RGB Parade: what is the variable on the horizontal axis?

[Guy Burns]

I'm running CS6. I thought I could find the answer to this question from Adobe, but no. Then I tried half a dozen sites – still no answer, so I've come to the forum.

What is the variable on the horizontal axis for the three colours of the RGB Parade?

[Ann Bens]

Might need to explain this more. dont understand your question.

[John T Smith]

I had never heard of RGB Parade so I went to Google

There are links to YouTube videos and tutorials to help learn

[Guy Burns]

Thanks for the replies, and the suggestion of tutorials, but I'm a reasonably capable user of the RGB Parade. I use it in conjunction with RGB curves to accomplish colour correction, similar to what I do in Photoshop – but it's not as easy in Premiere. Certain features available in PS are lacking.

I've never needed to know how the horizontal axis is calibrated, but today I thought I should look into it. And none of the dozen or so web sites that I visited told me what's along the horizontal axis.

Photoshop's Histogram

Let me go to a similar graph that I understand – Photoshop's histogram. The horizontal axis is the level (0-255), while the vertical axis is the number of pixels at each level. So for a dark image, you get a hump at the left, for example. Or you might get a bell curve for a well-exposed image with a good spread in the tonal range.

Premiere's RGB Parade

The vertical axis on the RGB Parade is the level. I used to think it was 0-255, but for certain clips that go right to the bottom (black), I am able to raise them and see a jagged bottom edge, which says to me the RGB Parade is not showing down to 0 on the vertical axis, but to a higher level, say 16. So the graph is being clipped at 16, which means when I brighten the clip, the levels below 16 become visible. At least that's what appears to happen.

So… the vertical axis shows the level (black at the bottom, white at the top) – but what is the horizontal axis showing? What is the variable along the horizontal axis?

[Ann Bens]

R Neil Haugen might be able to help you out here.

[Peru Bob]

The horizontal axis of the graph corresponds to the video image from left to right.

from here:

Use the Waveform monitors and vectorscope in Premiere Pro

[R Neil Haugen]

The vertical axis is (on the left side) 0-100, the right-side scale changes depending on the selection for 8-bit, float, or HDR. 8-bit, that's 0-255, float, 0-1, and HDR, 0-100.

Note the "clamped" check-box. In 8-bit or float, that when checked (signal clamped) shows no signal below 0, but when un-checked certainly can. It's greyed-out in HDR mode.

So ... if you're in 8-bit or float, and have the Clamp on, signal will be shown as clipped at 0, even if you've signal below that. So, lift your dark values, and you see the signal that was clipped before appearing above 0. Undo your value lift, uncheck "Clamp", and you'll see there's some trace showing below 0 on those clips you're seeing.

Neil

[Ann Bens]

Neil this is CS6.

[R Neil Haugen]

Oh ... right. No HDR then, is there? ... Ahem ... I believe the rest would still apply, though was the Clamp option in 6 or did it start with the first CC issue? I dropped CS6 on my rig a bit over a year ago.

Neil

[Ann Bens]

No, no clamp in CS6.

I having a bit of a trouble with the question on variable on the horizontal: for me that is 0

RGB always has shown slightly more then the Waveform.

[R Neil Haugen]

Yea ... and really, the horizontal axis (in a mathematical sense) this isn't ... it's just the image, left to right. With each section R-G-B shown complete, so you see the full image left-to-right in the Red channel, then the Green channel, then the Blue channel.

Neil