os.loadAPI("GIF")
local image = GIF.loadGIF("new")

local mon = peripheral.find("monitor")
mon.setTextScale(0.5)
term.redirect(mon)

local x, y = term.getSize()

if x < image.width or y < image.height then
        if x < math.floor(y / image.height * image.width) then
                image = GIF.resizeGIF(image, x)
        else
                image = GIF.resizeGIF(image, nil, y)
        end
end

GIF.animateGIF(image)