DiffPixels

Field	Type	What it is
data	Uint8ClampedArrayUint8List	Red, green, blue and alpha, a byte each, width * height * 4 long.
width	numberint
height	numberint

The same shape as ImageData, so what a canvas hands back can be passed straight in.

The same shape ui.Image.toByteData hands back in ui.ImageByteFormat.rawRgba, so a decoded picture reaches the engine without a copy of its own.