Lut Cube Howto
Posted 14 November 2011 - 06:14 AM
Posted 14 November 2011 - 06:26 AM
How was the material graded? If it was done in something like lustre or another profesional color system... On a recent project I was able to match primary grading or printer lights exactly using a multiplication in linear color space. So just remove the gamma, add a ColorGain tool and use the advanced color picker macro from vfxpedia to sample the color of a certain area. Then adjust the gain sliders until the color matches the original plate.
Posted 14 November 2011 - 09:19 AM
If you can make the CC's match curve (or any combination of color tools) to replicate the primary grading,
then you can take an instance of that CC (or color pipeline),
grade a LUTCubeCreator with it and utilize a LUTCubeAnalyzer to write out a 3DLUT for you
which then can be applied to raw material via the FileLUT tool e.g.
Posted 14 November 2011 - 09:33 AM
But the Fuses won't accept two images and calculate the difference, they need the LUTCubeCreator's test pattern.
Posted 14 November 2011 - 09:57 AM
Actually it is pretty obvious why not: a normal image only has a very tiny portion of the complete color space in it. So you could only match the difference for that particular subset of the colors that are used in the footage.
I actually wrote a (unaccelerated / time consuming) fuse for matching the difference but it's not worth it. You would need to extract the biggest possible color space from all the temporal information and still would need to guess / interpolate a big part of the LUT. Also any secondary grading obviously can lead to problems.
Bottom line: for safe results use the 1:1 LUT Cube. Please be aware,
Edited by bfloch, 14 November 2011 - 12:13 PM.
Posted 14 November 2011 - 10:11 AM
Posted 14 November 2011 - 10:13 AM
Posted 14 November 2011 - 11:28 AM
Connect your raw material to the BG input of the CC.
Connect the graded material to the FG input
In the histogram tab click "match".
If the result is okay you can use a copy of that CC to grade a color cube as mentioned before.
(Along with the color-subset restrictions pointed out by Blazej)
Posted 14 November 2011 - 11:48 AM
Posted 14 November 2011 - 12:12 PM
Yes you are right. Changed that. Thanks for pointing it out!
Posted 14 November 2011 - 01:30 PM
What's the correct grade for the mail box you just comped into this desert landscape? If the mail box is green, and your desert is just yellow sand and blue sky, who's to notice if the color comes out slightly wrong?
Posted 14 November 2011 - 08:35 PM
For similar shots the technique single frame method is pretty ok once you use bigger thresholds for matching the colors.
Any sugestions for the extrapolation? I was thinking about turning the known points to csplines and and giving control over the whites and blacks.
Posted 15 November 2011 - 10:28 AM
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