third-party/leptonica/src/seedfill.c
/*====================================================================*
- Copyright (C) 2001 Leptonica. All rights reserved.
-
- Redistribution and use in source and binary forms, with or without
- modification, are permitted provided that the following conditions
- are met:
- 1. Redistributions of source code must retain the above copyright
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- 2. Redistributions in binary form must reproduce the above
- copyright notice, this list of conditions and the following
- disclaimer in the documentation and/or other materials
- provided with the distribution.
-
- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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- CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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*====================================================================*/
/*
* seedfill.c
*
* Binary seedfill (source: Luc Vincent)
* PIX *pixSeedfillBinary()
* PIX *pixSeedfillBinaryRestricted()
*
* Applications of binary seedfill to find and fill holes,
* remove c.c. touching the border and fill bg from border:
* PIX *pixHolesByFilling()
* PIX *pixFillClosedBorders()
* PIX *pixExtractBorderConnComps()
* PIX *pixRemoveBorderConnComps()
* PIX *pixFillBgFromBorder()
*
* Hole-filling of components to bounding rectangle
* PIX *pixFillHolesToBoundingRect()
*
* Gray seedfill (source: Luc Vincent:fast-hybrid-grayscale-reconstruction)
* l_int32 pixSeedfillGray()
* l_int32 pixSeedfillGrayInv()
*
* Gray seedfill (source: Luc Vincent: sequential-reconstruction algorithm)
* l_int32 pixSeedfillGraySimple()
* l_int32 pixSeedfillGrayInvSimple()
*
* Gray seedfill variations
* PIX *pixSeedfillGrayBasin()
*
* Distance function (source: Luc Vincent)
* PIX *pixDistanceFunction()
*
* Seed spread (based on distance function)
* PIX *pixSeedspread()
*
* Local extrema:
* l_int32 pixLocalExtrema()
* static l_int32 pixQualifyLocalMinima()
* l_int32 pixSelectedLocalExtrema()
* PIX *pixFindEqualValues()
*
* Selection of minima in mask of connected components
* PTA *pixSelectMinInConnComp()
*
* Removal of seeded connected components from a mask
* PIX *pixRemoveSeededComponents()
*
*
* ITERATIVE RASTER-ORDER SEEDFILL
*
* The basic method in the Vincent seedfill (aka reconstruction)
* algorithm is simple. We describe here the situation for
* binary seedfill. Pixels are sampled in raster order in
* the seed image. If they are 4-connected to ON pixels
* either directly above or to the left, and are not masked
* out by the mask image, they are turned on (or remain on).
* (Ditto for 8-connected, except you need to check 3 pixels
* on the previous line as well as the pixel to the left
* on the current line. This is extra computational work
* for relatively little gain, so it is preferable
* in most situations to use the 4-connected version.)
* The algorithm proceeds from UR to LL of the image, and
* then reverses and sweeps up from LL to UR.
* These double sweeps are iterated until there is no change.
* At this point, the seed has entirely filled the region it
* is allowed to, as delimited by the mask image.
*
* The grayscale seedfill is a straightforward generalization
* of the binary seedfill, and is described in seedfillLowGray().
*
* For some applications, the filled seed will later be OR'd
* with the negative of the mask. This is used, for example,
* when you flood fill into a 4-connected region of OFF pixels
* and you want the result after those pixels are turned ON.
*
* Note carefully that the mask we use delineates which pixels
* are allowed to be ON as the seed is filled. We will call this
* a "filling mask". As the seed expands, it is repeatedly
* ANDed with the filling mask: s & fm. The process can equivalently
* be formulated using the inverse of the filling mask, which
* we will call a "blocking mask": bm = ~fm. As the seed
* expands, the blocking mask is repeatedly used to prevent
* the seed from expanding into the blocking mask. This is done
* by set subtracting the blocking mask from the expanded seed:
* s - bm. Set subtraction of the blocking mask is equivalent
* to ANDing with the inverse of the blocking mask: s & (~bm).
* But from the inverse relation between blocking and filling
* masks, this is equal to s & fm, which proves the equivalence.
*
* For efficiency, the pixels can be taken in larger units
* for processing, but still in raster order. It is natural
* to take them in 32-bit words. The outline of the work
* to be done for 4-cc (not including special cases for boundary
* words, such as the first line or the last word in each line)
* is as follows. Let the filling mask be m. The
* seed is to fill "under" the mask; i.e., limited by an AND
* with the mask. Let the current word be w, the word
* in the line above be wa, and the previous word in the
* current line be wp. Let t be a temporary word that
* is used in computation. Note that masking is performed by
* w & m. (If we had instead used a "blocking" mask, we
* would perform masking by the set subtraction operation,
* w - m, which is defined to be w & ~m.)
*
* The entire operation can be implemented with shifts,
* logical operations and tests. For each word in the seed image
* there are two steps. The first step is to OR the word with
* the word above and with the rightmost pixel in wp (call it "x").
* Because wp is shifted one pixel to its right, "x" is ORed
* to the leftmost pixel of w. We then clip to the ON pixels in
* the mask. The result is
* t <-- (w | wa | x000... ) & m
* We've now finished taking data from above and to the left.
* The second step is to allow filling to propagate horizontally
* in t, always making sure that it is properly masked at each
* step. So if filling can be done (i.e., t is neither all 0s
* nor all 1s), iteratively take:
* t <-- (t | (t >> 1) | (t << 1)) & m
* until t stops changing. Then write t back into w.
*
* Finally, the boundary conditions require we note that in doing
* the above steps:
* (a) The words in the first row have no wa
* (b) The first word in each row has no wp in that row
* (c) The last word in each row must be masked so that
* pixels don't propagate beyond the right edge of the
* actual image. (This is easily accomplished by
* setting the out-of-bound pixels in m to OFF.)
*/
#include "allheaders.h"
#ifndef NO_CONSOLE_IO
#define DEBUG_PRINT_ITERS 0
#endif /* ~NO_CONSOLE_IO */
/* Two-way (UL --> LR, LR --> UL) sweep iterations; typically need only 4 */
static const l_int32 MAX_ITERS = 40;
/* Static function */
static l_int32 pixQualifyLocalMinima(PIX *pixs, PIX *pixm, l_int32 maxval);
/*-----------------------------------------------------------------------*
* Vincent's Iterative Binary Seedfill method *
*-----------------------------------------------------------------------*/
/*!
* pixSeedfillBinary()
*
* Input: pixd (<optional>; this can be null, equal to pixs,
* or different from pixs; 1 bpp)
* pixs (1 bpp seed)
* pixm (1 bpp filling mask)
* connectivity (4 or 8)
* Return: pixd always
*
* Notes:
* (1) This is for binary seedfill (aka "binary reconstruction").
* (2) There are 3 cases:
* (a) pixd == null (make a new pixd)
* (b) pixd == pixs (in-place)
* (c) pixd != pixs
* (3) If you know the case, use these patterns for clarity:
* (a) pixd = pixSeedfillBinary(NULL, pixs, ...);
* (b) pixSeedfillBinary(pixs, pixs, ...);
* (c) pixSeedfillBinary(pixd, pixs, ...);
* (4) The resulting pixd contains the filled seed. For some
* applications you want to OR it with the inverse of
* the filling mask.
* (5) The input seed and mask images can be different sizes, but
* in typical use the difference, if any, would be only
* a few pixels in each direction. If the sizes differ,
* the clipping is handled by the low-level function
* seedfillBinaryLow().
*/
PIX *
pixSeedfillBinary(PIX *pixd,
PIX *pixs,
PIX *pixm,
l_int32 connectivity)
{
l_int32 i, boolval;
l_int32 hd, hm, wpld, wplm;
l_uint32 *datad, *datam;
PIX *pixt;
PROCNAME("pixSeedfillBinary");
if (!pixs || pixGetDepth(pixs) != 1)
return (PIX *)ERROR_PTR("pixs undefined or not 1 bpp", procName, pixd);
if (!pixm || pixGetDepth(pixm) != 1)
return (PIX *)ERROR_PTR("pixm undefined or not 1 bpp", procName, pixd);
if (connectivity != 4 && connectivity != 8)
return (PIX *)ERROR_PTR("connectivity not in {4,8}", procName, pixd);
/* Prepare pixd as a copy of pixs if not identical */
if ((pixd = pixCopy(pixd, pixs)) == NULL)
return (PIX *)ERROR_PTR("pixd not made", procName, NULL);
/* pixt is used to test for completion */
if ((pixt = pixCreateTemplate(pixs)) == NULL)
return (PIX *)ERROR_PTR("pixt not made", procName, pixd);
hd = pixGetHeight(pixd);
hm = pixGetHeight(pixm); /* included so seedfillBinaryLow() can clip */
datad = pixGetData(pixd);
datam = pixGetData(pixm);
wpld = pixGetWpl(pixd);
wplm = pixGetWpl(pixm);
pixSetPadBits(pixm, 0);
for (i = 0; i < MAX_ITERS; i++) {
pixCopy(pixt, pixd);
seedfillBinaryLow(datad, hd, wpld, datam, hm, wplm, connectivity);
pixEqual(pixd, pixt, &boolval);
if (boolval == 1) {
#if DEBUG_PRINT_ITERS
fprintf(stderr, "Binary seed fill converged: %d iters\n", i + 1);
#endif /* DEBUG_PRINT_ITERS */
break;
}
}
pixDestroy(&pixt);
return pixd;
}
/*!
* pixSeedfillBinaryRestricted()
*
* Input: pixd (<optional>; this can be null, equal to pixs,
* or different from pixs; 1 bpp)
* pixs (1 bpp seed)
* pixm (1 bpp filling mask)
* connectivity (4 or 8)
* xmax (max distance in x direction of fill into the mask)
* ymax (max distance in y direction of fill into the mask)
* Return: pixd always
*
* Notes:
* (1) See usage for pixSeedfillBinary(), which has unrestricted fill.
* In pixSeedfillBinary(), the filling distance is unrestricted
* and can be larger than pixs, depending on the topology of
* th mask.
* (2) There are occasions where it is useful not to permit the
* fill to go more than a certain distance into the mask.
* @xmax specifies the maximum horizontal distance allowed
* in the fill; @ymax does likewise in the vertical direction.
* (3) Operationally, the max "distance" allowed for the fill
* is a linear distance from the original seed, independent
* of the actual mask topology.
* (4) Another formulation of this problem, not implemented,
* would use the manhattan distance from the seed, as
* determined by a breadth-first search starting at the seed
* boundaries and working outward where the mask fg allows.
* How this might use the constraints of separate xmax and ymax
* is not clear.
*/
PIX *
pixSeedfillBinaryRestricted(PIX *pixd,
PIX *pixs,
PIX *pixm,
l_int32 connectivity,
l_int32 xmax,
l_int32 ymax)
{
l_int32 w, h;
PIX *pixr, *pixt;
PROCNAME("pixSeedfillBinaryRestricted");
if (xmax <= 0 && ymax <= 0) /* no filling permitted */
return pixClone(pixs);
if (xmax < 0 || ymax < 0)
return (PIX *)ERROR_PTR("pixt not made", procName, pixd);
/* Full fill from the seed into the mask. */
if ((pixt = pixSeedfillBinary(NULL, pixs, pixm, connectivity)) == NULL)
return (PIX *)ERROR_PTR("pixt not made", procName, pixd);
/* Dilate the seed. This gives the maximal region where changes
* are permitted. Invert to get the region where pixs is
* not allowed to change. */
pixr = pixDilateCompBrick(NULL, pixs, 2 * xmax + 1, 2 * ymax + 1);
pixInvert(pixr, pixr);
/* Blank the region of pixt specified by the fg of pixr.
* This is not the final result, because it may have fg that
* is not accessible from the seed in the restricted distance.
* There we treat this as a new mask, and eliminate the
* bad fg regions by doing a second seedfill from the original seed. */
pixGetDimensions(pixs, &w, &h, NULL);
pixRasterop(pixt, 0, 0, w, h, PIX_DST & PIX_NOT(PIX_SRC), pixr, 0, 0);
/* Fill again from the seed, into this new mask. */
pixd = pixSeedfillBinary(pixd, pixs, pixt, connectivity);
pixDestroy(&pixt);
pixDestroy(&pixr);
return pixd;
}
/*!
* pixHolesByFilling()
*
* Input: pixs (1 bpp)
* connectivity (4 or 8)
* Return: pixd (inverted image of all holes), or null on error
*
* Action:
* (1) Start with 1-pixel black border on otherwise white pixd
* (2) Use the inverted pixs as the filling mask to fill in
* all the pixels from the border to the pixs foreground
* (3) OR the result with pixs to have an image with all
* ON pixels except for the holes.
* (4) Invert the result to get the holes as foreground
*
* Notes:
* (1) To get 4-c.c. holes of the 8-c.c. as foreground, use
* 4-connected filling; to get 8-c.c. holes of the 4-c.c.
* as foreground, use 8-connected filling.
*/
PIX *
pixHolesByFilling(PIX *pixs,
l_int32 connectivity)
{
PIX *pixsi, *pixd;
PROCNAME("pixHolesByFilling");
if (!pixs || pixGetDepth(pixs) != 1)
return (PIX *)ERROR_PTR("pixs undefined or not 1 bpp", procName, NULL);
if (connectivity != 4 && connectivity != 8)
return (PIX *)ERROR_PTR("connectivity not 4 or 8", procName, NULL);
if ((pixd = pixCreateTemplate(pixs)) == NULL)
return (PIX *)ERROR_PTR("pixd not made", procName, NULL);
if ((pixsi = pixInvert(NULL, pixs)) == NULL)
return (PIX *)ERROR_PTR("pixsi not made", procName, NULL);
pixSetOrClearBorder(pixd, 1, 1, 1, 1, PIX_SET);
pixSeedfillBinary(pixd, pixd, pixsi, connectivity);
pixOr(pixd, pixd, pixs);
pixInvert(pixd, pixd);
pixDestroy(&pixsi);
return pixd;
}
/*!
* pixFillClosedBorders()
*
* Input: pixs (1 bpp)
* filling connectivity (4 or 8)
* Return: pixd (all topologically outer closed borders are filled
* as connected comonents), or null on error
*
* Notes:
* (1) Start with 1-pixel black border on otherwise white pixd
* (2) Subtract input pixs to remove border pixels that were
* also on the closed border
* (3) Use the inverted pixs as the filling mask to fill in
* all the pixels from the outer border to the closed border
* on pixs
* (4) Invert the result to get the filled component, including
* the input border
* (5) If the borders are 4-c.c., use 8-c.c. filling, and v.v.
* (6) Closed borders within c.c. that represent holes, etc., are filled.
*/
PIX *
pixFillClosedBorders(PIX *pixs,
l_int32 connectivity)
{
PIX *pixsi, *pixd;
PROCNAME("pixFillClosedBorders");
if (!pixs || pixGetDepth(pixs) != 1)
return (PIX *)ERROR_PTR("pixs undefined or not 1 bpp", procName, NULL);
if (connectivity != 4 && connectivity != 8)
return (PIX *)ERROR_PTR("connectivity not 4 or 8", procName, NULL);
if ((pixd = pixCreateTemplate(pixs)) == NULL)
return (PIX *)ERROR_PTR("pixd not made", procName, NULL);
pixSetOrClearBorder(pixd, 1, 1, 1, 1, PIX_SET);
pixSubtract(pixd, pixd, pixs);
if ((pixsi = pixInvert(NULL, pixs)) == NULL)
return (PIX *)ERROR_PTR("pixsi not made", procName, NULL);
pixSeedfillBinary(pixd, pixd, pixsi, connectivity);
pixInvert(pixd, pixd);
pixDestroy(&pixsi);
return pixd;
}
/*!
* pixExtractBorderConnComps()
*
* Input: pixs (1 bpp)
* filling connectivity (4 or 8)
* Return: pixd (all pixels in the src that are in connected
* components touching the border), or null on error
*/
PIX *
pixExtractBorderConnComps(PIX *pixs,
l_int32 connectivity)
{
PIX *pixd;
PROCNAME("pixExtractBorderConnComps");
if (!pixs || pixGetDepth(pixs) != 1)
return (PIX *)ERROR_PTR("pixs undefined or not 1 bpp", procName, NULL);
if (connectivity != 4 && connectivity != 8)
return (PIX *)ERROR_PTR("connectivity not 4 or 8", procName, NULL);
/* Start with 1 pixel wide black border as seed in pixd */
if ((pixd = pixCreateTemplate(pixs)) == NULL)
return (PIX *)ERROR_PTR("pixd not made", procName, NULL);
pixSetOrClearBorder(pixd, 1, 1, 1, 1, PIX_SET);
/* Fill in pixd from the seed, using pixs as the filling mask.
* This fills all components from pixs that are touching the border. */
pixSeedfillBinary(pixd, pixd, pixs, connectivity);
return pixd;
}
/*!
* pixRemoveBorderConnComps()
*
* Input: pixs (1 bpp)
* filling connectivity (4 or 8)
* Return: pixd (all pixels in the src that are not touching the
* border) or null on error
*
* Notes:
* (1) This removes all fg components touching the border.
*/
PIX *
pixRemoveBorderConnComps(PIX *pixs,
l_int32 connectivity)
{
PIX *pixd;
PROCNAME("pixRemoveBorderConnComps");
if (!pixs || pixGetDepth(pixs) != 1)
return (PIX *)ERROR_PTR("pixs undefined or not 1 bpp", procName, NULL);
if (connectivity != 4 && connectivity != 8)
return (PIX *)ERROR_PTR("connectivity not 4 or 8", procName, NULL);
/* Fill from a 1 pixel wide seed at the border into all components
* in pixs (the filling mask) that are touching the border */
pixd = pixExtractBorderConnComps(pixs, connectivity);
/* Save in pixd only those components in pixs not touching the border */
pixXor(pixd, pixd, pixs);
return pixd;
}
/*!
* pixFillBgFromBorder()
*
* Input: pixs (1 bpp)
* filling connectivity (4 or 8)
* Return: pixd (with the background c.c. touching the border
* filled to foreground), or null on error
*
* Notes:
* (1) This fills all bg components touching the border to fg.
* It is the photometric inverse of pixRemoveBorderConnComps().
* (2) Invert the result to get the "holes" left after this fill.
* This can be done multiple times, extracting holes within
* holes after each pair of fillings. Specifically, this code
* peels away n successive embeddings of components:
* pix1 = <initial image>
* for (i = 0; i < 2 * n; i++) {
* pix2 = pixFillBgFromBorder(pix1, 8);
* pixInvert(pix2, pix2);
* pixDestroy(&pix1);
* pix1 = pix2;
* }
*/
PIX *
pixFillBgFromBorder(PIX *pixs,
l_int32 connectivity)
{
PIX *pixd;
PROCNAME("pixFillBgFromBorder");
if (!pixs || pixGetDepth(pixs) != 1)
return (PIX *)ERROR_PTR("pixs undefined or not 1 bpp", procName, NULL);
if (connectivity != 4 && connectivity != 8)
return (PIX *)ERROR_PTR("connectivity not 4 or 8", procName, NULL);
/* Invert to turn bg touching the border to a fg component.
* Extract this by filling from a 1 pixel wide seed at the border. */
pixInvert(pixs, pixs);
pixd = pixExtractBorderConnComps(pixs, connectivity);
pixInvert(pixs, pixs); /* restore pixs */
/* Bit-or the filled bg component with pixs */
pixOr(pixd, pixd, pixs);
return pixd;
}
/*-----------------------------------------------------------------------*
* Hole-filling of components to bounding rectangle *
*-----------------------------------------------------------------------*/
/*!
* pixFillHolesToBoundingRect()
*
* Input: pixs (1 bpp)
* minsize (min number of pixels in the hole)
* maxhfract (max hole area as fraction of fg pixels in the cc)
* minfgfract (min fg area as fraction of bounding rectangle)
* Return: pixd (pixs, with some holes possibly filled and some c.c.
* possibly expanded to their bounding rects),
* or null on error
*
* Notes:
* (1) This does not fill holes that are smaller in area than 'minsize'.
* (2) This does not fill holes with an area larger than
* 'maxhfract' times the fg area of the c.c.
* (3) This does not expand the fg of the c.c. to bounding rect if
* the fg area is less than 'minfgfract' times the area of the
* bounding rect.
* (4) The decisions are made as follows:
* - Decide if we are filling the holes; if so, when using
* the fg area, include the filled holes.
* - Decide based on the fg area if we are filling to a bounding rect.
* If so, do it.
* If not, fill the holes if the condition is satisfied.
* (5) The choice of minsize depends on the resolution.
* (6) For solidifying image mask regions on printed materials,
* which tend to be rectangular, values for maxhfract
* and minfgfract around 0.5 are reasonable.
*/
PIX *
pixFillHolesToBoundingRect(PIX *pixs,
l_int32 minsize,
l_float32 maxhfract,
l_float32 minfgfract)
{
l_int32 i, x, y, w, h, n, nfg, nh, ntot, area;
l_int32 *tab;
l_float32 hfract; /* measured hole fraction */
l_float32 fgfract; /* measured fg fraction */
BOXA *boxa;
PIX *pixd, *pixfg, *pixh;
PIXA *pixa;
PROCNAME("pixFillHolesToBoundingRect");
if (!pixs || pixGetDepth(pixs) != 1)
return (PIX *)ERROR_PTR("pixs undefined or not 1 bpp", procName, NULL);
pixd = pixCopy(NULL, pixs);
boxa = pixConnComp(pixd, &pixa, 8);
n = boxaGetCount(boxa);
tab = makePixelSumTab8();
for (i = 0; i < n; i++) {
boxaGetBoxGeometry(boxa, i, &x, &y, &w, &h);
area = w * h;
if (area < minsize)
continue;
pixfg = pixaGetPix(pixa, i, L_COPY);
pixh = pixHolesByFilling(pixfg, 4); /* holes only */
pixCountPixels(pixfg, &nfg, tab);
pixCountPixels(pixh, &nh, tab);
hfract = (l_float32)nh / (l_float32)nfg;
ntot = nfg;
if (hfract <= maxhfract) /* we will fill the holes (at least) */
ntot = nfg + nh;
fgfract = (l_float32)ntot / (l_float32)area;
if (fgfract >= minfgfract) { /* fill to bounding rect */
pixSetAll(pixfg);
pixRasterop(pixd, x, y, w, h, PIX_SRC, pixfg, 0, 0);
} else if (hfract <= maxhfract) { /* fill just the holes */
pixRasterop(pixd, x, y, w, h, PIX_DST | PIX_SRC , pixh, 0, 0);
}
pixDestroy(&pixfg);
pixDestroy(&pixh);
}
boxaDestroy(&boxa);
pixaDestroy(&pixa);
FREE(tab);
return pixd;
}
/*-----------------------------------------------------------------------*
* Vincent's hybrid Grayscale Seedfill method *
*-----------------------------------------------------------------------*/
/*!
* pixSeedfillGray()
*
* Input: pixs (8 bpp seed; filled in place)
* pixm (8 bpp filling mask)
* connectivity (4 or 8)
* Return: 0 if OK, 1 on error
*
* Notes:
* (1) This is an in-place filling operation on the seed, pixs,
* where the clipping mask is always above or at the level
* of the seed as it is filled.
* (2) For details of the operation, see the description in
* seedfillGrayLow() and the code there.
* (3) As an example of use, see the description in pixHDome().
* There, the seed is an image where each pixel is a fixed
* amount smaller than the corresponding mask pixel.
* (4) Reference paper :
* L. Vincent, Morphological grayscale reconstruction in image
* analysis: applications and efficient algorithms, IEEE Transactions
* on Image Processing, vol. 2, no. 2, pp. 176-201, 1993.
*/
l_int32
pixSeedfillGray(PIX *pixs,
PIX *pixm,
l_int32 connectivity)
{
l_int32 h, w, wpls, wplm;
l_uint32 *datas, *datam;
PROCNAME("pixSeedfillGray");
if (!pixs || pixGetDepth(pixs) != 8)
return ERROR_INT("pixs not defined or not 8 bpp", procName, 1);
if (!pixm || pixGetDepth(pixm) != 8)
return ERROR_INT("pixm not defined or not 8 bpp", procName, 1);
if (connectivity != 4 && connectivity != 8)
return ERROR_INT("connectivity not in {4,8}", procName, 1);
/* Make sure the sizes of seed and mask images are the same */
if (pixSizesEqual(pixs, pixm) == 0)
return ERROR_INT("pixs and pixm sizes differ", procName, 1);
datas = pixGetData(pixs);
datam = pixGetData(pixm);
wpls = pixGetWpl(pixs);
wplm = pixGetWpl(pixm);
pixGetDimensions(pixs, &w, &h, NULL);
seedfillGrayLow(datas, w, h, wpls, datam, wplm, connectivity);
return 0;
}
/*!
* pixSeedfillGrayInv()
*
* Input: pixs (8 bpp seed; filled in place)
* pixm (8 bpp filling mask)
* connectivity (4 or 8)
* Return: 0 if OK, 1 on error
*
* Notes:
* (1) This is an in-place filling operation on the seed, pixs,
* where the clipping mask is always below or at the level
* of the seed as it is filled. Think of filling up a basin
* to a particular level, given by the maximum seed value
* in the basin. Outside the filled region, the mask
* is above the filling level.
* (2) Contrast this with pixSeedfillGray(), where the clipping mask
* is always above or at the level of the fill. An example
* of its use is the hdome fill, where the seed is an image
* where each pixel is a fixed amount smaller than the
* corresponding mask pixel.
* (3) The basin fill, pixSeedfillGrayBasin(), is a special case
* where the seed pixel values are generated from the mask,
* and where the implementation uses pixSeedfillGray() by
* inverting both the seed and mask.
*/
l_int32
pixSeedfillGrayInv(PIX *pixs,
PIX *pixm,
l_int32 connectivity)
{
l_int32 h, w, wpls, wplm;
l_uint32 *datas, *datam;
PROCNAME("pixSeedfillGrayInv");
if (!pixs || pixGetDepth(pixs) != 8)
return ERROR_INT("pixs not defined or not 8 bpp", procName, 1);
if (!pixm || pixGetDepth(pixm) != 8)
return ERROR_INT("pixm not defined or not 8 bpp", procName, 1);
if (connectivity != 4 && connectivity != 8)
return ERROR_INT("connectivity not in {4,8}", procName, 1);
/* Make sure the sizes of seed and mask images are the same */
if (pixSizesEqual(pixs, pixm) == 0)
return ERROR_INT("pixs and pixm sizes differ", procName, 1);
datas = pixGetData(pixs);
datam = pixGetData(pixm);
wpls = pixGetWpl(pixs);
wplm = pixGetWpl(pixm);
pixGetDimensions(pixs, &w, &h, NULL);
seedfillGrayInvLow(datas, w, h, wpls, datam, wplm, connectivity);
return 0;
}
/*-----------------------------------------------------------------------*
* Vincent's Iterative Grayscale Seedfill method *
*-----------------------------------------------------------------------*/
/*!
* pixSeedfillGraySimple()
*
* Input: pixs (8 bpp seed; filled in place)
* pixm (8 bpp filling mask)
* connectivity (4 or 8)
* Return: 0 if OK, 1 on error
*
* Notes:
* (1) This is an in-place filling operation on the seed, pixs,
* where the clipping mask is always above or at the level
* of the seed as it is filled.
* (2) For details of the operation, see the description in
* seedfillGrayLowSimple() and the code there.
* (3) As an example of use, see the description in pixHDome().
* There, the seed is an image where each pixel is a fixed
* amount smaller than the corresponding mask pixel.
* (4) Reference paper :
* L. Vincent, Morphological grayscale reconstruction in image
* analysis: applications and efficient algorithms, IEEE Transactions
* on Image Processing, vol. 2, no. 2, pp. 176-201, 1993.
*/
l_int32
pixSeedfillGraySimple(PIX *pixs,
PIX *pixm,
l_int32 connectivity)
{
l_int32 i, h, w, wpls, wplm, boolval;
l_uint32 *datas, *datam;
PIX *pixt;
PROCNAME("pixSeedfillGraySimple");
if (!pixs || pixGetDepth(pixs) != 8)
return ERROR_INT("pixs not defined or not 8 bpp", procName, 1);
if (!pixm || pixGetDepth(pixm) != 8)
return ERROR_INT("pixm not defined or not 8 bpp", procName, 1);
if (connectivity != 4 && connectivity != 8)
return ERROR_INT("connectivity not in {4,8}", procName, 1);
/* Make sure the sizes of seed and mask images are the same */
if (pixSizesEqual(pixs, pixm) == 0)
return ERROR_INT("pixs and pixm sizes differ", procName, 1);
/* This is used to test for completion */
if ((pixt = pixCreateTemplate(pixs)) == NULL)
return ERROR_INT("pixt not made", procName, 1);
datas = pixGetData(pixs);
datam = pixGetData(pixm);
wpls = pixGetWpl(pixs);
wplm = pixGetWpl(pixm);
pixGetDimensions(pixs, &w, &h, NULL);
for (i = 0; i < MAX_ITERS; i++) {
pixCopy(pixt, pixs);
seedfillGrayLowSimple(datas, w, h, wpls, datam, wplm, connectivity);
pixEqual(pixs, pixt, &boolval);
if (boolval == 1) {
#if DEBUG_PRINT_ITERS
L_INFO("Gray seed fill converged: %d iters\n", procName, i + 1);
#endif /* DEBUG_PRINT_ITERS */
break;
}
}
pixDestroy(&pixt);
return 0;
}
/*!
* pixSeedfillGrayInvSimple()
*
* Input: pixs (8 bpp seed; filled in place)
* pixm (8 bpp filling mask)
* connectivity (4 or 8)
* Return: 0 if OK, 1 on error
*
* Notes:
* (1) This is an in-place filling operation on the seed, pixs,
* where the clipping mask is always below or at the level
* of the seed as it is filled. Think of filling up a basin
* to a particular level, given by the maximum seed value
* in the basin. Outside the filled region, the mask
* is above the filling level.
* (2) Contrast this with pixSeedfillGraySimple(), where the clipping mask
* is always above or at the level of the fill. An example
* of its use is the hdome fill, where the seed is an image
* where each pixel is a fixed amount smaller than the
* corresponding mask pixel.
*/
l_int32
pixSeedfillGrayInvSimple(PIX *pixs,
PIX *pixm,
l_int32 connectivity)
{
l_int32 i, h, w, wpls, wplm, boolval;
l_uint32 *datas, *datam;
PIX *pixt;
PROCNAME("pixSeedfillGrayInvSimple");
if (!pixs || pixGetDepth(pixs) != 8)
return ERROR_INT("pixs not defined or not 8 bpp", procName, 1);
if (!pixm || pixGetDepth(pixm) != 8)
return ERROR_INT("pixm not defined or not 8 bpp", procName, 1);
if (connectivity != 4 && connectivity != 8)
return ERROR_INT("connectivity not in {4,8}", procName, 1);
/* Make sure the sizes of seed and mask images are the same */
if (pixSizesEqual(pixs, pixm) == 0)
return ERROR_INT("pixs and pixm sizes differ", procName, 1);
/* This is used to test for completion */
if ((pixt = pixCreateTemplate(pixs)) == NULL)
return ERROR_INT("pixt not made", procName, 1);
datas = pixGetData(pixs);
datam = pixGetData(pixm);
wpls = pixGetWpl(pixs);
wplm = pixGetWpl(pixm);
pixGetDimensions(pixs, &w, &h, NULL);
for (i = 0; i < MAX_ITERS; i++) {
pixCopy(pixt, pixs);
seedfillGrayInvLowSimple(datas, w, h, wpls, datam, wplm, connectivity);
pixEqual(pixs, pixt, &boolval);
if (boolval == 1) {
#if DEBUG_PRINT_ITERS
L_INFO("Gray seed fill converged: %d iters\n", procName, i + 1);
#endif /* DEBUG_PRINT_ITERS */
break;
}
}
pixDestroy(&pixt);
return 0;
}
/*-----------------------------------------------------------------------*
* Gray seedfill variations *
*-----------------------------------------------------------------------*/
/*!
* pixSeedfillGrayBasin()
*
* Input: pixb (binary mask giving seed locations)
* pixm (8 bpp basin-type filling mask)
* delta (amount of seed value above mask)
* connectivity (4 or 8)
* Return: pixd (filled seed) if OK, null on error
*
* Notes:
* (1) This fills from a seed within basins defined by a filling mask.
* The seed value(s) are greater than the corresponding
* filling mask value, and the result has the bottoms of
* the basins raised by the initial seed value.
* (2) The seed has value 255 except where pixb has fg (1), which
* are the seed 'locations'. At the seed locations, the seed
* value is the corresponding value of the mask pixel in pixm
* plus @delta. If @delta == 0, we return a copy of pixm.
* (3) The actual filling is done using the standard grayscale filling
* operation on the inverse of the mask and using the inverse
* of the seed image. After filling, we return the inverse of
* the filled seed.
* (4) As an example of use: pixm can describe a grayscale image
* of text, where the (dark) text pixels are basins of
* low values; pixb can identify the local minima in pixm (say, at
* the bottom of the basins); and delta is the amount that we wish
* to raise (lighten) the basins. We construct the seed
* (a.k.a marker) image from pixb, pixm and @delta.
*/
PIX *
pixSeedfillGrayBasin(PIX *pixb,
PIX *pixm,
l_int32 delta,
l_int32 connectivity)
{
PIX *pixbi, *pixmi, *pixsd;
PROCNAME("pixSeedfillGrayBasin");
if (!pixb || pixGetDepth(pixb) != 1)
return (PIX *)ERROR_PTR("pixb undefined or not 1 bpp", procName, NULL);
if (!pixm || pixGetDepth(pixm) != 8)
return (PIX *)ERROR_PTR("pixm undefined or not 8 bpp", procName, NULL);
if (connectivity != 4 && connectivity != 8)
return (PIX *)ERROR_PTR("connectivity not in {4,8}", procName, NULL);
if (delta <= 0) {
L_WARNING("delta <= 0; returning a copy of pixm\n", procName);
return pixCopy(NULL, pixm);
}
/* Add delta to every pixel in pixm */
pixsd = pixCopy(NULL, pixm);
pixAddConstantGray(pixsd, delta);
/* Prepare the seed. Write 255 in all pixels of
* ([pixm] + delta) where pixb is 0. */
pixbi = pixInvert(NULL, pixb);
pixSetMasked(pixsd, pixbi, 255);
/* Fill the inverse seed, using the inverse clipping mask */
pixmi = pixInvert(NULL, pixm);
pixInvert(pixsd, pixsd);
pixSeedfillGray(pixsd, pixmi, connectivity);
/* Re-invert the filled seed */
pixInvert(pixsd, pixsd);
pixDestroy(&pixbi);
pixDestroy(&pixmi);
return pixsd;
}
/*-----------------------------------------------------------------------*
* Vincent's Distance Function method *
*-----------------------------------------------------------------------*/
/*!
* pixDistanceFunction()
*
* Input: pixs (1 bpp source)
* connectivity (4 or 8)
* outdepth (8 or 16 bits for pixd)
* boundcond (L_BOUNDARY_BG, L_BOUNDARY_FG)
* Return: pixd, or null on error
*
* Notes:
* (1) This computes the distance of each pixel from the nearest
* background pixel. All bg pixels therefore have a distance of 0,
* and the fg pixel distances increase linearly from 1 at the
* boundary. It can also be used to compute the distance of
* each pixel from the nearest fg pixel, by inverting the input
* image before calling this function. Then all fg pixels have
* a distance 0 and the bg pixel distances increase linearly
* from 1 at the boundary.
* (2) The algorithm, described in Leptonica on the page on seed
* filling and connected components, is due to Luc Vincent.
* In brief, we generate an 8 or 16 bpp image, initialized
* with the fg pixels of the input pix set to 1 and the
* 1-boundary pixels (i.e., the boundary pixels of width 1 on
* the four sides set as either:
* * L_BOUNDARY_BG: 0
* * L_BOUNDARY_FG: max
* where max = 0xff for 8 bpp and 0xffff for 16 bpp.
* Then do raster/anti-raster sweeps over all pixels interior
* to the 1-boundary, where the value of each new pixel is
* taken to be 1 more than the minimum of the previously-seen
* connected pixels (using either 4 or 8 connectivity).
* Finally, set the 1-boundary pixels using the mirrored method;
* this removes the max values there.
* (3) Using L_BOUNDARY_BG clamps the distance to 0 at the
* boundary. Using L_BOUNDARY_FG allows the distance
* at the image boundary to "float".
* (4) For 4-connected, one could initialize only the left and top
* 1-boundary pixels, and go all the way to the right
* and bottom; then coming back reset left and top. But we
* instead use a method that works for both 4- and 8-connected.
*/
PIX *
pixDistanceFunction(PIX *pixs,
l_int32 connectivity,
l_int32 outdepth,
l_int32 boundcond)
{
l_int32 w, h, wpld;
l_uint32 *datad;
PIX *pixd;
PROCNAME("pixDistanceFunction");
if (!pixs || pixGetDepth(pixs) != 1)
return (PIX *)ERROR_PTR("!pixs or pixs not 1 bpp", procName, NULL);
if (connectivity != 4 && connectivity != 8)
return (PIX *)ERROR_PTR("connectivity not 4 or 8", procName, NULL);
if (outdepth != 8 && outdepth != 16)
return (PIX *)ERROR_PTR("outdepth not 8 or 16 bpp", procName, NULL);
if (boundcond != L_BOUNDARY_BG && boundcond != L_BOUNDARY_FG)
return (PIX *)ERROR_PTR("invalid boundcond", procName, NULL);
pixGetDimensions(pixs, &w, &h, NULL);
if ((pixd = pixCreate(w, h, outdepth)) == NULL)
return (PIX *)ERROR_PTR("pixd not made", procName, NULL);
datad = pixGetData(pixd);
wpld = pixGetWpl(pixd);
/* Initialize the fg pixels to 1 and the bg pixels to 0 */
pixSetMasked(pixd, pixs, 1);
if (boundcond == L_BOUNDARY_BG) {
distanceFunctionLow(datad, w, h, outdepth, wpld, connectivity);
} else { /* L_BOUNDARY_FG: set boundary pixels to max val */
pixRasterop(pixd, 0, 0, w, 1, PIX_SET, NULL, 0, 0); /* top */
pixRasterop(pixd, 0, h - 1, w, 1, PIX_SET, NULL, 0, 0); /* bot */
pixRasterop(pixd, 0, 0, 1, h, PIX_SET, NULL, 0, 0); /* left */
pixRasterop(pixd, w - 1, 0, 1, h, PIX_SET, NULL, 0, 0); /* right */
distanceFunctionLow(datad, w, h, outdepth, wpld, connectivity);
/* Set each boundary pixel equal to the pixel next to it */
pixSetMirroredBorder(pixd, 1, 1, 1, 1);
}
return pixd;
}
/*-----------------------------------------------------------------------*
* Seed spread (based on distance function) *
*-----------------------------------------------------------------------*/
/*!
* pixSeedspread()
*
* Input: pixs (8 bpp source)
* connectivity (4 or 8)
* Return: pixd, or null on error
*
* Notes:
* (1) The raster/anti-raster method for implementing this filling
* operation was suggested by Ray Smith.
* (2) This takes an arbitrary set of nonzero pixels in pixs, which
* can be sparse, and spreads (extrapolates) the values to
* fill all the pixels in pixd with the nonzero value it is
* closest to in pixs. This is similar (though not completely
* equivalent) to doing a Voronoi tiling of the image, with a
* tile surrounding each pixel that has a nonzero value.
* All pixels within a tile are then closer to its "central"
* pixel than to any others. Then assign the value of the
* "central" pixel to each pixel in the tile.
* (3) This is implemented by computing a distance function in parallel
* with the fill. The distance function uses free boundary
* conditions (assumed maxval outside), and it controls the
* propagation of the pixels in pixd away from the nonzero
* (seed) values. This is done in 2 traversals (raster/antiraster).
* In the raster direction, whenever the distance function
* is nonzero, the spread pixel takes on the value of its
* predecessor that has the minimum distance value. In the
* antiraster direction, whenever the distance function is nonzero
* and its value is replaced by a smaller value, the spread
* pixel takes the value of the predecessor with the minimum
* distance value.
* (4) At boundaries where a pixel is equidistant from two
* nearest nonzero (seed) pixels, the decision of which value
* to use is arbitrary (greedy in search for minimum distance).
* This can give rise to strange-looking results, particularly
* for 4-connectivity where the L1 distance is computed from
* steps in N,S,E and W directions (no diagonals).
*/
PIX *
pixSeedspread(PIX *pixs,
l_int32 connectivity)
{
l_int32 w, h, wplt, wplg;
l_uint32 *datat, *datag;
PIX *pixm, *pixt, *pixg, *pixd;
PROCNAME("pixSeedspread");
if (!pixs || pixGetDepth(pixs) != 8)
return (PIX *)ERROR_PTR("!pixs or pixs not 8 bpp", procName, NULL);
if (connectivity != 4 && connectivity != 8)
return (PIX *)ERROR_PTR("connectivity not 4 or 8", procName, NULL);
/* Add a 4 byte border to pixs. This simplifies the computation. */
pixg = pixAddBorder(pixs, 4, 0);
pixGetDimensions(pixg, &w, &h, NULL);
/* Initialize distance function pixt. Threshold pixs to get
* a 0 at the seed points where the pixs pixel is nonzero, and
* a 1 at all points that need to be filled. Use this as a
* mask to set a 1 in pixt at all non-seed points. Also, set all
* pixt pixels in an interior boundary of width 1 to the
* maximum value. For debugging, to view the distance function,
* use pixConvert16To8(pixt, 0) on small images. */
pixm = pixThresholdToBinary(pixg, 1);
pixt = pixCreate(w, h, 16);
pixSetMasked(pixt, pixm, 1);
pixRasterop(pixt, 0, 0, w, 1, PIX_SET, NULL, 0, 0); /* top */
pixRasterop(pixt, 0, h - 1, w, 1, PIX_SET, NULL, 0, 0); /* bot */
pixRasterop(pixt, 0, 0, 1, h, PIX_SET, NULL, 0, 0); /* left */
pixRasterop(pixt, w - 1, 0, 1, h, PIX_SET, NULL, 0, 0); /* right */
datat = pixGetData(pixt);
wplt = pixGetWpl(pixt);
/* Do the interpolation and remove the border. */
datag = pixGetData(pixg);
wplg = pixGetWpl(pixg);
seedspreadLow(datag, w, h, wplg, datat, wplt, connectivity);
pixd = pixRemoveBorder(pixg, 4);
pixDestroy(&pixm);
pixDestroy(&pixg);
pixDestroy(&pixt);
return pixd;
}
/*-----------------------------------------------------------------------*
* Local extrema *
*-----------------------------------------------------------------------*/
/*!
* pixLocalExtrema()
*
* Input: pixs (8 bpp)
* maxmin (max allowed for the min in a 3x3 neighborhood;
* use 0 for default which is to have no upper bound)
* minmax (min allowed for the max in a 3x3 neighborhood;
* use 0 for default which is to have no lower bound)
* &ppixmin (<optional return> mask of local minima)
* &ppixmax (<optional return> mask of local maxima)
* Return: 0 if OK, 1 on error
*
* Notes:
* (1) This gives the actual local minima and maxima.
* A local minimum is a pixel whose surrounding pixels all
* have values at least as large, and likewise for a local
* maximum. For the local minima, @maxmin is the upper
* bound for the value of pixs. Likewise, for the local maxima,
* @minmax is the lower bound for the value of pixs.
* (2) The minima are found by starting with the erosion-and-equality
* approach of pixSelectedLocalExtrema(). This is followed
* by a qualification step, where each c.c. in the resulting
* minimum mask is extracted, the pixels bordering it are
* located, and they are queried. If all of those pixels
* are larger than the value of that minimum, it is a true
* minimum and its c.c. is saved; otherwise the c.c. is
* rejected. Note that if a bordering pixel has the
* same value as the minimum, it must then have a
* neighbor that is smaller, so the component is not a
* true minimum.
* (3) The maxima are found by inverting the image and looking
* for the minima there.
* (4) The generated masks can be used as markers for
* further operations.
*/
l_int32
pixLocalExtrema(PIX *pixs,
l_int32 maxmin,
l_int32 minmax,
PIX **ppixmin,
PIX **ppixmax)
{
PIX *pixmin, *pixmax, *pixt1, *pixt2;
PROCNAME("pixLocalExtrema");
if (!pixs || pixGetDepth(pixs) != 8)
return ERROR_INT("pixs not defined or not 8 bpp", procName, 1);
if (!ppixmin && !ppixmax)
return ERROR_INT("neither &pixmin, &pixmax are defined", procName, 1);
if (maxmin <= 0) maxmin = 254;
if (minmax <= 0) minmax = 1;
if (ppixmin) {
pixt1 = pixErodeGray(pixs, 3, 3);
pixmin = pixFindEqualValues(pixs, pixt1);
pixDestroy(&pixt1);
pixQualifyLocalMinima(pixs, pixmin, maxmin);
*ppixmin = pixmin;
}
if (ppixmax) {
pixt1 = pixInvert(NULL, pixs);
pixt2 = pixErodeGray(pixt1, 3, 3);
pixmax = pixFindEqualValues(pixt1, pixt2);
pixDestroy(&pixt2);
pixQualifyLocalMinima(pixt1, pixmax, 255 - minmax);
*ppixmax = pixmax;
pixDestroy(&pixt1);
}
return 0;
}
/*!
* pixQualifyLocalMinima()
*
* Input: pixs (8 bpp image from which pixm has been extracted)
* pixm (1 bpp mask of values equal to min in 3x3 neighborhood)
* maxval (max allowed for the min in a 3x3 neighborhood;
* use 0 for default which is to have no upper bound)
* Return: 0 if OK, 1 on error
*
* Notes:
* (1) This function acts in-place to remove all c.c. in pixm
* that are not true local minima in pixs. As seen in
* pixLocalExtrema(), the input pixm are found by selecting those
* pixels of pixs whose values do not change with a 3x3
* grayscale erosion. Here, we require that for each c.c.
* in pixm, all pixels in pixs that correspond to the exterior
* boundary pixels of the c.c. have values that are greater
* than the value within the c.c.
* (2) The maximum allowed value for each local minimum can be
* bounded with @maxval. Use 0 for default, which is to have
* no upper bound (equivalent to maxval == 254).
*/
static l_int32
pixQualifyLocalMinima(PIX *pixs,
PIX *pixm,
l_int32 maxval)
{
l_int32 n, i, j, k, x, y, w, h, xc, yc, wc, hc, xon, yon;
l_int32 vals, wpls, wplc, ismin;
l_uint32 val;
l_uint32 *datas, *datac, *lines, *linec;
BOXA *boxa;
PIX *pixt1, *pixt2, *pixc;
PIXA *pixa;
PROCNAME("pixQualifyLocalMinima");
if (!pixs || pixGetDepth(pixs) != 8)
return ERROR_INT("pixs not defined or not 8 bpp", procName, 1);
if (!pixm || pixGetDepth(pixm) != 1)
return ERROR_INT("pixm not defined or not 1 bpp", procName, 1);
if (maxval <= 0) maxval = 254;
pixGetDimensions(pixs, &w, &h, NULL);
datas = pixGetData(pixs);
wpls = pixGetWpl(pixs);
boxa = pixConnComp(pixm, &pixa, 8);
n = pixaGetCount(pixa);
for (k = 0; k < n; k++) {
boxaGetBoxGeometry(boxa, k, &xc, &yc, &wc, &hc);
pixt1 = pixaGetPix(pixa, k, L_COPY);
pixt2 = pixAddBorder(pixt1, 1, 0);
pixc = pixDilateBrick(NULL, pixt2, 3, 3);
pixXor(pixc, pixc, pixt2); /* exterior boundary pixels */
datac = pixGetData(pixc);
wplc = pixGetWpl(pixc);
nextOnPixelInRaster(pixt1, 0, 0, &xon, &yon);
pixGetPixel(pixs, xc + xon, yc + yon, &val);
if (val > maxval) { /* too large; erase */
pixRasterop(pixm, xc, yc, wc, hc, PIX_XOR, pixt1, 0, 0);
pixDestroy(&pixt1);
pixDestroy(&pixt2);
pixDestroy(&pixc);
continue;
}
ismin = TRUE;
/* Check all values in pixs that correspond to the exterior
* boundary pixels of the c.c. in pixm. Verify that the
* value in the c.c. is always less. */
for (i = 0, y = yc - 1; i < hc + 2 && y >= 0 && y < h; i++, y++) {
lines = datas + y * wpls;
linec = datac + i * wplc;
for (j = 0, x = xc - 1; j < wc + 2 && x >= 0 && x < w; j++, x++) {
if (GET_DATA_BIT(linec, j)) {
vals = GET_DATA_BYTE(lines, x);
if (vals <= val) { /* not a minimum! */
ismin = FALSE;
break;
}
}
}
if (!ismin)
break;
}
if (!ismin) /* erase it */
pixRasterop(pixm, xc, yc, wc, hc, PIX_XOR, pixt1, 0, 0);
pixDestroy(&pixt1);
pixDestroy(&pixt2);
pixDestroy(&pixc);
}
boxaDestroy(&boxa);
pixaDestroy(&pixa);
return 0;
}
/*!
* pixSelectedLocalExtrema()
*
* Input: pixs (8 bpp)
* mindist (-1 for keeping all pixels; >= 0 specifies distance)
* &ppixmin (<return> mask of local minima)
* &ppixmax (<return> mask of local maxima)
* Return: 0 if OK, 1 on error
*
* Notes:
* (1) This selects those local 3x3 minima that are at least a
* specified distance from the nearest local 3x3 maxima, and v.v.
* for the selected set of local 3x3 maxima.
* The local 3x3 minima is the set of pixels whose value equals
* the value after a 3x3 brick erosion, and the local 3x3 maxima
* is the set of pixels whose value equals the value after
* a 3x3 brick dilation.
* (2) mindist is the minimum distance allowed between
* local 3x3 minima and local 3x3 maxima, in an 8-connected sense.
* mindist == 1 keeps all pixels found in step 1.
* mindist == 0 removes all pixels from each mask that are
* both a local 3x3 minimum and a local 3x3 maximum.
* mindist == 1 removes any local 3x3 minimum pixel that touches a
* local 3x3 maximum pixel, and likewise for the local maxima.
* To make the decision, visualize each local 3x3 minimum pixel
* as being surrounded by a square of size (2 * mindist + 1)
* on each side, such that no local 3x3 maximum pixel is within
* that square; and v.v.
* (3) The generated masks can be used as markers for further operations.
*/
l_int32
pixSelectedLocalExtrema(PIX *pixs,
l_int32 mindist,
PIX **ppixmin,
PIX **ppixmax)
{
PIX *pixmin, *pixmax, *pixt, *pixtmin, *pixtmax;
PROCNAME("pixSelectedLocalExtrema");
if (!pixs || pixGetDepth(pixs) != 8)
return ERROR_INT("pixs not defined or not 8 bpp", procName, 1);
if (!ppixmin || !ppixmax)
return ERROR_INT("&pixmin and &pixmax not both defined", procName, 1);
pixt = pixErodeGray(pixs, 3, 3);
pixmin = pixFindEqualValues(pixs, pixt);
pixDestroy(&pixt);
pixt = pixDilateGray(pixs, 3, 3);
pixmax = pixFindEqualValues(pixs, pixt);
pixDestroy(&pixt);
/* Remove all points that are within the prescribed distance
* from each other. */
if (mindist < 0) { /* remove no points */
*ppixmin = pixmin;
*ppixmax = pixmax;
} else if (mindist == 0) { /* remove points belonging to both sets */
pixt = pixAnd(NULL, pixmin, pixmax);
*ppixmin = pixSubtract(pixmin, pixmin, pixt);
*ppixmax = pixSubtract(pixmax, pixmax, pixt);
pixDestroy(&pixt);
} else {
pixtmin = pixDilateBrick(NULL, pixmin,
2 * mindist + 1, 2 * mindist + 1);
pixtmax = pixDilateBrick(NULL, pixmax,
2 * mindist + 1, 2 * mindist + 1);
*ppixmin = pixSubtract(pixmin, pixmin, pixtmax);
*ppixmax = pixSubtract(pixmax, pixmax, pixtmin);
pixDestroy(&pixtmin);
pixDestroy(&pixtmax);
}
return 0;
}
/*!
* pixFindEqualValues()
*
* Input: pixs1 (8 bpp)
* pixs2 (8 bpp)
* Return: pixd (1 bpp mask), or null on error
*
* Notes:
* (1) The two images are aligned at the UL corner, and the returned
* image has ON pixels where the pixels in pixs1 and pixs2
* have equal values.
*/
PIX *
pixFindEqualValues(PIX *pixs1,
PIX *pixs2)
{
l_int32 w1, h1, w2, h2, w, h;
l_int32 i, j, val1, val2, wpls1, wpls2, wpld;
l_uint32 *datas1, *datas2, *datad, *lines1, *lines2, *lined;
PIX *pixd;
PROCNAME("pixFindEqualValues");
if (!pixs1 || pixGetDepth(pixs1) != 8)
return (PIX *)ERROR_PTR("pixs1 undefined or not 8 bpp", procName, NULL);
if (!pixs2 || pixGetDepth(pixs2) != 8)
return (PIX *)ERROR_PTR("pixs2 undefined or not 8 bpp", procName, NULL);
pixGetDimensions(pixs1, &w1, &h1, NULL);
pixGetDimensions(pixs2, &w2, &h2, NULL);
w = L_MIN(w1, w2);
h = L_MIN(h1, h2);
pixd = pixCreate(w, h, 1);
datas1 = pixGetData(pixs1);
datas2 = pixGetData(pixs2);
datad = pixGetData(pixd);
wpls1 = pixGetWpl(pixs1);
wpls2 = pixGetWpl(pixs2);
wpld = pixGetWpl(pixd);
for (i = 0; i < h; i++) {
lines1 = datas1 + i * wpls1;
lines2 = datas2 + i * wpls2;
lined = datad + i * wpld;
for (j = 0; j < w; j++) {
val1 = GET_DATA_BYTE(lines1, j);
val2 = GET_DATA_BYTE(lines2, j);
if (val1 == val2)
SET_DATA_BIT(lined, j);
}
}
return pixd;
}
/*-----------------------------------------------------------------------*
* Selection of minima in mask connected components *
*-----------------------------------------------------------------------*/
/*!
* pixSelectMinInConnComp()
*
* Input: pixs (8 bpp)
* pixm (1 bpp)
* &pta (<return> pta of min pixel locations)
* &nav (<optional return> numa of minima values)
* Return: 0 if OK, 1 on error.
*
* Notes:
* (1) For each 8 connected component in pixm, this finds
* a pixel in pixs that has the lowest value, and saves
* it in a Pta. If several pixels in pixs have the same
* minimum value, it picks the first one found.
* (2) For a mask pixm of true local minima, all pixels in each
* connected component have the same value in pixs, so it is
* fastest to select one of them using a special seedfill
* operation. Not yet implemented.
*/
l_int32
pixSelectMinInConnComp(PIX *pixs,
PIX *pixm,
PTA **ppta,
NUMA **pnav)
{
l_int32 bx, by, bw, bh, i, j, c, n;
l_int32 xs, ys, minx, miny, wpls, wplt, val, minval;
l_uint32 *datas, *datat, *lines, *linet;
BOXA *boxa;
NUMA *nav;
PIX *pixt, *pixs2, *pixm2;
PIXA *pixa;
PTA *pta;
PROCNAME("pixSelectMinInConnComp");
if (!ppta)
return ERROR_INT("&pta not defined", procName, 1);
*ppta = NULL;
if (pnav) *pnav = NULL;
if (!pixs || pixGetDepth(pixs) != 8)
return ERROR_INT("pixs undefined or not 8 bpp", procName, 1);
if (!pixm || pixGetDepth(pixm) != 1)
return ERROR_INT("pixm undefined or not 1 bpp", procName, 1);
/* Crop to the min size if necessary */
if (pixCropToMatch(pixs, pixm, &pixs2, &pixm2)) {
pixDestroy(&pixs2);
pixDestroy(&pixm2);
return ERROR_INT("cropping failure", procName, 1);
}
/* Find value and location of min value pixel in each component */
boxa = pixConnComp(pixm2, &pixa, 8);
n = boxaGetCount(boxa);
pta = ptaCreate(n);
*ppta = pta;
nav = numaCreate(n);
datas = pixGetData(pixs2);
wpls = pixGetWpl(pixs2);
for (c = 0; c < n; c++) {
pixt = pixaGetPix(pixa, c, L_CLONE);
boxaGetBoxGeometry(boxa, c, &bx, &by, &bw, &bh);
if (bw == 1 && bh == 1) {
ptaAddPt(pta, bx, by);
numaAddNumber(nav, GET_DATA_BYTE(datas + by * wpls, bx));
pixDestroy(&pixt);
continue;
}
datat = pixGetData(pixt);
wplt = pixGetWpl(pixt);
minx = miny = 1000000;
minval = 256;
for (i = 0; i < bh; i++) {
ys = by + i;
lines = datas + ys * wpls;
linet = datat + i * wplt;
for (j = 0; j < bw; j++) {
xs = bx + j;
if (GET_DATA_BIT(linet, j)) {
val = GET_DATA_BYTE(lines, xs);
if (val < minval) {
minval = val;
minx = xs;
miny = ys;
}
}
}
}
ptaAddPt(pta, minx, miny);
numaAddNumber(nav, GET_DATA_BYTE(datas + miny * wpls, minx));
pixDestroy(&pixt);
}
boxaDestroy(&boxa);
pixaDestroy(&pixa);
if (pnav)
*pnav = nav;
else
numaDestroy(&nav);
pixDestroy(&pixs2);
pixDestroy(&pixm2);
return 0;
}
/*-----------------------------------------------------------------------*
* Removal of seeded connected components from a mask *
*-----------------------------------------------------------------------*/
/*!
* pixRemoveSeededComponents()
*
* Input: pixd (<optional>; this can be null or equal to pixm; 1 bpp)
* pixs (1 bpp seed)
* pixm (1 bpp filling mask)
* connectivity (4 or 8)
* bordersize (amount of border clearing)
* Return: pixd, or null on error
*
* Notes:
* (1) This removes each component in pixm for which there is
* at least one seed in pixs. If pixd == NULL, this returns
* the result in a new pixd. Otherwise, it is an in-place
* operation on pixm. In no situation is pixs altered,
* because we do the filling with a copy of pixs.
* (2) If bordersize > 0, it also clears all pixels within a
* distance @bordersize of the edge of pixd. This is here
* because pixLocalExtrema() typically finds local minima
* at the border. Use @bordersize >= 2 to remove these.
*/
PIX *
pixRemoveSeededComponents(PIX *pixd,
PIX *pixs,
PIX *pixm,
l_int32 connectivity,
l_int32 bordersize)
{
PIX *pixt;
PROCNAME("pixRemoveSeededComponents");
if (!pixs || pixGetDepth(pixs) != 1)
return (PIX *)ERROR_PTR("pixs undefined or not 1 bpp", procName, pixd);
if (!pixm || pixGetDepth(pixm) != 1)
return (PIX *)ERROR_PTR("pixm undefined or not 1 bpp", procName, pixd);
if (pixd && pixd != pixm)
return (PIX *)ERROR_PTR("operation not inplace", procName, pixd);
pixt = pixCopy(NULL, pixs);
pixSeedfillBinary(pixt, pixt, pixm, connectivity);
pixd = pixXor(pixd, pixm, pixt);
if (bordersize > 0)
pixSetOrClearBorder(pixd, bordersize, bordersize, bordersize,
bordersize, PIX_CLR);
pixDestroy(&pixt);
return pixd;
}