PictView: GIF display problem

JohnFredC · Post by **JohnFredC** » 04 Sep 2006, 19:03

In another Internet forum I encountered a discussion of a problematic GIF image.

The GIF in question is this one: http://phil.ipal.org/tc217.gif

PictView shows it incorrectly as does nearly every tool I have.

The only tools I have found so far that show it correctly are Opera(!) and theGIMP.

SvA · Post by **SvA** » 04 Sep 2006, 22:44

So, does the file comply to the specs?

What's your definition of correct in regard to displaying this image. Why do you call the rendering of the mentioned tools as correct and the rendering of others incorrect?

Mem · Post by **Mem** » 05 Sep 2006, 09:07

SvA - I saw that example in article on root.cz, it's really standard GIF but almost every viewer shows it bad (with delay between frames etc.)

And there is also thread in Czech forum about this topic - http://forum.altap.cz/viewtopic.php?t=1 ... hlight=gif

omega · Post by **omega** » 05 Sep 2006, 13:14

Irfanview even showed a red background with it. Plus the animation of the gif seems to repeat itself in Irfanview and in Pictview.
It looks like IE and FF displays the gif correctly.

Mem · Post by **Mem** » 05 Sep 2006, 15:01

omega: My FF does not display that GIF correctly, because AFAIK there is NO ANIMATION, it should display the whole high-color image at once (and my FF does it slowly block by block)

JohnFredC · Post by **JohnFredC** » 05 Sep 2006, 17:44

Yeh... I think maybe the animation is just an artifact of the technique used to force the GIF to display the 65k colors. Opera shows the animation to the final image, which I'm now thinking is wrong.

GIMP2 just shows the final color ramp, albeit with a hesitation while it (apparently) performs the animation "behind the scenes"...

omega · Post by **omega** » 05 Sep 2006, 21:11

If the gif should not show any animation at all and all the viewers does, then what tool was used to create this picture? There should be at least 1 program which shows the file correctly otherwise you can't say the other viewers and browsers display the image in a different way.

Post by **zarevak** » 05 Sep 2006, 23:38

The GIF picture itself could be made manualy in some HEX editor. Even if none of the well known viewers shows this picture right doesn't mean, that the picture is bad. AFAIK the picture is made according to basic GIF89a specification without the NETSCAPE animation extension (this extension enables setting delay between displaying the frames - without it, all frames should be displayed at the same time!)

The question is: Should PictView display the picture right (against the specification) or wrong = same way as it is displayed in other viewers?
- if PictView displays it right, it can confuse some users, that will say: hey, this picture has lost its animation.
- if the PictView continues to display the picture wrong, it harms the specification. It's kind of "quirks mode" in browsers (mode to "correctly" show web pages made for non-standard compliant IE4.0)

(all information are based on Czech article: Graphics format GIF on root.cz)

Post by **Jan Patera** » 07 Sep 2006, 20:11

zarevak wrote:The question is: Should PictView display the picture right (against the specification) or wrong = same way as it is displayed in other viewers?
- if PictView displays it right, it can confuse some users, that will say: hey, this picture has lost its animation.
- if the PictView continues to display the picture wrong, it harms the specification. It's kind of "quirks mode" in browsers (mode to "correctly" show web pages made for non-standard compliant IE4.0)

You are reading my mind. We are aware of this issue and will address it in the next release of Salamander (whatever it will be called

) Because of the confusion of the users we will keep animating this particular image. However some other images that do not have GCE chunks will no longer display animated (for samples please see the aforementioned Czech-language article).