Module blend 

PDF blend modes (PDF spec §11.3.5).

All separable modes operate per-channel with src and dst in [0, 255] and return a blended value in [0, 255]. For CMYK/DeviceN the caller inverts the channel values before calling (255 - v) and inverts again after — the subtractive complement trick used by the C++ splashOutBlend* functions.

Non-separable modes (Hue, Saturation, Color, Luminosity) operate on full RGB triples (always in additive space); CMYK callers convert first.

Functions

apply_nonseparable_rgb

Apply a non-separable blend mode (Hue/Saturation/Color/Luminosity) to an RGB triple.

apply_separable

Apply a separable blend mode to each corresponding byte pair from src and dst.

blend_color_burn

Color burn: darken dst to reflect src.

blend_color_dodge

Color dodge: brighten dst to reflect src.

blend_color_rgb

Non-separable Color blend: hue and saturation of src, luminosity of dst.

blend_darken

Darken: min(src, dst).

blend_difference

Difference: |src - dst|.

blend_exclusion

Exclusion: src + dst - 2 × div255(src × dst).

blend_hard_light

Hard light: Overlay(dst, src) — the src/dst roles are swapped vs Overlay.

blend_hue_rgb

Non-separable Hue blend: hue of src, saturation and luminosity of dst.

blend_lighten

Lighten: max(src, dst).

blend_luminosity_rgb

Non-separable Luminosity blend: luminosity of src, hue and saturation of dst.

blend_multiply

Multiply: div255(src * dst).

blend_normal

Normal: result is the source (Porter-Duff over handled in the pipe, not here).

blend_overlay

Overlay: hard-light of dst over src.

blend_saturation_rgb

Non-separable Saturation blend: saturation of src, hue and luminosity of dst.

blend_screen

Screen: src + dst - div255(src * dst).

blend_soft_light

Soft light (PDF spec §11.3.5.3).