I'd like to use LUT & applyColorMap in opencv.js. By default, they are not included, thus I tried doing a custom build, but I'm getting runtime errors when trying to use them:

LUT:

Uncaught (in promise) 6705216

That's pretty much all the information on the error there is.

applyColorMap:

Uncaught (in promise) TypeError: Cannot convert "[object Object]" to int

It seems only the first overload of applyColorMap is supported, but I need the second one with a custom userColor matrix (see docs).

Steps to reproduce

1. add 'LUT' to core section in ./platforms/js/opencv_js.config.py
2. add 'applyColorMap' to imgproc section in ./platforms/js/opencv_js.config.py
3. Build opencv.js with the following command:

$ emcmake python ./platforms/js/build_js.py build_wasm --build_wasm

4. call the functions in javascript, e.g. like this:

import cv_ from "./opencv.js"

(async () {
  const cv = await cv_

  // provide some `imgEl` here
  const img = cv.imread(imgEl)
  const lut = new cv.Mat.zeros(256, 4, cv.CV_8UC4)
  const out = new cv.Mat()
  // error is thrown here:
  cv.LUT(img, lut, out)
  // cv.applyColorMap(img, out, lut)
  lut.delete()
})()

System information

• OpenCV: 4.5.5
• OS: NixOS 22.05
• emscripten: 2.0.10