-
RGB image sequences into QT, colour shift
Argh.
I’ve trawled the forum archives about this problem, but I’m afraid that all I’ve found is confirmation that it is a problem, and I’m still on the hunt for a solution or work-around.
We’ve got lots of animation, as RGB image sequences. They’re photographs, so unlike CG, re-rendering is not an option.
When we use QuickTime to convert them into ProRes 4.2.2 HQ, the colours are changing, and the D.O.P. is unhappy.
I’m hoping somebody can point us in the right direction for either:
(a) an exact description of what the shift is so that we can accurately compensate for it in the grade or using filters
or
(b) a way of making RGB image sequences into ProRes .mov files that are visually the same to the human eye.Stuart
-
4 Replies
-
maybe try bringing them across to an RGB codec like animation and setting the display gamma they have been created in within the clip properties in final cut pro (in gamma under item properties or browser column)
you can set the still image duration to 1 frame and the gamma level to whatever the source system may have been with final cut same as RGB codec videos
alternatively Motion can read image sequences and bring them in as sequences if they numbered correctly in the folder, once in a motion with the correct project settings and duration, you just save and import into final cut pro, then render. not sure if the display gamma can be set in motion however.
if you have bars on the image sequence it makes checking black levels more easy
remember that if the stills have been created using a stills camera the white and black levels are also totally different from video and this adds further complexity e.g. r16b16g16 black in video rgb000 in stills, r235g235b235 white 100% video, r255g255b255 in stills
levels commands would help out here to fix– – – – – – – – –
Check my podcast at https://cowcast.creativecow.net/final_cut_pro/index.html
or my site at
https://www.benscottarts.co.uk/ – – – – – – – – – -
[Stuart Bruce] “When we use QuickTime to convert them into ProRes 4.2.2 HQ, the colours are changing, and the D.O.P. is unhappy.”
you are checking these on a broadcast monitor right?
quicktime will sometimes show washed out video where it actually isn’t.
within the quicktime preferences is a check box for maintaining color
compatability. Then it never has the problem. -
Thanks for the suggestions. We’re still looking into this and I’ll post again if and when we get somewhere.
The colour difference between the original image is definitely a problem on any monitors, including broadcast ones. As mentioned in other posts on this forum, taking an image sequence into QuickTime and exporting it again with supposedly the same settings gives you original and output images that are different.
The Motion route is looking promising, fingers firmly crossed.
-
I’ve found that using Apple’s Color to transcode RGB to YUV ProRes to be very accurate.
-Russ
Russell Lasson
Ridgeline Digital Cinema Mastering
Universal Post
Salt Lake City, UT
Reply to this Discussion! Login or Sign Up