notes.js

let chunkSize = 15;
let inputWidth = 25;
let image.dims = {
  w: 1920,
  h: 1080
}

const myFunc = gpu.createKernel(function(imageTexture, imageWidth, x1, y1, x2, y2) {
    let x1 = this.thread.x * chunkSize;
    let y1 = this.thread.y * chunkSize;
    let x2 = x1 + inputWidth;
    let y2 = y1 + inputWidth;
    let input = [];
    for (let x = x1; x < x2; x++) {
      for (let y = y1; y < y2; y++) {
        let index = (y * imageWidth) + x;
        input.push(imageTexture[index]);
      }
    }
    return input;
}).setOutput([inputWidth, inputWidth]);

let matchLocations = [];

for (let x1 = 0; x1 < image.dims.w - chunkSize; x1 += chunkSize){
  for (let y1 = 0; y1 < image.dims.y - chunkSize; y1 += chunkSize){
    let x2 = x1 + inputWidth;
    let y2 = y1 + inputWidth;
    if (subKernelThatRepresentsNetwork(myFunc(imageTexture, image.dims.w, x1, y1, x2, y2))[0] === 1){
      matchLocations.push([x1, y1]);
    }
  }
}

Move return subKernelThatRepresentsNetwork(imageTexture, x1, y1, x2, y2); //outputs 0 or 1 to outside of this function, and then simply do subKernelThatRepresentsNetwork(myFunc(imageTexture, x1, y1, x2, y2));

Don't forget to use (renamed from outputToTexture in v2 of GPU.js) pipeline: true, in the options.