old scanline renderers color issues

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foetz
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old scanline renderers color issues

Unread postby foetz » Sat Jan 10, 2015 9:13 pm

maybe someone had that issue in the past and found a solution. i never did, didn't care much either but it never stopped bugging me so here it is:

some of the old scanline renderers such as wavefront's image or prisms' crystal don't show the colors right. i didn't have to match colors often so it wasn't an issue mostly but just recently i found out by accident that both show the same difference from the correct color so i figured that might be something general.
i attached 2 images, one from wavefront (scanline) and one from poweranimator (raycaster). now the thing is for both materials i used the same rgb/hsv values and matched whatever else the programs provide. you can clearly see that the color is different. it's not a matter of lighting or something else but it's simply not the same color.
i tried different machines, different irix versions and different version of the programs but always the same result. and it's not that the renderer would run in some sort of limited color mode. if i adjust the color values a bit i get a fine match. the crucial incident was when i noticed that the old prisms renderer had the same color difference so the big question is why? :P
what do these scanline renderers have in common that's causing the same color difference? must be something general since it's affecting both and they're not related in any way.

and fwiw, even when i use mantra in prisms and set that to scanline the colors are correct so it has to be something exclusive to the old style renderers.
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k_wf.png

sgtprobe
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Re: old scanline renderers color issues

Unread postby sgtprobe » Sun Jan 11, 2015 6:40 am

Probably the gamma that is different, some default setting somewhere?

I "wrestle" with gamma everyday since I mostly work in linear space, but sometimes at gamma 2,2 and 1,8. Especially when applying standard texturemaps comming from photoshop or the likes (which usually have an applied gamma correction curve), I usually have to divide the gamma with 2.2. 1/2.2 = 0,4545. Otherwise the colors/contrasts (in the texture) looks washed out similarly to your pictures.
Image Image Image Image Image Image

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Re: old scanline renderers color issues

Unread postby foetz » Mon Jan 12, 2015 7:26 am

yeah gamma seems to be the best bet. even more tricky with wavefront because although setting a different gamma for the renderer wavefront's own image viewer ignores it so although the rendering is right you only see it if you're not using wavefront's viewer or set the gamma for that, too :P
and not enough it also has that "wrong" gamma applied to the material editor so getting it right for a different target gamma seems nasty. anyhow those who know wavefront know that it's an env var paradise so there might be one for the gamma, too


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