tesseract 4.1.1
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otsuthr.h
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1
2// File: otsuthr.h
3// Description: Simple Otsu thresholding for binarizing images.
4// Author: Ray Smith
5// Created: Fri Mar 07 12:14:01 PST 2008
6//
7// (C) Copyright 2008, Google Inc.
8// Licensed under the Apache License, Version 2.0 (the "License");
9// you may not use this file except in compliance with the License.
10// You may obtain a copy of the License at
11// http://www.apache.org/licenses/LICENSE-2.0
12// Unless required by applicable law or agreed to in writing, software
13// distributed under the License is distributed on an "AS IS" BASIS,
14// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15// See the License for the specific language governing permissions and
16// limitations under the License.
17//
19
20#ifndef TESSERACT_CCMAIN_OTSUTHR_H_
21#define TESSERACT_CCMAIN_OTSUTHR_H_
22
23struct Pix;
24
25namespace tesseract {
26
27const int kHistogramSize = 256; // The size of a histogram of pixel values.
28
29// Computes the Otsu threshold(s) for the given image rectangle, making one
30// for each channel. Each channel is always one byte per pixel.
31// Returns an array of threshold values and an array of hi_values, such
32// that a pixel value >threshold[channel] is considered foreground if
33// hi_values[channel] is 0 or background if 1. A hi_value of -1 indicates
34// that there is no apparent foreground. At least one hi_value will not be -1.
35// Delete thresholds and hi_values with delete [] after use.
36// The return value is the number of channels in the input image, being
37// the size of the output thresholds and hi_values arrays.
38int OtsuThreshold(Pix* src_pix, int left, int top, int width, int height,
39 int** thresholds, int** hi_values);
40
41// Computes the histogram for the given image rectangle, and the given
42// single channel. Each channel is always one byte per pixel.
43// Histogram is always a kHistogramSize(256) element array to count
44// occurrences of each pixel value.
45void HistogramRect(Pix* src_pix, int channel,
46 int left, int top, int width, int height,
47 int* histogram);
48
49// Computes the Otsu threshold(s) for the given histogram.
50// Also returns H = total count in histogram, and
51// omega0 = count of histogram below threshold.
52int OtsuStats(const int* histogram, int* H_out, int* omega0_out);
53
54} // namespace tesseract.
55
56#endif // TESSERACT_CCMAIN_OTSUTHR_H_
const int kHistogramSize
Definition: otsuthr.h:27
void HistogramRect(Pix *src_pix, int channel, int left, int top, int width, int height, int *histogram)
Definition: otsuthr.cpp:150
int OtsuThreshold(Pix *src_pix, int left, int top, int width, int height, int **thresholds, int **hi_values)
Definition: otsuthr.cpp:40
int OtsuStats(const int *histogram, int *H_out, int *omega0_out)
Definition: otsuthr.cpp:171