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776 lines
33 KiB
C++
776 lines
33 KiB
C++
// Copyright 2011 Google Inc. All Rights Reserved.
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// Author: rays@google.com (Ray Smith)
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifdef HAVE_CONFIG_H
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#include "config_auto.h"
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#endif
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#include "textlineprojection.h"
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#include "allheaders.h"
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#include "bbgrid.h" // Base class.
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#include "blobbox.h" // BlobNeighourDir.
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#include "blobs.h"
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#include "colpartition.h"
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#include "normalis.h"
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#include <algorithm>
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// Padding factor to use on definitely oriented blobs
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const int kOrientedPadFactor = 8;
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// Padding factor to use on not definitely oriented blobs.
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const int kDefaultPadFactor = 2;
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// Penalty factor for going away from the line center.
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const int kWrongWayPenalty = 4;
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// Ratio between parallel gap and perpendicular gap used to measure total
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// distance of a box from a target box in curved textline space.
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// parallel-gap is treated more favorably by this factor to allow catching
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// quotes and elipsis at the end of textlines.
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const int kParaPerpDistRatio = 4;
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// Multiple of scale_factor_ that the inter-line gap must be before we start
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// padding the increment box perpendicular to the text line.
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const int kMinLineSpacingFactor = 4;
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// Maximum tab-stop overrun for horizontal padding, in projection pixels.
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const int kMaxTabStopOverrun = 6;
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namespace tesseract {
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TextlineProjection::TextlineProjection(int resolution)
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: x_origin_(0), y_origin_(0), pix_(nullptr) {
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// The projection map should be about 100 ppi, whatever the input.
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scale_factor_ = IntCastRounded(resolution / 100.0);
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if (scale_factor_ < 1) scale_factor_ = 1;
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}
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TextlineProjection::~TextlineProjection() {
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pixDestroy(&pix_);
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}
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// Build the projection profile given the input_block containing lists of
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// blobs, a rotation to convert to image coords,
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// and a full-resolution nontext_map, marking out areas to avoid.
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// During construction, we have the following assumptions:
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// The rotation is a multiple of 90 degrees, ie no deskew yet.
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// The blobs have had their left and right rules set to also limit
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// the range of projection.
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void TextlineProjection::ConstructProjection(TO_BLOCK* input_block,
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const FCOORD& rotation,
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Pix* nontext_map) {
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pixDestroy(&pix_);
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TBOX image_box(0, 0, pixGetWidth(nontext_map), pixGetHeight(nontext_map));
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x_origin_ = 0;
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y_origin_ = image_box.height();
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int width = (image_box.width() + scale_factor_ - 1) / scale_factor_;
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int height = (image_box.height() + scale_factor_ - 1) / scale_factor_;
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pix_ = pixCreate(width, height, 8);
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ProjectBlobs(&input_block->blobs, rotation, image_box, nontext_map);
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ProjectBlobs(&input_block->large_blobs, rotation, image_box, nontext_map);
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Pix* final_pix = pixBlockconv(pix_, 1, 1);
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// Pix* final_pix = pixBlockconv(pix_, 2, 2);
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pixDestroy(&pix_);
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pix_ = final_pix;
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}
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// Display the blobs in the window colored according to textline quality.
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void TextlineProjection::PlotGradedBlobs(BLOBNBOX_LIST* blobs,
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ScrollView* win) {
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#ifndef GRAPHICS_DISABLED
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BLOBNBOX_IT it(blobs);
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for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
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BLOBNBOX* blob = it.data();
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const TBOX& box = blob->bounding_box();
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bool bad_box = BoxOutOfHTextline(box, nullptr, false);
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if (blob->UniquelyVertical())
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win->Pen(ScrollView::YELLOW);
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else
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win->Pen(bad_box ? ScrollView::RED : ScrollView::BLUE);
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win->Rectangle(box.left(), box.bottom(), box.right(), box.top());
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}
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win->Update();
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#endif // GRAPHICS_DISABLED
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}
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// Moves blobs that look like they don't sit well on a textline from the
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// input blobs list to the output small_blobs list.
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// This gets them away from initial textline finding to stop diacritics
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// from forming incorrect textlines. (Introduced mainly to fix Thai.)
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void TextlineProjection::MoveNonTextlineBlobs(
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BLOBNBOX_LIST* blobs, BLOBNBOX_LIST* small_blobs) const {
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BLOBNBOX_IT it(blobs);
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BLOBNBOX_IT small_it(small_blobs);
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for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
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BLOBNBOX* blob = it.data();
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const TBOX& box = blob->bounding_box();
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bool debug = AlignedBlob::WithinTestRegion(2, box.left(),
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box.bottom());
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if (BoxOutOfHTextline(box, nullptr, debug) && !blob->UniquelyVertical()) {
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blob->ClearNeighbours();
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small_it.add_to_end(it.extract());
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}
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}
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}
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// Create a window and display the projection in it.
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void TextlineProjection::DisplayProjection() const {
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#ifndef GRAPHICS_DISABLED
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int width = pixGetWidth(pix_);
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int height = pixGetHeight(pix_);
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Pix* pixc = pixCreate(width, height, 32);
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int src_wpl = pixGetWpl(pix_);
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int col_wpl = pixGetWpl(pixc);
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uint32_t* src_data = pixGetData(pix_);
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uint32_t* col_data = pixGetData(pixc);
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for (int y = 0; y < height; ++y, src_data += src_wpl, col_data += col_wpl) {
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for (int x = 0; x < width; ++x) {
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int pixel = GET_DATA_BYTE(src_data, x);
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l_uint32 result;
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if (pixel <= 17)
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composeRGBPixel(0, 0, pixel * 15, &result);
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else if (pixel <= 145)
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composeRGBPixel(0, (pixel - 17) * 2, 255, &result);
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else
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composeRGBPixel((pixel - 145) * 2, 255, 255, &result);
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col_data[x] = result;
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}
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}
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auto* win = new ScrollView("Projection", 0, 0,
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width, height, width, height);
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win->Image(pixc, 0, 0);
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win->Update();
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pixDestroy(&pixc);
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#endif // GRAPHICS_DISABLED
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}
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// Compute the distance of the box from the partition using curved projection
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// space. As DistanceOfBoxFromBox, except that the direction is taken from
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// the ColPartition and the median bounds of the ColPartition are used as
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// the to_box.
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int TextlineProjection::DistanceOfBoxFromPartition(const TBOX& box,
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const ColPartition& part,
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const DENORM* denorm,
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bool debug) const {
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// Compute a partition box that uses the median top/bottom of the blobs
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// within and median left/right for vertical.
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TBOX part_box = part.bounding_box();
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if (part.IsHorizontalType()) {
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part_box.set_top(part.median_top());
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part_box.set_bottom(part.median_bottom());
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} else {
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part_box.set_left(part.median_left());
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part_box.set_right(part.median_right());
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}
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// Now use DistanceOfBoxFromBox to make the actual calculation.
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return DistanceOfBoxFromBox(box, part_box, part.IsHorizontalType(),
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denorm, debug);
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}
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// Compute the distance from the from_box to the to_box using curved
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// projection space. Separation that involves a decrease in projection
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// density (moving from the from_box to the to_box) is weighted more heavily
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// than constant density, and an increase is weighted less.
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// If horizontal_textline is true, then curved space is used vertically,
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// as for a diacritic on the edge of a textline.
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// The projection uses original image coords, so denorm is used to get
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// back to the image coords from box/part space.
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// How the calculation works: Think of a diacritic near a textline.
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// Distance is measured from the far side of the from_box to the near side of
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// the to_box. Shown is the horizontal textline case.
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// |------^-----|
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// | from | box |
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// |------|-----|
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// perpendicular |
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// <------v-------->|--------------------|
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// parallel | to box |
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// |--------------------|
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// Perpendicular distance uses "curved space" See VerticalDistance below.
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// Parallel distance is linear.
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// Result is perpendicular_gap + parallel_gap / kParaPerpDistRatio.
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int TextlineProjection::DistanceOfBoxFromBox(const TBOX& from_box,
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const TBOX& to_box,
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bool horizontal_textline,
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const DENORM* denorm,
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bool debug) const {
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// The parallel_gap is the horizontal gap between a horizontal textline and
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// the box. Analogous for vertical.
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int parallel_gap = 0;
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// start_pt is the box end of the line to be modified for curved space.
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TPOINT start_pt;
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// end_pt is the partition end of the line to be modified for curved space.
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TPOINT end_pt;
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if (horizontal_textline) {
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parallel_gap = from_box.x_gap(to_box) + from_box.width();
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start_pt.x = (from_box.left() + from_box.right()) / 2;
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end_pt.x = start_pt.x;
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if (from_box.top() - to_box.top() >= to_box.bottom() - from_box.bottom()) {
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start_pt.y = from_box.top();
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end_pt.y = std::min(to_box.top(), start_pt.y);
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} else {
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start_pt.y = from_box.bottom();
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end_pt.y = std::max(to_box.bottom(), start_pt.y);
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}
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} else {
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parallel_gap = from_box.y_gap(to_box) + from_box.height();
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if (from_box.right() - to_box.right() >= to_box.left() - from_box.left()) {
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start_pt.x = from_box.right();
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end_pt.x = std::min(to_box.right(), start_pt.x);
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} else {
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start_pt.x = from_box.left();
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end_pt.x = std::max(to_box.left(), start_pt.x);
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}
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start_pt.y = (from_box.bottom() + from_box.top()) / 2;
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end_pt.y = start_pt.y;
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}
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// The perpendicular gap is the max vertical distance gap out of:
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// top of from_box to to_box top and bottom of from_box to to_box bottom.
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// This value is then modified for curved projection space.
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// Analogous for vertical.
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int perpendicular_gap = 0;
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// If start_pt == end_pt, then the from_box lies entirely within the to_box
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// (in the perpendicular direction), so we don't need to calculate the
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// perpendicular_gap.
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if (start_pt.x != end_pt.x || start_pt.y != end_pt.y) {
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if (denorm != nullptr) {
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// Denormalize the start and end.
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denorm->DenormTransform(nullptr, start_pt, &start_pt);
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denorm->DenormTransform(nullptr, end_pt, &end_pt);
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}
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if (abs(start_pt.y - end_pt.y) >= abs(start_pt.x - end_pt.x)) {
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perpendicular_gap = VerticalDistance(debug, start_pt.x, start_pt.y,
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end_pt.y);
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} else {
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perpendicular_gap = HorizontalDistance(debug, start_pt.x, end_pt.x,
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start_pt.y);
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}
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}
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// The parallel_gap weighs less than the perpendicular_gap.
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return perpendicular_gap + parallel_gap / kParaPerpDistRatio;
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}
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// Compute the distance between (x, y1) and (x, y2) using the rule that
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// a decrease in textline density is weighted more heavily than an increase.
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// The coordinates are in source image space, ie processed by any denorm
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// already, but not yet scaled by scale_factor_.
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// Going from the outside of a textline to the inside should measure much
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// less distance than going from the inside of a textline to the outside.
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// How it works:
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// An increase is cheap (getting closer to a textline).
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// Constant costs unity.
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// A decrease is expensive (getting further from a textline).
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// Pixels in projection map Counted distance
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// 2
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// 3 1/x
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// 3 1
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// 2 x
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// 5 1/x
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// 7 1/x
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// Total: 1 + x + 3/x where x = kWrongWayPenalty.
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int TextlineProjection::VerticalDistance(bool debug, int x,
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int y1, int y2) const {
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x = ImageXToProjectionX(x);
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y1 = ImageYToProjectionY(y1);
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y2 = ImageYToProjectionY(y2);
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if (y1 == y2) return 0;
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int wpl = pixGetWpl(pix_);
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int step = y1 < y2 ? 1 : -1;
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uint32_t* data = pixGetData(pix_) + y1 * wpl;
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wpl *= step;
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int prev_pixel = GET_DATA_BYTE(data, x);
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int distance = 0;
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int right_way_steps = 0;
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for (int y = y1; y != y2; y += step) {
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data += wpl;
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int pixel = GET_DATA_BYTE(data, x);
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if (debug)
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tprintf("At (%d,%d), pix = %d, prev=%d\n",
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x, y + step, pixel, prev_pixel);
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if (pixel < prev_pixel)
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distance += kWrongWayPenalty;
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else if (pixel > prev_pixel)
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++right_way_steps;
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else
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++distance;
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prev_pixel = pixel;
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}
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return distance * scale_factor_ +
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right_way_steps * scale_factor_ / kWrongWayPenalty;
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}
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// Compute the distance between (x1, y) and (x2, y) using the rule that
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// a decrease in textline density is weighted more heavily than an increase.
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int TextlineProjection::HorizontalDistance(bool debug, int x1, int x2,
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int y) const {
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x1 = ImageXToProjectionX(x1);
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x2 = ImageXToProjectionX(x2);
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y = ImageYToProjectionY(y);
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if (x1 == x2) return 0;
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int wpl = pixGetWpl(pix_);
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int step = x1 < x2 ? 1 : -1;
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uint32_t* data = pixGetData(pix_) + y * wpl;
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int prev_pixel = GET_DATA_BYTE(data, x1);
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int distance = 0;
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int right_way_steps = 0;
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for (int x = x1; x != x2; x += step) {
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int pixel = GET_DATA_BYTE(data, x + step);
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if (debug)
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tprintf("At (%d,%d), pix = %d, prev=%d\n",
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x + step, y, pixel, prev_pixel);
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if (pixel < prev_pixel)
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distance += kWrongWayPenalty;
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else if (pixel > prev_pixel)
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++right_way_steps;
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else
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++distance;
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prev_pixel = pixel;
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}
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return distance * scale_factor_ +
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right_way_steps * scale_factor_ / kWrongWayPenalty;
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}
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// Returns true if the blob appears to be outside of a textline.
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// Such blobs are potentially diacritics (even if large in Thai) and should
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// be kept away from initial textline finding.
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bool TextlineProjection::BoxOutOfHTextline(const TBOX& box,
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const DENORM* denorm,
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bool debug) const {
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int grad1 = 0;
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int grad2 = 0;
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EvaluateBoxInternal(box, denorm, debug, &grad1, &grad2, nullptr, nullptr);
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int worst_result = std::min(grad1, grad2);
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int total_result = grad1 + grad2;
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if (total_result >= 6) return false; // Strongly in textline.
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// Medium strength: if either gradient is negative, it is likely outside
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// the body of the textline.
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if (worst_result < 0)
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return true;
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return false;
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}
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// Evaluates the textlineiness of a ColPartition. Uses EvaluateBox below,
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// but uses the median top/bottom for horizontal and median left/right for
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// vertical instead of the bounding box edges.
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// Evaluates for both horizontal and vertical and returns the best result,
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// with a positive value for horizontal and a negative value for vertical.
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int TextlineProjection::EvaluateColPartition(const ColPartition& part,
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const DENORM* denorm,
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bool debug) const {
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if (part.IsSingleton())
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return EvaluateBox(part.bounding_box(), denorm, debug);
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// Test vertical orientation.
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TBOX box = part.bounding_box();
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// Use the partition median for left/right.
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box.set_left(part.median_left());
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box.set_right(part.median_right());
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int vresult = EvaluateBox(box, denorm, debug);
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// Test horizontal orientation.
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box = part.bounding_box();
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// Use the partition median for top/bottom.
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box.set_top(part.median_top());
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box.set_bottom(part.median_bottom());
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int hresult = EvaluateBox(box, denorm, debug);
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if (debug) {
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tprintf("Partition hresult=%d, vresult=%d from:", hresult, vresult);
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part.bounding_box().print();
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part.Print();
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}
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return hresult >= -vresult ? hresult : vresult;
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}
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// Computes the mean projection gradients over the horizontal and vertical
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// edges of the box:
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// -h-h-h-h-h-h
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// |------------| mean=htop -v|+v--------+v|-v
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// |+h+h+h+h+h+h| -v|+v +v|-v
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// | | -v|+v +v|-v
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// | box | -v|+v box +v|-v
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// | | -v|+v +v|-v
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// |+h+h+h+h+h+h| -v|+v +v|-v
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// |------------| mean=hbot -v|+v--------+v|-v
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// -h-h-h-h-h-h
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// mean=vleft mean=vright
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//
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// Returns MAX(htop,hbot) - MAX(vleft,vright), which is a positive number
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// for a horizontal textline, a negative number for a vertical textline,
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// and near zero for undecided. Undecided is most likely non-text.
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// All the gradients are truncated to remain non-negative, since negative
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// horizontal gradients don't give any indication of being vertical and
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// vice versa.
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// Additional complexity: The coordinates have to be transformed to original
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// image coordinates with denorm (if not null), scaled to match the projection
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// pix, and THEN step out 2 pixels each way from the edge to compute the
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// gradient, and tries 3 positions, each measuring the gradient over a
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// 4-pixel spread: (+3/-1), (+2/-2), (+1/-3). This complexity is handled by
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// several layers of helpers below.
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int TextlineProjection::EvaluateBox(const TBOX& box, const DENORM* denorm,
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bool debug) const {
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return EvaluateBoxInternal(box, denorm, debug, nullptr, nullptr, nullptr, nullptr);
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}
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// Internal version of EvaluateBox returns the unclipped gradients as well
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// as the result of EvaluateBox.
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// hgrad1 and hgrad2 are the gradients for the horizontal textline.
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int TextlineProjection::EvaluateBoxInternal(const TBOX& box,
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const DENORM* denorm, bool debug,
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int* hgrad1, int* hgrad2,
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int* vgrad1, int* vgrad2) const {
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int top_gradient = BestMeanGradientInRow(denorm, box.left(), box.right(),
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box.top(), true);
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int bottom_gradient = -BestMeanGradientInRow(denorm, box.left(), box.right(),
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box.bottom(), false);
|
|
int left_gradient = BestMeanGradientInColumn(denorm, box.left(), box.bottom(),
|
|
box.top(), true);
|
|
int right_gradient = -BestMeanGradientInColumn(denorm, box.right(),
|
|
box.bottom(), box.top(),
|
|
false);
|
|
int top_clipped = std::max(top_gradient, 0);
|
|
int bottom_clipped = std::max(bottom_gradient, 0);
|
|
int left_clipped = std::max(left_gradient, 0);
|
|
int right_clipped = std::max(right_gradient, 0);
|
|
if (debug) {
|
|
tprintf("Gradients: top = %d, bottom = %d, left= %d, right= %d for box:",
|
|
top_gradient, bottom_gradient, left_gradient, right_gradient);
|
|
box.print();
|
|
}
|
|
int result = std::max(top_clipped, bottom_clipped) -
|
|
std::max(left_clipped, right_clipped);
|
|
if (hgrad1 != nullptr && hgrad2 != nullptr) {
|
|
*hgrad1 = top_gradient;
|
|
*hgrad2 = bottom_gradient;
|
|
}
|
|
if (vgrad1 != nullptr && vgrad2 != nullptr) {
|
|
*vgrad1 = left_gradient;
|
|
*vgrad2 = right_gradient;
|
|
}
|
|
return result;
|
|
}
|
|
|
|
// Helper returns the mean gradient value for the horizontal row at the given
|
|
// y, (in the external coordinates) by subtracting the mean of the transformed
|
|
// row 2 pixels above from the mean of the transformed row 2 pixels below.
|
|
// This gives a positive value for a good top edge and negative for bottom.
|
|
// Returns the best result out of +2/-2, +3/-1, +1/-3 pixels from the edge.
|
|
int TextlineProjection::BestMeanGradientInRow(const DENORM* denorm,
|
|
int16_t min_x, int16_t max_x, int16_t y,
|
|
bool best_is_max) const {
|
|
TPOINT start_pt(min_x, y);
|
|
TPOINT end_pt(max_x, y);
|
|
int upper = MeanPixelsInLineSegment(denorm, -2, start_pt, end_pt);
|
|
int lower = MeanPixelsInLineSegment(denorm, 2, start_pt, end_pt);
|
|
int best_gradient = lower - upper;
|
|
upper = MeanPixelsInLineSegment(denorm, -1, start_pt, end_pt);
|
|
lower = MeanPixelsInLineSegment(denorm, 3, start_pt, end_pt);
|
|
int gradient = lower - upper;
|
|
if ((gradient > best_gradient) == best_is_max)
|
|
best_gradient = gradient;
|
|
upper = MeanPixelsInLineSegment(denorm, -3, start_pt, end_pt);
|
|
lower = MeanPixelsInLineSegment(denorm, 1, start_pt, end_pt);
|
|
gradient = lower - upper;
|
|
if ((gradient > best_gradient) == best_is_max)
|
|
best_gradient = gradient;
|
|
return best_gradient;
|
|
}
|
|
|
|
// Helper returns the mean gradient value for the vertical column at the
|
|
// given x, (in the external coordinates) by subtracting the mean of the
|
|
// transformed column 2 pixels left from the mean of the transformed column
|
|
// 2 pixels to the right.
|
|
// This gives a positive value for a good left edge and negative for right.
|
|
// Returns the best result out of +2/-2, +3/-1, +1/-3 pixels from the edge.
|
|
int TextlineProjection::BestMeanGradientInColumn(const DENORM* denorm, int16_t x,
|
|
int16_t min_y, int16_t max_y,
|
|
bool best_is_max) const {
|
|
TPOINT start_pt(x, min_y);
|
|
TPOINT end_pt(x, max_y);
|
|
int left = MeanPixelsInLineSegment(denorm, -2, start_pt, end_pt);
|
|
int right = MeanPixelsInLineSegment(denorm, 2, start_pt, end_pt);
|
|
int best_gradient = right - left;
|
|
left = MeanPixelsInLineSegment(denorm, -1, start_pt, end_pt);
|
|
right = MeanPixelsInLineSegment(denorm, 3, start_pt, end_pt);
|
|
int gradient = right - left;
|
|
if ((gradient > best_gradient) == best_is_max)
|
|
best_gradient = gradient;
|
|
left = MeanPixelsInLineSegment(denorm, -3, start_pt, end_pt);
|
|
right = MeanPixelsInLineSegment(denorm, 1, start_pt, end_pt);
|
|
gradient = right - left;
|
|
if ((gradient > best_gradient) == best_is_max)
|
|
best_gradient = gradient;
|
|
return best_gradient;
|
|
}
|
|
|
|
// Helper returns the mean pixel value over the line between the start_pt and
|
|
// end_pt (inclusive), but shifted perpendicular to the line in the projection
|
|
// image by offset pixels. For simplicity, it is assumed that the vector is
|
|
// either nearly horizontal or nearly vertical. It works on skewed textlines!
|
|
// The end points are in external coordinates, and will be denormalized with
|
|
// the denorm if not nullptr before further conversion to pix coordinates.
|
|
// After all the conversions, the offset is added to the direction
|
|
// perpendicular to the line direction. The offset is thus in projection image
|
|
// coordinates, which allows the caller to get a guaranteed displacement
|
|
// between pixels used to calculate gradients.
|
|
int TextlineProjection::MeanPixelsInLineSegment(const DENORM* denorm,
|
|
int offset,
|
|
TPOINT start_pt,
|
|
TPOINT end_pt) const {
|
|
TransformToPixCoords(denorm, &start_pt);
|
|
TransformToPixCoords(denorm, &end_pt);
|
|
TruncateToImageBounds(&start_pt);
|
|
TruncateToImageBounds(&end_pt);
|
|
int wpl = pixGetWpl(pix_);
|
|
uint32_t* data = pixGetData(pix_);
|
|
int total = 0;
|
|
int count = 0;
|
|
int x_delta = end_pt.x - start_pt.x;
|
|
int y_delta = end_pt.y - start_pt.y;
|
|
if (abs(x_delta) >= abs(y_delta)) {
|
|
if (x_delta == 0)
|
|
return 0;
|
|
// Horizontal line. Add the offset vertically.
|
|
int x_step = x_delta > 0 ? 1 : -1;
|
|
// Correct offset for rotation, keeping it anti-clockwise of the delta.
|
|
offset *= x_step;
|
|
start_pt.y += offset;
|
|
end_pt.y += offset;
|
|
TruncateToImageBounds(&start_pt);
|
|
TruncateToImageBounds(&end_pt);
|
|
x_delta = end_pt.x - start_pt.x;
|
|
y_delta = end_pt.y - start_pt.y;
|
|
count = x_delta * x_step + 1;
|
|
for (int x = start_pt.x; x != end_pt.x; x += x_step) {
|
|
int y = start_pt.y + DivRounded(y_delta * (x - start_pt.x), x_delta);
|
|
total += GET_DATA_BYTE(data + wpl * y, x);
|
|
}
|
|
} else {
|
|
// Vertical line. Add the offset horizontally.
|
|
int y_step = y_delta > 0 ? 1 : -1;
|
|
// Correct offset for rotation, keeping it anti-clockwise of the delta.
|
|
// Pix holds the image with y=0 at the top, so the offset is negated.
|
|
offset *= -y_step;
|
|
start_pt.x += offset;
|
|
end_pt.x += offset;
|
|
TruncateToImageBounds(&start_pt);
|
|
TruncateToImageBounds(&end_pt);
|
|
x_delta = end_pt.x - start_pt.x;
|
|
y_delta = end_pt.y - start_pt.y;
|
|
count = y_delta * y_step + 1;
|
|
for (int y = start_pt.y; y != end_pt.y; y += y_step) {
|
|
int x = start_pt.x + DivRounded(x_delta * (y - start_pt.y), y_delta);
|
|
total += GET_DATA_BYTE(data + wpl * y, x);
|
|
}
|
|
}
|
|
return DivRounded(total, count);
|
|
}
|
|
|
|
// Given an input pix, and a box, the sides of the box are shrunk inwards until
|
|
// they bound any black pixels found within the original box.
|
|
// The function converts between tesseract coords and the pix coords assuming
|
|
// that this pix is full resolution equal in size to the original image.
|
|
// Returns an empty box if there are no black pixels in the source box.
|
|
static TBOX BoundsWithinBox(Pix* pix, const TBOX& box) {
|
|
int im_height = pixGetHeight(pix);
|
|
Box* input_box = boxCreate(box.left(), im_height - box.top(),
|
|
box.width(), box.height());
|
|
Box* output_box = nullptr;
|
|
pixClipBoxToForeground(pix, input_box, nullptr, &output_box);
|
|
TBOX result_box;
|
|
if (output_box != nullptr) {
|
|
l_int32 x, y, width, height;
|
|
boxGetGeometry(output_box, &x, &y, &width, &height);
|
|
result_box.set_left(x);
|
|
result_box.set_right(x + width);
|
|
result_box.set_top(im_height - y);
|
|
result_box.set_bottom(result_box.top() - height);
|
|
boxDestroy(&output_box);
|
|
}
|
|
boxDestroy(&input_box);
|
|
return result_box;
|
|
}
|
|
|
|
// Splits the given box in half at x_middle or y_middle according to split_on_x
|
|
// and checks for nontext_map pixels in each half. Reduces the bbox so that it
|
|
// still includes the middle point, but does not touch any fg pixels in
|
|
// nontext_map. An empty box may be returned if there is no such box.
|
|
static void TruncateBoxToMissNonText(int x_middle, int y_middle,
|
|
bool split_on_x, Pix* nontext_map,
|
|
TBOX* bbox) {
|
|
TBOX box1(*bbox);
|
|
TBOX box2(*bbox);
|
|
TBOX im_box;
|
|
if (split_on_x) {
|
|
box1.set_right(x_middle);
|
|
im_box = BoundsWithinBox(nontext_map, box1);
|
|
if (!im_box.null_box()) box1.set_left(im_box.right());
|
|
box2.set_left(x_middle);
|
|
im_box = BoundsWithinBox(nontext_map, box2);
|
|
if (!im_box.null_box()) box2.set_right(im_box.left());
|
|
} else {
|
|
box1.set_bottom(y_middle);
|
|
im_box = BoundsWithinBox(nontext_map, box1);
|
|
if (!im_box.null_box()) box1.set_top(im_box.bottom());
|
|
box2.set_top(y_middle);
|
|
im_box = BoundsWithinBox(nontext_map, box2);
|
|
if (!im_box.null_box()) box2.set_bottom(im_box.top());
|
|
}
|
|
box1 += box2;
|
|
*bbox = box1;
|
|
}
|
|
|
|
|
|
// Helper function to add 1 to a rectangle in source image coords to the
|
|
// internal projection pix_.
|
|
void TextlineProjection::IncrementRectangle8Bit(const TBOX& box) {
|
|
int scaled_left = ImageXToProjectionX(box.left());
|
|
int scaled_top = ImageYToProjectionY(box.top());
|
|
int scaled_right = ImageXToProjectionX(box.right());
|
|
int scaled_bottom = ImageYToProjectionY(box.bottom());
|
|
int wpl = pixGetWpl(pix_);
|
|
uint32_t* data = pixGetData(pix_) + scaled_top * wpl;
|
|
for (int y = scaled_top; y <= scaled_bottom; ++y) {
|
|
for (int x = scaled_left; x <= scaled_right; ++x) {
|
|
int pixel = GET_DATA_BYTE(data, x);
|
|
if (pixel < 255)
|
|
SET_DATA_BYTE(data, x, pixel + 1);
|
|
}
|
|
data += wpl;
|
|
}
|
|
}
|
|
|
|
// Inserts a list of blobs into the projection.
|
|
// Rotation is a multiple of 90 degrees to get from blob coords to
|
|
// nontext_map coords, nontext_map_box is the bounds of the nontext_map.
|
|
// Blobs are spread horizontally or vertically according to their internal
|
|
// flags, but the spreading is truncated by set pixels in the nontext_map
|
|
// and also by the horizontal rule line limits on the blobs.
|
|
void TextlineProjection::ProjectBlobs(BLOBNBOX_LIST* blobs,
|
|
const FCOORD& rotation,
|
|
const TBOX& nontext_map_box,
|
|
Pix* nontext_map) {
|
|
BLOBNBOX_IT blob_it(blobs);
|
|
for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
|
|
BLOBNBOX* blob = blob_it.data();
|
|
TBOX bbox = blob->bounding_box();
|
|
ICOORD middle((bbox.left() + bbox.right()) / 2,
|
|
(bbox.bottom() + bbox.top()) / 2);
|
|
bool spreading_horizontally = PadBlobBox(blob, &bbox);
|
|
// Rotate to match the nontext_map.
|
|
bbox.rotate(rotation);
|
|
middle.rotate(rotation);
|
|
if (rotation.x() == 0.0f)
|
|
spreading_horizontally = !spreading_horizontally;
|
|
// Clip to the image before applying the increments.
|
|
bbox &= nontext_map_box; // This is in-place box intersection.
|
|
// Check for image pixels before spreading.
|
|
TruncateBoxToMissNonText(middle.x(), middle.y(), spreading_horizontally,
|
|
nontext_map, &bbox);
|
|
if (bbox.area() > 0) {
|
|
IncrementRectangle8Bit(bbox);
|
|
}
|
|
}
|
|
}
|
|
|
|
// Pads the bounding box of the given blob according to whether it is on
|
|
// a horizontal or vertical text line, taking into account tab-stops near
|
|
// the blob. Returns true if padding was in the horizontal direction.
|
|
bool TextlineProjection::PadBlobBox(BLOBNBOX* blob, TBOX* bbox) {
|
|
// Determine which direction to spread.
|
|
// If text is well spaced out, it can be useful to pad perpendicular to
|
|
// the textline direction, so as to ensure diacritics get absorbed
|
|
// correctly, but if the text is tightly spaced, this will destroy the
|
|
// blank space between textlines in the projection map, and that would
|
|
// be very bad.
|
|
int pad_limit = scale_factor_ * kMinLineSpacingFactor;
|
|
int xpad = 0;
|
|
int ypad = 0;
|
|
bool padding_horizontally = false;
|
|
if (blob->UniquelyHorizontal()) {
|
|
xpad = bbox->height() * kOrientedPadFactor;
|
|
padding_horizontally = true;
|
|
// If the text appears to be very well spaced, pad the other direction by a
|
|
// single pixel in the projection profile space to help join diacritics to
|
|
// the textline.
|
|
if ((blob->neighbour(BND_ABOVE) == nullptr ||
|
|
bbox->y_gap(blob->neighbour(BND_ABOVE)->bounding_box()) > pad_limit) &&
|
|
(blob->neighbour(BND_BELOW) == nullptr ||
|
|
bbox->y_gap(blob->neighbour(BND_BELOW)->bounding_box()) > pad_limit)) {
|
|
ypad = scale_factor_;
|
|
}
|
|
} else if (blob->UniquelyVertical()) {
|
|
ypad = bbox->width() * kOrientedPadFactor;
|
|
if ((blob->neighbour(BND_LEFT) == nullptr ||
|
|
bbox->x_gap(blob->neighbour(BND_LEFT)->bounding_box()) > pad_limit) &&
|
|
(blob->neighbour(BND_RIGHT) == nullptr ||
|
|
bbox->x_gap(blob->neighbour(BND_RIGHT)->bounding_box()) > pad_limit)) {
|
|
xpad = scale_factor_;
|
|
}
|
|
} else {
|
|
if ((blob->neighbour(BND_ABOVE) != nullptr &&
|
|
blob->neighbour(BND_ABOVE)->neighbour(BND_BELOW) == blob) ||
|
|
(blob->neighbour(BND_BELOW) != nullptr &&
|
|
blob->neighbour(BND_BELOW)->neighbour(BND_ABOVE) == blob)) {
|
|
ypad = bbox->width() * kDefaultPadFactor;
|
|
}
|
|
if ((blob->neighbour(BND_RIGHT) != nullptr &&
|
|
blob->neighbour(BND_RIGHT)->neighbour(BND_LEFT) == blob) ||
|
|
(blob->neighbour(BND_LEFT) != nullptr &&
|
|
blob->neighbour(BND_LEFT)->neighbour(BND_RIGHT) == blob)) {
|
|
xpad = bbox->height() * kDefaultPadFactor;
|
|
padding_horizontally = true;
|
|
}
|
|
}
|
|
bbox->pad(xpad, ypad);
|
|
pad_limit = scale_factor_ * kMaxTabStopOverrun;
|
|
// Now shrink horizontally to avoid stepping more than pad_limit over a
|
|
// tab-stop.
|
|
if (bbox->left() < blob->left_rule() - pad_limit) {
|
|
bbox->set_left(blob->left_rule() - pad_limit);
|
|
}
|
|
if (bbox->right() > blob->right_rule() + pad_limit) {
|
|
bbox->set_right(blob->right_rule() + pad_limit);
|
|
}
|
|
return padding_horizontally;
|
|
}
|
|
|
|
// Helper denormalizes the TPOINT with the denorm if not nullptr, then
|
|
// converts to pix_ coordinates.
|
|
void TextlineProjection::TransformToPixCoords(const DENORM* denorm,
|
|
TPOINT* pt) const {
|
|
if (denorm != nullptr) {
|
|
// Denormalize the point.
|
|
denorm->DenormTransform(nullptr, *pt, pt);
|
|
}
|
|
pt->x = ImageXToProjectionX(pt->x);
|
|
pt->y = ImageYToProjectionY(pt->y);
|
|
}
|
|
|
|
#if defined(_MSC_VER) && !defined(__clang__)
|
|
#pragma optimize("g", off)
|
|
#endif // _MSC_VER
|
|
// Helper truncates the TPOINT to be within the pix_.
|
|
void TextlineProjection::TruncateToImageBounds(TPOINT* pt) const {
|
|
pt->x = ClipToRange<int>(pt->x, 0, pixGetWidth(pix_) - 1);
|
|
pt->y = ClipToRange<int>(pt->y, 0, pixGetHeight(pix_) - 1);
|
|
}
|
|
#if defined(_MSC_VER) && !defined(__clang__)
|
|
#pragma optimize("", on)
|
|
#endif // _MSC_VER
|
|
|
|
// Transform tesseract image coordinates to coordinates used in the projection.
|
|
int TextlineProjection::ImageXToProjectionX(int x) const {
|
|
x = ClipToRange((x - x_origin_) / scale_factor_, 0, pixGetWidth(pix_) - 1);
|
|
return x;
|
|
}
|
|
int TextlineProjection::ImageYToProjectionY(int y) const {
|
|
y = ClipToRange((y_origin_ - y) / scale_factor_, 0, pixGetHeight(pix_) - 1);
|
|
return y;
|
|
}
|
|
|
|
} // namespace tesseract.
|