Dithering in Colour

Post by ack_complete » Thu, Mar 13, 2025, 7:56 PM UTC

obrhubr wrote: post #3

Clamchop wrote: post #2

They may not want to imply that didder's linearized rabbit is wrong, but I'm comfortable saying so. It's not just a little dark, it's way dark, to the point of hiding detail. The linearized RGB palette is similarly awful. It clobbers a whole swath of colors, rendering them as nearly black. Purples are particularly brutalized. Yellows disappeared and became white. On my phone, the middle palette doesn't appear too bri…

Thanks for your comment! I'm glad you're seeing the same thing :) I re-implemented the linearised dithering in python and got similar results. I checked and rechecked the colour profiles in GIMP, nothing... At this point I can only hope for an expert to appear and tell me what exactly I am doing wrong.

Post by vintagedave » Thu, Mar 13, 2025, 8:44 PM UTC

Post by bazzargh » Thu, Mar 13, 2025, 9:31 PM UTC

obrhubr wrote: post #3

Clamchop wrote: post #2

They may not want to imply that didder's linearized rabbit is wrong, but I'm comfortable saying so. It's not just a little dark, it's way dark, to the point of hiding detail. The linearized RGB palette is similarly awful. It clobbers a whole swath of colors, rendering them as nearly black. Purples are particularly brutalized. Yellows disappeared and became white. On my phone, the middle palette doesn't appear too bri…

Thanks for your comment! I'm glad you're seeing the same thing :) I re-implemented the linearised dithering in python and got similar results. I checked and rechecked the colour profiles in GIMP, nothing... At this point I can only hope for an expert to appear and tell me what exactly I am doing wrong.

    var img
    var pixel
    var threshold
    var error = [0, 0, 0]
    var a0

    function preload() {
      img = loadImage("https://upload.wikimedia.org/wikipedia/commons/thumb/4/44/Albrecht_D%C3%BCrer_-_Hare%2C_1502_-_Google_Art_Project.jpg/1920px-Albrecht_D%C3%BCrer_-_Hare%2C_1502_-_Google_Art_Project.jpg")
    }

    function setup() {
      // I'm just using a low discrepancy sequence for a quasirandom
      // dither and diffusing the error to the right, because it's
      // trivial to implement
      a0 = 1/sqrt(5)
      pixelDensity(2)
      createCanvas(400, 400);
      image(img, 0, 0, 400, 400)
      loadPixels()
      pixel = 0
      threshold = 0
    }

    function draw() {
      if (pixel > 400*400*16) {
        return
      }
      for (var i = 0; i  threshold * 255 ? 255 : 0
          error[j] += c - pixels[pixel + j]
        }
        pixel += 4
      }
      updatePixels()
    }

Post by marcusestes » Thu, Mar 13, 2025, 10:21 PM UTC

somewhereoutth wrote: post #48

See also FadeCandy by Micah: https://scanlime.org/2013/11/fadecandy-easier-tastier-and-mo... > Firmware that uses unique dithering and color correction algorithms to raise the bar for quality while getting out of the way of your creativity.

Post by toast0 » Thu, Mar 13, 2025, 10:37 PM UTC

kurthr wrote: post #42

Aardwolf wrote: post #31

Earlier quoted context omitted.

I think dithering should still be considered, since a super high detailed game otherwise pretty engine that then has banding in the sky is pretty ugly. 32-bit RGBA can still have visible banding which dithering can fix. 256 brightness levels per channel isn't all that much when it comes to subtle variations in sky colors, the eye is more sensitive than that 12-bit per channel color might be enough to never have visib…

With 100+Hz displays it's not that hard to do temporal dithering as well. Your cones are surprisingly low bandwidth (why old color TVs even worked at 30Hz), while your rods provide danger/flicker cues outside the fovea. Getting an extra 2bits of hue (ab) while maintaining luminance (L) is quite doable except at the chroma and brightness extremes where your eye mostly ignores them anyway. That could be done pretty hig…