Output 1D Unknown-Length Array from 2D Known-Length Array

I'm trying to generate an unknown-length array, from an input image or 2D array.

I want to distribute data using a **noise** image, for example:

For every white pixel -> Save the position of it (x, y) and push it to an array so you end up having a Z-length array. Where Z is the number of white pixels in the noise image.

**Input**

**Output**

`[[x1, y1], [x2, y2], .... [xZ, yZ]]`

In result I get all the locations of where a pixel is white.

I need to use GPU power, since noise images are huge in my use case and must be updated at least at 24 fps.