l_int32 renderTransformedBoxa(PIX *pixt, BOXA *boxa, l_int32 i) {
l_int32 j, n, rval, gval, bval;
BOX *box;
n = boxaGetCount(boxa);
rval = (1413 * i) % 256;
gval = (4917 * i) % 256;
bval = (7341 * i) % 256;
for (j = 0; j < n; j++) {
box = boxaGetBox(boxa, j, L_CLONE);
pixRenderHashBoxArb(pixt, box, 10, 3, i % 4, 1, rval, gval, bval);
boxDestroy(&box);
}
return 0;
}
/*!
* pixFindLargestRectangle()
*
* Input: pixs (1 bpp)
* polarity (0 within background, 1 within foreground)
* &box (<return> largest rectangle, either by area or
* by perimeter)
* debugflag (1 to output image with rectangle drawn on it)
* Return: 0 if OK, 1 on error
*
* Notes:
* (1) Why is this here? This is a simple and elegant solution to
* a problem in computational geometry that at first appears
* quite difficult: what is the largest rectangle that can
* be placed in the image, covering only pixels of one polarity
* (bg or fg)? The solution is O(n), where n is the number
* of pixels in the image, and it requires nothing more than
* using a simple recursion relation in a single sweep of the image.
* (2) In a sweep from UL to LR with left-to-right being the fast
* direction, calculate the largest white rectangle at (x, y),
* using previously calculated values at pixels #1 and #2:
* #1: (x, y - 1)
* #2: (x - 1, y)
* We also need the most recent "black" pixels that were seen
* in the current row and column.
* Consider the largest area. There are only two possibilities:
* (a) Min(w(1), horizdist) * (h(1) + 1)
* (b) Min(h(2), vertdist) * (w(2) + 1)
* where
* horizdist: the distance from the rightmost "black" pixel seen
* in the current row across to the current pixel
* vertdist: the distance from the lowest "black" pixel seen
* in the current column down to the current pixel
* and we choose the Max of (a) and (b).
* (3) To convince yourself that these recursion relations are correct,
* it helps to draw the maximum rectangles at #1 and #2.
* Then for #1, you try to extend the rectangle down one line,
* so that the height is h(1) + 1. Do you get the full
* width of #1, w(1)? It depends on where the black pixels are
* in the current row. You know the final width is bounded by w(1)
* and w(2) + 1, but the actual value depends on the distribution
* of black pixels in the current row that are at a distance
* from the current pixel that is between these limits.
* We call that value "horizdist", and the area is then given
* by the expression (a) above. Using similar reasoning for #2,
* where you attempt to extend the rectangle to the right
* by 1 pixel, you arrive at (b). The largest rectangle is
* then found by taking the Max.
*/
l_int32
pixFindLargestRectangle(PIX *pixs,
l_int32 polarity,
BOX **pbox,
const char *debugfile)
{
l_int32 i, j, w, h, d, wpls, val;
l_int32 wp, hp, w1, w2, h1, h2, wmin, hmin, area1, area2;
l_int32 xmax, ymax; /* LR corner of the largest rectangle */
l_int32 maxarea, wmax, hmax, vertdist, horizdist, prevfg;
l_int32 *lowestfg;
l_uint32 *datas, *lines;
l_uint32 **linew, **lineh;
BOX *box;
PIX *pixw, *pixh; /* keeps the width and height for the largest */
/* rectangles whose LR corner is located there. */
PROCNAME("pixFindLargestRectangle");
if (!pbox)
return ERROR_INT("&box not defined", procName, 1);
*pbox = NULL;
if (!pixs)
return ERROR_INT("pixs not defined", procName, 1);
pixGetDimensions(pixs, &w, &h, &d);
if (d != 1)
return ERROR_INT("pixs not 1 bpp", procName, 1);
if (polarity != 0 && polarity != 1)
return ERROR_INT("invalid polarity", procName, 1);
/* Initialize lowest "fg" seen so far for each column */
lowestfg = (l_int32 *)CALLOC(w, sizeof(l_int32));
for (i = 0; i < w; i++)
lowestfg[i] = -1;
/* The combination (val ^ polarity) is the color for which we
* are searching for the maximum rectangle. For polarity == 0,
* we search in the bg (white). */
pixw = pixCreate(w, h, 32); /* stores width */
pixh = pixCreate(w, h, 32); /* stores height */
linew = (l_uint32 **)pixGetLinePtrs(pixw, NULL);
lineh = (l_uint32 **)pixGetLinePtrs(pixh, NULL);
datas = pixGetData(pixs);
wpls = pixGetWpl(pixs);
maxarea = xmax = ymax = wmax = hmax = 0;
for (i = 0; i < h; i++) {
lines = datas + i * wpls;
prevfg = -1;
for (j = 0; j < w; j++) {
val = GET_DATA_BIT(lines, j);
if ((val ^ polarity) == 0) { /* bg (0) if polarity == 0, etc. */
if (i == 0 && j == 0) {
wp = hp = 1;
}
else if (i == 0) {
wp = linew[i][j - 1] + 1;
hp = 1;
}
else if (j == 0) {
wp = 1;
hp = lineh[i - 1][j] + 1;
}
else {
/* Expand #1 prev rectangle down */
w1 = linew[i - 1][j];
h1 = lineh[i - 1][j];
horizdist = j - prevfg;
wmin = L_MIN(w1, horizdist); /* width of new rectangle */
area1 = wmin * (h1 + 1);
/* Expand #2 prev rectangle to right */
w2 = linew[i][j - 1];
h2 = lineh[i][j - 1];
vertdist = i - lowestfg[j];
hmin = L_MIN(h2, vertdist); /* height of new rectangle */
area2 = hmin * (w2 + 1);
if (area1 > area2) {
wp = wmin;
hp = h1 + 1;
}
else {
wp = w2 + 1;
hp = hmin;
}
}
}
else { /* fg (1) if polarity == 0; bg (0) if polarity == 1 */
prevfg = j;
lowestfg[j] = i;
wp = hp = 0;
}
linew[i][j] = wp;
lineh[i][j] = hp;
if (wp * hp > maxarea) {
maxarea = wp * hp;
xmax = j;
ymax = i;
wmax = wp;
hmax = hp;
}
}
}
/* Translate from LR corner to Box coords (UL corner, w, h) */
box = boxCreate(xmax - wmax + 1, ymax - hmax + 1, wmax, hmax);
*pbox = box;
if (debugfile) {
PIX *pixdb;
pixdb = pixConvertTo8(pixs, TRUE);
pixRenderHashBoxArb(pixdb, box, 6, 2, L_NEG_SLOPE_LINE, 1, 255, 0, 0);
pixWrite(debugfile, pixdb, IFF_PNG);
pixDestroy(&pixdb);
}
FREE(linew);
FREE(lineh);
FREE(lowestfg);
pixDestroy(&pixw);
pixDestroy(&pixh);
return 0;
}
main(int argc,
char **argv)
{
l_int32 i, n, ws, hs, w, h, rval, gval, bval, order;
l_float32 *mat1, *mat2, *mat3;
l_float32 matd[9];
BOX *box, *boxt;
BOXA *boxa, *boxat, *boxa1, *boxa2, *boxa3, *boxa4, *boxa5;
PIX *pix, *pixs, *pixb, *pixc, *pixt, *pixt1, *pixt2, *pixt3;
PIXA *pixa;
static char mainName[] = "xformbox_reg";
/* ----------------------------------------------------------- *
* Test hash rendering in 3 modes *
* ----------------------------------------------------------- */
pixs = pixRead("feyn.tif");
box = boxCreate(461, 429, 1393, 342);
pixt1 = pixClipRectangle(pixs, box, NULL);
boxa = pixConnComp(pixt1, NULL, 8);
n = boxaGetCount(boxa);
pixt2 = pixConvertTo8(pixt1, 1);
pixt3 = pixConvertTo32(pixt1);
for (i = 0; i < n; i++) {
boxt = boxaGetBox(boxa, i, L_CLONE);
rval = (1413 * i) % 256;
gval = (4917 * i) % 256;
bval = (7341 * i) % 256;
pixRenderHashBox(pixt1, boxt, 8, 2, i % 4, 1, L_SET_PIXELS);
pixRenderHashBoxArb(pixt2, boxt, 7, 2, i % 4, 1, rval, gval, bval);
pixRenderHashBoxBlend(pixt3, boxt, 7, 2, i % 4, 1, rval, gval, bval,
0.5);
boxDestroy(&boxt);
}
pixDisplay(pixt1, 0, 0);
pixDisplay(pixt2, 0, 300);
pixDisplay(pixt3, 0, 570);
pixWrite("/tmp/junkpixt1.png", pixt1, IFF_PNG);
pixWrite("/tmp/junkpixt2.png", pixt2, IFF_PNG);
pixWrite("/tmp/junkpixt3.png", pixt3, IFF_PNG);
boxaDestroy(&boxa);
boxDestroy(&box);
pixDestroy(&pixs);
pixDestroy(&pixt1);
pixDestroy(&pixt2);
pixDestroy(&pixt3);
/* ----------------------------------------------------------- *
* Test box transforms with either translation or scaling *
* combined with rotation, using the simple 'ordered' *
* function. Show that the order of the operations does *
* not matter; different hashing schemes end up in the *
* identical boxes. *
* ----------------------------------------------------------- */
pix = pixRead("feyn.tif");
box = boxCreate(420, 360, 1500, 465);
pixt = pixClipRectangle(pix, box, NULL);
pixs = pixAddBorderGeneral(pixt, 0, 200, 0, 0, 0);
boxDestroy(&box);
pixDestroy(&pix);
pixDestroy(&pixt);
boxa = pixConnComp(pixs, NULL, 8);
n = boxaGetCount(boxa);
pixa = pixaCreate(0);
pixt = pixConvertTo32(pixs);
for (i = 0; i < 3; i++) {
if (i == 0)
order = L_TR_SC_RO;
else if (i == 1)
order = L_TR_RO_SC;
else
order = L_SC_TR_RO;
boxat = boxaTransformOrdered(boxa, SHIFTX_2, SHIFTY_2, 1.0, 1.0,
450, 250, ROTATION_2, order);
RenderTransformedBoxa(pixt, boxat, i);
boxaDestroy(&boxat);
}
pixSaveTiled(pixt, pixa, 1, 1, 30, 32);
pixDestroy(&pixt);
pixt = pixConvertTo32(pixs);
for (i = 0; i < 3; i++) {
if (i == 0)
order = L_RO_TR_SC;
else if (i == 1)
order = L_RO_SC_TR;
else
order = L_SC_RO_TR;
boxat = boxaTransformOrdered(boxa, SHIFTX_2, SHIFTY_2, 1.0, 1.0,
450, 250, ROTATION_2, order);
RenderTransformedBoxa(pixt, boxat, i + 4);
boxaDestroy(&boxat);
}
pixSaveTiled(pixt, pixa, 1, 1, 30, 0);
pixDestroy(&pixt);
pixt = pixConvertTo32(pixs);
for (i = 0; i < 3; i++) {
if (i == 0)
order = L_TR_SC_RO;
else if (i == 1)
order = L_SC_RO_TR;
else
order = L_SC_TR_RO;
boxat = boxaTransformOrdered(boxa, 0, 0, SCALEX_2, SCALEY_2,
450, 250, ROTATION_2, order);
RenderTransformedBoxa(pixt, boxat, i + 8);
boxaDestroy(&boxat);
}
pixSaveTiled(pixt, pixa, 1, 1, 30, 0);
pixDestroy(&pixt);
pixt = pixConvertTo32(pixs);
for (i = 0; i < 3; i++) {
if (i == 0)
order = L_RO_TR_SC;
else if (i == 1)
order = L_RO_SC_TR;
else
order = L_TR_RO_SC;
boxat = boxaTransformOrdered(boxa, 0, 0, SCALEX_2, SCALEY_2,
450, 250, ROTATION_2, order);
RenderTransformedBoxa(pixt, boxat, i + 16);
boxaDestroy(&boxat);
}
pixSaveTiled(pixt, pixa, 1, 1, 30, 0);
pixDestroy(&pixt);
pixt = pixaDisplay(pixa, 0, 0);
pixWrite("/tmp/junkxform1.png", pixt, IFF_PNG);
pixDisplay(pixt, 1000, 0);
pixDestroy(&pixt);
pixDestroy(&pixs);
boxaDestroy(&boxa);
pixaDestroy(&pixa);
/* ----------------------------------------------------------- *
* Do more testing of box and pta transforms. Show that *
* resulting boxes are identical by three methods. *
* ----------------------------------------------------------- */
/* Set up pix and boxa */
pixa = pixaCreate(0);
pix = pixRead("lucasta.1.300.tif");
pixTranslate(pix, pix, 70, 0, L_BRING_IN_WHITE);
pixt = pixCloseBrick(NULL, pix, 14, 5);
pixOpenBrick(pixt, pixt, 1, 2);
boxa = pixConnComp(pixt, NULL, 8);
pixs = pixConvertTo32(pix);
pixc = pixCopy(NULL, pixs);
RenderTransformedBoxa(pixc, boxa, 113);
pixSaveTiled(pixc, pixa, 2, 1, 30, 32);
pixDestroy(&pix);
pixDestroy(&pixc);
pixDestroy(&pixt);
/* (a) Do successive discrete operations: shift, scale, rotate */
pixt1 = pixTranslate(NULL, pixs, SHIFTX_3, SHIFTY_3, L_BRING_IN_WHITE);
boxa1 = boxaTranslate(boxa, SHIFTX_3, SHIFTY_3);
pixc = pixCopy(NULL, pixt1);
RenderTransformedBoxa(pixc, boxa1, 213);
pixSaveTiled(pixc, pixa, 2, 0, 30, 32);
pixDestroy(&pixc);
pixt2 = pixScale(pixt1, SCALEX_3, SCALEY_3);
boxa2 = boxaScale(boxa1, SCALEX_3, SCALEY_3);
pixc = pixCopy(NULL, pixt2);
RenderTransformedBoxa(pixc, boxa2, 313);
pixSaveTiled(pixc, pixa, 2, 1, 30, 32);
pixDestroy(&pixc);
pixGetDimensions(pixt2, &w, &h, NULL);
pixt3 = pixRotateAM(pixt2, ROTATION_3, L_BRING_IN_WHITE);
boxa3 = boxaRotate(boxa2, w / 2, h / 2, ROTATION_3);
pixc = pixCopy(NULL, pixt3);
RenderTransformedBoxa(pixc, boxa3, 413);
pixSaveTiled(pixc, pixa, 2, 0, 30, 32);
pixDestroy(&pixc);
/* (b) Set up and use the composite transform */
mat1 = createMatrix2dTranslate(SHIFTX_3, SHIFTY_3);
mat2 = createMatrix2dScale(SCALEX_3, SCALEY_3);
mat3 = createMatrix2dRotate(w / 2, h / 2, ROTATION_3);
l_productMat3(mat3, mat2, mat1, matd, 3);
boxa4 = boxaAffineTransform(boxa, matd);
pixc = pixCopy(NULL, pixt3);
RenderTransformedBoxa(pixc, boxa4, 513);
pixSaveTiled(pixc, pixa, 2, 1, 30, 32);
pixDestroy(&pixc);
/* (c) Use the special 'ordered' function */
pixGetDimensions(pixs, &ws, &hs, NULL);
boxa5 = boxaTransformOrdered(boxa, SHIFTX_3, SHIFTY_3,
SCALEX_3, SCALEY_3,
ws / 2, hs / 2, ROTATION_3, L_TR_SC_RO);
pixc = pixCopy(NULL, pixt3);
RenderTransformedBoxa(pixc, boxa5, 613);
pixSaveTiled(pixc, pixa, 2, 0, 30, 32);
pixDestroy(&pixc);
pixDestroy(&pixt1);
pixDestroy(&pixt2);
pixDestroy(&pixt3);
boxaDestroy(&boxa1);
boxaDestroy(&boxa2);
boxaDestroy(&boxa3);
boxaDestroy(&boxa4);
boxaDestroy(&boxa5);
lept_free(mat1);
lept_free(mat2);
lept_free(mat3);
pixt = pixaDisplay(pixa, 0, 0);
pixWrite("/tmp/junkxform2.png", pixt, IFF_PNG);
pixDisplay(pixt, 1000, 300);
pixDestroy(&pixt);
pixDestroy(&pixs);
boxaDestroy(&boxa);
pixaDestroy(&pixa);
return 0;
}
main(int argc,
char **argv)
{
l_int32 i, w, h, bx, by, bw, bh, index, rval, gval, bval;
BOX *box;
BOXA *boxa;
PIX *pixm, *pixs, *pixg, *pixt, *pixd;
PIXA *pixa;
PIXCMAP *cmap;
PTA *pta;
PTAA *ptaa;
L_REGPARAMS *rp;
if (regTestSetup(argc, argv, &rp))
return 1;
pixa = pixaCreate(0);
/* ---------------- Shortest path in binary maze ---------------- */
/* Generate the maze */
pixm = generateBinaryMaze(200, 200, 20, 20, 0.65, 0.25);
pixd = pixExpandBinaryReplicate(pixm, 3);
pixSaveTiledOutline(pixd, pixa, 1, 1, 20, 2, 32);
pixDestroy(&pixd);
/* Find the shortest path between two points */
pta = pixSearchBinaryMaze(pixm, 20, 20, 170, 170, NULL);
pixt = pixDisplayPta(NULL, pixm, pta);
pixd = pixScaleBySampling(pixt, 3., 3.);
pixSaveTiledOutline(pixd, pixa, 1, 0, 20, 2, 32);
regTestWritePixAndCheck(rp, pixd, IFF_PNG); /* 0 */
ptaDestroy(&pta);
pixDestroy(&pixt);
pixDestroy(&pixd);
pixDestroy(&pixm);
/* ---------------- Shortest path in gray maze ---------------- */
pixg = pixRead("test8.jpg");
pixGetDimensions(pixg, &w, &h, NULL);
ptaa = ptaaCreate(NPATHS);
for (i = 0; i < NPATHS; i++) {
if (x0[i] >= w || x1[i] >= w || y0[i] >= h || y1[i] >= h) {
fprintf(stderr, "path %d extends beyond image; skipping\n", i);
continue;
}
pta = pixSearchGrayMaze(pixg, x0[i], y0[i], x1[i], y1[i], NULL);
ptaaAddPta(ptaa, pta, L_INSERT);
}
pixt = pixDisplayPtaa(pixg, ptaa);
pixd = pixScaleBySampling(pixt, 2., 2.);
pixSaveTiledOutline(pixd, pixa, 1, 1, 20, 2, 32);
regTestWritePixAndCheck(rp, pixd, IFF_PNG); /* 1 */
ptaaDestroy(&ptaa);
pixDestroy(&pixg);
pixDestroy(&pixt);
pixDestroy(&pixd);
/* ---------------- Largest rectangles in image ---------------- */
pixs = pixRead("test1.png");
pixd = pixConvertTo8(pixs, FALSE);
cmap = pixcmapCreateRandom(8, 1, 1);
pixSetColormap(pixd, cmap);
boxa = boxaCreate(0);
for (i = 0; i < NBOXES; i++) {
pixFindLargestRectangle(pixs, POLARITY, &box, NULL);
boxGetGeometry(box, &bx, &by, &bw, &bh);
pixSetInRect(pixs, box);
fprintf(stderr, "bx = %5d, by = %5d, bw = %5d, bh = %5d, area = %d\n",
bx, by, bw, bh, bw * bh);
boxaAddBox(boxa, box, L_INSERT);
}
for (i = 0; i < NBOXES; i++) {
index = 32 + (i & 254);
pixcmapGetColor(cmap, index, &rval, &gval, &bval);
box = boxaGetBox(boxa, i, L_CLONE);
pixRenderHashBoxArb(pixd, box, 6, 2, L_NEG_SLOPE_LINE, 1,
rval, gval, bval);
boxDestroy(&box);
}
pixSaveTiledOutline(pixd, pixa, 1, 1, 20, 2, 32);
regTestWritePixAndCheck(rp, pixd, IFF_PNG); /* 2 */
pixDestroy(&pixs);
pixDestroy(&pixd);
boxaDestroy(&boxa);
pixd = pixaDisplay(pixa, 0, 0);
regTestWritePixAndCheck(rp, pixd, IFF_PNG); /* 3 */
pixDisplayWithTitle(pixd, 100, 100, NULL, rp->display);
pixDestroy(&pixd);
pixaDestroy(&pixa);
return regTestCleanup(rp);
}
