Approximation of K-means clustering?

[jcupitt]

Discussed in #2840

^{Originally posted by kipcole9 June 4, 2022}
Any advice on a libvips mechanism to do k-means clustering on an image? Basically to identify the most common colours in an image, and the number of pixels that are in that cluster. Similar to Method 3 described here but using libvips only.

[jcupitt]

Expose the GIF / PNG / etc. quantizer as an operator.

[jcupitt]

Let's move any discussion to the PR.