local src=app.open(app.params.source)
local img=Image(src.cels[1].image)
local x0,y0,x1,y1=img.width,img.height,-1,-1
for p in img:pixels() do
  local c=p()
  if app.pixelColor.rgbaA(c)>=192 then
    p(app.pixelColor.rgba(app.pixelColor.rgbaR(c),app.pixelColor.rgbaG(c),app.pixelColor.rgbaB(c),255))
    x0,y0,x1,y1=math.min(x0,p.x),math.min(y0,p.y),math.max(x1,p.x),math.max(y1,p.y)
  else p(0) end
end
local crop=Image(x1-x0+1,y1-y0+1,ColorMode.RGB)
crop:drawImage(img,Point(-x0,-y0));src:close()
src=Sprite(crop.width,crop.height,ColorMode.RGB)
src.cels[1].image=crop
local factor=math.min(40/src.width,tonumber(app.params.height)/src.height)
local w,h=math.floor(src.width*factor+0.5),math.floor(src.height*factor+0.5)
app.command.SpriteSize{ui=false,width=w,height=h,method='nearest-neighbor'}
local frame=Image(48,64,ColorMode.RGB)
frame:drawImage(src.cels[1].image,Point(math.floor((48-w)/2),61-h));src:close()
-- Preserve the complete pose; an idle rectangle would erase its raised arms.
local out=Sprite(48,64,ColorMode.RGB)
out.cels[1].image=frame;out:saveAs(app.params.output)
app.command.SpriteSize{ui=false,width=144,height=192,method='nearest-neighbor'}
out:saveAs(app.params.preview);out:close()