/**********************************************************************
* SetBlobStrokeWidth
*
* Set the horizontal and vertical stroke widths in the blob.
**********************************************************************/
void SetBlobStrokeWidth(Pix* pix, BLOBNBOX* blob) {
// Cut the blob rectangle into a Pix.
int pix_height = pixGetHeight(pix);
const TBOX& box = blob->bounding_box();
int width = box.width();
int height = box.height();
Box* blob_pix_box = boxCreate(box.left(), pix_height - box.top(),
width, height);
Pix* pix_blob = pixClipRectangle(pix, blob_pix_box, nullptr);
boxDestroy(&blob_pix_box);
Pix* dist_pix = pixDistanceFunction(pix_blob, 4, 8, L_BOUNDARY_BG);
pixDestroy(&pix_blob);
// Compute the stroke widths.
uint32_t* data = pixGetData(dist_pix);
int wpl = pixGetWpl(dist_pix);
// Horizontal width of stroke.
STATS h_stats(0, width + 1);
for (int y = 0; y < height; ++y) {
uint32_t* pixels = data + y*wpl;
int prev_pixel = 0;
int pixel = GET_DATA_BYTE(pixels, 0);
for (int x = 1; x < width; ++x) {
int next_pixel = GET_DATA_BYTE(pixels, x);
// We are looking for a pixel that is equal to its vertical neighbours,
// yet greater than its left neighbour.
if (prev_pixel < pixel &&
(y == 0 || pixel == GET_DATA_BYTE(pixels - wpl, x - 1)) &&
(y == height - 1 || pixel == GET_DATA_BYTE(pixels + wpl, x - 1))) {
if (pixel > next_pixel) {
// Single local max, so an odd width.
h_stats.add(pixel * 2 - 1, 1);
} else if (pixel == next_pixel && x + 1 < width &&
pixel > GET_DATA_BYTE(pixels, x + 1)) {
// Double local max, so an even width.
h_stats.add(pixel * 2, 1);
}
}
prev_pixel = pixel;
pixel = next_pixel;
}
}
// Vertical width of stroke.
STATS v_stats(0, height + 1);
for (int x = 0; x < width; ++x) {
int prev_pixel = 0;
int pixel = GET_DATA_BYTE(data, x);
for (int y = 1; y < height; ++y) {
uint32_t* pixels = data + y*wpl;
int next_pixel = GET_DATA_BYTE(pixels, x);
// We are looking for a pixel that is equal to its horizontal neighbours,
// yet greater than its upper neighbour.
if (prev_pixel < pixel &&
(x == 0 || pixel == GET_DATA_BYTE(pixels - wpl, x - 1)) &&
(x == width - 1 || pixel == GET_DATA_BYTE(pixels - wpl, x + 1))) {
if (pixel > next_pixel) {
// Single local max, so an odd width.
v_stats.add(pixel * 2 - 1, 1);
} else if (pixel == next_pixel && y + 1 < height &&
pixel > GET_DATA_BYTE(pixels + wpl, x)) {
// Double local max, so an even width.
v_stats.add(pixel * 2, 1);
}
}
prev_pixel = pixel;
pixel = next_pixel;
}
}
pixDestroy(&dist_pix);
// Store the horizontal and vertical width in the blob, keeping both
// widths if there is enough information, otherwse only the one with
// the most samples.
// If there are insufficient samples, store zero, rather than using
// 2*area/perimeter, as the numbers that gives do not match the numbers
// from the distance method.
if (h_stats.get_total() >= (width + height) / 4) {
blob->set_horz_stroke_width(h_stats.ile(0.5f));
if (v_stats.get_total() >= (width + height) / 4)
blob->set_vert_stroke_width(v_stats.ile(0.5f));
else
blob->set_vert_stroke_width(0.0f);
} else {
if (v_stats.get_total() >= (width + height) / 4 ||
v_stats.get_total() > h_stats.get_total()) {
blob->set_horz_stroke_width(0.0f);
blob->set_vert_stroke_width(v_stats.ile(0.5f));
} else {
blob->set_horz_stroke_width(h_stats.get_total() > 2 ? h_stats.ile(0.5f)
: 0.0f);
blob->set_vert_stroke_width(0.0f);
}
}
}
/**********************************************************************
* SetBlobStrokeWidth
*
* Set the horizontal and vertical stroke widths in the blob.
**********************************************************************/
void SetBlobStrokeWidth(bool debug, BLOBNBOX* blob) {
#ifdef HAVE_LIBLEPT
// Cut the blob rectangle into a Pix.
// TODO(rays) make the page_image a Pix so this is more direct.
const TBOX& box = blob->bounding_box();
IMAGE blob_im;
int width = box.width();
int height = box.height();
blob_im.create(width, height, 1);
copy_sub_image(&page_image, box.left(), box.bottom(), width, height,
&blob_im, 0, 0, false);
Pix* pix = blob_im.ToPix();
Pix* dist_pix = pixDistanceFunction(pix, 4, 8, L_BOUNDARY_BG);
if (debug) {
pixWrite("cutpix.png", pix, IFF_PNG);
pixWrite("distpix.png", dist_pix, IFF_PNG);
}
pixDestroy(&pix);
// Compute the stroke widths.
uinT32* data = pixGetData(dist_pix);
int wpl = pixGetWpl(dist_pix);
// Horizontal width of stroke.
STATS h_stats(0, width + 1);
for (int y = 0; y < height; ++y) {
uinT32* pixels = data + y*wpl;
int prev_pixel = 0;
int pixel = GET_DATA_BYTE(pixels, 0);
for (int x = 1; x < width; ++x) {
int next_pixel = GET_DATA_BYTE(pixels, x);
// We are looking for a pixel that is equal to its vertical neighbours,
// yet greater than its left neighbour.
if (prev_pixel < pixel &&
(y == 0 || pixel == GET_DATA_BYTE(pixels - wpl, x - 1)) &&
(y == height - 1 || pixel == GET_DATA_BYTE(pixels + wpl, x - 1))) {
if (pixel > next_pixel) {
// Single local max, so an odd width.
h_stats.add(pixel * 2 - 1, 1);
} else if (pixel == next_pixel && x + 1 < width &&
pixel > GET_DATA_BYTE(pixels, x + 1)) {
// Double local max, so an even width.
h_stats.add(pixel * 2, 1);
}
}
prev_pixel = pixel;
pixel = next_pixel;
}
}
if (debug) {
h_stats.print(stderr, true);
}
// Vertical width of stroke.
STATS v_stats(0, height + 1);
for (int x = 0; x < width; ++x) {
int prev_pixel = 0;
int pixel = GET_DATA_BYTE(data, x);
for (int y = 1; y < height; ++y) {
uinT32* pixels = data + y*wpl;
int next_pixel = GET_DATA_BYTE(pixels, x);
// We are looking for a pixel that is equal to its horizontal neighbours,
// yet greater than its upper neighbour.
if (prev_pixel < pixel &&
(x == 0 || pixel == GET_DATA_BYTE(pixels - wpl, x - 1)) &&
(x == width - 1 || pixel == GET_DATA_BYTE(pixels - wpl, x + 1))) {
if (pixel > next_pixel) {
// Single local max, so an odd width.
v_stats.add(pixel * 2 - 1, 1);
} else if (pixel == next_pixel && y + 1 < height &&
pixel > GET_DATA_BYTE(pixels + wpl, x)) {
// Double local max, so an even width.
v_stats.add(pixel * 2, 1);
}
}
prev_pixel = pixel;
pixel = next_pixel;
}
}
if (debug) {
v_stats.print(stderr, true);
}
pixDestroy(&dist_pix);
// Store the horizontal and vertical width in the blob, keeping both
// widths if there is enough information, otherwse only the one with
// the most samples.
// If there are insufficent samples, store zero, rather than using
// 2*area/perimeter, as the numbers that gives do not match the numbers
// from the distance method.
if (debug) {
tprintf("box=%d,%d->%d,%d, hcount=%d, vcount=%d, target=%d\n",
box.left(), box.bottom(), box.right(), box.top(),
h_stats.get_total(), v_stats.get_total(), (width+height) /4);
tprintf("hstats median=%f, lq=%f, uq=%f, sd=%f\n",
h_stats.median(), h_stats.ile(0.25f), h_stats.ile(0.75f),
h_stats.sd());
tprintf("vstats median=%f, lq=%f, uq=%f, sd=%f\n",
v_stats.median(), v_stats.ile(0.25f), v_stats.ile(0.75f),
v_stats.sd());
}
if (h_stats.get_total() >= (width + height) / 4) {
blob->set_horz_stroke_width(h_stats.ile(0.5f));
if (v_stats.get_total() >= (width + height) / 4)
blob->set_vert_stroke_width(v_stats.ile(0.5f));
else
blob->set_vert_stroke_width(0.0f);
} else {
if (v_stats.get_total() >= (width + height) / 4 ||
v_stats.get_total() > h_stats.get_total()) {
blob->set_horz_stroke_width(0.0f);
blob->set_vert_stroke_width(v_stats.ile(0.5f));
} else {
blob->set_horz_stroke_width(h_stats.get_total() > 2 ? h_stats.ile(0.5f)
: 0.0f);
blob->set_vert_stroke_width(0.0f);
}
}
#else
// Without leptonica present, use the 2*area/perimeter as an approximation.
float width = 2.0f * blob->cblob()->area();
width /= blob->cblob()->perimeter();
blob->set_horz_stroke_width(width);
blob->set_vert_stroke_width(width);
#endif
}
