Color Picker and comparison

Point and area samples

The live readout follows the pixel under the pointer. A click pins that color; a drag pins the average of a rectangle. An area average is generally more repeatable for textured material, sensor noise, antialiasing, or compressed imagery because it does not depend on one pixel.

The appropriate sample size depends on the question. A point can inspect a specific graphic value or edge pixel. A small, visually uniform area is better for comparing surfaces, skin, sky, or another naturally varying subject. Avoid averaging across boundaries unless the mixture itself is what you intend to measure.

Values and assumptions

SideScopes reports the captured RGB code values and derives perceptual coordinates by treating those values as sRGB under a D65 white point. It does not read the source document profile, timeline working space, display ICC profile, mastering metadata, or printer profile.

The readout is therefore a measurement of the screen-captured result under a stated assumption. It is not a probe into the source application’s internal pixel values, and it is not a spectrophotometer measurement of emitted or reflected light.

CIEDE2000 comparison

When a pinned color is selected as the reference, SideScopes converts both samples from assumed sRGB to CIELAB and reports ΔE00 using the CIEDE2000 formula. It also shows signed diagnostic components:

• ΔL*: change in CIELAB lightness;
• ΔC*: change in CIELAB chroma;
• ΔH*: a chroma-weighted hue-difference term.

These components describe the difference; they do not map one-to-one to exposure, saturation, white-balance, or grading controls. CIEDE2000 also weights and couples its lightness, chroma, and hue terms, so its total is not a simple sum of the three displayed components.

Interpreting ΔE00

A smaller ΔE00 means the two assumed-sRGB samples are closer under the CIEDE2000 model; zero means their converted CIELAB values are identical. There is no universal pass/fail threshold. Visibility and acceptability depend on the colors involved, image structure, sample area, viewing conditions, display, observer, and the requirements of the workflow.

Use ΔE00 to compare like with like: the same patch before and after a change, corresponding regions in two outputs, or repeated measurements through a controlled path. Do not treat it as proof that two physical objects, displays, or prints match.

Reference: the CIE publishes the normative CIEDE2000 color-difference formula.