float Textord::filter_noise_blobs(
BLOBNBOX_LIST *src_list, // original list
BLOBNBOX_LIST *noise_list, // noise list
BLOBNBOX_LIST *small_list, // small blobs
BLOBNBOX_LIST *large_list) { // large blobs
int16_t height; //height of blob
int16_t width; //of blob
BLOBNBOX *blob; //current blob
float initial_x; //first guess
BLOBNBOX_IT src_it = src_list; //iterators
BLOBNBOX_IT noise_it = noise_list;
BLOBNBOX_IT small_it = small_list;
BLOBNBOX_IT large_it = large_list;
STATS size_stats (0, MAX_NEAREST_DIST);
//blob heights
float min_y; //size limits
float max_y;
float max_x;
float max_height; //of good blobs
for (src_it.mark_cycle_pt(); !src_it.cycled_list(); src_it.forward()) {
blob = src_it.data();
if (blob->bounding_box().height() < textord_max_noise_size)
noise_it.add_after_then_move(src_it.extract());
else if (blob->enclosed_area() >= blob->bounding_box().height()
* blob->bounding_box().width() * textord_noise_area_ratio)
small_it.add_after_then_move(src_it.extract());
}
for (src_it.mark_cycle_pt(); !src_it.cycled_list(); src_it.forward()) {
size_stats.add(src_it.data()->bounding_box().height(), 1);
}
initial_x = size_stats.ile(textord_initialx_ile);
max_y = ceil(initial_x *
(tesseract::CCStruct::kDescenderFraction +
tesseract::CCStruct::kXHeightFraction +
2 * tesseract::CCStruct::kAscenderFraction) /
tesseract::CCStruct::kXHeightFraction);
min_y = floor (initial_x / 2);
max_x = ceil (initial_x * textord_width_limit);
small_it.move_to_first ();
for (small_it.mark_cycle_pt (); !small_it.cycled_list ();
small_it.forward ()) {
height = small_it.data()->bounding_box().height();
if (height > max_y)
large_it.add_after_then_move(small_it.extract ());
else if (height >= min_y)
src_it.add_after_then_move(small_it.extract ());
}
size_stats.clear ();
for (src_it.mark_cycle_pt (); !src_it.cycled_list (); src_it.forward ()) {
height = src_it.data ()->bounding_box ().height ();
width = src_it.data ()->bounding_box ().width ();
if (height < min_y)
small_it.add_after_then_move (src_it.extract ());
else if (height > max_y || width > max_x)
large_it.add_after_then_move (src_it.extract ());
else
size_stats.add (height, 1);
}
max_height = size_stats.ile (textord_initialasc_ile);
// tprintf("max_y=%g, min_y=%g, initial_x=%g, max_height=%g,",
// max_y,min_y,initial_x,max_height);
max_height *= tesseract::CCStruct::kXHeightCapRatio;
if (max_height > initial_x)
initial_x = max_height;
// tprintf(" ret=%g\n",initial_x);
return initial_x;
}
// Creates and returns a Pix with the same resolution as the original
// in which 1 (black) pixels represent likely non text (photo, line drawing)
// areas of the page, deleting from the blob_block the blobs that were
// determined to be non-text.
// The photo_map is used to bias the decision towards non-text, rather than
// supplying definite decision.
// The blob_block is the usual result of connected component analysis,
// holding the detected blobs.
// The returned Pix should be PixDestroyed after use.
Pix* CCNonTextDetect::ComputeNonTextMask(bool debug, Pix* photo_map,
TO_BLOCK* blob_block) {
// Insert the smallest blobs into the grid.
InsertBlobList(&blob_block->small_blobs);
InsertBlobList(&blob_block->noise_blobs);
// Add the medium blobs that don't have a good strokewidth neighbour.
// Those that do go into good_grid as an antidote to spreading beyond the
// real reaches of a noise region.
BlobGrid good_grid(gridsize(), bleft(), tright());
BLOBNBOX_IT blob_it(&blob_block->blobs);
for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
BLOBNBOX* blob = blob_it.data();
double perimeter_area_ratio = blob->cblob()->perimeter() / 4.0;
perimeter_area_ratio *= perimeter_area_ratio / blob->enclosed_area();
if (blob->GoodTextBlob() == 0 || perimeter_area_ratio < kMinGoodTextPARatio)
InsertBBox(true, true, blob);
else
good_grid.InsertBBox(true, true, blob);
}
noise_density_ = ComputeNoiseDensity(debug, photo_map, &good_grid);
good_grid.Clear(); // Not needed any more.
Pix* pix = noise_density_->ThresholdToPix(max_noise_count_);
if (debug) {
pixWrite("junknoisemask.png", pix, IFF_PNG);
}
ScrollView* win = NULL;
#ifndef GRAPHICS_DISABLED
if (debug) {
win = MakeWindow(0, 400, "Photo Mask Blobs");
}
#endif // GRAPHICS_DISABLED
// Large and medium blobs are not text if they overlap with "a lot" of small
// blobs.
MarkAndDeleteNonTextBlobs(&blob_block->large_blobs,
kMaxLargeOverlapsWithSmall,
win, ScrollView::DARK_GREEN, pix);
MarkAndDeleteNonTextBlobs(&blob_block->blobs, kMaxMediumOverlapsWithSmall,
win, ScrollView::WHITE, pix);
// Clear the grid of small blobs and insert the medium blobs.
Clear();
InsertBlobList(&blob_block->blobs);
MarkAndDeleteNonTextBlobs(&blob_block->large_blobs,
kMaxLargeOverlapsWithMedium,
win, ScrollView::DARK_GREEN, pix);
// Clear again before we start deleting the blobs in the grid.
Clear();
MarkAndDeleteNonTextBlobs(&blob_block->noise_blobs, -1,
win, ScrollView::CORAL, pix);
MarkAndDeleteNonTextBlobs(&blob_block->small_blobs, -1,
win, ScrollView::GOLDENROD, pix);
MarkAndDeleteNonTextBlobs(&blob_block->blobs, -1,
win, ScrollView::WHITE, pix);
if (debug) {
#ifndef GRAPHICS_DISABLED
win->Update();
#endif // GRAPHICS_DISABLED
pixWrite("junkccphotomask.png", pix, IFF_PNG);
#ifndef GRAPHICS_DISABLED
delete win->AwaitEvent(SVET_DESTROY);
delete win;
#endif // GRAPHICS_DISABLED
}
return pix;
}
