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SubtractImages

Header:	AVL.h
Namespace:	avl
Module:	FoundationLite

Subtracts two images pixel by pixel. The result is signed.

Syntax

void avl::SubtractImages
(
	const avl::Image& inImage1,
	const avl::Image& inImage2,
	atl::Optional<const avl::Region&> inRoi,
	float inScale,
	avl::Image& outImage
)

Parameters

Name	Type	Default	Description
inImage1	const Image&		First input image
inImage2	const Image&		Second input image
inRoi	Optional<const Region&>	NIL	Range of pixels to be processed
inScale	float	1.0f	Output image scaling factor
outImage	Image&		Output image

In-place Processing

This function supports in-place data processing - you can pass the same reference to inImage1 and outImage, inImage2 and outImage

Description

Operation subtracts two images. Each outImage pixel is equal to the difference of corresponding pixels of the input images.

The result of the operation is multiplied by inScale factor, which may be used to avoid clipping when the produced values exceed the range of correct pixel values. However it should be noted that when the value of inScale is other than 1.0, the filter uses a slower, not SSE-optimized implementation.

Whenever the resulting value exceeds the range of pixel values, it is clipped to the nearest proper value. In multichannel (color) images each pixel channel is processed separately.

The operation requires that the images being processed have equal format and dimensions, otherwise an error with appropriate description occurs. To obtain an image of desired dimensions one can use ResizeImage or CropImage filter. To alter the pixel type of an image one can use ConvertPixelType filter. ConvertToMultichannel and AverageChannels filters allow to alter the number of image channels.

Examples

SubtractImages performed on the sample images.

Hardware Acceleration

This operation is optimized for SSE2 technology for pixels of types: UINT8, SINT16, REAL, SINT8(for inScale=1), UINT16(for inScale=1).

This operation is optimized for SSE41 technology for pixels of types: UINT16(for inScale!=1).

This operation is optimized for AVX2 technology for pixels of types: UINT8, SINT16, UINT16, REAL, SINT8(for inScale=1).

This operation supports automatic parallelization for multicore and multiprocessor systems.

Errors

List of possible exceptions:

Error type	Description
DomainError	Image formats are not the same in SubtractImages.
DomainError	Image sizes are not equal in SubtractImages.
DomainError	Region exceeds an input image in SubtractImages.