--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/tesseract/src/ccstruct/otsuthr.h	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,58 @@
+///////////////////////////////////////////////////////////////////////
+// File:        otsuthr.h
+// Description: Simple Otsu thresholding for binarizing images.
+// Author:      Ray Smith
+//
+// (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_
+
+#include "image.h"
+
+#include <vector> // for std::vector
+
+struct Pix;
+
+namespace tesseract {
+
+const int kHistogramSize = 256; // The size of a histogram of pixel values.
+
+// Computes 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.
+// The return value is the number of channels in the input image, being
+// the size of the output thresholds and hi_values arrays.
+int OtsuThreshold(Image src_pix, int left, int top, int width, int height,
+                  std::vector<int> &thresholds,
+                  std::vector<int> &hi_values);
+
+// Computes the histogram for the given image rectangle, and the given
+// single channel. Each channel is always one byte per pixel.
+// Histogram is always a kHistogramSize(256) element array to count
+// occurrences of each pixel value.
+void HistogramRect(Image src_pix, int channel, int left, int top, int width, int height,
+                   int *histogram);
+
+// Computes 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_