Tilemap monochrome deviation generator

main.js

const Canvas = require('canvas')
const fs = require('fs')

const dimensions = [15, 15]
const imageCount = 15

// const color = [154, 131, 78] // poopy brown
// const color = [17, 124, 17] // plant stuff
const color = [121, 121, 121] // sad gray

const getRandomInt = (min, max) => Math.floor(Math.random() * (Math.floor(max) - Math.ceil(min))) + Math.ceil(min)

const setToRandomColor = (imgObj, base) => {
    for (let i = 0; i < 3; i++) 
        imgObj[base + i] = color[i] + getRandomInt(-10, 11)
    imgObj[base + 3] = 255
}

const generateImage = out => {
    const c = new Canvas(...dimensions)
    const ctx = c.getContext('2d')
    let imgData = ctx.createImageData(...dimensions)
    for (let i = 0; i < imgData.data.length; i += 4)
    setToRandomColor(imgData.data, i)
    ctx.putImageData(imgData, 0, 0)
    const stream = c.pngStream()

    stream.on('data', chunk => {
      out.write(chunk)
    })
     
    stream.on('end', () => {
      console.log('saved png')
    })
}

for (let z = 0; z < imageCount; z++) {
    const out = fs.createWriteStream(__dirname + `/output/tilemap (${z + 1}).png`)
    generateImage(out)
}

This runs in Node.js and requires the NPM package canvas as a dependency. This also requires some local dependencies per machine that are detailed on their NPM page.