NAME

bitstat -- Perform bit statistics of image frames

USAGE

bitstat images output

PARAMETERS

images

List of input images. It can be any image template, and image subraster specifications are allowed.

output

Output file name. This is a text file containing the output for all images in the input list. If the string STDOUT is specified, the output is written to the terminal.

DESCRIPTION

The main purpose of this task is to test the acquisition electronics of CCD's by counting the number of times a bit has a zero (0) or one (1) logical value. Under normal conditions each bit should have roughly the same number of zero and one counts. If not that means that there is a problem with the electronics.
This task performs bit statistics of each image frame in the input list. It is possible to specify an image section to each or all images in the input list, making it possible to make statistics of subrasters. Input images can be of any dimension, and of type ushort , short , int , or long .
The output of the task is a five column table for each image in the input list. The first column contains the bit number, the second one contains the total number of zeroes (0) per bit, the third one contains the total number of ones (1) per bit, the fourth one the percentage of zeroes (0), and the last one the percentage of ones (1). A title in pinted at the beginning of each file with the image name, pixel type, and the total number of pixels in the image.

EXAMPLES

1.- Perform bit statistics of the dev$pix image, printing the results on the terminal:

ct> bitstat dev$pix STDOUT

dev$pix[short], npix=262144

bit         0's         1's   %0's   %1's
---  ----------  ----------  -----  -----
  0      131152      130992   50.0   49.0
  1      131020      131124   49.0   50.0
  2      132229      129915   50.0   49.0
  3      125539      136605   47.0   52.0
  4      137719      124425   52.0   47.0
  5      117754      144390   44.0   55.0
  6      125001      137143   47.0   52.0
  7      201862       60282   77.0   22.0
  8      255708        6436   97.0    2.0
  9      260336        1808   99.0    0.0
 10      261726         418   99.0    0.0
 11      262076          68   99.0    0.0
 12      262127          17   99.0    0.0
 13      262139           5   99.0    0.0
 14      262142           2   99.0    0.0
 15      262144           0  100.0    0.0
     ----------  ----------  -----  -----
        3190674     1003630   76.1   23.9

ct> bitstat dev$pix[1:10,1:20] STDOUT

dev$pix[1:10,1:20][short], npix=200

bit         0's         1's   %0's   %1's
---  ----------  ----------  -----  -----
  0          55         145   27.0   72.0
  1         124          76   62.0   38.0
  2          74         126   37.0   63.0
  3         131          69   65.0   34.0
  4         200           0  100.0    0.0
  5           0         200    0.0  100.0
  6         200           0  100.0    0.0
  7         200           0  100.0    0.0
  8         200           0  100.0    0.0
  9         200           0  100.0    0.0
 10         200           0  100.0    0.0
 11         200           0  100.0    0.0
 12         200           0  100.0    0.0
 13         200           0  100.0    0.0
 14         200           0  100.0    0.0
 15         200           0  100.0    0.0
     ----------  ----------  -----  -----
           2584         616   80.8   19.3

ct> bitstat *.imh STDOUT

ct> bitstat @list output

TIME REQUIREMENTS

On a SUN4/280, it takes about eight seconds to run over a 512x512 short image, with a constant value of 30000. The time required increases with large pixel values and decreases with small pixel values.

SEE ALSO

images.imstat