Tuesday, August 28, 2012

LUT for viewing CF raw

After some messing around I finally made a LUT that makes raw cineform files look like both transforms discussed in previous post (sensor > XYZ and XYZ > sRGB) have been applied.

EDIT: lut file link is broken at the moment, try to fix it soon...
Download the LUT file (.cube format) here:

Register the LUT file by doubleclicking on it (Windows), this installs it to Firstlight LUT directory.

To apply the lut, make sure that input and output curves are set to the same setting and that primary corrections are disabled. For some reason enabling primary corrections makes image slightly pink in highlights.

This lut works nicely in NLEs and video players but for some reason Resolve does not show any Cineform corrections. It seems that Resolve is able to reference raw file directly and bypasses Cineform renderer (confirmed in bmcuser forum by David Newman from Cineform)

WB correction, dammit!
Previous LUT makes image viewable but it still looks a bit too green. This is due to missing white balancing step which I tried to get working and got working (kind of) but I'm not sure I made it correctly.

DNG files contain metadata called as-shot-neutral which should be the value which is considered white (according to which illuminant? must dig more). In BMCC files, values read something like 0.63 1.00 0.79. If we take them as RGB values, it doesn't make any sense because RGB white should be 1.00 1.00 1.00. I figured it must be in either sensor values or in XYZ. Messing around with it, I thought that applying sensor > XYZ transform to this colour would give me white in XYZ space that I could then use to grade raw data in XYZ space by setting it's white point to my values. It works, kind of, because it removes the green tint but colors still seem a bit off.

Some sources (dcRaw developer for example) suggest that WB correction values to be applied before debayering because it prevents some debayer artifacts. If I could do it, I would try it... Seems that I must code my own test engine to try out my genius ideas... maybe even make it work on CUDA...

2 comments:

  1. Hi Hendrik, any updates on this? The lut is "file-not-found" I'd like to use Cineform with Resolve and get rid of the green, did you find a way?

    ReplyDelete
    Replies
    1. Sorry, didn't notice your comment before...

      The link is broken as I don't have access to that server anymore. I try to find the file and upload it to my new server as soon as possible.

      Delete