added flag for 256-color support for older terminals and screen

rose_256.img

@@ -0,0 +1,40 @@
+                                                                                                    
+                                                                                                    
+                                                                                                    
+                                                                                                    
+                                                                                                    
+                                                                                                    
+                                                               ooo.                                 
+                                                           oo oooooo                                
+                                  oox                   ooooooooooooo                               
+                                 xxoooooooo.   oooooooooooooooooooooooo                             
+                                 ooooooooooooooooooooooooooooooooooooooo .                          
+                                 oooooooooooooooooxoooooooooooooooooooooooo                         
+                                oooooooooooooooooooooooooooooooooooooooooooooooooo                  
+                               oooooooooooooxxoooooooooxxoooooxooooooooooooooooox.                  
+                               ooooooooooooooooooooxxxoooooooooxoooooooooooooooxx                   
+                              ooooooooooooxoooxxxxxooxxxxxoooooooooxooooooooooxx                    
+                            .ooooooooooooxxoooxxxooxooxxxooooooxooooooooooooooxx                    
+                          oooooooooooooooooooxoooxxooxxxooxooooooooooxoooooooxxx                    
+                  .xooooooooooooooooooooooooooooooooooooooooooooooooxxooooooooxx                    
+                    xxxxooooooooooooooooooooooooooooooxxxxoooxoooooo.xooooooooox                    
+                     xxxooooooooooooooooooooooxooooxxxxoooooxoooooox xoooooooooo                    
+                      xxxxoooooooooooooooooooooooooooooooxooooooox.  ooooooxxoo                     
+                      .xooooooooooooooooooooooooooxoooxoooooooooxxxxoooooxxx.                       
+                       xxxxxooooooxooooooxx.oooooooxooooooooxxxxxxooooooxxxx                        
+                       xxxoxxxoooooxxoooooooxxxxxxxooox.xxxxooooooooooxxxxx                         
+                       xxxxxxxxxxoooxxxxxxxxoooooooooooooooooooxxoooxxxxx.                          
+                       xx..xxxxxxxxoxxxooooooooooooooooooooxxx..oooxxx..                            
+                            xxxxxxxxxx.xxxxxxxxxxx...xxxx......xoxxx..                              
+                            xxxxx.xxxxxx.........        ......xxx..                                
+                            ooooooooxxxxxx.........     .xx......                                   
+                            oooooooooooxxx...        .........                                      
+                           ooooooooooooooooooxx.......x....x..                                      
+                          oooooooooooooooooooooooooxx.......                                        
+                         ooxxxxxxxxxxxxxoooooooooooooo....                                          
+                            x...xxxxxxxxxxxxxxoooooxxxx.                                            
+                                 ...........xxxxooxxx.                                              
+                                               .xox                                                 
+                                                                                                    
+                                                                                                    
+                                                                                                    

src/Main.hs

@@ -16,13 +16,15 @@ data Options = Options
              { srcFile :: String
              , width   :: Int
              , height  :: Int
+             , trueColor :: Bool
              }
 
 options :: Parser Options
 options = Options
         <$> argument str (metavar "SRC" <> help "source file (or - for stdin)")
         <*> argument auto (metavar "WIDTH" <> help "resulting width")
-        <*> argument auto (metavar "HEIGH" <> help "resulting height")
+        <*> argument auto (metavar "HEIGHT" <> help "resulting height")
+        <*> flag True False (long "256-colors" <> short 'c' <> help "only use 256-color-mode for old terminals")
 
 opthelp :: ParserInfo Options
 opthelp = info (helper <*> options)
@@ -35,7 +37,7 @@ main :: IO ()
 main = execParser opthelp >>= run
 
 run :: Options -> IO ()
-run (Options src w h) = do
+run (Options src w h c) = do
        src' <- if src == "-" then B.getContents else B.readFile src
        case decodeImage src' of
          Left err -> putStrLn err
@@ -43,7 +45,7 @@ run (Options src w h) = do
             case extractDynImage img >>= pixelize w h of
                  Nothing -> return ()
                  Just (f,b) ->
-                     let str = img2ascii conv (f,b)
+                     let str = if c then img2ascii conv (f,b) else img2ascii conv256 (f,b)
                       in mapM_ (\x -> putStr x >> putStrLn "\x1b[0m") (concat <$> str)
 
 chunksof :: Int -> [a] -> [[a]]
@@ -63,6 +65,24 @@ conv (fp@(PixelRGB8 fr fg fb),PixelRGB8 br bg bb) = printf "\x1b[48;2;%d;%d;%dm\
           | x > 10    = '.'
           | otherwise = ' '
 
+conv256 :: (PixelRGB8,PixelRGB8) -> String
+conv256 (fp@(PixelRGB8 fr fg fb),PixelRGB8 br bg bb) = printf "\x1b[48;5;%dm\x1b[38;5;%dm%c" bcolor fcolor (lumi.computeLuma $ fp)
+   where
+     -- converts [0..255] -> [0..5]
+     s = (`div` 51)
+     -- conversion: 6x6x6 rgb-cube so color is red * 36 + green * 6 + blue + 16 offset with red/green/blue in [0..5]
+     bcolor = s br * 36 + s bg * 6 + s bb + 16
+     fcolor = s fr * 36 + s fg * 6 + s fb + 16
+     lumi :: Word8 -> Char
+     lumi x
+          | x > 225   = '@'
+          | x > 180   = 'O'
+          | x > 150   = 'X'
+          | x > 50    = 'o'
+          | x > 25    = 'x'
+          | x > 10    = '.'
+          | otherwise = ' '
+
 img2ascii :: ((PixelRGB8,PixelRGB8) -> String) -> (Image PixelRGB8,Image PixelRGB8) -> [[String]]
 img2ascii c (fg@(Image w h _),bg@(Image w' h' _)) = (fmap.fmap) (c.(uncurry (pixelAt fg) &&& uncurry (pixelAt bg))) [[(x,y) | x <- [0..w-1]] | y <- [0..h-1]]