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Some questions about grading and chroma subsampling from a cinematography noob


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#1 Evan Richards

Evan Richards

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Posted 14 September 2017 - 11:16 AM

Ok, so I'm a relative noob to cinematography in the sense that I've basically only ever shot with the 5d mk II and other cameras that shoot in h.264 formats. I'm interested to see how far I can push better footage. 4:4:4 footages and 4:2:2 footages. So I went on Kinefinity's site and downloaded some of their test footage.

 

Correct me if any of the following information seems wrong. I'm just trying to figure things out.

 

I brought the raw cineform .mov footage into after effects.

In case it matters I'm specifically using this clip: https://www.dropbox....028-A1-5426.zip

 

I set the project settings to 16 bit with working space set to "none". I realize the footage isn't 16 bit but that should give me the color leeway I need to make sure I don't lose any information which would happen if I set the project settings to 8 bit (right).

OK. So I have my raw footage. Raw footage is by its nature 4:4:4 right? The chroma subsampling is always a result of the compression correct? You'd never get a subsampled image from the sensor would you?

I bring it into after effects and drop it into a timeline. I then export it three different ways. I export a prores 4444 (with export depth set to trillions of colors) and prores 422 (with export depth set to trillions of colors) and apple intermediate codec which I've read is a 4:2:0 codec (with export depth set to millions of colors).

 

Then I import these three clips into my timeline. So now I have 4 tracks, each one the same shot.

1. My original file which is an uncompressed cineform .mov

2. An apple prores 4444 (hopefully this won't look much if any different from the source file)

3. An apple prores 422

4. An apple intermediate codec (4:2:0 I believe)

 

When I start pushing these around the only difference I notice is that on the 4:2:0 shots the red colors seem a little more saturated. Some colors are slightly shifted as well. More green it seems.

When I adjust the exposure though, it doesn't seem to give me any more latitude in the car headlights in the raw footage that it does in the 4:2:0 footage.

When I crank up the saturation the 4:2:0 footage does seem to be a little blockier than the raw footage.

But overall the difference between 4:4:4 and 4:2:0 seems to be pretty negligible and I know that can't be right. The differences between editing a quicktime movies I've shot on my 5D and editing a raw photo is night and day and I have to imagine a 14-16 dynamic range camera like the Kinefinity 6K the difference would be even greater.

 

The only reason I used after effects is because I know how to use it pretty well and it was the only software I have that would read all the different formats (resolve wouldn't read the apple intermediate codec and I couldn't export an h.264 at the 6k and I didn't want the variables introduced if I resized anything.

 

So what's going on. What am I doing wrong. Is there a better way to test this out?

 

Please advise.

Thanks!!

Evan


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