Color Crush.

[The Mastermind]

My editor and I have been doing some color timing changes to our short film, shot on high-def digital video. Generally speaking, it involves desaturating the image a bit and increasing the blue a bit to give the overall look a colder look than it would otherwise has.

However, as we did so we noticed that there's some noticeable digital crush/splotches in many parts of the image, especially in shadows (though they appear elsewhere in the lighter areas and midtones, too). A slight crush had been there in the original footage, but it seems the color corrections, saturation changes and other changes have made them more pronounced.

We're using Final Cut Pro to edit and complete these picture changes.

What is causing the crush and what can be done to eliminate (or at least reduce) it?

 

[escher]

Possibility 1: Due to the nature of 8-bit footage and the noise inherent in the blue channel (blue is the noisiest), you're running into clipping/grain that is only noticeable when you push up the blues. Run NeatVideo on your footage before grading to smooth that out.

Possibility 2: Early steps in the grading process are clipping your color channels and later steps are bringing that to light. If you can tell FCP to work in 24-bits, that might give you some extra latitude. Also read up on the filters you're using to see if they lose information that clips or if that information is still available to later filters before the final 8-bit clipped video is produced.

 

[The Mastermind]

Possibility 1: Due to the nature of 8-bit footage and the noise inherent in the blue channel (blue is the noisiest), you're running into clipping/grain that is only noticeable when you push up the blues. Run NeatVideo on your footage before grading to smooth that out.

Possibility 2: Early steps in the grading process are clipping your color channels and later steps are bringing that to light. If you can tell FCP to work in 24-bits, that might give you some extra latitude. Also read up on the filters you're using to see if they lose information that clips or if that information is still available to later filters before the final 8-bit clipped video is produced.

Thanks, escher, I'll explore both of those possibilities and solutions.

 

[knightly]

Which version of FCP? The older versions were 8-bit only... which is one of the really strong reasons one would send it to color after editing it to do your color correction and grading work... another is the more robust toolset therein. Not sure about FCPx in terms of bit depth, but it still doesn't have as powerful tools as the previous. I actually refuse to move up yet as they haven't suitably replicated the capabilities of the previous suite that they EOL'd... and I use... specifically the Audio, Compositing and Grading tools. Once they address these deficiencies, I'm all over it as the interface is SOOOO much better.

 

[The Mastermind]

I'll ask my editor what version of FCP he's using.

We plan to upload the film to share and eventually exhibit online. We've noticed that on certain very high quality settings, the color timed image looks fine, with no crush or artifacts. But the file size is enormous (nearly 20GB for a film that runs just over 15 minutes). So, now we think a lot of the problem lies in the compression or some other settings when we create the movie files.

But we need to use settings that are practical for online delivery yet retain good image quality. We tried using settings that many sites and forum posts have recommended:

Video setting: Compression: H.264
Quality: High Bit rate: 3000
Encoding mode: multi-pass dimensions
Optimized for: Streaming
Audio Setting: Format: ACC
Sample rate: 44.100 kHz
Channels: Stereo (L R)
Bit rate: 128 kbps
Prepare for internet Streaming: Fast start

However, we still see crush with these settings.

 

[jax_rox]

Never do your online edit at compressed settings. Always use the raw master files to do your online edit and colour grade. Export out a large file, uncompressed is best but ProRes or similar will be fine. From that, you can compress your video down for internet streaming or whatever you need.

 

[AudioPostExpert]

But we need to use settings that are practical for online delivery yet retain good image quality. We tried using settings that many sites and forum posts have recommended:

Video setting: Compression: H.264
Quality: High Bit rate: 3000
Encoding mode: multi-pass dimensions
Optimized for: Streaming
Audio Setting: Format: ACC
Sample rate: 44.100 kHz
Channels: Stereo (L R)
Bit rate: 128 kbps
Prepare for internet Streaming: Fast start.

Just some notes about your settings you may wish to consider.

"Audio Setting: Format: ACC" :- I take it you mean AAC. Some players may have a problem with this format, it was invented by Apple but is more ubiquitous than it was a few years ago.

"Sample rate: 44.100 kHz" :- 44.1kHz is the sample rate only used in the music business. Everything else, all Film and TV for example, uses a 48kHz sample rate. You shouldn't hear much difference between these two sample rates in practice though, so this is more of a "by the way".

"Bit rate: 128 kbps" :- This is likely to be more of a sound quality compromise. Ideally you would use an uncompressed audio format (such as wav) but that requires a bit rate of at least 1,400+kbps, which is a bit excessive. If you're trying to shrink file sizes without affecting audio quality too much I would recommend an MP3 audio format at no lower than 256kbps.

G

 

[The Mastermind]

Which version of FCP? The older versions were 8-bit only... which is one of the really strong reasons one would send it to color after editing it to do your color correction and grading work... another is the more robust toolset therein. Not sure about FCPx in terms of bit depth, but it still doesn't have as powerful tools as the previous. I actually refuse to move up yet as they haven't suitably replicated the capabilities of the previous suite that they EOL'd... and I use... specifically the Audio, Compositing and Grading tools. Once they address these deficiencies, I'm all over it as the interface is SOOOO much better.

My editor told me he's using Final Cut Pro 7. How would this version affect the color correction issue?

 

[The Mastermind]

Never do your online edit at compressed settings. Always use the raw master files to do your online edit and colour grade. Export out a large file, uncompressed is best but ProRes or similar will be fine. From that, you can compress your video down for internet streaming or whatever you need.

Thanks, jax, for this tip. I don't know if he used the raw files to edit so you may have just hit on something. I'll pass your advice on to him.

 

[The Mastermind]

Just some notes about your settings you may wish to consider.

"Audio Setting: Format: ACC" :- I take it you mean AAC. Some players may have a problem with this format, it was invented by Apple but is more ubiquitous than it was a few years ago.

"Sample rate: 44.100 kHz" :- 44.1kHz is the sample rate only used in the music business. Everything else, all Film and TV for example, uses a 48kHz sample rate. You shouldn't hear much difference between these two sample rates in practice though, so this is more of a "by the way".

"Bit rate: 128 kbps" :- This is likely to be more of a sound quality compromise. Ideally you would use an uncompressed audio format (such as wav) but that requires a bit rate of at least 1,400+kbps, which is a bit excessive. If you're trying to shrink file sizes without affecting audio quality too much I would recommend an MP3 audio format at no lower than 256kbps.

G

Thanks, I'll also pass this on to my editor.

 

[knightly]

In FCP7, he should have access to Color. That has a much higher bit depth for the footage. I would generate prores clips from the h.264 ones you're currently using and swap those into the timeline, then "send to color" and perform your CC and Grading there. Your results should be much more pleasing there.

 

[2001 Productions]

I would generate prores clips from the h.264 ones you're currently using and swap those into the timeline, then "send to color" and perform your CC and Grading there.

YES! Do this! You'll be SO glad you did.

BTW, I'm going to pretend that it really bothers me when people who have never worked with FILM use the phrase "color timing". No. Sorry. Can't allow that. Gotta earn that right.

 

[jax_rox]

BTW, I'm going to pretend that it really bothers me when people who have never worked with FILM use the phrase "color timing". No. Sorry. Can't allow that. Gotta earn that right.

I generally associate 'colour timing' with the actual process of colour timing film.

These days, digital 'colour timing' is a 'colour grade' for sure. If it's done digitally, it's a grade.

But then, many people don't know that 'pan down' is wrong, so..

 

[2001 Productions]

But then, many people don't know that 'pan down' is wrong, so..

Aaargh! Don't get me started!