Whether to change black levels and colour matrix of video?

[ballsoup]

I captured some video from a Sony DCR-TRV530 camcorder via i.LINK. I've seen some avisynth scripts use ColorYUV(levels="PC") to change the black level and fix clipped whites. Is this something that should be used on videos captured by Sony Digital8 cameras? I'm just wondering because some detail is exposed when I use that line, but the blacks become a bit too gray. I also heard that this shouldn't even be needed since with i.LINK a perfect capture of the source is given.

Another related question I have is about the color matrix. The videos are recorded in YV12, and some Digital8 restoration scripts use ColorMatrix(source=2, dest=0). The avisynth wiki says this:

# overbright reds, faded greens: perform a 601->709 conversion

This does seem to make reds look a bit richer, but again, I want an accurate looking video. Is this something I should add in my script or is it not required?

[johnmeyer]

Is your monitor calibrated? If not, then you can do a lot of unnecessary damage to a video by "correcting" it to make it look good on a monitor whose color and luma levels are not calibrated.

Does your editing software include histograms, RGB parade, vectorscope, or other aids to determine levels? Again, if not, you are shooting in the dark.

[jagabo]

Make sure your DV decoder is putting out YUV, not RGB. Then check your levels with Histogram(). The blackest blacks and brightest brights should just touch the yellow/brown bars. Adjust you levels accordingly.

[ballsoup]

I'm doing the editing on my Retina Macbook Pro, but I'm running Windows, so I don't know how well calibrated the screen is. But I suppose it's good enough, right?

I'm not really using anything to determine levels. I will use the histogram feature and report back.

[jagabo]

The default Histogram() in AviSynth is vertical instead of horizontal. If you prefer a horizontal graph use TurnRight().Histogram().TurnLeft(). That will get you a horizontal graph above the image. Info about the waveform graph returned by Histogram():

https://forum.videohelp.com/threads/340804-colorspace-conversation-elaboration#post2121568

[Master Tape]

Is your monitor calibrated? If not, then you can do a lot of unnecessary damage to a video by "correcting" it to make it look good on a monitor whose color and luma levels are not calibrated.

Does your editing software include histograms, RGB parade, vectorscope, or other aids to determine levels? Again, if not, you are shooting in the dark.

I've read it's best to correct levels on an old CRT monitor due to it having the best blacks. Would you still get as good results on say a calibrated Dell UltraSharp?

[jagabo]

You don't even need to see the picture to get black/white levels correct. Just use a waveform monitor.

[Master Tape]

You don't even need to see the picture to get black/white levels correct. Just use a waveform monitor.

Ohright, nice. Is that also the case with correcting colour levels?

[johnmeyer]

You don't even need to see the picture to get black/white levels correct. Just use a waveform monitor.

Ohright, nice. Is that also the case with correcting colour levels?

Only if your tape includes color bars, and only if your actual video was calibrated with a white card (if it is camcorder video). In that case you can use a vectorscope. Otherwise, a calibrated monitor is the way to go.

I use a Spyder colorimeter to do the calibration. Even if you don't want to spend the money for calibration hardware, you should at least attempt some sort of software color calibration. Having a calibrated monitor is the only way to "get it right every time." Maybe you can find someone who has some calibration hardware you can borrow for a few minutes. The calibration procedure is neither difficult nor time-consuming, once you have the hardware in hand.

[jagabo]

You don't even need to see the picture to get black/white levels correct. Just use a waveform monitor.

Ohright, nice. Is that also the case with correcting colour levels?

No, working with colors is much more complicated so you nned to see the picture.

And to be clear, when I was talking about adjusting levels without seeing the picture I was talking about gross levels adjustment (for example, when setting the levels for a video capture of mixed material), not shot by shot or frame by frame adjustments. Not all shots will have full blacks and/or full brights. For that you need to see the picture.