histo_2dim__ ( Regions, ImageCol, ImageRow : Histo2Dim : : )

Calculate the histogram of two-channel gray value images.

The operator histo_2dim__ calculates the 2-dimensional histogram of two images within Regions. The gray values of channel 1 (ImageCol) are interpreted as row index, those of channel 2 (ImageRow) as colmun index. The gray value at one point P(g1,g2) in the output image Histo2Dim indicates the frequency of the gray value combination (g1,g2) with g1 indicating the line index and g2 the column index.


Parameters

Regions (input_object)
region(-array) -> object
Region in which the histogram is to be calculated.

ImageCol (input_object)
image -> object : byte
Channel 1.

ImageRow (input_object)
image -> object : byte
Channel 2.

Histo2Dim (output_object)
image -> object : int4
Histogram to be calculated.


Example
read_image(:Image:'affe':) >
laws_byte(Image:Texture:'el',1,5:) >
draw_region(:Region::) >
histo_2dim__(Region,Texture,Image:Histo2Dim::) >
disp_image(Histo2Dim:::).

Complexity

If F is the plane of the region, the runtime complexity is O(F + 256^2).


Result

The operator histo_2dim__ returns the value TRUE if both images have defined gray values. The behavior in case of empty input (no input images available) is set via the operator set_system(::'no_object_result',<Result>:), the behavior in case of empty region is set via set_system(::'empty_region_result',<Result>:). If necessary an exception is raised.


Possible Predecessors

decompose3, decompose2, draw_region


Possible Successors

threshold__, class_2dim__, pouring, local_max, grey_skeleton__


Alternatives

histo__


See also

get_greyval__



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