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git-svn-id: https://tesseract-ocr.googlecode.com/svn/trunk@648 d0cd1f9f-072b-0410-8dd7-cf729c803f20
88 lines
4.1 KiB
C++
88 lines
4.1 KiB
C++
///////////////////////////////////////////////////////////////////////
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// File: ccnontextdetect.h
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// Description: Connected-Component-based non-text detection.
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// Copyright 2011 Google Inc. All Rights Reserved.
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// Author: rays@google.com (Ray Smith)
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// Created: Sat Jun 11 09:52:01 PST 2011
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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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//
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///////////////////////////////////////////////////////////////////////
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#ifndef TESSERACT_TEXTORD_CCPHOTODETECT_H_
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#define TESSERACT_TEXTORD_CCPHOTODETECT_H_
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#include "blobgrid.h"
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#include "scrollview.h"
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namespace tesseract {
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// The CCNonTextDetect class contains grid-based operations on blobs to create
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// a full-resolution image mask analogous yet complementary to
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// pixGenHalftoneMask as it is better at line-drawings, graphs and charts.
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class CCNonTextDetect : public BlobGrid {
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public:
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CCNonTextDetect(int gridsize, const ICOORD& bleft, const ICOORD& tright);
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virtual ~CCNonTextDetect();
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// Creates and returns a Pix with the same resolution as the original
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// in which 1 (black) pixels represent likely non text (photo, line drawing)
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// areas of the page, deleting from the blob_block the blobs that were
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// determined to be non-text.
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// The photo_map (binary image mask) is used to bias the decision towards
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// non-text, rather than supplying a definite decision.
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// The blob_block is the usual result of connected component analysis,
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// holding the detected blobs.
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// The returned Pix should be PixDestroyed after use.
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Pix* ComputeNonTextMask(bool debug, Pix* photo_map, TO_BLOCK* blob_block);
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private:
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// Computes and returns the noise_density IntGrid, at the same gridsize as
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// this by summing the number of small elements in a 3x3 neighbourhood of
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// each grid cell. good_grid is filled with blobs that are considered most
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// likely good text, and this is filled with small and medium blobs that are
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// more likely non-text.
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// The photo_map is used to bias the decision towards non-text, rather than
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// supplying definite decision.
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IntGrid* ComputeNoiseDensity(bool debug, Pix* photo_map, BlobGrid* good_grid);
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// Tests each blob in the list to see if it is certain non-text using 2
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// conditions:
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// 1. blob overlaps a cell with high value in noise_density_ (previously set
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// by ComputeNoiseDensity).
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// OR 2. The blob overlaps more than max_blob_overlaps in *this grid. This
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// condition is disabled with max_blob_overlaps == -1.
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// If it does, the blob is declared non-text, and is used to mark up the
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// nontext_mask. Such blobs are fully deleted, and non-noise blobs have their
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// neighbours reset, as they may now point to deleted data.
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// WARNING: The blobs list blobs may be in the *this grid, but they are
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// not removed. If any deleted blobs might be in *this, then this must be
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// Clear()ed immediately after MarkAndDeleteNonTextBlobs is called.
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// If the win is not NULL, deleted blobs are drawn on it in red, and kept
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void MarkAndDeleteNonTextBlobs(BLOBNBOX_LIST* blobs,
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int max_blob_overlaps,
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ScrollView* win, ScrollView::Color ok_color,
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Pix* nontext_mask);
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// Returns true if the given blob overlaps more than max_overlaps blobs
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// in the current grid.
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bool BlobOverlapsTooMuch(BLOBNBOX* blob, int max_overlaps);
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// Max entry in noise_density_ before the cell is declared noisy.
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int max_noise_count_;
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// Completed noise density map, which we keep around to use for secondary
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// noise detection.
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IntGrid* noise_density_;
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};
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} // namespace tesseract.
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#endif // TESSERACT_TEXTORD_CCPHOTODETECT_H_
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