Image Adjustment

Image Adjustment is an image-in / image-out filter that follows the generator contract: it takes an Image input, renders to an offscreen texture, and outputs Image, Width and Height — where Width/Height simply pass the source's content dimensions through (this is a 1:1 filter; nothing is resized or moved). When Enable is false or no source is connected, the output texture is cleared so a Canvas downstream never shows a stale frame.

The whole grade is a single pointwise compute kernel — one GPU thread per pixel, no intermediate passes. Source textures are premultiplied alpha (the Grafit generator convention), so the kernel first un-premultiplies, grades the straight RGB, then clamps and re-premultiplies on write. Alpha itself is never modified — transparent regions stay transparent.

Operations apply in a fixed, deliberate order (each stage feeds the next):

1. White balance — Temperature shifts red/blue (−1 cool … +1 warm), Tint shifts green/magenta.
2. Exposure — photographic stops: gain = 2^EV.
3. Levels — Blacks and Whites remap the black/white points: rgb = (rgb − Blacks) / (Whites − Blacks).
4. Shadows / Highlights — luma-masked lifts: shadows weighted by (1 − luma)², highlights by luma².
5. Contrast — pivot at 0.5: rgb = (rgb − 0.5) · (1 + Contrast) + 0.5.
6. Gamma — rgb = rgb^(1/Gamma); above 1 brightens midtones.
7. Hue Shift — YIQ hue rotation in degrees.
8. Saturation + Vibrance — blend toward luminance gray; Vibrance adds extra saturation scaled by how unsaturated a pixel already is, protecting skin tones and already-vivid colors.
9. Selective color — Color Filter measures each pixel's hue distance (on the hue circle) to Key Color within Color Range, feathered by Color Softness. Remove Color desaturates matching pixels; Isolate Color desaturates everything else (the "Sin City" look).
10. Posterize — quantizes each channel to N levels (active from 2 upward; 0 = off).
11. Film grain — animated noise refreshed at 24 fps (film cadence), sized by Grain Size in pixels. Weighting follows a classic film curve — strongest in midtones, 4·luma·(1−luma) — and Grain on Blacks morphs that toward a shadows-weighted curve (1−luma)² that leaves whites clean.
12. Vignette — aspect-correct radial darkening from the frame center, feathered by Vignette Softness.
13. Mix — final linear blend between the untouched original and the fully graded result.

Tone

Color

Finish

Order matters between parameters: Blacks/Whites re-span the histogram before Shadows/Highlights and Contrast act on it, and Saturation is applied after Hue Shift — so a hue-rotated image desaturates exactly as you'd expect. Vibrance stacks additively with Saturation.

• Classic black & white: Video Player → Image Adjustment (Saturation 0, then shape with Contrast, Blacks/Whites, Shadows/Highlights, finish with Grain and Vignette) → Canvas.
• The "Sin City" look: Camera Input → Image Adjustment (Color Filter = Isolate Color, Key Color red, Color Range ≈ 0.1) → Canvas — only red survives on a monochrome frame.
• VJ color pulse: Audio FFT band → Hue Shift or Exposure — the grade breathes with the music; keep Mix around 0.7 so the source stays readable.
• Film emulation chain: Image node → Image Adjustment (Temperature warm, lifted Blacks, soft Highlights, Grain 0.4 with Grain Size 1.5, Vignette 0.3) → Canvas.
• Poster art: any generator → Image Adjustment (Posterize 4–6, high Contrast, Saturation 1.5) → Composite over a flat background color.
• Day-for-night: Exposure −2, Temperature −0.6, crushed Shadows, gentle Vignette on live camera input.

• A generator's texture only reaches the screen through a Canvas node — chain Image Adjustment between the source and its Canvas.
• Filters chain freely: Image Transform → Image Adjustment → Composite all speak the same Image contract, and each stays a single GPU pass.
• Mix is the fastest way to make an aggressive grade tasteful — dial the full look in at Mix 1, then back off.
• Grain is animated from the global time at a fixed 24 fps refresh, so it flickers like film even on a 120 fps output; Grain on Blacks = 1 gives the "lifted shadows on scanned negative" texture without peppering highlights.
• The selective color filter matches on hue only — very dark or desaturated pixels have unstable hue, so widen Color Softness if edges sizzle.
• Alpha is preserved untouched: grading a transparent-background generator (text, shapes) grades only the visible pixels and composites cleanly downstream.