Don't forget about (lossy) jpeg compression. You'd be better off using GIF or TIFF for this experiment.
identify -verbose  identify -verbose artificial_black_n_white.jpg 
 
Image: artificial_black_n_white.jpg
  Format: JPEG (Joint Photographic Experts Group JFIF format)
  Geometry: 24x12
  Class: DirectClass
  Type: Grayscale
  Endianess: Undefined
  Colorspace: Gray
  Channel depth:
    Gray: 8-bits
  Channel statistics:
    Gray:
      Min: 0 (0)
      Max: 255 (1)
      Mean: 141.299 (0.554112)
      Standard deviation: 123.716 (0.485162)
  Colors: 30
  Histogram:
        72: (  0,  0,  0)       black
         8: (  3,  3,  3)       grey1
         8: (  2,  2,  2)       #020202
         6: (  4,  4,  4)       #040404
         4: (  5,  5,  5)       grey2
         2: (  7,  7,  7)       #070707
         4: (  6,  6,  6)       #060606
         6: (  8,  8,  8)       grey3
         4: ( 10, 10, 10)       grey4
         2: ( 11, 11, 11)       #0B0B0B
         6: ( 12, 12, 12)       #0C0C0C
         2: ( 13, 13, 13)       grey5
         2: ( 15, 15, 15)       grey6
         2: ( 17, 17, 17)       #111111
         2: (233,233,233)       #E9E9E9
         2: (237,237,237)       grey93
         2: (239,239,239)       #EFEFEF
         4: (241,241,241)       #F1F1F1
         2: (240,240,240)       grey94
         2: (242,242,242)       grey95
         2: (245,245,245)       grey96
         2: (246,246,246)       #F6F6F6
        14: (249,249,249)       #F9F9F9
         6: (248,248,248)       #F8F8F8
         6: (251,251,251)       #FBFBFB
         6: (250,250,250)       grey98
        12: (252,252,252)       grey99
        10: (253,253,253)       #FDFDFD
        86: (255,255,255)       white
         2: (254,254,254)       #FEFEFE
  Rendering-intent: Undefined
  Units: PixelsPerCentimeter
  Filesize: 834
  Interlace: None
  Background Color: white
  Border Color: #DFDFDF
  Matte Color: grey74
  Dispose: Undefined
  Iterations: 0
  Compression: JPEG
  Quality: 75
  Orientation: Undefined
  JPEG-Colorspace: 2
  JPEG-Sampling-factors: 2x2,1x1,1x1
  Signature: 50739cd131be1b05025077e282769fe030553bfc888402b09988530af
+56e96f0
  Tainted: False
  Version: ImageMagick 6.2.5 09/21/06 Q16 file:/usr/share/ImageMagick-
+6.2.5/doc/index.html

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grep
One dead unjugged rabbit fish later

In reply to Re^6: Perl Image Analysis by grep
in thread Perl Image Analysis by Anonymous Monk

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