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ResizePixelVectors

Header:	FIL.h
Namespace:	fil
Module:	FoundationBasic

Rescales an image treating pixels as vectors.

Syntax

void fil::ResizePixelVectors
(
	const fil::Image& inImage,
	ftl::Optional<const fil::Region&> inRoi,
	const float inVectorLength,
	fil::Image& outImage
)

Parameters

Name	Type	Range	Default	Description
inImage	const Image&			Input image
inRoi	Optional<const Region&>		NIL	Region of interest
inVectorLength	const float	0.0 -	255.0f	Desired vector length after normalization
outImage	Image&			Rescaled image

Description

The filter treats pixels as a vector (each channel value as a coordinate). The operation scales pixels values to desired vector length:

\[ \begin{aligned} \lvert \lvert Pixel \rvert \rvert &= \sqrt{Pixel.X^2 + Pixel.Y^2 + Pixel.Z^2 + Pixel.W^2}\\ Pixel.X &= \frac{Pixel.X}{\lvert \lvert Pixel \rvert \rvert}\cdot inVectorLength\\ Pixel.Y &= \frac{Pixel.Y}{\lvert \lvert Pixel \rvert \rvert}\cdot inVectorLength\\ Pixel.Z &= \frac{Pixel.Z}{\lvert \lvert Pixel \rvert \rvert}\cdot inVectorLength\\ Pixel.W &= \frac{Pixel.W}{\lvert \lvert Pixel \rvert \rvert}\cdot inVectorLength \end{aligned} \]

Remarks

If a vector length of a pixel from an input image is zero, the output value equals zero.

If computed channel value exceeds its range, it is cut to maximal allowed value. Therefore the resulting vector length can be smaller than desired.

Computed values are rounded down to the next integer for integer pixel types.

Hardware Acceleration

This operation supports automatic parallelization for multicore and multiprocessor systems.

Errors

List of possible exceptions:

Error type	Description
DomainError	Region exceeds an input image in ResizePixelVectors.