Color Checker

Color Checker is a camera calibration: photograph a reference chart in the same light as the subject, and Heeler fits the white balance, an exposure correction, and a 3x3 color matrix that bring the chart's measured patches onto its published values. The section sits at the bottom of the Adjustments panel, below Lens, and corrects the camera before any grading: in the graph its node runs after the warps and the Depth Map, before Color.

The workflow

1. Shoot the chart in the light you are working in, square on if you can, large enough that each patch is a clean area. One frame with the chart is enough for the whole session.
2. Pick the chart from the section's menu: ColorChecker Classic, Passport, and SG, in both the current and the pre-November 2014 printings, and Datacolor SpyderCHECKR 24 and 48. The values are the makers' published ones.
3. Place chart shows the chart grid over the photograph. Drag the four corners onto the chart's corners; a tilted chart reads square-on. Click a patch to leave it out of the fit (a second click brings it back), and drag a patch to nudge its center when a print has drifted off its grid.
4. Calibrate samples each patch and fits. White balance says where the fit's temperature and tint go: To node writes them to the Color section's white balance, where you can still move them, and the matrix carries none of it; In matrix leaves that node alone and folds the same gains into the matrix. Amount fades the whole correction.

The section is laid out as the work goes: the chart and its placement first, then the calibration and what to do with it, then the look of the chart lines over the photograph. 5. Save calibration names the result and keeps it under Calibrations in the Presets tab. Applying one to another photograph from the same camera and light is one click from the section's menu; if the saved camera differs from the photograph's, the section says so and applies anyway.

The sample area

Each patch's reading comes from a circle at its center, drawn over the photograph as the ellipse that circle becomes under the chart's tilt. Sample sets the circle's size, 10 to 90 percent of the patch, 40 to start, in the section and on the node alike. Dragging any circle's rim sizes every circle together, with the number showing while you drag. Smaller circles sit tighter on small patches; larger ones average more of a patch that printed unevenly. Calibrate measures exactly the region the overlay draws, so what you see is what the fit reads.

The lines

The grid, the circles and the corner handles draw in the shared line color and thickness, the same settings Shape Warp's outlines use. The LINES row picks a hue and brightness or leaves them automatic (the opposite of the photograph's own average), and THICKNESS overrides the preference for this photograph alone. One setting serves every tool, so a color chosen here is there for the warps, and vice versa.

Reading the report

The report under the buttons is the fit's account of itself: the mean dE (CIEDE2000) across the fitted patches, the worst patches first with a before and after swatch pair each, and a guess at the illuminant from the fitted temperature. Under a dE of 1 is below what an eye separates; single digits are a good fit. A patch outlined dashed in the grid was flagged: clip means its reading climbed toward the white patch, so it is likely clipped or flared, and glare means the sample circle caught an edge or a reflection. Flagged patches are left out of the fit. The last line is the provenance: which camera the fit was made on, and when.

The fit needs at least one gray patch for the white balance and four usable patches with three chromatic ones for the matrix. With fewer it fits the white balance and exposure alone, leaves the matrix at identity, and the report's note says so.

Custom charts

A card of your own, or a chart Heeler does not ship, calibrates the same way. Custom chart... opens the editor over the photograph: set the rows and columns (the fields drag sideways like every other number, or type), click a cell, and give it a target. The palette lists every patch of every built-in chart, the Classic's 24 first, grouped under their source chart, with a filter once the list runs long. A color of your own types as sRGB hex or as Lab from the card's datasheet: the two modes convert into each other, and the swatch shows live what the fit will aim at. Clear empties a cell again; a cell with no target is ignored by the fit. Without a gray control the editor warns that white balance cannot be fitted; a white or near-white control also lets the fit spot clipped patches. The chart saves beside the built-ins and lives as one JSON file in the charts folder of the presets library; the editor's Import and Export share chart files the way the Presets tab shares looks.

The same sampler, the same fit, and the same report apply to a custom chart, and a calibration fitted on one saves and applies like any other.