilla plugin) The lossless mode doesn't seem much better than the blazing fast, and free png, but jp2 lossy is a big leap from jpg.

Mmmm... JPG2000, or JP2 for short, is, as far as I know, very far from being free... Do you have any info on that?

I prefer to use plain JPG for now, I don't want to end up with all my digital photos unreadable later on when standards change. JPG seems to have a long life ahead due to the free viewers. I would like more information on the licensing of the JP2 format.

all i could find about the license is this snippet from the jpeg website

Try XNView - totally free and extremely comprehensive. View, convert, crop - you name it.
And for JPEG compression, have a look at Advanced JPEG Compressor.

JPEG2000 is very much PATENTED software. Good luck with it, after the GIF and JPEG patent fiascos, I don't see why anyone would use JPEG2000.

about 8bit png version (gif replacer) - how is alpha implemented ? (1 and 0 as gif or something better, and what software to use to get that? (nope, photoshop wont do it))

my 32bit png test :
http://smokeamiga.virtualave.net/png/png_test.htm (~200 k)
(will render corectly in mozzila based browsers)
but i want that cloud to be 8bit with some clever alpha if possible of course...
------------------------------------------------------------------------------------------------------
nice stuff, png vs tiff:


This post has been edited by smok3: Apr 3 2003, 16:37

Blah. Blah!!! I'm not supporting anything (I can't say the same about you, PNG zealot boy). I just said that, if your main concern for ditching GIFs is patents, you don't need to worry much anymore.

Tiff is kinda of a image container format. If you want to compare it with something else, you must specify what compression algorithm you used: none, RunLenght (lossless), LZW (lossless), JPEG (lossy), CCITT3 (lossy, BW), CCITT4 (lossy, BW)...

from what i read png is always lossless..., so it is lzw tiff compression vs whatever png uses.

Even if the patents expire, it doesn't fix the fundamental weaknesses of GIF.
PNG always and will always beat GIF in compression efficiency except in rare cases, has 24bit and full alpha transparency support, better interlacing support etc. Just don't understand why people are so scared to embrace a better thing.....

That actually looks quite free. There are patents, but you don't need a license. Similar to Ogg Theora (On2 VP3).

I guess the q=100 vs q=95 is the same as in JPEG, i.e. the bitrate flies way up if you effectively disable quantization (q=100).