VP 18: Color Grading/Correction Guidance (balancing waveform and histo

sakendrick wrote on 10/15/2020, 10:25 AM

I've reviewed a handful of YouTube vids on color grading using the grading tool but it seems whenever I tweak to get the Histogram in a good spot the Wave form is then out of whack and vice versa. Specifically, I adjust to get the waveform to fall within 0 and 100, then I go adjust to expand to get between 0 and 255, and center as appropriate, the results look good, then back to check the Waveform and it's outside the 0 to 100 bounds.

Is there a right order in terms of knobs to adjust to keep everything where it should be?

One other thing I notice - On the edges of histogram and the waveform - I've got some hard lines (spikes on the left and right of the histogram)... should this be more rounded and any idea what causes this?

Thanks all!

Comments

Musicvid wrote on 10/15/2020, 10:28 AM

Adjust your histogram to fall within 16 and 235. Do not change your waveform settings. They are set correctly.

Marco. wrote on 10/15/2020, 10:40 AM

Beware the new VP18 levels mode tries to equal all input levels to be processed as full levels internally, thus the histogram view is 0 - 255 even for limited levels inputs.

Musicvid wrote on 10/15/2020, 1:11 PM

What a mess...

sakendrick wrote on 10/15/2020, 9:54 PM

Beware the new VP18 levels mode tries to equal all input levels to be processed as full levels internally, thus the histogram view is 0 - 255 even for limited levels inputs.

Not sure I follow...

Musicvid wrote on 10/15/2020, 10:11 PM

You're not alone.

https://www.vegascreativesoftware.info/us/forum/vp18-notes-on-the-8-bit-full-level-option--122749/

RogerS wrote on 10/16/2020, 1:15 AM

These tools are also showing you data in a somewhat different way. I just opened up a test project in 8-bit full to see how the scopes differ.

For setting end points I'd use RGB parade in separate mode. I think it's clearer than the waveform as to where important data starts and ends. The Vegas histogram is so low resolution I don't find it useful for much of anything.

With the waveform, are you seeing this in luminance or composite mode? I'd use luminance to see better where the highlights are going and if any are being crushed against the 100 ceiling. Composite seems to show data above 100, which is probably just specular highlights (it is on the footage I'm looking at)

When you render, Vegas will go from full to limited levels by default, so it's okay to edit using in 0-255 looking at the histogram and RGB parade.

Hard lines on the highlight side are probably from a jump in brightness with a light source or specular highlight that is clipping. Not an issue. On the shadow side, some kind of deep shadow? RGB parade might give more of a clue as to what is what. In any case, don't worry about the shape.

NickHope wrote on 10/16/2020, 1:40 AM

Disregarding the new VP18 levels mode, visual noise is much more visible on the VEGAS histogram than the waveform. So what looks like the black and white areas of your shot on the histogram might really be just a few insignificant pixels that are beyond the general luminance extents of the rest of the image (i.e. noise). So the waveform is generally better for deciding what to target for your black and white points.

A screengrab showing your "hard lines" would be useful. Even more useful if you screengrab the accompanying video preview too. A band at the far left of your histogram may indicate a black band at one or more edges of your frame. Not sure about hard lines on the right... some spikiness is normal. Sharpnening might accentuate it, so don't overdo that.

sakendrick wrote on 10/16/2020, 7:57 AM

Thanks all... I've read the thread on levels but it's quite a bit over my head... is this a feature that I can just turn on to help with color correction, and how do I do it? I'll grab some screen captures shortly.

RogerS wrote on 10/16/2020, 8:52 AM

You don't need to think about it so much. Leave it at the default of 8-bit full range and the scopes work as expected with all videos appearing to be full range. Instead of the histogram, stick to waveform, or RGB parade if you want to see what's happening in each channel, and you'll be fine for color correction.

Spikes in a histogram just indicate a large presence of pixels of a certain brightness value. So if there's a black border you'd see a tall black line. Ditto something that is pure white, like a light or reflection of a light.

Musicvid wrote on 10/16/2020, 9:13 AM

I'm pretty sure I wouldn't use it -- every idiot switch one adds to the chain raises the probability of making an error by ^2.

sakendrick wrote on 10/16/2020, 9:15 AM

That makes sense regarding spikes at either end. I'll focus on wave form/RGB parade in future projects. Usually I find contrast is the biggest item that needs adjustment which is why I was focused on the histogram.

Musicvid wrote on 10/16/2020, 9:44 AM

Spikes at either end indicate clipping, even if just caused by a thin black border or single specular highlight. It is characteristic of Vegas' logarithmic scopes, where domains are switched in the display, as Nick just pointed out with his example.