See Also: HIS, NUM, ImageWorks
Name Prompt Count Type FILE Database File Name 1-64 Char DBIC Database Input Channel List 1-1024 Int MASK Area Mask (Window or Bitmap) 0-4 Int HISW Histogram Window 0-4 Real NUMBIN Number of Histogram Bins 0-1 Int HISFORM Histogram Dump Format 0-9 Char REPORT Report Mode: TERM/OFF/filename 1-64 Char
EASI>FILE="filespec"
EASI>DBIC=i,j,...,p
EASI>MASK=xoff,yoff,xsize,ysize | process window
EASI>MASK=b | process only under bitmap
| stored in segment b
EASI>MASK= | process entire channel
The HISW, and NUMBIN parameters together control the way that the histogram data is binned. The default binning approach loses no accuracy, and hence seldom needs to be overridden for eight bit, and sixteen bit data types. However, meaningful histograming of 32 bit real data may require explicit user control.
EASI>HISW=mingreylevel,maxgreylevelNote that HISW gives the low bound of the first bin, and the upper bin of the highest bin. It does not specify the center of the first and last bins.
Pixels that do not fall within the binning range will be ignored, and not included in the resulting histogram.
EASI> NUMBIN = | Default EASI> NUMBIN = 1000 | 1000 bins
EASI> HISFORM = "RAW" | Just the count data EASI> HISFORM = "" | HITCENTER
EASI>REPORT="filename"The following names have special meaning:
EASI>REPORT="TERM" | generates reports on your terminal
EASI>REPORT="DISK" | generates reports on file "IMPRPT.LST"
EASI>REPORT="OFF" | usually cancels report generation, but
| HIS forces REPORT to terminal output
This source image channels (DBIC) are read from a named PCIDSK file (FILE). The user can provide a window, or graphic plane in the MASK parameter to restrict the set of pixels sampled.
When computing a histogram, a histogram table is established with each entry in the table being called a bin. A particular bin will contain a count of all sampled pixels falling between the bin's minimum (inclusive), and maximum (not included) grey level values. The number of bins NUMBIN), and overall binning range (HISW) can be controlled by the user in order to control the accuracy of the histogram bins.
The default binning approach loses no accuracy, and hence seldom needs to be overridden for eight bit, and sixteen bit data types. However, meaningful histograming of 32 bit real data may require explicit user control.
The HISFORM parameter can be used to control the format of the report to be generated. The simplest form is a HISFORM="RAW" report. This generates one report line per histogram table bin, with the line containing the counts for each channel (DBIC) sampled.
The RANGE, and CENTER report types add column(s) at the beginning of each line containing the grey level range for the bin, or the central grey level value for the bin.
The HITRANGE, and HITCENTER report types are similar but only contain lines for bins that have at least one non-zero count.
The HIS program should be used to generate human friendly histogram reports. The ImageWorks/View/Histograms program also contains an interactive histograming tool from which a text data file, or PostScript plots can be generated.
EASI> file = "/pci/demo/irvine.pix" EASI> dbic = 1,2,3,4,5 EASI> mask = 9 | Sample under bitmap 9 EASI> hisform = | Default to HITCENTER EASI> numbin = EASI> hisw = EASI> report = "hist.txt" | Write to hist.txt file.The first 12 lines of hist.txt are shown here. The first column is the grey level value for the center of the sampled bins. Following that are the counts for each bin from channels ones through five.
0 0 0 0 0 15 1 0 0 0 0 25 2 0 0 0 0 66 3 0 0 0 4 91 4 0 0 0 3 125 5 0 0 0 9 77 6 0 0 1 22 34 7 0 0 0 25 12 8 0 0 0 38 6 9 0 0 1 103 3 10 0 0 0 172 3 11 0 0 2 44 4