filter(OPAQUE) darkens semi-transparent colors

[davepagurek]

Most appropriate sub-area of p5.js?

• Accessibility
• Color
• Core/Environment/Rendering
• Data
• DOM
• Events
• Image
• IO
• Math
• Typography
• Utilities
• WebGL
• Build Process
• Unit Testing
• Internalization
• Friendly Errors
• Other (specify if possible)

p5.js version

main branch

Web browser and version

Firefox 117

Operating System

macOS 14

Steps to reproduce this

Steps:

1. Create semi transparent content
2. Apply filter(OPAQUE)
   It currently is blending with black due to the filter not correctly handling premultiplied alpha.

Snippet:

function setup() {
  createCanvas(400, 400)
}

function draw() {
  clear()
  background(255, 0, 0, 50)
  filter(OPAQUE)
}

Live: https://editor.p5js.org/davepagurek/sketches/mJ1j4EOYl