gray_histo_abs — Calculate the gray value distribution.
The operator gray_histo_abs calculates for the image (Image) within Regions the absolute (AbsoluteHisto) ) histogram of the gray values.
The parameter Quantization defines, how many frequencies of neighbored gray values are added for one frequency value. The resulting histogram AbsoluteHisto is a tuple, whose indices are mapped on the gray values of the input image Image and whose elements contain the frequencies of the gray values. The indices i of the frequency value are calculated from the gray values g and the quantisation q as follows:
i = ceil((g+0.5)/q) for unsigned image types, i = ceil((g-(MIN-0.5))/q) for signed image types,
whereas MIN denotes the minimal gray value, e.g., -128 for an int1 image type. Therefore, the size of the tuple results from the ratio of the full domain of gray values and the quantisation, e.g. for images of int2 in ceil(65536/3.0) = 21846 . The origin gray value of the signed image types int1 resp. int2 is mapped on the index 128 resp. 32768, negative resp. positive gray values have smaller resp. greater indices.
The histogram can also be returned directly as a graphic via the operators set_paint(::WindowHandle,'histogram':) and disp_image.
Note that the operator gray_histo_abs only considers the given Regions and ignores any previously set domain of the input image Image.
Region in which the histogram is to be calculated.
Image the gray value distribution of which is to be calculated.
Quantization of the gray values.
Default value: 1.0
List of values: 1.0, 2.0, 3.0, 5.0, 10.0
Restriction: Quantization >= 1.0
Absolute frequencies of the gray values.
The operator gray_histo_abs returns the value 2 (H_MSG_TRUE) if the image has 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 behavior in case of empty region is set via set_system(::'empty_region_result',<Result>:). If necessary an exception is raised.
min_max_gray, intensity, gray_histo, gray_histo_range
set_paint, disp_image, histo_2dim, scale_image_max, entropy_gray