@lionkunonly Thank you!

@jlb6740 Could you please check this patch in your environment?

Hi @alalek @lionkunonly, sorry only noticed this update here. Yes! I tried the patch and indeed it appears to resolve the issue. The steps I followed were:

#using emscripten 2.0.15
emcmake python3 platforms/js/build_js.py build_wasm --build_wasm --simd --build_wasm_intrin_test --build_perf

cd build_wasm/bin/perf

#using node 14.15.5 (probably not all these flags are needed)
node --experimental-wasi-unstable-preview1 --experimental-wasm-simd --experimental-wasm-threads --experimental-wasm-type-reflection --experimental-wasm-mv --wasm-atomics-on-non-shared-memory perf_imgproc/perf_threshold.js

I also tested cvtColor.js which worked fine.

@jlb6740 Thank you for checking this!

@lionkunonly
This patch should go into 3.4 branch first.
We will merge changes from 3.4 into master regularly (weekly/bi-weekly).

Please:

• change "base" branch of this PR: master => 3.4 (use "Edit" button near PR title)
• rebase your commits from master onto 3.4 branch. For example:
  git rebase -i --onto upstream/3.4 upstream/master
  (check list of your commits, save and quit (Esc + "wq" + Enter)
  where upstream is configured by following this GitHub guide and fetched (git fetch upstream).
• push rebased commits into source branch of your fork (with --force option)

Note: no needs to re-open PR, apply changes "inplace".

@lionkunonly I'm not able to update PR source branch because your fork is not forked from opencv/opencv repository:

lionkunonly / opencv
forked from huningxin/opencv

You can grab rebased commit from here: https://github.com/alalek/opencv/commits/pr19771_r