mirror of
https://github.com/tesseract-ocr/tesseract.git
synced 2024-11-24 19:19:05 +08:00
903a4ffe9d
git-svn-id: https://tesseract-ocr.googlecode.com/svn/trunk@289 d0cd1f9f-072b-0410-8dd7-cf729c803f20
59 lines
2.6 KiB
C++
59 lines
2.6 KiB
C++
///////////////////////////////////////////////////////////////////////
|
|
// File: otsuthr.h
|
|
// Description: Simple Otsu thresholding for binarizing images.
|
|
// Author: Ray Smith
|
|
// Created: Fri Mar 07 12:14:01 PST 2008
|
|
//
|
|
// (C) Copyright 2008, Google Inc.
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
//
|
|
///////////////////////////////////////////////////////////////////////
|
|
|
|
#ifndef TESSERACT_CCMAIN_OTSUTHR_H__
|
|
#define TESSERACT_CCMAIN_OTSUTHR_H__
|
|
|
|
namespace tesseract {
|
|
|
|
const int kHistogramSize = 256; // The size of a histogram of pixel values.
|
|
|
|
// Compute the Otsu threshold(s) for the given image rectangle, making one
|
|
// for each channel. Each channel is always one byte per pixel.
|
|
// Returns an array of threshold values and an array of hi_values, such
|
|
// that a pixel value >threshold[channel] is considered foreground if
|
|
// hi_values[channel] is 0 or background if 1. A hi_value of -1 indicates
|
|
// that there is no apparent foreground. At least one hi_value will not be -1.
|
|
// Delete thresholds and hi_values with delete [] after use.
|
|
void OtsuThreshold(const unsigned char* imagedata,
|
|
int bytes_per_pixel, int bytes_per_line,
|
|
int left, int top, int width, int height,
|
|
int** thresholds, int** hi_values);
|
|
|
|
// Compute the histogram for the given image rectangle, and the given
|
|
// channel. (Channel pointed to by imagedata.) Each channel is always
|
|
// one byte per pixel.
|
|
// Bytes per pixel is used to skip channels not being
|
|
// counted with this call in a multi-channel (pixel-major) image.
|
|
// Histogram is always a 256 element array to count occurrences of
|
|
// each pixel value.
|
|
void HistogramRect(const unsigned char* imagedata,
|
|
int bytes_per_pixel, int bytes_per_line,
|
|
int left, int top, int width, int height,
|
|
int* histogram);
|
|
|
|
// Compute the Otsu threshold(s) for the given histogram.
|
|
// Also returns H = total count in histogram, and
|
|
// omega0 = count of histogram below threshold.
|
|
int OtsuStats(const int* histogram, int* H_out, int* omega0_out);
|
|
|
|
} // namespace tesseract.
|
|
|
|
#endif // TESSERACT_CCMAIN_OTSUTHR_H__
|