#endif /* HAVE_CONFIG_H */
#include "allheaders.h"
static l_int32 pixSearchForRectangle(PIX *pixs, BOX *boxs, l_int32 minsum,
l_int32 skipdist, l_int32 delta,
l_int32 maxbg, l_int32 sideflag,
BOXA *boxat, NUMA *nascore);
#ifndef NO_CONSOLE_IO
#define DEBUG_SPLIT 0
#endif /* ~NO_CONSOLE_IO */
/*---------------------------------------------------------------------*
* Boxa/Boxaa painting into Pix *
*---------------------------------------------------------------------*/
/*!
* \brief pixMaskConnComp()
*
* \param[in] pixs 1 bpp
* \param[in] connectivity 4 or 8
* \param[out] pboxa [optional] bounding boxes of c.c.
* \return pixd 1 bpp mask over the c.c., or NULL on error
*
*
* Notes:
* (1) This generates a mask image with ON pixels over the
* b.b. of the c.c. in pixs. If there are no ON pixels in pixs,
* pixd will also have no ON pixels.
*
*/
PIX *
pixMaskConnComp(PIX *pixs,
l_int32 connectivity,
BOXA **pboxa)
{
BOXA *boxa;
PIX *pixd;
PROCNAME("pixMaskConnComp");
if (pboxa) *pboxa = NULL;
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);
boxa = pixConnComp(pixs, NULL, connectivity);
pixd = pixCreateTemplate(pixs);
if (boxaGetCount(boxa) != 0)
pixMaskBoxa(pixd, pixd, boxa, L_SET_PIXELS);
if (pboxa)
*pboxa = boxa;
else
boxaDestroy(&boxa);
return pixd;
}
/*!
* \brief pixMaskBoxa()
*
* \param[in] pixd [optional] may be NULL
* \param[in] pixs any depth; not cmapped
* \param[in] boxa of boxes, to paint
* \param[in] op L_SET_PIXELS, L_CLEAR_PIXELS, L_FLIP_PIXELS
* \return pixd with masking op over the boxes, or NULL on error
*
*
* Notes:
* (1) This can be used with:
* pixd = NULL (makes a new pixd)
* pixd = pixs (in-place)
* (2) If pixd == NULL, this first makes a copy of pixs, and then
* bit-twiddles over the boxes. Otherwise, it operates directly
* on pixs.
* (3) This simple function is typically used with 1 bpp images.
* It uses the 1-image rasterop function, rasteropUniLow(),
* to set, clear or flip the pixels in pixd.
* (4) If you want to generate a 1 bpp mask of ON pixels from the boxes
* in a Boxa, in a pix of size (w,h):
* pix = pixCreate(w, h, 1);
* pixMaskBoxa(pix, pix, boxa, L_SET_PIXELS);
*
*/
PIX *
pixMaskBoxa(PIX *pixd,
PIX *pixs,
BOXA *boxa,
l_int32 op)
{
l_int32 i, n, x, y, w, h;
BOX *box;
PROCNAME("pixMaskBoxa");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (pixGetColormap(pixs))
return (PIX *)ERROR_PTR("pixs is cmapped", procName, NULL);
if (pixd && (pixd != pixs))
return (PIX *)ERROR_PTR("if pixd, must be in-place", procName, NULL);
if (!boxa)
return (PIX *)ERROR_PTR("boxa not defined", procName, NULL);
if (op != L_SET_PIXELS && op != L_CLEAR_PIXELS && op != L_FLIP_PIXELS)
return (PIX *)ERROR_PTR("invalid op", procName, NULL);
pixd = pixCopy(pixd, pixs);
if ((n = boxaGetCount(boxa)) == 0) {
L_WARNING("no boxes to mask\n", procName);
return pixd;
}
for (i = 0; i < n; i++) {
box = boxaGetBox(boxa, i, L_CLONE);
boxGetGeometry(box, &x, &y, &w, &h);
if (op == L_SET_PIXELS)
pixRasterop(pixd, x, y, w, h, PIX_SET, NULL, 0, 0);
else if (op == L_CLEAR_PIXELS)
pixRasterop(pixd, x, y, w, h, PIX_CLR, NULL, 0, 0);
else /* op == L_FLIP_PIXELS */
pixRasterop(pixd, x, y, w, h, PIX_NOT(PIX_DST), NULL, 0, 0);
boxDestroy(&box);
}
return pixd;
}
/*!
* \brief pixPaintBoxa()
*
* \param[in] pixs any depth, can be cmapped
* \param[in] boxa of boxes, to paint
* \param[in] val rgba color to paint
* \return pixd with painted boxes, or NULL on error
*
*
* Notes:
* (1) If pixs is 1 bpp or is colormapped, it is converted to 8 bpp
* and the boxa is painted using a colormap; otherwise,
* it is converted to 32 bpp rgb.
* (2) There are several ways to display a box on an image:
* * Paint it as a solid color
* * Draw the outline
* * Blend the outline or region with the existing image
* We provide painting and drawing here; blending is in blend.c.
* When painting or drawing, the result can be either a
* cmapped image or an rgb image. The dest will be cmapped
* if the src is either 1 bpp or has a cmap that is not full.
* To force RGB output, use pixConvertTo8(pixs, FALSE)
* before calling any of these paint and draw functions.
*
*/
PIX *
pixPaintBoxa(PIX *pixs,
BOXA *boxa,
l_uint32 val)
{
l_int32 i, n, d, rval, gval, bval, newindex;
l_int32 mapvacancy; /* true only if cmap and not full */
BOX *box;
PIX *pixd;
PIXCMAP *cmap;
PROCNAME("pixPaintBoxa");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (!boxa)
return (PIX *)ERROR_PTR("boxa not defined", procName, NULL);
if ((n = boxaGetCount(boxa)) == 0) {
L_WARNING("no boxes to paint; returning a copy\n", procName);
return pixCopy(NULL, pixs);
}
mapvacancy = FALSE;
if ((cmap = pixGetColormap(pixs)) != NULL) {
if (pixcmapGetCount(cmap) < 256)
mapvacancy = TRUE;
}
if (pixGetDepth(pixs) == 1 || mapvacancy)
pixd = pixConvertTo8(pixs, TRUE);
else
pixd = pixConvertTo32(pixs);
if (!pixd)
return (PIX *)ERROR_PTR("pixd not made", procName, NULL);
d = pixGetDepth(pixd);
if (d == 8) { /* colormapped */
cmap = pixGetColormap(pixd);
extractRGBValues(val, &rval, &gval, &bval);
if (pixcmapAddNewColor(cmap, rval, gval, bval, &newindex)) {
pixDestroy(&pixd);
return (PIX *)ERROR_PTR("cmap full; can't add", procName, NULL);
}
}
for (i = 0; i < n; i++) {
box = boxaGetBox(boxa, i, L_CLONE);
if (d == 8)
pixSetInRectArbitrary(pixd, box, newindex);
else
pixSetInRectArbitrary(pixd, box, val);
boxDestroy(&box);
}
return pixd;
}
/*!
* \brief pixSetBlackOrWhiteBoxa()
*
* \param[in] pixs any depth, can be cmapped
* \param[in] boxa [optional] of boxes, to clear or set
* \param[in] op L_SET_BLACK, L_SET_WHITE
* \return pixd with boxes filled with white or black, or NULL on error
*/
PIX *
pixSetBlackOrWhiteBoxa(PIX *pixs,
BOXA *boxa,
l_int32 op)
{
l_int32 i, n, d, index;
l_uint32 color;
BOX *box;
PIX *pixd;
PIXCMAP *cmap;
PROCNAME("pixSetBlackOrWhiteBoxa");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (!boxa)
return pixCopy(NULL, pixs);
if ((n = boxaGetCount(boxa)) == 0)
return pixCopy(NULL, pixs);
pixd = pixCopy(NULL, pixs);
d = pixGetDepth(pixd);
if (d == 1) {
for (i = 0; i < n; i++) {
box = boxaGetBox(boxa, i, L_CLONE);
if (op == L_SET_WHITE)
pixClearInRect(pixd, box);
else
pixSetInRect(pixd, box);
boxDestroy(&box);
}
return pixd;
}
cmap = pixGetColormap(pixs);
if (cmap) {
color = (op == L_SET_WHITE) ? 1 : 0;
pixcmapAddBlackOrWhite(cmap, color, &index);
} else if (d == 8) {
color = (op == L_SET_WHITE) ? 0xff : 0x0;
} else if (d == 32) {
color = (op == L_SET_WHITE) ? 0xffffff00 : 0x0;
} else if (d == 2) {
color = (op == L_SET_WHITE) ? 0x3 : 0x0;
} else if (d == 4) {
color = (op == L_SET_WHITE) ? 0xf : 0x0;
} else if (d == 16) {
color = (op == L_SET_WHITE) ? 0xffff : 0x0;
} else {
pixDestroy(&pixd);
return (PIX *)ERROR_PTR("invalid depth", procName, NULL);
}
for (i = 0; i < n; i++) {
box = boxaGetBox(boxa, i, L_CLONE);
if (cmap)
pixSetInRectArbitrary(pixd, box, index);
else
pixSetInRectArbitrary(pixd, box, color);
boxDestroy(&box);
}
return pixd;
}
/*!
* \brief pixPaintBoxaRandom()
*
* \param[in] pixs any depth, can be cmapped
* \param[in] boxa of boxes, to paint
* \return pixd with painted boxes, or NULL on error
*
*
* Notes:
* (1) If pixs is 1 bpp, we paint the boxa using a colormap;
* otherwise, we convert to 32 bpp.
* (2) We use up to 254 different colors for painting the regions.
* (3) If boxes overlap, the later ones paint over earlier ones.
*
*/
PIX *
pixPaintBoxaRandom(PIX *pixs,
BOXA *boxa)
{
l_int32 i, n, d, rval, gval, bval, index;
l_uint32 val;
BOX *box;
PIX *pixd;
PIXCMAP *cmap;
PROCNAME("pixPaintBoxaRandom");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (!boxa)
return (PIX *)ERROR_PTR("boxa not defined", procName, NULL);
if ((n = boxaGetCount(boxa)) == 0) {
L_WARNING("no boxes to paint; returning a copy\n", procName);
return pixCopy(NULL, pixs);
}
if (pixGetDepth(pixs) == 1)
pixd = pixConvert1To8(NULL, pixs, 255, 0);
else
pixd = pixConvertTo32(pixs);
if (!pixd)
return (PIX *)ERROR_PTR("pixd not made", procName, NULL);
cmap = pixcmapCreateRandom(8, 1, 1);
d = pixGetDepth(pixd); /* either 8 or 32 */
if (d == 8) /* colormapped */
pixSetColormap(pixd, cmap);
for (i = 0; i < n; i++) {
box = boxaGetBox(boxa, i, L_CLONE);
index = 1 + (i % 254);
if (d == 8) {
pixSetInRectArbitrary(pixd, box, index);
} else { /* d == 32 */
pixcmapGetColor(cmap, index, &rval, &gval, &bval);
composeRGBPixel(rval, gval, bval, &val);
pixSetInRectArbitrary(pixd, box, val);
}
boxDestroy(&box);
}
if (d == 32)
pixcmapDestroy(&cmap);
return pixd;
}
/*!
* \brief pixBlendBoxaRandom()
*
* \param[in] pixs any depth; can be cmapped
* \param[in] boxa of boxes, to blend/paint
* \param[in] fract of box color to use
* \return pixd 32 bpp, with blend/painted boxes, or NULL on error
*
*
* Notes:
* (1) pixs is converted to 32 bpp.
* (2) This differs from pixPaintBoxaRandom(), in that the
* colors here are blended with the color of pixs.
* (3) We use up to 254 different colors for painting the regions.
* (4) If boxes overlap, the final color depends only on the last
* rect that is used.
*
*/
PIX *
pixBlendBoxaRandom(PIX *pixs,
BOXA *boxa,
l_float32 fract)
{
l_int32 i, n, rval, gval, bval, index;
l_uint32 val;
BOX *box;
PIX *pixd;
PIXCMAP *cmap;
PROCNAME("pixBlendBoxaRandom");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (!boxa)
return (PIX *)ERROR_PTR("boxa not defined", procName, NULL);
if (fract < 0.0 || fract > 1.0) {
L_WARNING("fract must be in [0.0, 1.0]; setting to 0.5\n", procName);
fract = 0.5;
}
if ((n = boxaGetCount(boxa)) == 0) {
L_WARNING("no boxes to paint; returning a copy\n", procName);
return pixCopy(NULL, pixs);
}
if ((pixd = pixConvertTo32(pixs)) == NULL)
return (PIX *)ERROR_PTR("pixd not defined", procName, NULL);
cmap = pixcmapCreateRandom(8, 1, 1);
for (i = 0; i < n; i++) {
box = boxaGetBox(boxa, i, L_CLONE);
index = 1 + (i % 254);
pixcmapGetColor(cmap, index, &rval, &gval, &bval);
composeRGBPixel(rval, gval, bval, &val);
pixBlendInRect(pixd, box, val, fract);
boxDestroy(&box);
}
pixcmapDestroy(&cmap);
return pixd;
}
/*!
* \brief pixDrawBoxa()
*
* \param[in] pixs any depth; can be cmapped
* \param[in] boxa of boxes, to draw
* \param[in] width of lines
* \param[in] val rgba color to draw
* \return pixd with outlines of boxes added, or NULL on error
*
*
* Notes:
* (1) If pixs is 1 bpp or is colormapped, it is converted to 8 bpp
* and the boxa is drawn using a colormap; otherwise,
* it is converted to 32 bpp rgb.
*
*/
PIX *
pixDrawBoxa(PIX *pixs,
BOXA *boxa,
l_int32 width,
l_uint32 val)
{
l_int32 rval, gval, bval, newindex;
l_int32 mapvacancy; /* true only if cmap and not full */
PIX *pixd;
PIXCMAP *cmap;
PROCNAME("pixDrawBoxa");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (!boxa)
return (PIX *)ERROR_PTR("boxa not defined", procName, NULL);
if (width < 1)
return (PIX *)ERROR_PTR("width must be >= 1", procName, NULL);
if (boxaGetCount(boxa) == 0) {
L_WARNING("no boxes to draw; returning a copy\n", procName);
return pixCopy(NULL, pixs);
}
mapvacancy = FALSE;
if ((cmap = pixGetColormap(pixs)) != NULL) {
if (pixcmapGetCount(cmap) < 256)
mapvacancy = TRUE;
}
if (pixGetDepth(pixs) == 1 || mapvacancy)
pixd = pixConvertTo8(pixs, TRUE);
else
pixd = pixConvertTo32(pixs);
if (!pixd)
return (PIX *)ERROR_PTR("pixd not made", procName, NULL);
extractRGBValues(val, &rval, &gval, &bval);
if (pixGetDepth(pixd) == 8) { /* colormapped */
cmap = pixGetColormap(pixd);
pixcmapAddNewColor(cmap, rval, gval, bval, &newindex);
}
pixRenderBoxaArb(pixd, boxa, width, rval, gval, bval);
return pixd;
}
/*!
* \brief pixDrawBoxaRandom()
*
* \param[in] pixs any depth, can be cmapped
* \param[in] boxa of boxes, to draw
* \param[in] width thickness of line
* \return pixd with box outlines drawn, or NULL on error
*
*
* Notes:
* (1) If pixs is 1 bpp, we draw the boxa using a colormap;
* otherwise, we convert to 32 bpp.
* (2) We use up to 254 different colors for drawing the boxes.
* (3) If boxes overlap, the later ones draw over earlier ones.
*
*/
PIX *
pixDrawBoxaRandom(PIX *pixs,
BOXA *boxa,
l_int32 width)
{
l_int32 i, n, rval, gval, bval, index;
BOX *box;
PIX *pixd;
PIXCMAP *cmap;
PTAA *ptaa;
PROCNAME("pixDrawBoxaRandom");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (!boxa)
return (PIX *)ERROR_PTR("boxa not defined", procName, NULL);
if (width < 1)
return (PIX *)ERROR_PTR("width must be >= 1", procName, NULL);
if ((n = boxaGetCount(boxa)) == 0) {
L_WARNING("no boxes to draw; returning a copy\n", procName);
return pixCopy(NULL, pixs);
}
/* Input depth = 1 bpp; generate cmapped output */
if (pixGetDepth(pixs) == 1) {
ptaa = generatePtaaBoxa(boxa);
pixd = pixRenderRandomCmapPtaa(pixs, ptaa, 1, width, 1);
ptaaDestroy(&ptaa);
return pixd;
}
/* Generate rgb output */
pixd = pixConvertTo32(pixs);
cmap = pixcmapCreateRandom(8, 1, 1);
for (i = 0; i < n; i++) {
box = boxaGetBox(boxa, i, L_CLONE);
index = 1 + (i % 254);
pixcmapGetColor(cmap, index, &rval, &gval, &bval);
pixRenderBoxArb(pixd, box, width, rval, gval, bval);
boxDestroy(&box);
}
pixcmapDestroy(&cmap);
return pixd;
}
/*!
* \brief boxaaDisplay()
*
* \param[in] pixs [optional] 1 bpp
* \param[in] baa boxaa, typically from a 2d sort
* \param[in] linewba line width to display outline of each boxa
* \param[in] linewb line width to display outline of each box
* \param[in] colorba color to display boxa
* \param[in] colorb color to display box
* \param[in] w width of outupt pix; use 0 if determined by %pixs or %baa
* \param[in] h height of outupt pix; use 0 if determined by %pixs or %baa
* \return 0 if OK, 1 on error
*
*
* Notes:
* (1) If %pixs exists, this renders the boxes over an 8 bpp version
* of it. Otherwise, it renders the boxes over an empty image
* with a white background.
* (2) If %pixs exists, the dimensions of %pixd are the same,
* and input values of %w and %h are ignored.
* If %pixs is NULL, the dimensions of %pixd are determined by
* - %w and %h if both are > 0, or
* - the minimum size required using all boxes in %baa.
*
*
*/
PIX *
boxaaDisplay(PIX *pixs,
BOXAA *baa,
l_int32 linewba,
l_int32 linewb,
l_uint32 colorba,
l_uint32 colorb,
l_int32 w,
l_int32 h)
{
l_int32 i, j, n, m, rbox, gbox, bbox, rboxa, gboxa, bboxa;
BOX *box;
BOXA *boxa;
PIX *pixd;
PIXCMAP *cmap;
PROCNAME("boxaaDisplay");
if (!baa)
return (PIX *)ERROR_PTR("baa not defined", procName, NULL);
if (w <= 0 || h <= 0) {
if (pixs)
pixGetDimensions(pixs, &w, &h, NULL);
else
boxaaGetExtent(baa, &w, &h, NULL, NULL);
}
if (pixs) {
pixd = pixConvertTo8(pixs, 1);
cmap = pixGetColormap(pixd);
} else {
pixd = pixCreate(w, h, 8);
cmap = pixcmapCreate(8);
pixSetColormap(pixd, cmap);
pixcmapAddColor(cmap, 255, 255, 255);
}
extractRGBValues(colorb, &rbox, &gbox, &bbox);
extractRGBValues(colorba, &rboxa, &gboxa, &bboxa);
pixcmapAddColor(cmap, rbox, gbox, bbox);
pixcmapAddColor(cmap, rboxa, gboxa, bboxa);
n = boxaaGetCount(baa);
for (i = 0; i < n; i++) {
boxa = boxaaGetBoxa(baa, i, L_CLONE);
boxaGetExtent(boxa, NULL, NULL, &box);
pixRenderBoxArb(pixd, box, linewba, rboxa, gboxa, bboxa);
boxDestroy(&box);
m = boxaGetCount(boxa);
for (j = 0; j < m; j++) {
box = boxaGetBox(boxa, j, L_CLONE);
pixRenderBoxArb(pixd, box, linewb, rbox, gbox, bbox);
boxDestroy(&box);
}
boxaDestroy(&boxa);
}
return pixd;
}
/*!
* \brief pixaDisplayBoxaa()
*
* \param[in] pixas any depth, can be cmapped
* \param[in] baa boxes to draw on input pixa
* \param[in] colorflag L_DRAW_RED, L_DRAW_GREEN, etc
* \param[in] width thickness of lines
* \return pixa with box outlines drawn on each pix, or NULL on error
*
*
* Notes:
* (1) All pix in %pixas that are not rgb are converted to rgb.
* (2) Each boxa in %baa contains boxes that will be drawn on
* the corresponding pix in %pixas.
* (3) The color of the boxes drawn on each pix are selected with
* %colorflag:
* * For red, green or blue: use L_DRAW_RED, etc.
* * For sequential r, g, b: use L_DRAW_RGB
* * For random colors: use L_DRAW_RANDOM
*
*/
PIXA *
pixaDisplayBoxaa(PIXA *pixas,
BOXAA *baa,
l_int32 colorflag,
l_int32 width)
{
l_int32 i, j, nba, n, nbox, rval, gval, bval;
l_uint32 color;
l_uint32 colors[255];
BOXA *boxa;
BOX *box;
PIX *pix;
PIXA *pixad;
PROCNAME("pixaDisplayBoxaa");
if (!pixas)
return (PIXA *)ERROR_PTR("pixas not defined", procName, NULL);
if (!baa)
return (PIXA *)ERROR_PTR("baa not defined", procName, NULL);
if (width < 1)
return (PIXA *)ERROR_PTR("width must be >= 1", procName, NULL);
if ((nba = boxaaGetCount(baa)) < 1)
return (PIXA *)ERROR_PTR("no boxa in baa", procName, NULL);
if ((n = pixaGetCount(pixas)) == 0)
return (PIXA *)ERROR_PTR("no pix in pixas", procName, NULL);
if (n != nba)
return (PIXA *)ERROR_PTR("num pix != num boxa", procName, NULL);
if (colorflag == L_DRAW_RED)
color = 0xff000000;
else if (colorflag == L_DRAW_GREEN)
color = 0x00ff0000;
else if (colorflag == L_DRAW_BLUE)
color = 0x0000ff00;
else if (colorflag == L_DRAW_RGB)
color = 0x000000ff;
else if (colorflag == L_DRAW_RANDOM)
color = 0x00000000;
else
return (PIXA *)ERROR_PTR("invalid colorflag", procName, NULL);
if (colorflag == L_DRAW_RED || colorflag == L_DRAW_GREEN ||
colorflag == L_DRAW_BLUE) {
for (i = 0; i < 255; i++)
colors[i] = color;
} else if (colorflag == L_DRAW_RGB) {
for (i = 0; i < 255; i++) {
if (i % 3 == L_DRAW_RED)
colors[i] = 0xff000000;
else if (i % 3 == L_DRAW_GREEN)
colors[i] = 0x00ff0000;
else /* i % 3 == L_DRAW_BLUE) */
colors[i] = 0x0000ff00;
}
} else if (colorflag == L_DRAW_RANDOM) {
for (i = 0; i < 255; i++) {
rval = (l_uint32)rand() & 0xff;
gval = (l_uint32)rand() & 0xff;
bval = (l_uint32)rand() & 0xff;
composeRGBPixel(rval, gval, bval, &colors[i]);
}
}
pixad = pixaCreate(n);
for (i = 0; i < n; i++) {
pix = pixaGetPix(pixas, i, L_COPY);
boxa = boxaaGetBoxa(baa, i, L_CLONE);
nbox = boxaGetCount(boxa);
for (j = 0; j < nbox; j++) {
box = boxaGetBox(boxa, j, L_CLONE);
extractRGBValues(colors[j % 255], &rval, &gval, &bval);
pixRenderBoxArb(pix, box, width, rval, gval, bval);
boxDestroy(&box);
}
boxaDestroy(&boxa);
pixaAddPix(pixad, pix, L_INSERT);
}
return pixad;
}
/*---------------------------------------------------------------------*
* Split mask components into Boxa *
*---------------------------------------------------------------------*/
/*!
* \brief pixSplitIntoBoxa()
*
* \param[in] pixs 1 bpp
* \param[in] minsum minimum pixels to trigger propagation
* \param[in] skipdist distance before computing sum for propagation
* \param[in] delta difference required to stop propagation
* \param[in] maxbg maximum number of allowed bg pixels in ref scan
* \param[in] maxcomps use 0 for unlimited number of subdivided components
* \param[in] remainder set to 1 to get b.b. of remaining stuff
* \return boxa of rectangles covering the fg of pixs, or NULL on error
*
*
* Notes:
* (1) This generates a boxa of rectangles that covers
* the fg of a mask. For each 8-connected component in pixs,
* it does a greedy partitioning, choosing the largest
* rectangle found from each of the four directions at each iter.
* See pixSplitComponentIntoBoxa() for details.
* (2) The input parameters give some flexibility for boundary
* noise. The resulting set of rectangles may cover some
* bg pixels.
* (3) This should be used when there are a small number of
* mask components, each of which has sides that are close
* to horizontal and vertical. The input parameters %delta
* and %maxbg determine whether or not holes in the mask are covered.
* (4) The parameter %maxcomps gives the maximum number of allowed
* rectangles extracted from any single connected component.
* Use 0 if no limit is to be applied.
* (5) The flag %remainder specifies whether we take a final bounding
* box for anything left after the maximum number of allowed
* rectangle is extracted.
*
*/
BOXA *
pixSplitIntoBoxa(PIX *pixs,
l_int32 minsum,
l_int32 skipdist,
l_int32 delta,
l_int32 maxbg,
l_int32 maxcomps,
l_int32 remainder)
{
l_int32 i, n;
BOX *box;
BOXA *boxa, *boxas, *boxad;
PIX *pix;
PIXA *pixas;
PROCNAME("pixSplitIntoBoxa");
if (!pixs || pixGetDepth(pixs) != 1)
return (BOXA *)ERROR_PTR("pixs undefined or not 1 bpp", procName, NULL);
boxas = pixConnComp(pixs, &pixas, 8);
n = boxaGetCount(boxas);
boxad = boxaCreate(0);
for (i = 0; i < n; i++) {
pix = pixaGetPix(pixas, i, L_CLONE);
box = boxaGetBox(boxas, i, L_CLONE);
boxa = pixSplitComponentIntoBoxa(pix, box, minsum, skipdist,
delta, maxbg, maxcomps, remainder);
boxaJoin(boxad, boxa, 0, -1);
pixDestroy(&pix);
boxDestroy(&box);
boxaDestroy(&boxa);
}
pixaDestroy(&pixas);
boxaDestroy(&boxas);
return boxad;
}
/*!
* \brief pixSplitComponentIntoBoxa()
*
* \param[in] pix 1 bpp
* \param[in] box [optional] location of pix w/rt an origin
* \param[in] minsum minimum pixels to trigger propagation
* \param[in] skipdist distance before computing sum for propagation
* \param[in] delta difference required to stop propagation
* \param[in] maxbg maximum number of allowed bg pixels in ref scan
* \param[in] maxcomps use 0 for unlimited number of subdivided components
* \param[in] remainder set to 1 to get b.b. of remaining stuff
* \return boxa of rectangles covering the fg of pix, or NULL on error
*
*
* Notes:
* (1) This generates a boxa of rectangles that covers
* the fg of a mask. It does so by a greedy partitioning of
* the mask, choosing the largest rectangle found from
* each of the four directions at each step.
* (2) The input parameters give some flexibility for boundary
* noise. The resulting set of rectangles must cover all
* the fg pixels and, in addition, may cover some bg pixels.
* Using small input parameters on a noiseless mask (i.e., one
* that has only large vertical and horizontal edges) will
* result in a proper covering of only the fg pixels of the mask.
* (3) The input is assumed to be a single connected component, that
* may have holes. From each side, sweep inward, counting
* the pixels. If the count becomes greater than %minsum,
* and we have moved forward a further amount %skipdist,
* record that count ('countref'), but don't accept if the scan
* contains more than %maxbg bg pixels. Continue the scan
* until we reach a count that differs from countref by at
* least %delta, at which point the propagation stops. The box
* swept out gets a score, which is the sum of fg pixels
* minus a penalty. The penalty is the number of bg pixels
* in the box. This is done from all four sides, and the
* side with the largest score is saved as a rectangle.
* The process repeats until there is either no rectangle
* left, or there is one that can't be captured from any
* direction. For the latter case, we simply accept the
* last rectangle.
* (4) The input box is only used to specify the location of
* the UL corner of pix, with respect to an origin that
* typically represents the UL corner of an underlying image,
* of which pix is one component. If %box is null,
* the UL corner is taken to be (0, 0).
* (5) The parameter %maxcomps gives the maximum number of allowed
* rectangles extracted from any single connected component.
* Use 0 if no limit is to be applied.
* (6) The flag %remainder specifies whether we take a final bounding
* box for anything left after the maximum number of allowed
* rectangle is extracted.
* (7) So if %maxcomps > 0, it specifies that we want no more than
* the first %maxcomps rectangles that satisfy the input
* criteria. After this, we can get a final rectangle that
* bounds everything left over by setting %remainder == 1.
* If %remainder == 0, we only get rectangles that satisfy
* the input criteria.
* (8) It should be noted that the removal of rectangles can
* break the original c.c. into several c.c.
* (9) Summing up:
* * If %maxcomp == 0, the splitting proceeds as far as possible.
* * If %maxcomp > 0, the splitting stops when %maxcomps are
* found, or earlier if no more components can be selected.
* * If %remainder == 1 and components remain that cannot be
* selected, they are returned as a single final rectangle;
* otherwise, they are ignored.
*
*/
BOXA *
pixSplitComponentIntoBoxa(PIX *pix,
BOX *box,
l_int32 minsum,
l_int32 skipdist,
l_int32 delta,
l_int32 maxbg,
l_int32 maxcomps,
l_int32 remainder)
{
l_int32 i, w, h, boxx, boxy, bx, by, bw, bh, maxdir, maxscore;
l_int32 iter;
BOX *boxs; /* shrinks as rectangular regions are removed */
BOX *boxt1, *boxt2, *boxt3;
BOXA *boxat; /* stores rectangle data for each side in an iteration */
BOXA *boxad;
NUMA *nascore, *nas;
PIX *pixs;
PROCNAME("pixSplitComponentIntoBoxa");
if (!pix || pixGetDepth(pix) != 1)
return (BOXA *)ERROR_PTR("pix undefined or not 1 bpp", procName, NULL);
pixs = pixCopy(NULL, pix);
pixGetDimensions(pixs, &w, &h, NULL);
if (box)
boxGetGeometry(box, &boxx, &boxy, NULL, NULL);
else
boxx = boxy = 0;
boxs = boxCreate(0, 0, w, h);
boxad = boxaCreate(0);
iter = 0;
while (boxs != NULL) {
boxGetGeometry(boxs, &bx, &by, &bw, &bh);
boxat = boxaCreate(4); /* potential rectangular regions */
nascore = numaCreate(4);
for (i = 0; i < 4; i++) {
pixSearchForRectangle(pixs, boxs, minsum, skipdist, delta, maxbg,
i, boxat, nascore);
}
nas = numaGetSortIndex(nascore, L_SORT_DECREASING);
numaGetIValue(nas, 0, &maxdir);
numaGetIValue(nascore, maxdir, &maxscore);
#if DEBUG_SPLIT
lept_stderr("Iteration: %d\n", iter);
boxPrintStreamInfo(stderr, boxs);
boxaWriteStderr(boxat);
lept_stderr("\nmaxdir = %d, maxscore = %d\n\n", maxdir, maxscore);
#endif /* DEBUG_SPLIT */
if (maxscore > 0) { /* accept this */
boxt1 = boxaGetBox(boxat, maxdir, L_CLONE);
boxt2 = boxTransform(boxt1, boxx, boxy, 1.0, 1.0);
boxaAddBox(boxad, boxt2, L_INSERT);
pixClearInRect(pixs, boxt1);
boxDestroy(&boxt1);
pixClipBoxToForeground(pixs, boxs, NULL, &boxt3);
boxDestroy(&boxs);
boxs = boxt3;
if (boxs) {
boxGetGeometry(boxs, NULL, NULL, &bw, &bh);
if (bw < 2 || bh < 2)
boxDestroy(&boxs); /* we're done */
}
} else { /* no more valid rectangles can be found */
if (remainder == 1) { /* save the last box */
boxt1 = boxTransform(boxs, boxx, boxy, 1.0, 1.0);
boxaAddBox(boxad, boxt1, L_INSERT);
}
boxDestroy(&boxs); /* we're done */
}
boxaDestroy(&boxat);
numaDestroy(&nascore);
numaDestroy(&nas);
iter++;
if ((iter == maxcomps) && boxs) {
if (remainder == 1) { /* save the last box */
boxt1 = boxTransform(boxs, boxx, boxy, 1.0, 1.0);
boxaAddBox(boxad, boxt1, L_INSERT);
}
boxDestroy(&boxs); /* we're done */
}
}
pixDestroy(&pixs);
return boxad;
}
/*!
* \brief pixSearchForRectangle()
*
* \param[in] pixs 1 bpp
* \param[in] boxs current region to investigate
* \param[in] minsum minimum pixels to trigger propagation
* \param[in] skipdist distance before computing sum for propagation
* \param[in] delta difference required to stop propagation
* \param[in] maxbg maximum number of allowed bg pixels in ref scan
* \param[in] sideflag side to search from
* \param[in] boxat add result of rectangular region found here
* \param[in] nascore add score for this rectangle here
* \return 0 if OK, 1 on error
*
*
* Notes:
* (1) See pixSplitComponentIntoBoxa() for an explanation of the algorithm.
* This does the sweep from a single side. For each iteration
* in pixSplitComponentIntoBoxa(), this will be called 4 times,
* for %sideflag = {0, 1, 2, 3}.
* (2) If a valid rectangle is not found, add a score of 0 and
* input a minimum box.
*
*/
static l_int32
pixSearchForRectangle(PIX *pixs,
BOX *boxs,
l_int32 minsum,
l_int32 skipdist,
l_int32 delta,
l_int32 maxbg,
l_int32 sideflag,
BOXA *boxat,
NUMA *nascore)
{
l_int32 bx, by, bw, bh, width, height, setref, atref;
l_int32 minincol, maxincol, mininrow, maxinrow, minval, maxval, bgref;
l_int32 x, y, x0, y0, xref, yref, colsum, rowsum, score, countref, diff;
void **lines1;
BOX *boxr;
PROCNAME("pixSearchForRectangle");
if (!pixs || pixGetDepth(pixs) != 1)
return ERROR_INT("pixs undefined or not 1 bpp", procName, 1);
if (!boxs)
return ERROR_INT("boxs not defined", procName, 1);
if (!boxat)
return ERROR_INT("boxat not defined", procName, 1);
if (!nascore)
return ERROR_INT("nascore not defined", procName, 1);
lines1 = pixGetLinePtrs(pixs, NULL);
boxGetGeometry(boxs, &bx, &by, &bw, &bh);
boxr = NULL;
setref = 0;
atref = 0;
maxval = 0;
minval = 100000;
score = 0; /* sum of all (fg - bg) pixels seen in the scan */
xref = yref = 100000; /* init to impossibly big number */
if (sideflag == L_FROM_LEFT) {
for (x = bx; x < bx + bw; x++) {
colsum = 0;
maxincol = 0;
minincol = 100000;
for (y = by; y < by + bh; y++) {
if (GET_DATA_BIT(lines1[y], x)) {
colsum++;
if (y > maxincol) maxincol = y;
if (y < minincol) minincol = y;
}
}
score += colsum;
/* Enough fg to sweep out a rectangle? */
if (!setref && colsum >= minsum) {
setref = 1;
xref = x + 10;
if (xref >= bx + bw)
goto failure;
}
/* Reached the reference line; save the count;
* if there is too much bg, the rectangle is invalid. */
if (setref && x == xref) {
atref = 1;
countref = colsum;
bgref = maxincol - minincol + 1 - countref;
if (bgref > maxbg)
goto failure;
}
/* Have we left the rectangle? If so, save it along
* with the score. */
if (atref) {
diff = L_ABS(colsum - countref);
if (diff >= delta || x == bx + bw - 1) {
height = maxval - minval + 1;
width = x - bx;
if (x == bx + bw - 1) width = x - bx + 1;
boxr = boxCreate(bx, minval, width, height);
score = 2 * score - width * height;
goto success;
}
}
maxval = L_MAX(maxval, maxincol);
minval = L_MIN(minval, minincol);
}
goto failure;
} else if (sideflag == L_FROM_RIGHT) {
for (x = bx + bw - 1; x >= bx; x--) {
colsum = 0;
maxincol = 0;
minincol = 100000;
for (y = by; y < by + bh; y++) {
if (GET_DATA_BIT(lines1[y], x)) {
colsum++;
if (y > maxincol) maxincol = y;
if (y < minincol) minincol = y;
}
}
score += colsum;
if (!setref && colsum >= minsum) {
setref = 1;
xref = x - 10;
if (xref < bx)
goto failure;
}
if (setref && x == xref) {
atref = 1;
countref = colsum;
bgref = maxincol - minincol + 1 - countref;
if (bgref > maxbg)
goto failure;
}
if (atref) {
diff = L_ABS(colsum - countref);
if (diff >= delta || x == bx) {
height = maxval - minval + 1;
x0 = x + 1;
if (x == bx) x0 = x;
width = bx + bw - x0;
boxr = boxCreate(x0, minval, width, height);
score = 2 * score - width * height;
goto success;
}
}
maxval = L_MAX(maxval, maxincol);
minval = L_MIN(minval, minincol);
}
goto failure;
} else if (sideflag == L_FROM_TOP) {
for (y = by; y < by + bh; y++) {
rowsum = 0;
maxinrow = 0;
mininrow = 100000;
for (x = bx; x < bx + bw; x++) {
if (GET_DATA_BIT(lines1[y], x)) {
rowsum++;
if (x > maxinrow) maxinrow = x;
if (x < mininrow) mininrow = x;
}
}
score += rowsum;
if (!setref && rowsum >= minsum) {
setref = 1;
yref = y + 10;
if (yref >= by + bh)
goto failure;
}
if (setref && y == yref) {
atref = 1;
countref = rowsum;
bgref = maxinrow - mininrow + 1 - countref;
if (bgref > maxbg)
goto failure;
}
if (atref) {
diff = L_ABS(rowsum - countref);
if (diff >= delta || y == by + bh - 1) {
width = maxval - minval + 1;
height = y - by;
if (y == by + bh - 1) height = y - by + 1;
boxr = boxCreate(minval, by, width, height);
score = 2 * score - width * height;
goto success;
}
}
maxval = L_MAX(maxval, maxinrow);
minval = L_MIN(minval, mininrow);
}
goto failure;
} else if (sideflag == L_FROM_BOT) {
for (y = by + bh - 1; y >= by; y--) {
rowsum = 0;
maxinrow = 0;
mininrow = 100000;
for (x = bx; x < bx + bw; x++) {
if (GET_DATA_BIT(lines1[y], x)) {
rowsum++;
if (x > maxinrow) maxinrow = x;
if (x < mininrow) mininrow = x;
}
}
score += rowsum;
if (!setref && rowsum >= minsum) {
setref = 1;
yref = y - 10;
if (yref < by)
goto failure;
}
if (setref && y == yref) {
atref = 1;
countref = rowsum;
bgref = maxinrow - mininrow + 1 - countref;
if (bgref > maxbg)
goto failure;
}
if (atref) {
diff = L_ABS(rowsum - countref);
if (diff >= delta || y == by) {
width = maxval - minval + 1;
y0 = y + 1;
if (y == by) y0 = y;
height = by + bh - y0;
boxr = boxCreate(minval, y0, width, height);
score = 2 * score - width * height;
goto success;
}
}
maxval = L_MAX(maxval, maxinrow);
minval = L_MIN(minval, mininrow);
}
goto failure;
}
failure:
numaAddNumber(nascore, 0);
boxaAddBox(boxat, boxCreate(0, 0, 1, 1), L_INSERT); /* min box */
LEPT_FREE(lines1);
return 0;
success:
numaAddNumber(nascore, score);
boxaAddBox(boxat, boxr, L_INSERT);
LEPT_FREE(lines1);
return 0;
}
/*---------------------------------------------------------------------*
* Represent horizontal or vertical mosaic strips *
*---------------------------------------------------------------------*/
/*!
* \brief makeMosaicStrips()
*
* \param[in] w, h
* \param[in] direction L_SCAN_HORIZONTAL or L_SCAN_VERTICAL
* \param[in] size of strips in the scan direction
* \return boxa, or NULL on error
*
*
* Notes:
* (1) For example, this can be used to generate a pixa of
* vertical strips of width 10 from an image, using:
* pixGetDimensions(pix, &w, &h, NULL);
* boxa = makeMosaicStrips(w, h, L_SCAN_HORIZONTAL, 10);
* pixa = pixClipRectangles(pix, boxa);
* All strips except the last will be the same width. The
* last strip will have width w % 10.
*
*/
BOXA *
makeMosaicStrips(l_int32 w,
l_int32 h,
l_int32 direction,
l_int32 size)
{
l_int32 i, nstrips, extra;
BOX *box;
BOXA *boxa;
PROCNAME("makeMosaicStrips");
if (w < 1 || h < 1)
return (BOXA *)ERROR_PTR("invalid w or h", procName, NULL);
if (direction != L_SCAN_HORIZONTAL && direction != L_SCAN_VERTICAL)
return (BOXA *)ERROR_PTR("invalid direction", procName, NULL);
if (size < 1)
return (BOXA *)ERROR_PTR("size < 1", procName, NULL);
boxa = boxaCreate(0);
if (direction == L_SCAN_HORIZONTAL) {
nstrips = w / size;
for (i = 0; i < nstrips; i++) {
box = boxCreate(i * size, 0, size, h);
boxaAddBox(boxa, box, L_INSERT);
}
if ((extra = w % size) > 0) {
box = boxCreate(nstrips * size, 0, extra, h);
boxaAddBox(boxa, box, L_INSERT);
}
} else {
nstrips = h / size;
for (i = 0; i < nstrips; i++) {
box = boxCreate(0, i * size, w, size);
boxaAddBox(boxa, box, L_INSERT);
}
if ((extra = h % size) > 0) {
box = boxCreate(0, nstrips * size, w, extra);
boxaAddBox(boxa, box, L_INSERT);
}
}
return boxa;
}
/*---------------------------------------------------------------------*
* Comparison between boxa *
*---------------------------------------------------------------------*/
/*!
* \brief boxaCompareRegions()
*
* \param[in] boxa1, boxa2
* \param[in] areathresh minimum area of boxes to be considered
* \param[out] pnsame true if same number of boxes
* \param[out] pdiffarea fractional difference in total area
* \param[out] pdiffxor [optional] fractional difference in xor of regions
* \param[out] ppixdb [optional] debug pix showing two boxa
* \return 0 if OK, 1 on error
*
*
* Notes:
* (1) This takes 2 boxa, removes all boxes smaller than a given area,
* and compares the remaining boxes between the boxa.
* (2) The area threshold is introduced to help remove noise from
* small components. Any box with a smaller value of w * h
* will be removed from consideration.
* (3) The xor difference is the most stringent test, requiring alignment
* of the corresponding boxes. It is also more computationally
* intensive and is optionally returned. Alignment is to the
* UL corner of each region containing all boxes, as given by
* boxaGetExtent().
* (4) Both fractional differences are with respect to the total
* area in the two boxa. They range from 0.0 to 1.0.
* A perfect match has value 0.0. If both boxa are empty,
* we return 0.0; if one is empty we return 1.0.
* (5) An example input might be the rectangular regions of a
* segmentation mask for text or images from two pages.
*
*/
l_ok
boxaCompareRegions(BOXA *boxa1,
BOXA *boxa2,
l_int32 areathresh,
l_int32 *pnsame,
l_float32 *pdiffarea,
l_float32 *pdiffxor,
PIX **ppixdb)
{
l_int32 w, h, x3, y3, w3, h3, x4, y4, w4, h4, n3, n4, area1, area2;
l_int32 count3, count4, countxor;
l_int32 *tab;
BOX *box3, *box4;
BOXA *boxa3, *boxa4, *boxa3t, *boxa4t;
PIX *pix1, *pix2, *pix3, *pix4, *pix5;
PIXA *pixa;
PROCNAME("boxaCompareRegions");
if (pdiffxor) *pdiffxor = 1.0;
if (ppixdb) *ppixdb = NULL;
if (pnsame) *pnsame = FALSE;
if (pdiffarea) *pdiffarea = 1.0;
if (!boxa1 || !boxa2)
return ERROR_INT("boxa1 and boxa2 not both defined", procName, 1);
if (!pnsame)
return ERROR_INT("&nsame not defined", procName, 1);
if (!pdiffarea)
return ERROR_INT("&diffarea not defined", procName, 1);
boxa3 = boxaSelectByArea(boxa1, areathresh, L_SELECT_IF_GTE, NULL);
boxa4 = boxaSelectByArea(boxa2, areathresh, L_SELECT_IF_GTE, NULL);
n3 = boxaGetCount(boxa3);
n4 = boxaGetCount(boxa4);
if (n3 == n4)
*pnsame = TRUE;
/* There are no boxes in one or both */
if (n3 == 0 || n4 == 0) {
boxaDestroy(&boxa3);
boxaDestroy(&boxa4);
if (n3 == 0 && n4 == 0) { /* they are both empty: we say they are the
* same; otherwise, they differ maximally
* and retain the default value. */
*pdiffarea = 0.0;
if (pdiffxor) *pdiffxor = 0.0;
}
return 0;
}
/* There are boxes in both */
boxaGetArea(boxa3, &area1);
boxaGetArea(boxa4, &area2);
*pdiffarea = (l_float32)L_ABS(area1 - area2) / (l_float32)(area1 + area2);
if (!pdiffxor) {
boxaDestroy(&boxa3);
boxaDestroy(&boxa4);
return 0;
}
/* The easiest way to get the xor of aligned boxes is to work
* with images of each boxa. This is done by translating each
* boxa so that the UL corner of the region that includes all
* boxes in the boxa is placed at the origin of each pix. */
boxaGetExtent(boxa3, &w, &h, &box3);
boxaGetExtent(boxa4, &w, &h, &box4);
boxGetGeometry(box3, &x3, &y3, &w3, &h3);
boxGetGeometry(box4, &x4, &y4, &w4, &h4);
boxa3t = boxaTransform(boxa3, -x3, -y3, 1.0, 1.0);
boxa4t = boxaTransform(boxa4, -x4, -y4, 1.0, 1.0);
w = L_MAX(x3 + w3, x4 + w4);
h = L_MAX(y3 + h3, y4 + h4);
pix3 = pixCreate(w, h, 1); /* use the max to keep everything in the xor */
pix4 = pixCreate(w, h, 1);
pixMaskBoxa(pix3, pix3, boxa3t, L_SET_PIXELS);
pixMaskBoxa(pix4, pix4, boxa4t, L_SET_PIXELS);
tab = makePixelSumTab8();
pixCountPixels(pix3, &count3, tab);
pixCountPixels(pix4, &count4, tab);
pix5 = pixXor(NULL, pix3, pix4);
pixCountPixels(pix5, &countxor, tab);
LEPT_FREE(tab);
*pdiffxor = (l_float32)countxor / (l_float32)(count3 + count4);
if (ppixdb) {
pixa = pixaCreate(2);
pix1 = pixCreate(w, h, 32);
pixSetAll(pix1);
pixRenderHashBoxaBlend(pix1, boxa3, 5, 1, L_POS_SLOPE_LINE, 2,
255, 0, 0, 0.5);
pixRenderHashBoxaBlend(pix1, boxa4, 5, 1, L_NEG_SLOPE_LINE, 2,
0, 255, 0, 0.5);
pixaAddPix(pixa, pix1, L_INSERT);
pix2 = pixCreate(w, h, 32);
pixPaintThroughMask(pix2, pix3, x3, y3, 0xff000000);
pixPaintThroughMask(pix2, pix4, x4, y4, 0x00ff0000);
pixAnd(pix3, pix3, pix4);
pixPaintThroughMask(pix2, pix3, x3, y3, 0x0000ff00);
pixaAddPix(pixa, pix2, L_INSERT);
*ppixdb = pixaDisplayTiledInRows(pixa, 32, 1000, 1.0, 0, 30, 2);
pixaDestroy(&pixa);
}
boxDestroy(&box3);
boxDestroy(&box4);
boxaDestroy(&boxa3);
boxaDestroy(&boxa3t);
boxaDestroy(&boxa4);
boxaDestroy(&boxa4t);
pixDestroy(&pix3);
pixDestroy(&pix4);
pixDestroy(&pix5);
return 0;
}
/*---------------------------------------------------------------------*
* Reliable selection of a single large box *
*---------------------------------------------------------------------*/
/*!
* \brief pixSelectLargeULComp()
*
* \param[in] pixs 1 bpp
* \param[in] areaslop fraction near but less than 1.0
* \param[in] yslop number of pixels in y direction
* \param[in] connectivity 4 or 8
* \return box, or NULL on error
*
*
* Notes:
* (1) This selects a box near the top (first) and left (second)
* of the image, from the set of all boxes that have
* area >= %areaslop * (area of biggest box),
* where %areaslop is some fraction; say ~ 0.9.
* (2) For all boxes satisfying the above condition, select
* the left-most box that is within %yslop (say, 20) pixels
* of the box nearest the top.
* (3) This can be used to reliably select a specific one of
* the largest regions in an image, for applications where
* there are expected to be small variations in region size
* and location.
* (4) See boxSelectLargeULBox() for implementation details.
*
*/
BOX *
pixSelectLargeULComp(PIX *pixs,
l_float32 areaslop,
l_int32 yslop,
l_int32 connectivity)
{
BOX *box;
BOXA *boxa1;
PROCNAME("pixSelectLargeULComp");
if (!pixs)
return (BOX *)ERROR_PTR("pixs not defined", procName, NULL);
if (areaslop < 0.0 || areaslop > 1.0)
return (BOX *)ERROR_PTR("invalid value for areaslop", procName, NULL);
yslop = L_MAX(0, yslop);
boxa1 = pixConnCompBB(pixs, connectivity);
if (boxaGetCount(boxa1) == 0) {
boxaDestroy(&boxa1);
return NULL;
}
box = boxaSelectLargeULBox(boxa1, areaslop, yslop);
boxaDestroy(&boxa1);
return box;
}
/*!
* \brief boxaSelectLargeULBox()
*
* \param[in] boxas 1 bpp
* \param[in] areaslop fraction near but less than 1.0
* \param[in] yslop number of pixels in y direction
* \return box, or NULL on error
*
*
* Notes:
* (1) See usage notes in pixSelectLargeULComp().
*
*/
BOX *
boxaSelectLargeULBox(BOXA *boxas,
l_float32 areaslop,
l_int32 yslop)
{
l_int32 w, h, i, n, x1, y1, x2, y2, select;
l_float32 area, max_area;
BOX *box;
BOXA *boxa1, *boxa2, *boxa3;
PROCNAME("boxaSelectLargeULBox");
if (!boxas)
return (BOX *)ERROR_PTR("boxas not defined", procName, NULL);
if (boxaGetCount(boxas) == 0)
return (BOX *)ERROR_PTR("no boxes in boxas", procName, NULL);
if (areaslop < 0.0 || areaslop > 1.0)
return (BOX *)ERROR_PTR("invalid value for areaslop", procName, NULL);
yslop = L_MAX(0, yslop);
boxa1 = boxaSort(boxas, L_SORT_BY_AREA, L_SORT_DECREASING, NULL);
boxa2 = boxaSort(boxa1, L_SORT_BY_Y, L_SORT_INCREASING, NULL);
n = boxaGetCount(boxa2);
boxaGetBoxGeometry(boxa1, 0, NULL, NULL, &w, &h); /* biggest box by area */
max_area = (l_float32)(w * h);
/* boxa3 collects all boxes eligible by area, sorted top-down */
boxa3 = boxaCreate(4);
for (i = 0; i < n; i++) {
boxaGetBoxGeometry(boxa2, i, NULL, NULL, &w, &h);
area = (l_float32)(w * h);
if (area / max_area >= areaslop) {
box = boxaGetBox(boxa2, i, L_COPY);
boxaAddBox(boxa3, box, L_INSERT);
}
}
/* Take the first (top-most box) unless the second (etc) has
* nearly the same y value but a smaller x value. */
n = boxaGetCount(boxa3);
boxaGetBoxGeometry(boxa3, 0, &x1, &y1, NULL, NULL);
select = 0;
for (i = 1; i < n; i++) {
boxaGetBoxGeometry(boxa3, i, &x2, &y2, NULL, NULL);
if (y2 - y1 < yslop && x2 < x1) {
select = i;
x1 = x2; /* but always compare against y1 */
}
}
box = boxaGetBox(boxa3, select, L_COPY);
boxaDestroy(&boxa1);
boxaDestroy(&boxa2);
boxaDestroy(&boxa3);
return box;
}