HIS

Description

Prints numeric or graphic histograms of specified image channels on the report device.

Parameters

Name	Type	Length	Value range
Input: Raster Layer: Input raster channel *	Raster port	1 - 1024
Port Settings: Resample Mode: Port Settings: Resample mode	Raster port	1 - 1024	Nearest | Bilinear | Cubic Default: Nearest
Graphic Mode	String	0 - 1	ON | OFF Default: ON
Cumulative Mode	String	0 - 1	ON | OFF Default: ON
Percentage Mode	String	0 - 1	ON | OFF Default: ON
Number of Pixel Values to Sample	Integer	0 - 1	0 -
Tail Trimming % Left	Float	0 - 2
Tail Trimming % Right	Float	0 - 2
Minimum Gray Level	Float	0 - 4
Maximum Gray Level	Float	0 - 4
Minimum Pixel Count	Float	0 - 4
Maximum Pixel Count	Float	0 - 4
Mask	Integer	0 - 4
Image Mean	Float	0 - 13
Image Median (8-bit only)	Float	0 - 13
Image Standard Deviation	Float	0 - 13

* Required parameter

Parameter descriptions

Input: Raster Layer: Input raster channel

Specifies the image channels from which histogram data is extracted.

Port Settings: Resample Mode: Port Settings: Resample mode

Specifies the type of image resampling desired.

Graphic Mode

Specifies graphic or numeric display of histogram data.

Cumulative Mode

Specifies the plotting density function of the histogram.

Percentage Mode

Specifies the count mode of the histogram data.

Number of Pixel Values to Sample

Specifies the number of pixel samples used to construct the histogram.

If set to 0, all pixels in the image (or under a specified window) are sampled.

If set to n , the actual n number of pixels in the image (or under a specified bitmap or window) are sampled, using a square grid to sample the required pixels.

The value specified for this parameter affects the speed and accuracy of the function.

Tail Trimming % Left

Specifies the percentage of the left (low) tail of the histogram to be trimmed before being plotted.

Tail Trimming % Right

Specifies the percentage of the right (high) tail of the histogram to be trimmed before being plotted.

Minimum Gray Level

One of four parameters used to specify the portion of the histogram to print, specifies the minimum gray level to display.

Maximum Gray Level

One of four parameters used to specify the portion of the histogram to print, specifies the maximum gray level to display.

Minimum Pixel Count

One of four parameters used to specify the portion of the histogram to print, specifies the minimum number of pixels to display.

Maximum Pixel Count

One of four parameters used to specify the portion of the histogram to print, specifies the maximum number of pixels to display.

Mask

Specifies the window or bitmap that defines the area to be processed within the input raster.

If no value is specified, the entire channel is processed.

Image Mean

Upon completion, HIS writes the image channel's mean information to this parameter.

Image Median (8-bit only)

Upon completion, HIS writes the image channel's median information to this parameter.

Image Standard Deviation

Upon completion, HIS writes the image channel's standard deviation information to this parameter.

Details

HIS calculates and prints histograms of sampled gray-level values of up to 16 image channels. Both graphic histograms (Graphic Mode = "ON") and numeric histograms (Graphic Mode = "OFF") may be plotted. The plotted histogram may be cumulative (Cumulative Mode = "ON") or non-cumulative (Cumulative Mode = "OFF").

Values of the plotted histogram may represent either pixel counts (Percentage Mode = "OFF") or a percentage of the total count (Percentage Mode = "ON"). The user may choose to print only a portion of the histogram using the Histogram Window or Tail Trimming parameters.

The MASK parameter specifies the area within the input channel which will be processed. Only the area under MASK will be processed; the rest of the image remains unchanged.

If MASK is not specified, the entire image is processed.

The number of samples used to construct the histogram may also be specified. The functionality of these parameters is particularly useful in that histogramming takes considerably less time for smaller sample sizes than it does for larger ones.

HIS can generate histograms for 8-bit unsigned integer, 16-bit signed integer, 16-bit unsigned integer, and 32-bit real channels. These channels have the following ranges for data:

Type                          Min                    Max

8-bit unsigned integer          0                    255
16-bit signed integer      -32768                  32767
16-bit unsigned integer         0                  65535
32-bit signed integer  -2147483648            2147483647
32-bit unsigned integer         0             4294967295
32-bit real              -3.4E+38                3.4E+38
64-bit unsigned integer         0               2E64 - 1
64-bit signed integer       -9E18                   9E18
64-bit real              -1.8E308                1.8E308

HIS writes image data statistics to the output parameters Image Mean, Image Median (8-bit only), and Image Standard Deviation.

HIS must perform a binning operation when computing the histogram. For data types other than 8-bit unsigned, this binning results in grouping different pixel values into a single bin. If explicit binning control is required, use the HISDUMP function.