What exactly is Matrox up to .... get the <facts>

[Indiana]

GIF is lossless because it uses some Huffmann algorithm for packing which is a lossless one.
And while the normal JPEG compression is lossy due to it's algorithm regardless of the selected quality (Maggi is right here), there is in fact also a lossless JPEG variant, but this is usually a different codec and normally called LJPG. Could be that some Photoshop versions switch from JPEG to LJPG for the highest quality setting, leading to the different results people are getting here.

[DukeP]

Lol..

All very informative, but could we get back to speculating about the upcomming matrox card??

Btw TIF also has a variant that uses lossy compression..

[IcedEarth]

Originally posted by Indiana
GIF is lossless because it uses some Huffmann algorithm for packing which is a lossless one.

Uhm.... that's not true. As long as your color palette has no more than 256 colors, GIF is lossless. But if you save a 24-bit picture in GIF-format, it will only save 256 colors which results in a lossy version of the original 24-bit picture. That's what wombat meant I guess

[rubank]

Duke,
I can understand your frustration
but I have to answer the magpie

Maggi,
of course I wouldn´t use a JPEG file saved as a TIFF file, I´m not that kind of guy.
And as for detail, I´d say you can´t tell without seeing the pic in original size. Furthermore brightness values are just as important (as a measure of file contents) and if there is not ONE SINGLE PIXEL of difference, I´d say the compression is de facto lossless regardless of what the format dipicts.

Is the emperor naked? Yes. Does the pope have a beard? Yes. Can JPEG be lossless? Yes.


rubank

[Indiana]

Originally posted by IcedEarth


Uhm.... that's not true. As long as your color palette has no more than 256 colors, GIF is lossless. But if you save a 24-bit picture in GIF-format, it will only save 256 colors which results in a lossy version of the original 24-bit picture. That's what wombat meant I guess

The compression algorithm used in GIF still is LOSSLESS by design in contrary to JPEG which has a lossy compression (independant of the quality-setting). Of course GIF has the limitation of supporting max. 8Bit / 256 colors, but that has nothing to do with it being a lossy or lossless compression. You simply cannot store a >256 color pic in GIF so the application has to downscale it to 256 colors before saving. The saved GIF still is lossless compared to the 256 color image it got from Photoshop/...
Another lossless format is PNG, this has the advantage of having higher compression ratios and supporting bitdepths >8.

The lossless LJPG is different in design from JPEG (i.e. not just a JPEG with a high quality-setting), it's merely from the same group - like JPEG2000 for example.

So in short:
1. GIF, PNG are lossless, JPG is lossy.
2. There is a lossless LJPG, yes but it uses completely different algorithm then the usual JPEG.

P.S.: Rubank, for general use you're right with your "defacto-lossless" statement, but not if you're doing many editing steps on a picture. The small losses will more than add with every step so you should use a REAL lossless format (where each pixel is EXACTLY the same it was) for any editing. You can still convert the final result to a more convenient format afterwards.

[IcedEarth]

I know Indiana, but what I said, was to support Wombat when he asked whether or not the GIF was lossless. In design GIF IS lossless but if the picture you saved in GIF only has 256 color while the original has a couple of thousands, I'd say the result is lossy. It's just a matter of point of view

[rev]

offtopic sucks!

guys, you are way toooo offtopic

we should really get back to the subject, does anybody know anything new? I'm really excited about the new matrox card, especially if it'll have specs we have mentioned. Some publication or info from matrox would be heaven

keep on rollin' guys...

[rubank]

I APPOLOGIZE TO YOU ALL AND WILL HUMBLY ACCEPT MY PUNISHMENT AND EAT A SHOVEL OF DIRT.

Maggi and Indiana are totally right, I just made an unforgivable mistake. I take back everything I said and state the opposite.

(I didn´t close and reopen the JPEG file before doing the difference calculations. In Photoshop that´s a problem, in Photopaint it isn´t)


rubank

[Tempest]

Originally posted by IcedEarth
In design GIF IS lossless but if the picture you saved in GIF only has 256 color while the original has a couple of thousands, I'd say the result is lossy. It's just a matter of point of view

It's not the file format that dithers/decreases those colors, it is the app that knows the limits of the GIF file format and does the conversion for you. So it's not poor GIF's fault if you try to save a picture with millions of colors and it doesn't show up as expected. It's like trying to save a BMP file with more than 2^24 colors, the result could be said to be lossy but the fact is that the file format was never designed to handle such information.

Oh yes, this is really getting offtopic now... But I'm sure that as soon as someone has some real news they will appear here
Edit: Oh yes, if someone wants some graphics related news then ATI has finally begun shipping the Radeon 8500DV.

[IcedEarth]

Originally posted by Tempest
It's not the file format that dithers/decreases those colors, it is the app that knows the limits of the GIF file format and does the conversion for you. So it's not poor GIF's fault if you try to save a picture with millions of colors and it doesn't show up as expected. It's like trying to save a BMP file with more than 2^24 colors, the result could be said to be lossy but the fact is that the file format was never designed to handle such information.

I know, I know... it's the prog, not the picformat but the result is still lossy isn't it?

BTW: I got myself a second hand MAX last month, while waiting for THE NEW MATROX VIDEO CARD! (getting back on-topic)

[Maggi]

no prob ...

[Indiana]

Re: offtopic sucks!

Originally posted by rev
guys, you are way toooo offtopic

we should really get back to the subject, does anybody know anything new?

Probably no, and this is the reason why this thread got that OT...

[DukeP]

On the other hand: It was by far funnier when people where arguing over something (althoug rather irrelevant), than this silence.

What about a guessing contest: What would be the price for this new magic Matrox card?
I might as well start..

/me dust off his magic but old crystal ball...

I foresee that the next magic highpowered superdeluxe dual petheradoctyl card from matrox will cost: 298$




~~DukeP~~

[Ant]

£300 or £600 if you want the full 256MB of DDR memory

[DukeP]

ROFL!



Well... I might even buy the full Monthy..


~~DukeP~~