Color Engine

Color Engine

Image Draw Bot maps source-image colors to colors the selected target can actually draw.

The color system includes:

• OKLab-based perceptual color matching
• calibrated target palettes
• color grouping and reduction
• Named Color Intelligence
• CSS4 and Tk/X11 compatible color names
• RGB, RGBA, ARGB and HEX parsing
• human-readable color diagnostics

Named colors are diagnostic/input helpers. They do not automatically add extra colors to a calibrated target palette.

Why can a photo look posterized?

Quantized target shows the colors selected by the current plan. A limited target palette can replace many skin tones and shadows with the same pink, gray or white. This can happen before any strokes are drawn.

Check the target profile: Other drawing app with palette Unavailable / exact Unavailable is not a calibrated Microsoft Paint preview. Choose Microsoft Paint and calibrate its RGB controls. For image-specific colors, use Adaptive exact (recommended) or Exact custom + palette fallback, with Faithful or Exact fidelity, then rebuild the preview. More colors can preserve more gradients but increase drawing time.

Custom color palette for picture analyzes image colors and, from rc7, saves up to 24 of them into Paint Custom colors using + with a pause between additions. From rc8, the completed picture palette is shared by Pixel Accurate, normal color-run planning, the preview and runtime selectors for that same loaded image. Earlier releases could keep showing an old preview or bypass this palette in Pixel Accurate. Run the picture-palette button again after updating, then rebuild the preview. A photograph is still reduced to a limited number of representative colors. Calibration alone does not undo quantization.

The diagnostic luminance +15% measures brightness drift in the mapped colors; it is not a brightness adjustment setting. A pair such as LightGray→White describes a detected color substitution. Compare the rebuilt Quantized target and Simulated final before a full drawing. Neither is a guarantee of the actual Paint result.

Finer picture tones in rc9

The image palette now receives a bounded OKLab refinement pass. It uses up to 16,384 source samples and eight iterations, fills unused palette slots when useful, and preserves tiny color accents. A refinement step must lower squared sample error without worsening its 95th-percentile error. Image-palette matching uses nearest OKLab distance rather than the brightness preference used for coarse standard palettes. Preview and drawing still share the same ordered RGB palette.

Rerun Custom color palette for picture after updating, then Build preview. The Paint preparation limit remains 24 colors; additional slots or faster input are not required. These changes improve the palette approximation, not the precision of the mouse or Paint brush itself.