Safe Haskell	None
Language	Haskell2010

Vision.Image.Filter

Contents

Classes and type
Morphological operators
Blur
Derivation
Others

Description

Provides high level filtering functions for images.

Use Internal if you want to create new image filters.

Filters are operations on images on which the surrounding of each processed pixel is considered according to a kernel.

See http://en.wikipedia.org/wiki/Kernel_(image_processing) for details.

The radius argument of some filters is used to determine the kernel size. A radius as of 1 means a kernel of size 3, 2 a kernel of size 5 and so on.

Note: filters are currently not supported on multi-channel images (RGB, RGBA ...) are currently not supported.

Synopsis

Classes and type

class Filterable src res f Source #

Provides an implementation to execute a type of filter.

src is the original image, res the resulting image and f the filter.

Minimal complete definition

apply

Instances

(Image src, FromFunction res, (~) * src_pix (ImagePixel src), (~) * res_pix (FromFunctionPixel res), SeparatelyFiltrable src res src_pix) => Filterable src res (SeparableFilter1 src_pix init res_pix) Source #	Separable filters initialized using the first pixel of the kernel.
Methods apply :: SeparableFilter1 src_pix init res_pix -> src -> res Source #
(Image src, FromFunction res, (~) * src_pix (ImagePixel src), (~) * res_pix (FromFunctionPixel res)) => Filterable src res (BoxFilter1 src_pix init res_pix) Source #	Box filters initialized using the first pixel of the kernel.
Methods apply :: BoxFilter1 src_pix init res_pix -> src -> res Source #
(Image src, FromFunction res, (~) * src_pix (ImagePixel src), (~) * res_pix (FromFunctionPixel res), SeparatelyFiltrable src res acc) => Filterable src res (SeparableFilter src_pix init acc res_pix) Source #	Separable filters initialized with a given value.
Methods apply :: SeparableFilter src_pix init acc res_pix -> src -> res Source #
(Image src, FromFunction res, (~) * src_pix (ImagePixel src), (~) * res_pix (FromFunctionPixel res)) => Filterable src res (BoxFilter src_pix init acc res_pix) Source #	Box filters initialized with a given value.
Methods apply :: BoxFilter src_pix init acc res_pix -> src -> res Source #

data Filter src kernel init fold acc res Source #

Instances

(Image src, FromFunction res, (~) * src_pix (ImagePixel src), (~) * res_pix (FromFunctionPixel res), SeparatelyFiltrable src res src_pix) => Filterable src res (SeparableFilter1 src_pix init res_pix) Source #	Separable filters initialized using the first pixel of the kernel.
Methods apply :: SeparableFilter1 src_pix init res_pix -> src -> res Source #
(Image src, FromFunction res, (~) * src_pix (ImagePixel src), (~) * res_pix (FromFunctionPixel res)) => Filterable src res (BoxFilter1 src_pix init res_pix) Source #	Box filters initialized using the first pixel of the kernel.
Methods apply :: BoxFilter1 src_pix init res_pix -> src -> res Source #
(Image src, FromFunction res, (~) * src_pix (ImagePixel src), (~) * res_pix (FromFunctionPixel res), SeparatelyFiltrable src res acc) => Filterable src res (SeparableFilter src_pix init acc res_pix) Source #	Separable filters initialized with a given value.
Methods apply :: SeparableFilter src_pix init acc res_pix -> src -> res Source #
(Image src, FromFunction res, (~) * src_pix (ImagePixel src), (~) * res_pix (FromFunctionPixel res)) => Filterable src res (BoxFilter src_pix init acc res_pix) Source #	Box filters initialized with a given value.
Methods apply :: BoxFilter src_pix init acc res_pix -> src -> res Source #

class (Image (SeparableFilterAccumulator src res acc), ImagePixel (SeparableFilterAccumulator src res acc) ~ acc, FromFunction (SeparableFilterAccumulator src res acc), FromFunctionPixel (SeparableFilterAccumulator src res acc) ~ acc) => SeparatelyFiltrable src res acc Source #

Used to determine the type of the accumulator image used when computing separable filters.

src and res are respectively the source and the result image types while acc is the pixel type of the accumulator.

Instances

Storable acc => SeparatelyFiltrable src (Delayed p) acc Source #
Associated Types type SeparableFilterAccumulator src (Delayed p) acc :: * Source #
Storable acc => SeparatelyFiltrable src (Manifest p) acc Source #
Associated Types type SeparableFilterAccumulator src (Manifest p) acc :: * Source #

Morphological operators

dilate Source #

Arguments

:: (Image src, Ord (ImagePixel src), FromFunction res, FromFunctionPixel res ~ ImagePixel src, SeparatelyFiltrable src res (ImagePixel src))
=> Int	Kernel radius.
-> src
-> res

erode Source #

Arguments

:: (Image src, Ord (ImagePixel src), FromFunction res, FromFunctionPixel res ~ ImagePixel src, SeparatelyFiltrable src res (ImagePixel src))
=> Int	Kernel radius.
-> src
-> res

Blur

blur Source #

Arguments

:: (Image src, Integral (ImagePixel src), FromFunction res, Num (FromFunctionPixel res), SeparatelyFiltrable src res Int32)
=> Int	Blur radius.
-> src
-> res

Blurs the image by averaging the pixel inside the kernel.

Uses an Int32 as accumulator during the averaging operation.

gaussianBlur Source #

Arguments

:: (Image src, Integral (ImagePixel src), FromFunction res, Integral (FromFunctionPixel res), Floating acc, RealFrac acc, Storable acc, SeparatelyFiltrable src res acc)
=> Int	Blur radius.
-> Maybe acc	Sigma value of the Gaussian function. If not given, will be automatically computed from the radius so that the kernel fits 3σ of the distribution.
-> src
-> res

Blurs the image by averaging the pixel inside the kernel using a Gaussian function.

See http://en.wikipedia.org/wiki/Gaussian_blur

Derivation

data DerivativeType Source #

Constructors

DerivativeX
DerivativeY

scharr :: (Image src, Integral (ImagePixel src), FromFunction res, Integral (FromFunctionPixel res), Storable (FromFunctionPixel res), SeparatelyFiltrable src res (FromFunctionPixel res)) => DerivativeType -> src -> res Source #

Estimates the first derivative using the Scharr's 3x3 kernel.

Convolves the following kernel for the X derivative:

 -3   0   3
-10   0  10
 -3   0   3

And this kernel for the Y derivative:

 -3 -10  -3
  0   0   0
  3  10   3

Uses an Int32 as accumulator during kernel application.

sobel Source #

Arguments

:: (Image src, Integral (ImagePixel src), FromFunction res, Integral (FromFunctionPixel res), Storable (FromFunctionPixel res), SeparatelyFiltrable src res (FromFunctionPixel res))
=> Int	Kernel radius.
-> DerivativeType
-> src
-> res

Estimates the first derivative using a Sobel's kernel.

Prefer scharr when radius equals 1 as Scharr's kernel is more accurate and is implemented faster.

Uses an Int32 as accumulator during kernel application.

Others

mean :: (Image src, Integral (ImagePixel src), FromFunction res, Fractional (FromFunctionPixel res), SeparatelyFiltrable src res Int32) => Size -> src -> res Source #

Computes the average of a kernel of the given size.

This is similar to blur but with a rectangular kernel and a Fractional result.

Uses an Int32 as accumulator during the averaging operation.