-- Minor native-pixel cleanup of an ImageGen expression variant.
-- Preserve the neutral portrait's hair, clothing, jaw and alpha silhouette.
-- Copy only generated brows/eyes and mouth, with no scaling or warping.
local neutral=app.open(app.params.neutral)
local out=Image(neutral.cels[1].image)
neutral:close()
local variant=app.open(app.params.variant)
local face=Image(variant.cels[1].image)
assert(out.width==160 and out.height==192 and face.width==160 and face.height==192)
local regions={{81,64,46,24},{95,98,22,14}}
if app.params.regions then
  regions={}
  for x,y,w,h in app.params.regions:gmatch('(%d+),(%d+),(%d+),(%d+)') do
    table.insert(regions,{tonumber(x),tonumber(y),tonumber(w),tonumber(h)})
  end
  assert(#regions>0, 'Provide x,y,width,height rectangles')
end
for _,box in ipairs(regions) do
  for y=box[2],box[2]+box[4]-1 do
    for x=box[1],box[1]+box[3]-1 do
      if app.pixelColor.rgbaA(out:getPixel(x,y))==255 and app.pixelColor.rgbaA(face:getPixel(x,y))==255 then
        out:drawPixel(x,y,face:getPixel(x,y))
      end
    end
  end
end
variant:close()
local result=Sprite(160,192,ColorMode.RGB)
result.cels[1].image=out
result:saveAs(app.params.output)
result:close()