min_max_gray

Herror ::min_max_gray ( Hobject Regions, Hobject Image, const HTuple &Percent, double *Min, double *Max, double *Range ) Herror ::min_max_gray ( Hobject Regions, Hobject Image, const HTuple &Percent, HTuple *Min, HTuple *Max, HTuple *Range ) double HRegion::MinMaxGray ( const HImage &Image, const HTuple &Percent, double *Max, double *Range ) const HTuple HRegionArray::MinMaxGray ( const HImage &Image, const HTuple &Percent, HTuple *Max, HTuple *Range ) const

Determine the minimum and maximum gray values within regions.

The operator ::min_max_gray creates the histogram of the absolute frequencies of the gray values within Regions in the input image Image (see ::gray_histo) and calculates the number of pixels Percent corresponding to the area of the input image. Then it goes inwards on both sides of the histogram by this number of pixels and determines the smallest and the largest gray value:

  e.g.:
    Area = 60, percent = 5, i.e. 3 pixels
    Histogram = [2,8,0,7,13,0,0,...,0,10,10,5,3,1,1]
    => Maximum = 255, Minimum = 0, Range = 255

    min_max_gray returns: Maximum = 253, Minimum = 1, Range = 252

If Percent is set at 50, Min = Max = Median. If Percent is 0 no histogram is calculated in order to enhance the runtime.

Attention

In case of int2, int4- and real-images Percent has to be 0.

Parameters

`Regions` (input_object)	region(-array) `->` Hobject: HRegion(Array)
Regions, the features of which are to be calculated.

`Image` (input_object)	image `->` Hobject: HImage ( byte / int1 / int2 / int4 / real )
Gray value image.

`Percent` (input_control)	number `->` HTuple.double / long
Percentage below (above) the absolute maximum (minimum).
Default value: 0
Suggested values: 0, 1, 2, 5, 7, 10, 15, 20, 30, 40, 50
Restriction: `(0 <= Percent) && (Percent <= 50)`

`Min` (output_control)	real(-array) `->` (HTuple.) double *
``Minimum'' gray value.

`Max` (output_control)	real(-array) `->` (HTuple.) double *
``Maximum'' gray value.
Assertion: `Max >= Min`

`Range` (output_control)	real(-array) `->` (HTuple.) double *
Difference between Max and Min.
Assertion: `Range >= 0`

Example

#include  <iostream.h>
#include  "HalconCpp.h"

main()
{
  HImage   img ("fabrik");
  HWindow  w;

  Htuple   range, max;

  img.Display (w);
  w.Click ();

  HRegion   reg = w.DrawRegion ();
  HImage    rdd = img.ReduceDomain (reg);

  Htuple min = reg.MinMaxGray (rdd, 5, &max, &range);

  HRegionArray imgseg = ((img >= min[0].I()).Connection() &
			   (img <= max[0].I()).Connection());

  cout << "Min = " << min[0].I() << endl;
  cout << "Max = " << max[0].I() << endl;

  imgseg.Display (w);
  w.Click ();
  return(0);
}

Complexity

If F is the area of the region the runtime complexity is O(F) if Percent = 0, O(F + 255) otherwise.

Result

The operator ::min_max_gray returns the value H_MSG_TRUE if the input image has the defined gray values and the parameters are correct. The behavior in case of empty input (no input images available) is set via the operator ::set_system('no_object_result',<Result>). The behaviour in case of an empty region is set via the operator ::set_system('empty_region_result',<Result>). If necessary an exception handling is raised.

Possible Predecessors

::draw_region, ::gen_circle, ::gen_ellipse, ::gen_rectangle1, ::threshold, ::regiongrowing

Possible Successors

::threshold

Alternatives

::select_gray, ::intensity

Module

Image filters