Histograms, CIE and Plots
Every kind on this page shares the pane’s Display block.
The Four Histograms
Section titled “The Four Histograms”- Luma Histogram counts luma amplitude.
- RGB Histogram counts each channel and overlays the three additively.
- Hue Histogram counts hue round 0 to 360 degrees.
- Saturation Histogram counts saturation from 0 to 100%.
The Value Axis
Section titled “The Value Axis”Every rule and number, and the legal pair, appears while Grid is on.
| Kind | Rules and numbers |
|---|---|
| Luma Histogram and RGB Histogram | 0, 25, 50, 75, 100, plus 64 and 940 while Legal range is on |
| Hue Histogram | 0, 60, 120, 180, 240, 300 degrees |
| Saturation Histogram | 25, 50, 75, 100, and no rule at the foot |
Orientation, Scale and Shape
Section titled “Orientation, Scale and Shape”Orientation offers Vertical, the stock choice, with the value axis across, and Horizontal, which swaps the axes.
Scale offers Linear and Log, starting at Linear. Log spans two decades, the usual choice for a frame with a few hot pixels and a large dark area.
- Adaptive scales each bar against its own local maximum, lifting a small cluster into view without moving a sample between bins.
- Fill runs 0.05 to 1.0, and sets the opacity of every row of a bar. The row along the value axis stays at a fixed 0.85. At a low Fill a bar shows a lit line at its foot.
The Per-Kind Switches
Section titled “The Per-Kind Switches”- Split RGB on RGB Histogram alone divides the plot into three panels, one a channel, with a rule at each boundary.
- HDR overlay on Luma Histogram alone rules the plot at the PQ code of 100, 203 and 1000 nits, and labels each rung with its number. It shows the share of measured samples at or above 100 nit, as a percentage. Those rungs appear whether or not Grid is on.
- Luma band only on all four counts only the pixels inside the QC luma band, the Luma limits pair on the QC and the Error Log pane.
- Gradient on RGB Histogram alone tints each bar by its own signal value, blue at a low value to red at a high one.
The CIE Plot
Section titled “The CIE Plot”The plot is CIE 1931 xy by default, and the CIE 1976 u’v’ box switches the projection. The spectral locus runs from 380 to 700 nm, and a Planckian locus from about 1500 K to 20000 K appears as well.
Gamut chooses one of seven triangles: Rec.709, Rec.2020, DCI-P3, Adobe RGB, ProPhoto, ACES AP1 or ACES AP0. Rec.709 is at stock, with a white-point marker inside it.
Custom primaries replaces the chosen triangle with your own, in the rows Red, Green, Blue and White.
Zoom magnifies the whole diagram, its curves, its grid, its gamut triangle and its trace together, about the middle of the tile, and at 1x it fits the tile.
Out-of-gamut adds a second gamut menu, Error gamut, which starts at DCI-P3. A cell is flagged only when more than half of its hits fall outside that triangle. The Gamut Scope shows that limit in words: the space the source is taken as, and the space it is checked against.
The Channel Plot
Section titled “The Channel Plot”X channel and Y channel build a two-dimensional plot, one component against the other. A caption above the plot shows the pair as Luma / Cb.
Both axes are ruled and labelled at 0%, 25%, 50%, 75% and 100%, and Crosshair adds the middle pair of rules.
Each menu lists eleven channels: R, G, B, Luma, Cb, Cr, X, Y, Z, x and y. Choose your pair from R, G, B, Luma, Cb and Cr, the six a saved layout stores.
Saturation vs Luma
Section titled “Saturation vs Luma”Saturation vs Luma puts luma on the X axis and the magnitude of the chroma vector on the Y axis.
Its rows are Space, one of BT.601, BT.709 or BT.2020 with BT.709 at stock, and the Trace choice of Dots or Traces.