A small Lua benchmark including table creation and usage, arithmetics, function calls and upvalues

lua-image-ramp-bench.lua

print ("Starting Lua ramp bench")
local startTime = os.clock()
do
    local floor = math.floor
    
    local function image_ramp_green(n)
        local img = {}
        local f = 255/(n-1)
        for i=1,n do
            img[i] = { red = 0, green = floor((i-1)*f), blue = 0, alpha = 255 }
        end
        return img
    end
    
    local function image_to_grey(img, n)
        for i=1,n do
            local pixel = img[i]
            local y = floor(0.3*pixel.red + 0.59*pixel.green + 0.11*pixel.blue)
            local greyPixel = {red = y, green = y, blue = y }
            img[i]= greyPixel
        end
    end
    
    local N = 400*400
    local img = image_ramp_green(N)
    for i=1,100 do
        image_to_grey(img, N)
    end
end
local endtime = os.clock ()
print ("Elapsed time: " .. (endtime - startTime))