Operators

# intensity (Operator)

## Name

intensity — Calculate the mean and deviation of gray values.

## Signature

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

## Description

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

Note that the operator intensity only considers the given Regions and ignores any previously set domain of the input image Image. 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.

## Parallelization

• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Automatically parallelized on tuple level.

## Parameters

Regions (input_object)  region(-array) object

Regions in which the features are calculated.

Image (input_object)  singlechannelimage 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 is raised.