Haskell でサムネイル #2 ref: http://qiita.com/satosystems/items/669a8b3fdfa535582cb4

file0.txt

$ identify original.jpg
original.jpg JPEG 3264x2448 3264x2448+0+0 8-bit sRGB 3.288MB 0.000u 0:00.000

file1.txt

$ identify -format "%w %h" original.jpg 
3264 2448

file2.txt

$ convert -resize 200x150 original.jpg thumb.jpg

file3.txt

$ convert -auto-orient -strip -resize 200x200 original.jpg thumb.jpg

file5.hs

  thumb <- mkThumbnail' ((50, 50), (200, 200)) contents
  case thumb of
    (Left _) -> return Nothing
    (Right t) -> return $ Just (fst $ sz t, snd $ sz t)

file6.hs

  system $ "convert -auto-orient -strip -resize 200x200 " ++ org ++ " " ++ thumb
  wh <- readProcess "identify" ["-format", "%w %h", thumb] []
  let a = " " `splitOn` wh
  return $ Just (read $ a !! 0, read $ a !! 1)

Sample.hs

import Data.Either (either)
import Data.Map.Lazy (fromList)
import Graphics.HsExif (getOrientation, parseFileExif)

file :: FilePath
file = "tools/4f517b31-caea-4ade-9cc5-069d6c9970dd.jpeg"

main :: IO ()
main = do
  eexif <- parseFileExif file
  let exif = either (\a -> fromList []) id eexif
      mio = getOrientation exif
  print mio