Colour grading bug?

What is your operating system?
Windows 10

What is your Shotcut version (see Help > About Shotcut)? Is it 32-bit?

Can you repeat the problem? If so, what are the steps?
(Please be specific and use the names as seen in Shotcut, preferably English. Include a screenshot or screen recording if you can. Also, you can attach logs from either View > Application Log or right-click a job and choose View Log.)

I add a log video to a track and add the LUT filter then apply a rec709 lut. Then if I add another LUT filter but with no file loaded or add the colour grading filter without changing anything the colours change.

If no lut file has been loaded and no change in the colour grading filter the colours should not change.

Or am I missing something?

Would you give a before and after screenshot with an example clip. This would help to determine how big or small the difference is, just to test I have also tested this on the trial version of on another video editing software and it also does the same thing, I don’t know if it’s a bug or something which is normal to happen.

Also are you able to reproduce the problem on another clips or it just happens on a particular clip?

Made three screen dumps of the waveform.

  1. Unaltered
    2.With LUT but no file loaded, video gets heavy banding.
    3.With LUT but no file loaded and Colour grading filter but with no change.

In my opinion adding the LUT filter but no file loaded shouldnt change anything, adding colour grading filter with no change should also do nothing.

I belive that if you have applied one filter then the next should affect the result from the previus filter.

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Hmm? Seems something different, lut and color grading both changes the color without changing the parameter, the most possible guess is, this is a bug (Could be wrong, I am not a bug category expert), Have you encountered the same problem in the latest stable version 21.03.21, If yes than it might be a problem that’s there but unknown from the older versions, If no then the release you are using is having same problem.

Yes, it’s there also.

I wonder what values gets loaded when no lut has been loaded and do those values stay when a lut is loaded or do they get replaced?

I also noticed that applying Color Grading without change in the stable version generates worse change than no changes than in the latest.

And waths with the Luma, those spikes?

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Compared to Davinci:

Than this proves it’s a bug (atleast for me), Brian could help to solve this in the next updates, or it just happens normally in shotcut. I wonder🤔 still, why Vegas Pro does the same (But in Vegas it only happens with color grading after luts).

Is Davinci doing the same or it’s just in Shotcut and Vegas?

Luma means the brightness of the image or video.

Luma means the brightness of the image or video. And the only solution to avoid this bug (problem?) Until next update, Is to just export the video after lut is applied and then again add it to shotcut for adding color grade or second lut.

I know but why doesn’t the spikes show in davinci?

Haven’t found how to apply lut’s in davinci yet, I will try later.

Okay, So it was really a bug and now it is approved. It might be solved soon.

Because Davinci’s UI is very different than shotcut, studio version of Davinci also has rotobrush (which is also in AE), So it makes the layout different even more different. And Davinci is one of the most best, stabilized and powerful software you could get, that’s make it totally different than shotcut.

Okay! I’ll keep my eyes out for a new version.

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