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Local::Local(3)	      User Contributed Perl Documentation      Local::Local(3)

NAME
       IPA::Local - methods that produce images	where every pixel is a
       function	of pixels in the neighborhood

DESCRIPTION
       Contains	functions that operate in the vicinity of a pixel, and produce
       image where every pixel is dependant on the values of the source	pixel
       and the values of its neighbors.	 The process can be described with the
       mapping function

		|r(i,j),r(i+1,j)...|
	  s = M	|...		   |
		|r(j+1,i) ...	   |

       where "r" and "s" are the pixel values in the input and output images,
       respectively.

       crispening IMAGE
	   Applies the crispening algorithm to IMAGE and returns the result.

	   Supported types: Byte

       sobel IMAGE [ jobMask = sobelNWSE|sobelNESW, conversionType =
       conversionScaleAbs, combineType = combineMaxAbs,	divisor	= 1]
	   Applies Sobel edge detector to IMAGE.

	   Supported types: Byte

	   Parameters:

	   jobMask INTEGER
	       Combination of the integer constants, that mask the pixels in
	       Sobel 3x3 kernel.  If the kernel	is to be drawn as

		 | (-1,1) (0,1)	(1,1) |
		 | (-1,0) (0,0)	(1,0) |
		 | (-1,-1)(0,-1)(1,-1)|

	       Then the	constants mask the following points:

		  sobelRow	- (-1,0),(1,0)
		  sobelColumn	- (0,1),(0,-1)
		  sobelNESW	- (1,1),(-1,-1)
		  sobelNWSE	- (-1,1),(1,-1)

	       (0,0) point is always masked.

	   divisor INTEGER
	       The resulting pixel value is divided to "divisor" value after
	       the kernel convolution is applied.

	   "conversionType" and	<combineType> parameters described in combine.

       GEF IMAGE [ a0 =	1.3, s = 0.7]
	   Applies GEF algorithm ( first derivative operator for symmetric
	   exponential filter) to IMAGE.

	   Supported types: Byte

       SDEF IMAGE [ a0 = 1.3, s	= 0.7]
	   Applies SDEF	algorithm ( second derivative operator for symmetric
	   exponential filter) to IMAGE.

	   Supported types: Byte

       deriche IMAGE [ alpha ]
	   Applies Deriche edge	detector.

	   Supported types: Byte

       filter3x3 IMAGE [ matrix, expandEdges = 0, edgecolor = 0,
       conversionType =	conversionScaleAbs, rawOutput =	0, divisor = 1 ]
	   Applies convolution with a custom 3x3 kernel, passed	in "matrix".

	   Supported types: Byte

	   Parameters:

	   matrix ARRAY
	       Array of	9 integers, a 3x3 kernel, to be	convoluted with	IMAGE.
	       Indexes are:

		 |0 1 2|
		 |3 4 5|
		 |6 7 8|

	   expandEdges BOOLEAN
	       If false, the edge pixels ( borders ) not used in the
	       convolution as center pixels. If	true, the edge pixels used,
	       and in this case	"edgecolor" value is used to substitute	the
	       pixels outside the image.

	   edgecolor INTEGER
	       Integer value, used for substitution of pixel values outside
	       IMAGE, when "expandEdges" parameter is set to 1.

	   divisor INTEGER
	       The resulting pixel value is divided to "divisor" value after
	       the kernel convolution is applied.

	   conversionType
	       See combine

	   rawOutput
	       See combine

       median IMAGE [ w	= 3, h = 3 ]
	   Performs adaptive thresholding with median filter with window
	   dimensions "w" and "h".

       unionFind IMAGE [ method, threshold  ]
	   Applies a union find	algorithm selected by "method".	The only
	   implemented method is average-based region grow ( 'ave' string
	   constant ). Its only	parameter is "threshold", integer value	of the
	   balance merger function.

	   Supported types: Byte

       hysteresis IMAGE, thresold => [ thr0, thr1], neighborhood => 4 or 8
	   Perform binary hysteresis thresholding of Byte image	with two
	   thresholds, thr0 and	thr1. A	pixel is set to	1, if its value	is
	   larger than thr1 or if it is	larger than thr0 and the pixel is
	   adjacent to already marked pixels.

	   Default value of neighborhood is 8.

	   Supported types: Byte

       gaussian	SIZE, SIGMA
	   Generates a square image of the given SIZe and populates with with
	   gaussian function with given	SIGMA.

       laplacian SIZE, SIGMA
	   Generates a square image of the given SIZe and populates with with
	   inverse gaussian function with given	SIGMA.

       gradients IMAGE
	   This	function computes a two-dimensional gradient (magnitude	and
	   direction) of an image, using two convolution kernels.  The
	   magnitude is	computed as the	vector magnitude of the	output of the
	   two kernels,	and the	direction is computed as the angle between the
	   two orthogonal gradient vectors.

	   The convolution kernels are (currently limited to) 3x3 masks	for
	   calculating separate	vertical and horizontal	derivatives.

	   (Copyright (c) 1988 by the University of Arizona Digital Image
	   Analysis Lab).

       canny IMAGE [ size = 3, sigma = 2, ridge	= 0 ]
	   First part of the Canny edge	detector (without ridge	strength
	   selection). The ridge strength must be supplied by the user.

       nms IMAGE [ set = 255, clear = 0	]
	   Applies non-maximal suppression to the image, and replaces all non-
	   maximal pixels with the "clear" color, and maximal with "set"
	   color.

       scale IMAGE [ size = 3, sigma_square = 4	]
	   Convolves a given image with	a gaussian, where the latter is
	   calculated with the given size and square root of sigma_square.

       ridge IMAGE [ anorm = false, mul	= 1, scale = 2,	size = 3 ]
	   First part of the Lindeberg edge detector (without scale
	   selection).	The scale must be supplied by the user.	"size" is used
	   in generation of the	gaussian kernel. "mul" is the custom multiply
	   factor to the calclated ridge strength, the maximum absolute	value
	   to the principal curvatures.	"anorm"	selects	whether	the Laplacian
	   blob	response should	be included ( "false" )	), or suppressed (
	   "true" ).

       convolution IMAGE, KERNEL
	   Convolves IMAGE with	the given KERNEL.

       zerocross IMAGE,	cmp = 0
	   Creates a map from IMAGE where white	pixels are assigned to spots
	   where image crosses the zero	plane. The zero	level is 0 by default,
	   but can be changed by setting the "cmp" argument.

perl v5.24.1			  2011-05-08		       Local::Local(3)

NAME | DESCRIPTION

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