extract_palette

Pull a color palette from image items on a board, with roles and WCAG contrast checks. Optionally place the colors as swatches.

Plan	Quota	Changes data	Hints
All	Swatches count as items	Saves the palette; swatches with `addSwatches`

Thumbnails are read in memory from allowlisted image hosts, the colors are computed with a median cut quantizer, and the images are dropped right away. Nothing is stored but the colors.

Inputs

Name	Type	Required	Limits and default	What it does
`canvasId`	string	Yes	1 to 100 characters	The board
`itemIds`	string[]	Yes	1 to 12	Image item ids from `get_canvas` or `add_to_canvas`
`size`	integer	No	5 to 9, default 6	Number of colors
`addSwatches`	boolean	No	default false	Place the colors on the board as swatches

Output

palette[]: hex, oklch, role (primary, secondary, accent, neutral, surface, on-surface).
contrast[]: every color against the surface, the on-surface color, white and black: fg, bg, ratio, passesText (4.5:1, SC 1.4.3), passesUi (3:1, SC 1.4.11), and tag: ship when it passes for text, else explore.
skipped[]: items that could not be read, with a reason.
swatches[]: placed swatches. A swatch is tagged ship when its color is in a passing pair. They go in the section all source images share, else below the board.

Example call

{
  "name": "extract_palette",
  "arguments": {
    "canvasId": "c3f1a0d2-6b1e-4d8a-9f4b-0a1b2c3d4e5f",
    "itemIds": ["it_42", "it_43", "it_44"],
    "size": 6,
    "addSwatches": true
  }
}

Example output

Shape of the answer, with example values:

Palette of 6 colors:
- #f4f1ea oklch(95.6% 0.011 84.6) (surface)
- #1d2a5c oklch(29.5% 0.084 270.2) (on-surface)
…
5 of 18 contrast pairs pass 4.5:1 for text (ship); the rest are explore only.
- #1d2a5c on #f4f1ea: 12.4:1
Skipped it_44: its format (for example WebP) is not supported yet.
Added 6 swatches to the canvas.
Web link: https://gobanana.fun/c/c3f1a0d2-…

Skip reasons

not an image item on this canvas · its image host is not on the allowlist · its image link is not valid · the image could not be loaded · the link did not return an image · the image is too large · the image took too long to load · the image link redirects too many times · its format (for example WebP) is not supported yet · the image could not be read.

If no image could be read: “No image could be read, so there is no palette.” with the reason per item.

Guide: Palette and contrast.