Simple script to set your image or palette to 15-bit safe colors.

[Arthur]

Hello! I made two simple scripts to set the RGB values of your images/palettes to a valid 15-bit color. This is useful if you are making homebrew for older consoles or just want to simulate them.
I made this one focusing on PS1 and N64 homebrew, so it does not apply to other consoles such as the SNES and Genesis. It should work for anything that uses 15-bit color, RGB 5:5:5 (5 bits per channel)

Here's the script to transform the palette values:

----------------------------------------------------------------------
-- Set palette 15-bit safe colors.
----------------------------------------------------------------------

local spr = app.activeSprite
if not spr then
  return app.alert("There is no active sprite")
end

app.transaction(
  function()
    local pal = spr.palettes[1]
    for i = 0,#pal-1 do
      -- Modify each color of the palette by dividing it by
      -- 8 so it goes to 0 - 31 range, round it down and expand
      -- it back to 0 - 255 so that colors are displayed correctly.
      local ncolor = pal:getColor(i)
      pal:setColor(i, Color{ r=math.floor(ncolor.red/8)*8,
                             g=math.floor(ncolor.green/8)*8,
                             b=math.floor(ncolor.blue/8)*8 })
    end
  end)

app.refresh()

And this one is to set the whole image if you're using RGBA:

----------------------------------------------------------------------
-- Set the image pixels to a 15-bit safe value.
--
-- It works for RGB/GRAY color modes.
----------------------------------------------------------------------

if app.apiVersion < 1 then
  return app.alert("This script requires Aseprite v1.2.10-beta3")
end

local cel = app.activeCel
if not cel then
  return app.alert("There is no active image")
end

local img = cel.image:clone()

if img.colorMode == ColorMode.RGB then
  local rgba = app.pixelColor.rgba
  local rgbaA = app.pixelColor.rgbaA
  for it in img:pixels() do
    local pixelValue = it()
    local redValue = math.floor(app.pixelColor.rgbaR(pixelValue)/8)*8
    local greenValue = math.floor(app.pixelColor.rgbaG(pixelValue)/8)*8
    local blueValue = math.floor(app.pixelColor.rgbaB(pixelValue)/8)*8
    it(rgba(redValue,
            greenValue,
            blueValue, rgbaA(it())))
  end
elseif img.colorMode == ColorMode.GRAY then
  local graya = app.pixelColor.graya
  local grayaA = app.pixelColor.grayaA
  for it in img:pixels() do
    local pixelColor = it()
    local pixelValue = math.floor(app.pixelColor.grayaV(pixelColor)/8)*8
    it(graya(pixelValue, grayaA(it())))
  end
end

cel.image = img

app.refresh()

I haven't tested this script properly yet, but the output is similar to what conversion tools will output, so it seems to match.

[Sigmund Froid]

Although I've no real idea what I'll do with that, it's really a nice thing to have just in case, thank you kind stranger!

[Seven-Colored Puppeteer]

should work for GBC and SNES as well!

[yeetface513]

Originally posted by Sigmund Froid:

Although I've no real idea what I'll do with that, it's really a nice thing to have just in case, thank you kind stranger!

exactly