README.md

GET IMAGE DATA TOOL

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You can get data from image instead of using context.getImageData();

Contents

• Why
• RGBA Controls examples
• Options
• Particle example
• Iteration examples

Why

I made two examples with the same image - 6312 particles:

• link (48 FPS on my computer) with context.getImageData
• link (60 FPS on my computer) without context.getImageData, it is just an image array with coordinates which I obtained with this tool.

When I use context.getImageData() sometimes FPS sags even if I want to get 1px. More problem if I need to get data from several images, or I use several canvases or use routing.

As far as I understood it very much depends on how much RAM you have.

I was very surprised that the situation changed a lot when I added another 8gb of memory (before was 16gb)

Then I tested a small image (44 particles) on my old very weak laptop with 4gb of memory:

• 38-40 FPS with context.getImageData(); (44 particles)
• 60 FPS just array with coordinates; (44 particles)

RGBA Controls examples

Example	Solution
remove black background	black - (0, 0, 0), to remove you need to set r or g or b more than 0
remove white background	white - (255, 255, 255), to remove you need to set r or g or b less than 255
remove red background	red - (255, 0, 0), to remove you need to set r less than 255 or set g or b more than 0

Options:

Option	Sample	Description
r g b	[[r, g, b], [...], ...]	get all coordinates image.width * image.height, you need to use jpg rather than png or svg; otherwise when you set: this.color = 'rgb(${r},${g},${b})' all transparent parts (if exist) will be black.
r g b a	[[r, g, b, a], [...], ...]	get all coordinates image.width * image.height, in case, if an image has small transparent parts then better copy all coordinates than add x and y to each particle, then when you iterate data you can create a particle if a > 0
x y r g b	[[x, y, r, g, b], [...], ...]	get only selected coordinates with x, y and color, then you can iterate data.length with one loop or randomly draw some particles, ALL COORDINATES WITH alpha < 1 EXCLUDED.
x y r g b a	[[x, y, r, g, b, a], [...], ...]	the same as xy rgb but also include coordinates with alpha < 1, here you can control with A range which coordinates will be included.
x y	[[x, y], [...], ....]	the only position of every selected pixel without color, ok if you create some text or shapes animation with the same color.

Particle example

class Particle {
  constructor({ x, y, r, g, b, a, width, height, color }) {
    this.x = x
    this.y = y
    this.color = color ? color : `rgba(${r}, ${g}, ${b}, ${a})`
    this.width = width
    this.height = height
  }

  draw() {
    context.beginPath()
    context.fillStyle = this.color
    context.rect(this.x, this.y, this.width, this.height)
    context.fill()
  }
}

Iteration examples

• Iterate rgb or rgba with two loops

  import { data } from './data.js' // your copied data
  
  /* set real dimensions of your image */
  const image = {
    width: 100,
    height: 100,
  }
  
  /* multiply x and y if you want to make big image
  with visible pixels */
  const scale = 1
  
  let i = 0
  for (let y = 0; y < image.height; y++) {
    for (let x = 0; x < image.width; x++) {
      const [r, g, b, a] = data[i]
  
      particles.push(
        new Particle({
          x: x * scale,
          y: y * scale,
          r,
          g,
          b,
          /* rgba */
          a,
          /* rgb */
          a: 1,
  
          /* set width and height to scale, if you scale it*/
          width: scale,
          height: scale,
        })
      )
  
      i++
    }
  }

• Iterate rgb or rgba with one loop

  import { data } from './data.js' // your copied data
  
  /* set a real width of your image */
  const image = {
    width: 300,
  }
  
  /* multiply x and y if you want to make big image
  with visible pixels */
  const scale = 1
  
  for (let i = 0; i < data.length; i++) {
    const [r, g, b, a] = data[i]
  
    particles.push(
      new Particle({
        x: (i % image.width) * scale,
        y: Math.floor(i / image.width) * scale,
        r,
        g,
        b,
        /* rgba */
        a,
        /* rgb */
        a: 1,
  
        /* set width and height to scale, if you scale it */
        width: scale,
        height: scale,
      })
    )
  }

• Iterate xyrgb or xyrgba

  import { data } from './data.js' // your copied data
  
  /* multiply x and y if you want to make big image
  with visible pixels */
  const scale = 1
  
  for (let i = 0; i < data.length; i++) {
    const [x, y, r, g, b, a] = data[i]
  
    particles.push(
      new Particle({
        x: x * scale,
        y: y * scale,
        r,
        g,
        b,
        /* xy rgba */
        a,
        /* xy rgb */
        a: 1,
  
        /* set width and height to scale, if you scale it*/
        width: scale,
        height: scale,
      })
    )
  }

• Iterate xy

  import { data } from './data.js' // your copied data
  
  /* multiply x and y if you want to make big image
  with visible pixels */
  const scale = 1
  
  for (let i = 0; i < data.length; i++) {
    const [x, y] = data[i]
  
    particles.push(
      new Particle({
        x: x * scale,
        y: y * scale,
        color: 'purple',
        /* set width and height to scale, if you scale it*/
        width: scale,
        height: scale,
      })
    )
  }