[Chromium-dev] Re: Pixel-image compression within Chromium?

[Brian P. <bri...@tu...>]

Do you suspect it's texture images that are the source of the problem? 
  Or glDrawPixels?  You mentioned images in your post.

Textures are typically specified in GL_RGB or GL_RGBA format with 
GLubytes.  Since those are byte-sized components, there shouldn't be 
any endian issues.

If you see the problem with any small, simple GL demos (like the 
redbook or GLUT demos) that would help narrow it down.  Even a screen 
shot showing the problem could give us a clue.

Chromium doesn't normally do any image compression.

-Brian


aac...@ad... wrote:
> Hello,
> 
> I posted something about this problem before, but have not gotten any response.  To re-iterate, certain colors on certain applications run through Chromium from a Windows Box (mothership and crappfaker) to a crserver running with OMP (like DMX) on an SGI Onyx 4 running IRIX do not appear correctly.   
> 
> One problem is that the Chromium Print-SPU doesn't include data in its output; only the address of the texture image in memory, so I can't see the data that the application's sending to Chromium.
> 
> For those of you who know the inner workings of Chromium, is it possible that Chromium is doing some kind of pixel-image compression, and there are bit errors being introduced because of that?  If it does do pixel-image compression, is it possible to turn this compression off??
> 
> Thanks for your help,
> Alicia
> 
> 
> 
> 
> 
> 
>>From:  <aac...@ad...>
>>To: chr...@li...
>>Subject: [Chromium-dev] disparate colors using Windows->Onyx4
>>Date: Fri, 10 Dec 2004 15:58:49 -0800
>>
>>Hello Chromium community,
>>
> 
>   
> 
> We are setting up Chromium to run (mothership and crappfaker) on a Windows box and the crserver on an SGI Onyx 4 with IRIX.  
> 
> 
> When running some applications, the colors that show-up on the Onyx 4 rendering nodes have disparate colors and apparent dithering.  Many OpenGL programs such as Atlantis, City, etc, do not have any color variations at all.  BUT, some important in-house applications and other third-party applications do not show the color-schemes one would expect.  Oceans that normally appear blue on a globe, might look purple, etc when passed through Chromium and displayed on the Onyx 4 crserver.  
> 
> 
> Not all colors are off, but noticeably some are.      
> 
>  
> 
> I was wondering if anyone has seen this effect before?  I know I'd seen displays show all-white when textures could not be rendered due to video-card problems, but I haven't seen color-abnormalities like are appearing now. 
> 
>  
> 
> The video cards on the 2x2 SGI display are not all the same.  Two of the video cards are Firegl GL X2 and two of the other video cards are Firegl GL X1.  The Windows box also has a Firegl GL X1.  
> 
>  
> 
> Some of the ideas to fix this problem have been:
> 
> 
> Big-endian, Little-endian...perhaps going between Windows to Onyx results in some kind of color-transformation via the Big-endian, Little-endian of the color values?
> 
> 
> We bought an identical Video card for the Windows machine, in the hopes that that would ensure identical color-map for both the Onyx and Windows machines.  Apparently that was not the issue either, as everything still has the same color difficulties.
> 
> 
> Does the Windows box have one color-map, and the Onyx a different color map that is being referenced that would cause these problems?
> 
> 
> Let me know if you have any ideas.
> 
>  
> 
> Thanks so much for your help,
> 
> Alicia 
> 
>  
> 
> 
> 
> 
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