Color & samples, one decision at a time

A teaching model for storage arithmetic and color decisions. Change a scenario to see storage arithmetic and required decisions. This does not encode pixels, render calibrated HDR, or simulate an OS color manager.

Scenario

Three different truths

Origin

What the file said. Preserve raw ICC/CICP and coding details as provenance.

Current

Output

One sample, several meanings

nominal blacknominal white

The marker clips to the drawing bounds; the numeric value does not. This is a code-value diagram, not a color swatch. Limited-range chroma uses a different neutral point and nominal upper bound.

Where the bytes go

Run the plane/component examples in the pixel explorer. Interleaved CbCr already uses ordinary planes; RGB10 + alpha1 also works through per-component CodePlane readers.

Decisions & assumptions

Cross-platform reality

Working-space white, display white and HDR peak are different values. Windows scRGB's nominal 1.0 is 80 nits; the CSS HDR draft uses 203 nits for SDR reference-white anchoring. Neither is a universal image default. Apple's EDR pipeline introduces its own display/headroom context.

PNG defines color-chunk precedence; carrying two blocks does not mean both are equally authoritative. Destination encoders must follow their format's rules. This model marks platform support unknown rather than guessing from a file extension.

PNG specification · CSS HDR working draft · Windows Advanced Color · Apple EDR