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ImageAverage

Header:	AVL.h
Namespace:	avl
Module:	FoundationLite

Computes the average of the image pixel values.

Syntax

void avl::ImageAverage
(
	const avl::Image& inImage,
	atl::Optional<const avl::Region&> inRoi,
	avl::Pixel& outAverageColor,
	atl::Optional<float&> outAverageValue = atl::NIL
)

Parameters

Name	Type	Default	Description
inImage	const Image&		Input image
inRoi	Optional<const Region&>	NIL	Range of pixels to be processed
outAverageColor	Pixel&		Average of each channel
outAverageValue	Optional<float&>	NIL	Average of the entire image

Optional Outputs

The computation of following outputs can be switched off by passing value atl::NIL to these parameters: outAverageValue.

Description

The function calculates average of pixel values in the inImage.

Average values of pixels calculated for each channel are returned in outAverageColor, while calculated for the region of interest - in outAverageValue. If region of interest isn't specified, average is calculated for the entire image.

Hints

Connect inImage with the output of your image acquisition filter.

Examples

In this single-channel image, average will be 127.5 for the channel and for the entire image (if the region of interested isn't specified).	In this three-channel RGB image, average will be 0 for R and G channels and 255 for the B channel. If we don't specify the region of interest, average of the image will be 85.0 (because arithmetic mean of 0, 0, and 255 is 85.0).
In this three-channel RGB image, average will be 63.75 for R and B channels and 127.5 for the G channel. If we don't specify the region of interest, average of the image will be 85.0 (because arithmetic mean of 63.75, 63.75 and 127.5 is 85.0).

Remarks

Minimal image size requirement

The input image shouldn't be empty.

Minimal region of interest size requirement

The input region of interest shouldn't be empty.

Hardware Acceleration

This operation supports automatic parallelization for multicore and multiprocessor systems.

Errors

List of possible exceptions:

Error type	Description
DomainError	Empty image on input in ImageAverage.
DomainError	Empty region of interest on input in ImageAverage.
DomainError	Region exceeds an input image in ImageAverage.