Histogram Display

The intensity histogram for an image provides valuable information about how grey levels are being utilized. The histogram is calculated by simply counting the number of pixels at each intensity level in the image. The cumulative histogram is the integral of the histogram and gives an indication of the number of pixels less than or equal to each intensity level in the image. The histo program calculates the histogram and cumulative histogram for an image and displays this information in a table. By using the -a switch the output of histo can be directed to xgraph for graphic display. (see code)

Command Usage

histo [options] infile [outfile]
      [-d]    Print debugging information
      [-a]    Output ascii for xgraph

Example

histo -a input.im | xgraph -bar -brw 3



histo input.im
HISTO Program - KUIM Version 3.0

   Intensity Range       Histogram      Cumulative
[ 74.00 ..  78.64)     4134   6.31     4134   6.31
[ 78.64 ..  83.28)      437   0.67     4571   6.97
[ 83.28 ..  87.92)     1048   1.60     5619   8.57
[ 87.92 ..  92.56)     2575   3.93     8194  12.50
[ 92.56 ..  97.21)     2705   4.13    10899  16.63
[ 97.21 .. 101.85)     1565   2.39    12464  19.02
[101.85 .. 106.49)     1514   2.31    13978  21.33
[106.49 .. 111.13)     1283   1.96    15261  23.29
[111.13 .. 115.77)     1034   1.58    16295  24.86
[115.77 .. 120.41)     1228   1.87    17523  26.74
[120.41 .. 125.05)     1217   1.86    18740  28.59
[125.05 .. 129.69)      938   1.43    19678  30.03
[129.69 .. 134.33)     1985   3.03    21663  33.06
[134.33 .. 138.97)     1841   2.81    23504  35.86
[138.97 .. 143.62)     1834   2.80    25338  38.66
[143.62 .. 148.26)     1585   2.42    26923  41.08
[148.26 .. 152.90)     1498   2.29    28421  43.37
[152.90 .. 157.54)     2110   3.22    30531  46.59
[157.54 .. 162.18)     2856   4.36    33387  50.94
[162.18 .. 166.82)     2108   3.22    35495  54.16
[166.82 .. 171.46)     1934   2.95    37429  57.11
[171.46 .. 176.10)     2174   3.32    39603  60.43
[176.10 .. 180.74)     1672   2.55    41275  62.98
[180.74 .. 185.38)     2185   3.33    43460  66.31
[185.38 .. 190.03)     1928   2.94    45388  69.26
[190.03 .. 194.67)     1563   2.38    46951  71.64
[194.67 .. 199.31)     2084   3.18    49035  74.82
[199.31 .. 203.95)     1547   2.36    50582  77.18
[203.95 .. 208.59)     1743   2.66    52325  79.84
[208.59 .. 213.23)     1347   2.06    53672  81.90
[213.23 .. 217.87)      914   1.39    54586  83.29
[217.87 .. 222.51)     1176   1.79    55762  85.09
[222.51 .. 227.15)     1183   1.81    56945  86.89
[227.15 .. 231.79)      957   1.46    57902  88.35
[231.79 .. 236.44)      798   1.22    58700  89.57
[236.44 .. 241.08)      705   1.08    59405  90.64
[241.08 .. 245.72)      688   1.05    60093  91.69
[245.72 .. 250.36)      917   1.40    61010  93.09
[250.36 .. 255.00)     1133   1.73    62143  94.82
[255.00 .. 259.64)     3393   5.18    65536 100.00