Anonymous user
Percentage difference between images: Difference between revisions
→{{header|Lua}}
Line 913:
The percentage difference is 1.625593%
</pre>
=={{header|Lua}}==
Using the Bitmap class from [[Bitmap/Bresenham%27s_line_algorithm#Lua|here]] and ImageMagick to preprocess jpg->ppm to simplify loading:
<lang lua>Bitmap.loadPPM = function(self, filename)
local fp = io.open( filename, "rb" )
if fp == nil then return false end
local head, width, height, depth, tail = fp:read("*line", "*number", "*number", "*number", "*line")
self.width, self.height = width, height
self:alloc()
self:clear( {0,0,0} )
for y = 1, self.height do
for x = 1, self.width do
self.pixels[y][x] = { string.byte(fp:read(1)), string.byte(fp:read(1)), string.byte(fp:read(1)) }
end
end
fp:close()
return true
end
Bitmap.percentageDifference = function(self, other)
if self.width ~= other.width or self.height ~= other.height then return end
local dif, abs, spx, opx = 0, math.abs, self.pixels, other.pixels
for y = 1, self.height do
for x = 1, self.width do
local sp, op = spx[y][x], opx[y][x]
dif = dif + abs(sp[1]-op[1]) + abs(sp[2]-op[2]) + abs(sp[3]-op[3])
end
end
return dif/255/self.width/self.height/3*100
end
local bm50 = Bitmap(0,0)
bm50:loadPPM("Lenna50.ppm")
local bm100 = Bitmap(0,0)
bm100:loadPPM("Lenna100.ppm")
print("%diff:", bm100:percentageDifference(bm50))</lang>
{{out}}
<pre>%diff: 1.6255930981605</pre>
=={{header|Liberty BASIC}}==
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