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

NAME
       IPA::Global - methods that produce images where every pixel is a
       function	of all pixels in the source image

DESCRIPTION
       Contains	methods	that produce images, where every pixel is a function
       of all pixels in	the source image.  The process can be described	with
       the mapping function

	  s = M(R)

       where "s" is the	pixel value in the output images, and R	is the source
       image.

       close_edges IMAGE [ gradient, maxlen, minedgelen, mingradient ]
	   Closes edges	of shapes on IMAGE, according to specified "gradient"
	   image.  The unclosed	shapes converted to the	closed if the gradient
	   spot	between	the suspected dents falls under	"maxlen" maximal
	   length increment, "mingradient" the minimal gradient	value and the
	   edge	is longer than "minedgelen".

	   Supported types: Byte

	   Parameters:

	   gradient IMAGE
	       Specifies the gradient image

	   maxlen INTEGER
	       Maximal edge length

	   minedgelen INTEGER
	       Minimal edge length

	   mingradient INTEGER
	       Minimal gradient	value

       fill_holes IMAGE	[ inPlace = 0, edgeSize	= 1, backColor = 0, foreColor
       = 255, neighborhood = 4]
	   Fills closed	shapes to eliminate the	contours with holes in IMAGE.

	   Supported types: Byte

	   Parameters:

	   inPlace BOOLEAN
	       If true,	the original image is changed

	   edgeSize INTEGER
	       The edge	breadth	that is	not touched by the algorithm

	   backColor INTEGER
	       The pixel value used for	determination whether a	pixel belongs
	       to the background.

	   foreColor INTEGER
	       The pixel value used for	hole filling.

	   neighborhood	INTEGER
	       Must be either 4	or 8.  Selects whether the algorithm must
	       assume 4- or 8- pixel connection.

       area_filter IMAGE [ minArea = 0,	maxArea	= INT_MAX, inPlace = 0,
       edgeSize	= 1, backColor = 0, foreColor =	255, neighborhood = 4]
	   Identifies the objects on IMAGE and filters out these that have
	   their area less than	"minArea" and more than	"maxArea". The other
	   parameters are identical to those passed to fill_holes.

       identify_contours IMAGE [ edgeSize = 1, backColor = 0, foreColor	= 255,
       neighborhood = 4]
	   Identifies the objects on IMAGE and returns the contours as array
	   of anonymous	arrays of 4- or	8- connected pixel coordinates.

	   The parameters are identical	to those passed	to fill_holes.

	   Supported types: Byte

	   See also IPA::Region.

       identify_scanlines IMAGE	[ edgeSize = 1,	backColor = 0, foreColor =
       255, neighborhood = 4]
	   Same	as "identify_contours" but returns a set of scan lines.

       identify_pixels IMAGE [ match =>	0, eq => 0 ]
	   Returns coordinates of all pixels that match	(if "eq" is 1) or not
	   match ("eq" is 0) color "match".

       fft IMAGE [ inverse = 0 ]
	   Performs direct and inverse ( governed by "inverse" boolean flag )
	   fast	Fourier	transform. IMAGE must have dimensions of power of 2.
	   The resulted	image is always	of DComplex type.

	   Supported types: all

       fourier IMAGE [ inverse = 0 ]
	   Performs direct and inverse ( governed by "inverse" boolean flag )
	   fast	Fourier	transform. If IMAGE dimensions not of power of 2, then
	   IMAGE is scaled up to the closest power of 2, and the result	is
	   scaled back to the original dimensions.

	   The resulted	image is always	of DComplex type.

	   Supported types: all

       band_filter IMAGE [ low = 0, spatial = 1, homomorph = 0,	power =	2.0,
       cutoff =	20.0, boost = 0.7 ]
	   Performs band filtering of IMAGE in frequency domain.  IMAGE	must
	   have	dimensions of power of 2.  The resulted	image is always	of
	   DComplex type.

	   Supported types: all

	   Parameters:

	   low BOOLEAN
	       Boolean flag, indicates whether the low-pass or the high-pass
	       is to be	performed.

	   spatial BOOLEAN
	       Boolean flag, indicates if IMAGE	must be	treated	as if it is in
	       the spatial domain, and therefore conversion to the frequency
	       domain must be performed	first.

	   homomorph BOOLEAN
	       Boolean flag, indicates if the homomorph	( exponential )
	       equalization must be performed. Cannot be set to	true if	the
	       image is	in frequency domain ( if "spatial" parameter set to
	       true ).

	   power FLOAT
	       Power operator applied to the input frequency.

	   cutoff FLOAT
	       Threshold value of the filter.

	   boost FLOAT
	       Multiplication factor used in homomorph equalization.

       butterworth IMAGE [ low = 0, spatial = 1, homomorph = 0,	power =	2.0,
       cutoff =	20.0, boost = 0.7 ]
	   Performs band filtering of IMAGE in frequency domain.  If IMAGE
	   dimensions not of power of 2, then IMAGE is scaled up to the
	   closest power of 2, and the result is scaled	back to	the original
	   dimensions.

	   The resulted	image is always	of DComplex type.

	   Supported types: all

	   The parameters are same as those passed to band_filter.

       hough IMAGE [ type = "line", direct = 1,	resolution = 500 ]
	   Realizes Hough transform. If	type is	"line",	linear transform is
	   performed.  With direct transform, "resolution" is width of the
	   resulted image.

	   Note: Returns a 8-bit grayscale image, which	means that for all
	   practical purposes the image	shouldn't possibly contain more	than
	   256 line candidates.

	   Supported types: all

       hough2lines IMAGE [ width = 1000, height	= 1000 ]
	   Takes a Hough-transformed image, where each pixel is	a line.	For
	   each	non-zero pixel a line projection on a rectangle	with given
	   width and height is calculated.  Returns array of quad values in
	   format [x0,y0,x1,y2]	where the coordinates stand for	the start and
	   the end of a	line.

	   So, if the direct transform was called as

	      $h = hough( $i );

	   then	plotting lines back (after $h was filtered) would be

	      $i-> line(@$_) for @{ hough2lines( $h,
		   width  => $i-> width,
		   height => $i-> height
	      )	};

	   Supported types: 8-bit (expects result from "hough" function).

   Optimized plotting
       The following functions can draw	lines on images, and are optimized for
       speed, because Prima doesn't support drawing on images outside
       "begin_paint"/"end_paint" scope.

       bar IMAGE, X1, Y1, X2, Y2, COLOR
	   Fill	the given rectangular area with	COLOR.

       hlines IMAGE, OFFSET_X, OFFSET_Y, LINES,	COLOR
	   Draws set of	horizontal lines as defined by LINES with COLOR.
	   LINES is an array of	triplet	integers, where	each contains [X1, X2,
	   Y] coordinates - beginning of hline,	end of hline, and vline.

       line IMAGE, X1, Y1, X2, Y2, COLOR
	   Draws a single line from X1,Y1 to X2,Y2 .

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

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