CGTalk - Smoothing gradients

king_max

05-25-2006, 11:51 AM

I have an upcoming job that will involve a gradient-like background (probably done in max). Since I encountered that problem before, my question is on how to achieve a smooth colour gradient once exported? I noticed a progressive degradation moving from the 3D app through compositing and to the final sequence. I assume it's colour depth related, but even if i render to a 10/12 bit format the result is the same. I found many videos made both for TV broadcast and digital playback that have seamless colour transitions, how to achieve that?

Kai01W

05-25-2006, 05:15 PM

Add grain!!!

If you're talking about masks... they almost always have a linear transition so I find myself very often bluring the output of a mask to avoid the look of hard edges (even if they correctly speaking have none). I have not found a single compositing package that would allow for changing the interpolation of mask gradients from linear to something else....

...but I guess you mean something else. Did I say "add grain!" already?

-k

king_max

05-25-2006, 07:18 PM

yes, I wasn't speaking about masks but rather linear gradients intended like fill or paint (transition from i.e. black to white). This "problem" is often present when you have a spotlight illuminating a flat dark panel (speaking in terms of a 3D application). The transition from bright to dark areas tend to get blotchy once composited (i.e. as background) and exported as a video (even uncompressed)

thatoneguy

05-26-2006, 08:59 PM

Render out in 16 or 32 bits per channel. You'll be able to color correct without banding.

GutenBar

05-28-2006, 05:24 PM

You can try to export to an image sequence.

king_max

05-29-2006, 11:10 AM

Thanks guys. I knew that, but eventually that image sequence will be compiled into a mpeg2 video and the thing will still persist. I'll try to upload a piece of video to illustrate what I'm talking about since I think I've been misunderstood.

GutenBar

05-30-2006, 09:33 PM

1- I did use different programs to export a given video using the same codec and they did give me different results, including something like this problem.

2- Same chose ocour when I did use sequenced images export to different codecs. QuickTime did show me the best result. You can try to export to QT and from its to MPEG.

king_max

06-04-2006, 01:58 PM

Here is a frame from an animation I did some time ago. Notice the volume light in the upper part of the image. Regardless of what format I comile the video, that problem persist and in fact it gets worse (since the camera is moving too).

seedo

06-07-2006, 04:45 PM

use bit depth converter and turn of the LUT,
dont forget to set the depth to 16 bit in the pit depth converter operator

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