/*!
* \brief pixCountConnComp()
*
* \param[in] pixs 1 bpp
* \param[in] connectivity 4 or 8
* \param[out] pcount
* \return 0 if OK, 1 on error
*
* Notes:
* (1 This is the top-level call for getting the number of
* 4- or 8-connected components in a 1 bpp image.
* 2 It works on a copy of the input pix. The c.c. are located
* in raster order and erased one at a time.
*/
l_int32
pixCountConnComp(PIX *pixs,
l_int32 connectivity,
l_int32 *pcount)
{
l_int32 h, iszero;
l_int32 x, y, xstart, ystart;
PIX *pixt;
L_STACK *stack, *auxstack;
PROCNAME("pixCountConnComp");
if (!pcount)
return ERROR_INT("&count not defined", procName, 1);
*pcount = 0; /* initialize the count to 0 */
if (!pixs || pixGetDepth(pixs) != 1)
return ERROR_INT("pixs not defined or not 1 bpp", procName, 1);
if (connectivity != 4 && connectivity != 8)
return ERROR_INT("connectivity not 4 or 8", procName, 1);
pixt = NULL;
stack = NULL;
pixZero(pixs, &iszero);
if (iszero)
return 0;
if ((pixt = pixCopy(NULL, pixs)) == NULL)
return ERROR_INT("pixt not made", procName, 1);
h = pixGetHeight(pixs);
if ((stack = lstackCreate(h)) == NULL) {
L_ERROR("stack not made\n", procName);
goto cleanup;
}
auxstack = lstackCreate(0);
stack->auxstack = auxstack;
xstart = 0;
ystart = 0;
while (1) {
if (!nextOnPixelInRaster(pixt, xstart, ystart, &x, &y))
break;
pixSeedfill(pixt, stack, x, y, connectivity);
(*pcount)++;
xstart = x;
ystart = y;
}
/* Cleanup, freeing the fillsegs on each stack */
cleanup:
lstackDestroy(&stack, TRUE);
pixDestroy(&pixt);
return 0;
}
/*!
* pixSubsampleBoundaryPixels()
*
* Input: pixs (1 bpp, with only boundary pixels in fg)
* skip (number to skip between samples as you traverse boundary)
* Return: pta, or null on error
*
* Notes:
* (1) If skip = 0, we take all the fg pixels.
* (2) We try to traverse the boundaries in a regular way.
* Some pixels may be missed, and these are then subsampled
* randomly with a fraction determined by 'skip'.
* (3) The most natural approach is to use a depth first (stack-based)
* method to find the fg pixels. However, the pixel runs are
* 4-connected and there are relatively few branches. So
* instead of doing a proper depth-first search, we get nearly
* the same result using two nested while loops: the outer
* one continues a raster-based search for the next fg pixel,
* and the inner one does a reasonable job running along
* each 4-connected coutour.
*/
PTA *
pixSubsampleBoundaryPixels(PIX *pixs,
l_int32 skip)
{
l_int32 x, y, xn, yn, xs, ys, xa, ya, count;
PIX *pixt;
PTA *pta;
PROCNAME("pixSubsampleBoundaryPixels");
if (!pixs)
return (PTA *)ERROR_PTR("pixs not defined", procName, NULL);
if (pixGetDepth(pixs) != 1)
return (PTA *)ERROR_PTR("pixs not 1 bpp", procName, NULL);
if (skip < 0)
return (PTA *)ERROR_PTR("skip < 0", procName, NULL);
if (skip == 0)
return ptaGetPixelsFromPix(pixs, NULL);
pta = ptaCreate(0);
pixt = pixCopy(NULL, pixs);
xs = ys = 0;
while (nextOnPixelInRaster(pixt, xs, ys, &xn, &yn)) { /* new series */
xs = xn;
ys = yn;
/* Add first point in this series */
ptaAddPt(pta, xs, ys);
/* Trace out boundary, erasing all and saving every (skip + 1)th */
x = xs;
y = ys;
pixSetPixel(pixt, x, y, 0);
count = 0;
while (adjacentOnPixelInRaster(pixt, x, y, &xa, &ya)) {
x = xa;
y = ya;
pixSetPixel(pixt, x, y, 0);
if (count == skip) {
ptaAddPt(pta, x, y);
count = 0;
}
else {
count++;
}
}
}
pixDestroy(&pixt);
return pta;
}
/*!
* \brief pixConnCompBB()
*
* \param[in] pixs 1 bpp
* \param[in] connectivity 4 or 8
* \return boxa, or NULL on error
*
* <pre>
* Notes:
* (1) Finds bounding boxes of 4- or 8-connected components
* in a binary image.
* (2) This works on a copy of the input pix. The c.c. are located
* in raster order and erased one at a time. In the process,
* the b.b. is computed and saved.
* </pre>
*/
BOXA *
pixConnCompBB(PIX *pixs,
l_int32 connectivity)
{
l_int32 h, iszero;
l_int32 x, y, xstart, ystart;
PIX *pixt;
BOX *box;
BOXA *boxa;
L_STACK *stack, *auxstack;
PROCNAME("pixConnCompBB");
if (!pixs || pixGetDepth(pixs) != 1)
return (BOXA *)ERROR_PTR("pixs undefined or not 1 bpp", procName, NULL);
if (connectivity != 4 && connectivity != 8)
return (BOXA *)ERROR_PTR("connectivity not 4 or 8", procName, NULL);
boxa = NULL;
pixt = NULL;
stack = NULL;
pixZero(pixs, &iszero);
if (iszero)
return boxaCreate(1); /* return empty boxa */
if ((pixt = pixCopy(NULL, pixs)) == NULL)
return (BOXA *)ERROR_PTR("pixt not made", procName, NULL);
h = pixGetHeight(pixs);
if ((stack = lstackCreate(h)) == NULL) {
L_ERROR("stack not made\n", procName);
goto cleanup;
}
auxstack = lstackCreate(0);
stack->auxstack = auxstack;
boxa = boxaCreate(0);
xstart = 0;
ystart = 0;
while (1) {
if (!nextOnPixelInRaster(pixt, xstart, ystart, &x, &y))
break;
if ((box = pixSeedfillBB(pixt, stack, x, y, connectivity)) == NULL) {
L_ERROR("box not made\n", procName);
boxaDestroy(&boxa);
goto cleanup;
}
boxaAddBox(boxa, box, L_INSERT);
xstart = x;
ystart = y;
}
#if DEBUG
pixCountPixels(pixt, &iszero, NULL);
fprintf(stderr, "Number of remaining pixels = %d\n", iszero);
pixWrite("junkremain", pixt1, IFF_PNG);
#endif /* DEBUG */
/* Cleanup, freeing the fillsegs on each stack */
cleanup:
lstackDestroy(&stack, TRUE);
pixDestroy(&pixt);
return boxa;
}
/*!
* \brief pixConnCompPixa()
*
* \param[in] pixs 1 bpp
* \param[out] ppixa pixa of each c.c.
* \param[in] connectivity 4 or 8
* \return boxa, or NULL on error
*
* <pre>
* Notes:
* (1) This finds bounding boxes of 4- or 8-connected components
* in a binary image, and saves images of each c.c
* in a pixa array.
* (2) It sets up 2 temporary pix, and for each c.c. that is
* located in raster order, it erases the c.c. from one pix,
* then uses the b.b. to extract the c.c. from the two pix using
* an XOR, and finally erases the c.c. from the second pix.
* (3) A clone of the returned boxa (where all boxes in the array
* are clones) is inserted into the pixa.
* (4) If the input is valid, this always returns a boxa and a pixa.
* If pixs is empty, the boxa and pixa will be empty.
* </pre>
*/
BOXA *
pixConnCompPixa(PIX *pixs,
PIXA **ppixa,
l_int32 connectivity)
{
l_int32 h, iszero;
l_int32 x, y, xstart, ystart;
PIX *pix1, *pix2, *pix3, *pix4;
PIXA *pixa;
BOX *box;
BOXA *boxa;
L_STACK *stack, *auxstack;
PROCNAME("pixConnCompPixa");
if (!ppixa)
return (BOXA *)ERROR_PTR("&pixa not defined", procName, NULL);
*ppixa = NULL;
if (!pixs || pixGetDepth(pixs) != 1)
return (BOXA *)ERROR_PTR("pixs undefined or not 1 bpp", procName, NULL);
if (connectivity != 4 && connectivity != 8)
return (BOXA *)ERROR_PTR("connectivity not 4 or 8", procName, NULL);
boxa = NULL;
pix1 = pix2 = pix3 = pix4 = NULL;
stack = NULL;
pixZero(pixs, &iszero);
if (iszero)
return boxaCreate(1); /* return empty boxa */
pix1 = pixCopy(NULL, pixs);
pix2 = pixCopy(NULL, pixs);
if (!pix1 || !pix2) {
L_ERROR("pix1 or pix2 not made\n", procName);
goto cleanup;
}
h = pixGetHeight(pixs);
if ((stack = lstackCreate(h)) == NULL) {
L_ERROR("stack not made\n", procName);
goto cleanup;
}
auxstack = lstackCreate(0);
stack->auxstack = auxstack;
pixa = pixaCreate(0);
boxa = boxaCreate(0);
xstart = 0;
ystart = 0;
while (1) {
if (!nextOnPixelInRaster(pix1, xstart, ystart, &x, &y))
break;
if ((box = pixSeedfillBB(pix1, stack, x, y, connectivity)) == NULL) {
L_ERROR("box not made\n", procName);
pixaDestroy(&pixa);
boxaDestroy(&boxa);
goto cleanup;
}
boxaAddBox(boxa, box, L_INSERT);
/* Save the c.c. and remove from pix2 as well */
pix3 = pixClipRectangle(pix1, box, NULL);
pix4 = pixClipRectangle(pix2, box, NULL);
pixXor(pix3, pix3, pix4);
pixRasterop(pix2, box->x, box->y, box->w, box->h, PIX_SRC ^ PIX_DST,
pix3, 0, 0);
pixaAddPix(pixa, pix3, L_INSERT);
pixDestroy(&pix4);
xstart = x;
ystart = y;
}
#if DEBUG
pixCountPixels(pix1, &iszero, NULL);
fprintf(stderr, "Number of remaining pixels = %d\n", iszero);
pixWrite("junkremain", pix1, IFF_PNG);
#endif /* DEBUG */
/* Remove old boxa of pixa and replace with a clone copy */
boxaDestroy(&pixa->boxa);
pixa->boxa = boxaCopy(boxa, L_CLONE);
*ppixa = pixa;
/* Cleanup, freeing the fillsegs on each stack */
cleanup:
lstackDestroy(&stack, TRUE);
pixDestroy(&pix1);
pixDestroy(&pix2);
return boxa;
}
