## 2. What option 31 shows

- **Only the 14 swatches above the scene are used.** No mixing on a palette: every dab is a pure colour, and the in-between shades exist only in your eye.
- **The dots are chosen, not random.** Each small block of dots is filled in order. Every dot picks the palette colour closest to what's still "owed," then passes the leftover error to its neighbours (error diffusion). The *average* of each patch matches the intended colour.
- **The mixing is done in light, the way eyes blend.** Averages are computed in linear light, not screen values, so blends keep their brightness.
- **The bot hops along the bank, redrawn 12 times a second.** Its shadow side is blue-violet, the complement of the warm afternoon light, as Seurat would paint it.

## 3. Experiments

1. **Zoom to 8×.** The camera follows the bot's face. It becomes a scatter of lemon, rose, cobalt and white dabs, with no white paint doing all the work.
2. **Tick "Squint."** The frame is shrunk and re-enlarged, which approximates stepping back from the canvas. Dots melt into smooth, glowing colour.
3. **Tap "Premixed paint."** The same dots are mixed *as pigment* in each patch. Everything turns dull and dark. This is why Seurat painted in dots: mixed pigments absorb more light; side-by-side dots don't.
4. **Dot size 8.** Big dabs look closer to mosaic. At 3 they read almost photographic from a distance.

## 4. Less obvious details

- **Complementary halos come from Seurat's theory.** With the option on, the grass just around the bright bot darkens slightly (making it glow by contrast), and a few orange dots appear inside blue shadows. He took these ideas from colour scientists of his day, notably Chevreul.
- **The canvas shows between dabs.** Dots are slightly oval and don't fully overlap. The warm ground adds to the mix.
- **Error diffusion stays in blocks of 10×10 dots.** A moving bot therefore only changes dots near it. Across the whole image, errors would ripple far and make the background shimmer.
- **This is how printers and screens work too.** Printers use dots of four inks; screens use tiny red, green and blue lights. Seurat was a century early.

## Examples

**Error diffusion on dots**
```
want colour (plus error owed)  →  pick nearest pure colour
leftover error → neighbours:       ●  →7/16
                             3/16 ↙ ↓5/16 ↘1/16
result: patch average ≈ intended colour
```

**Optical vs pigment mixing**
```
blue dot + yellow dot (optical)  → average of light  → bright green-grey
blue paint + yellow paint (mixed) → each absorbs more → dull, darker green
```

**Scene recipe**
```
sky (lavender→warm) │ far trees (green/blue-green)
river (blue + light streaks, sail)
bank (sunlit yellow-green, tree shade blue-green)
bot: warm highlight · pink mid · violet shadow · green bounce from grass
```