Image::Leptonica::Func::morphapp
version 0.03
morphapp.c
morphapp.c These are some useful and/or interesting composite image processing operations, of the type that are often useful in applications. Most are morphological in nature. Extraction of boundary pixels PIX *pixExtractBoundary() Selective morph sequence operation under mask PIX *pixMorphSequenceMasked() Selective morph sequence operation on each component PIX *pixMorphSequenceByComponent() PIXA *pixaMorphSequenceByComponent() Selective morph sequence operation on each region PIX *pixMorphSequenceByRegion() PIXA *pixaMorphSequenceByRegion() Union and intersection of parallel composite operations PIX *pixUnionOfMorphOps() PIX *pixIntersectionOfMorphOps() Selective connected component filling PIX *pixSelectiveConnCompFill() Removal of matched patterns PIX *pixRemoveMatchedPattern() Display of matched patterns PIX *pixDisplayMatchedPattern() Iterative morphological seed filling (don't use for real work) PIX *pixSeedfillMorph() Granulometry on binary images NUMA *pixRunHistogramMorph() Composite operations on grayscale images PIX *pixTophat() PIX *pixHDome() PIX *pixFastTophat() PIX *pixMorphGradient() Centroid of component PTA *pixaCentroids() l_int32 pixCentroid()
l_int32 pixCentroid ( PIX *pix, l_int32 *centtab, l_int32 *sumtab, l_float32 *pxave, l_float32 *pyave )
pixCentroid() Input: pix (1 or 8 bpp) centtab (<optional> table for finding centroids; can be null) sumtab (<optional> table for finding pixel sums; can be null) &xave, &yave (<return> coordinates of centroid, relative to the UL corner of the pix) Return: 0 if OK, 1 on error Notes: (1) Any table not passed in will be made internally and destroyed after use.
PIX * pixDisplayMatchedPattern ( PIX *pixs, PIX *pixp, PIX *pixe, l_int32 x0, l_int32 y0, l_uint32 color, l_float32 scale, l_int32 nlevels )
pixDisplayMatchedPattern() Input: pixs (input image, 1 bpp) pixp (pattern to be removed from image, 1 bpp) pixe (image after erosion by Sel that approximates pixp, 1 bpp) x0, y0 (center of Sel) color (to paint the matched patterns; 0xrrggbb00) scale (reduction factor for output pixd) nlevels (if scale < 1.0, threshold to this number of levels) Return: pixd (8 bpp, colormapped), or null on error Notes: (1) A 4 bpp colormapped image is generated. (2) If scale <= 1.0, do scale to gray for the output, and threshold to nlevels of gray. (3) You can use various functions in selgen to create a Sel that will generate pixe from pixs. (4) This function is applied after pixe has been computed. It finds the centroid of each c.c., and colors the output pixels using pixp (appropriately aligned) as a stencil. Alignment is done using the origin of the Sel and the centroid of the eroded image to place the stencil pixp.
PIX * pixExtractBoundary ( PIX *pixs, l_int32 type )
pixExtractBoundary() Input: pixs (1 bpp) type (0 for background pixels; 1 for foreground pixels) Return: pixd, or null on error Notes: (1) Extracts the fg or bg boundary pixels for each component. Components are assumed to end at the boundary of pixs.
PIX * pixFastTophat ( PIX *pixs, l_int32 xsize, l_int32 ysize, l_int32 type )
pixFastTophat() Input: pixs xsize (width of max/min op, smoothing; any integer >= 1) ysize (height of max/min op, smoothing; any integer >= 1) type (L_TOPHAT_WHITE: image - min L_TOPHAT_BLACK: max - image) Return: pixd, or null on error Notes: (1) Don't be fooled. This is NOT a tophat. It is a tophat-like operation, where the result is similar to what you'd get if you used an erosion instead of an opening, or a dilation instead of a closing. (2) Instead of opening or closing at full resolution, it does a fast downscale/minmax operation, then a quick small smoothing at low res, a replicative expansion of the "background" to full res, and finally a removal of the background level from the input image. The smoothing step may not be important. (3) It does not remove noise as well as a tophat, but it is 5 to 10 times faster. If you need the preciseness of the tophat, don't use this. (4) The L_TOPHAT_WHITE flag emphasizes small bright regions, whereas the L_TOPHAT_BLACK flag emphasizes small dark regions.
PIX * pixHDome ( PIX *pixs, l_int32 height, l_int32 connectivity )
pixHDome() Input: pixs (8 bpp, filling mask) height (of seed below the filling maskhdome; must be >= 0) connectivity (4 or 8) Return: pixd (8 bpp), or null on error Notes: (1) It is more efficient to use a connectivity of 4 for the fill. (2) This fills bumps to some level, and extracts the unfilled part of the bump. To extract the troughs of basins, first invert pixs and then apply pixHDome(). (3) It is useful to compare the HDome operation with the TopHat. The latter extracts peaks or valleys that have a width not exceeding the size of the structuring element used in the opening or closing, rsp. The height of the peak is irrelevant. By contrast, for the HDome, the gray seedfill is used to extract all peaks that have a height not exceeding a given value, regardless of their width! (4) Slightly more precisely, suppose you set 'height' = 40. Then all bumps in pixs with a height greater than or equal to 40 become, in pixd, bumps with a max value of exactly 40. All shorter bumps have a max value in pixd equal to the height of the bump. (5) The method: the filling mask, pixs, is the image whose peaks are to be extracted. The height of a peak is the distance between the top of the peak and the highest "leak" to the outside -- think of a sombrero, where the leak occurs at the highest point on the rim. (a) Generate a seed, pixd, by subtracting some value, p, from each pixel in the filling mask, pixs. The value p is the 'height' input to this function. (b) Fill in pixd starting with this seed, clipping by pixs, in the way described in seedfillGrayLow(). The filling stops before the peaks in pixs are filled. For peaks that have a height > p, pixd is filled to the level equal to the (top-of-the-peak - p). For peaks of height < p, the peak is left unfilled from its highest saddle point (the leak to the outside). (c) Subtract the filled seed (pixd) from the filling mask (pixs). Note that in this procedure, everything is done starting with the filling mask, pixs. (6) For segmentation, the resulting image, pixd, can be thresholded and used as a seed for another filling operation.
PIX * pixIntersectionOfMorphOps ( PIX *pixs, SELA *sela, l_int32 type )
pixIntersectionOfMorphOps() Input: pixs (binary) sela type (L_MORPH_DILATE, etc.) Return: pixd (intersection of the specified morphological operation on pixs for each Sel in the Sela), or null on error
PIX * pixMorphGradient ( PIX *pixs, l_int32 hsize, l_int32 vsize, l_int32 smoothing )
pixMorphGradient() Input: pixs hsize (of Sel; must be odd; origin implicitly in center) vsize (ditto) smoothing (half-width of convolution smoothing filter. The width is (2 * smoothing + 1), so 0 is no-op. Return: pixd, or null on error
PIX * pixMorphSequenceByComponent ( PIX *pixs, const char *sequence, l_int32 connectivity, l_int32 minw, l_int32 minh, BOXA **pboxa )
pixMorphSequenceByComponent() Input: pixs (1 bpp) sequence (string specifying sequence) connectivity (4 or 8) minw (minimum width to consider; use 0 or 1 for any width) minh (minimum height to consider; use 0 or 1 for any height) &boxa (<optional> return boxa of c.c. in pixs) Return: pixd, or null on error Notes: (1) See pixMorphSequence() for composing operation sequences. (2) This operates separately on each c.c. in the input pix. (3) The dilation does NOT increase the c.c. size; it is clipped to the size of the original c.c. This is necessary to keep the c.c. independent after the operation. (4) You can specify that the width and/or height must equal or exceed a minimum size for the operation to take place. (5) Use NULL for boxa to avoid returning the boxa.
PIX * pixMorphSequenceByRegion ( PIX *pixs, PIX *pixm, const char *sequence, l_int32 connectivity, l_int32 minw, l_int32 minh, BOXA **pboxa )
pixMorphSequenceByRegion() Input: pixs (1 bpp) pixm (mask specifying regions) sequence (string specifying sequence) connectivity (4 or 8, used on mask) minw (minimum width to consider; use 0 or 1 for any width) minh (minimum height to consider; use 0 or 1 for any height) &boxa (<optional> return boxa of c.c. in pixm) Return: pixd, or null on error Notes: (1) See pixMorphCompSequence() for composing operation sequences. (2) This operates separately on the region in pixs corresponding to each c.c. in the mask pixm. It differs from pixMorphSequenceByComponent() in that the latter does not have a pixm (mask), but instead operates independently on each component in pixs. (3) Dilation will NOT increase the region size; the result is clipped to the size of the mask region. This is necessary to make regions independent after the operation. (4) You can specify that the width and/or height of a region must equal or exceed a minimum size for the operation to take place. (5) Use NULL for @pboxa to avoid returning the boxa.
PIX * pixMorphSequenceMasked ( PIX *pixs, PIX *pixm, const char *sequence, l_int32 dispsep )
pixMorphSequenceMasked() Input: pixs (1 bpp) pixm (<optional> 1 bpp mask) sequence (string specifying sequence of operations) dispsep (horizontal separation in pixels between successive displays; use zero to suppress display) Return: pixd, or null on error Notes: (1) This applies the morph sequence to the image, but only allows changes in pixs for pixels under the background of pixm. (5) If pixm is NULL, this is just pixMorphSequence().
l_int32 pixRemoveMatchedPattern ( PIX *pixs, PIX *pixp, PIX *pixe, l_int32 x0, l_int32 y0, l_int32 dsize )
pixRemoveMatchedPattern() Input: pixs (input image, 1 bpp) pixp (pattern to be removed from image, 1 bpp) pixe (image after erosion by Sel that approximates pixp, 1 bpp) x0, y0 (center of Sel) dsize (number of pixels on each side by which pixp is dilated before being subtracted from pixs; valid values are {0, 1, 2, 3, 4}) Return: 0 if OK, 1 on error Notes: (1) This is in-place. (2) You can use various functions in selgen to create a Sel that is used to generate pixe from pixs. (3) This function is applied after pixe has been computed. It finds the centroid of each c.c., and subtracts (the appropriately dilated version of) pixp, with the center of the Sel used to align pixp with pixs.
NUMA * pixRunHistogramMorph ( PIX *pixs, l_int32 runtype, l_int32 direction, l_int32 maxsize )
pixRunHistogramMorph() Input: pixs runtype (L_RUN_OFF, L_RUN_ON) direction (L_HORIZ, L_VERT) maxsize (size of largest runlength counted) Return: numa of run-lengths
PIX * pixSeedfillMorph ( PIX *pixs, PIX *pixm, l_int32 maxiters, l_int32 connectivity )
pixSeedfillMorph() Input: pixs (seed) pixm (mask) maxiters (use 0 to go to completion) connectivity (4 or 8) Return: pixd (after filling into the mask) or null on error Notes: (1) This is in general a very inefficient method for filling from a seed into a mask. Use it for a small number of iterations, but if you expect more than a few iterations, use pixSeedfillBinary(). (2) We use a 3x3 brick SEL for 8-cc filling and a 3x3 plus SEL for 4-cc.
PIX * pixSelectiveConnCompFill ( PIX *pixs, l_int32 connectivity, l_int32 minw, l_int32 minh )
pixSelectiveConnCompFill() Input: pixs (binary) connectivity (4 or 8) minw (minimum width to consider; use 0 or 1 for any width) minh (minimum height to consider; use 0 or 1 for any height) Return: pix (with holes filled in selected c.c.), or null on error
PIX * pixTophat ( PIX *pixs, l_int32 hsize, l_int32 vsize, l_int32 type )
pixTophat() Input: pixs hsize (of Sel; must be odd; origin implicitly in center) vsize (ditto) type (L_TOPHAT_WHITE: image - opening L_TOPHAT_BLACK: closing - image) Return: pixd, or null on error Notes: (1) Sel is a brick with all elements being hits (2) If hsize = vsize = 1, returns an image with all 0 data. (3) The L_TOPHAT_WHITE flag emphasizes small bright regions, whereas the L_TOPHAT_BLACK flag emphasizes small dark regions. The L_TOPHAT_WHITE tophat can be accomplished by doing a L_TOPHAT_BLACK tophat on the inverse, or v.v.
PIX * pixUnionOfMorphOps ( PIX *pixs, SELA *sela, l_int32 type )
pixUnionOfMorphOps() Input: pixs (binary) sela type (L_MORPH_DILATE, etc.) Return: pixd (union of the specified morphological operation on pixs for each Sel in the Sela), or null on error
PTA * pixaCentroids ( PIXA *pixa )
pixaCentroids() Input: pixa of components (1 or 8 bpp) Return: pta of centroids relative to the UL corner of each pix, or null on error Notes: (1) An error message is returned if any pix has something other than 1 bpp or 8 bpp depth, and the centroid from that pix is saved as (0, 0).
PIXA * pixaMorphSequenceByComponent ( PIXA *pixas, const char *sequence, l_int32 minw, l_int32 minh )
pixaMorphSequenceByComponent() Input: pixas (of 1 bpp pix) sequence (string specifying sequence) minw (minimum width to consider; use 0 or 1 for any width) minh (minimum height to consider; use 0 or 1 for any height) Return: pixad, or null on error Notes: (1) See pixMorphSequence() for composing operation sequences. (2) This operates separately on each c.c. in the input pixa. (3) You can specify that the width and/or height must equal or exceed a minimum size for the operation to take place. (4) The input pixa should have a boxa giving the locations of the pix components.
PIXA * pixaMorphSequenceByRegion ( PIX *pixs, PIXA *pixam, const char *sequence, l_int32 minw, l_int32 minh )
pixaMorphSequenceByRegion() Input: pixs (1 bpp) pixam (of 1 bpp mask elements) sequence (string specifying sequence) minw (minimum width to consider; use 0 or 1 for any width) minh (minimum height to consider; use 0 or 1 for any height) Return: pixad, or null on error Notes: (1) See pixMorphSequence() for composing operation sequences. (2) This operates separately on each region in the input pixs defined by the components in pixam. (3) You can specify that the width and/or height of a mask component must equal or exceed a minimum size for the operation to take place. (4) The input pixam should have a boxa giving the locations of the regions in pixs.
Zakariyya Mughal <zmughal@cpan.org>
This software is copyright (c) 2014 by Zakariyya Mughal.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
To install Image::Leptonica, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Image::Leptonica
CPAN shell
perl -MCPAN -e shell install Image::Leptonica
For more information on module installation, please visit the detailed CPAN module installation guide.