intensity

intensity ( Regions, Image : : : Mean, Deviation )

Calculate the mean and deviation of gray values.

The operator intensity calculates the mean and the deviation of the gray values in the input image within Regions. If R is a region, p a pixel from R with the gray value g(p) and F the plane (F = |R|), the features are defined by:

                ----
                \
   Mean      =  /     g(p)
                ----
               p in R
               -----------
                    F

                 -----------------------
                 |    ----
                 | 1  \                2
   Deviation =   | -  /     (g(p)-Mean)
               \ | F  ----
                \|   p in R

Attention

The calculation of Deviation does not follow the usual definition if the region of the image contains only one pixel. In this case 0.0 is returned.

Parameters

`Regions` (input_object)	region(-array) `->` object
Regions the features of which are to be calculated.

`Image` (input_object)	image `->` object : byte / direction / cyclic / int1 / int2 / uint2 / int4 / real
Gray value image.

`Mean` (output_control)	real(-array) `->` real
Mean gray value of a region.

`Deviation` (output_control)	real(-array) `->` real
Deviation of gray values within a region.

Complexity

If F is the area of the region, the runtime complexity is O(F).

Result

The operator intensity returns the value 2 (H_MSG_TRUE). 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 handling is raised.

Parallelization Information

intensity is reentrant and automatically parallelized (on tuple level).

Possible Successors

threshold

Alternatives

select_gray, min_max_gray

Module

Image filters