From 4401f681d33f534a7d7ef8f4f940bd54b60710c3 Mon Sep 17 00:00:00 2001
From: Chris Xiong <chirs241097@gmail.com>
Date: Sun, 18 Sep 2022 01:52:26 -0400
Subject: Move stuff around to accommodate new family members.

---
 xsig/src/imageutil.cpp | 131 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 131 insertions(+)
 create mode 100644 xsig/src/imageutil.cpp

(limited to 'xsig/src/imageutil.cpp')

diff --git a/xsig/src/imageutil.cpp b/xsig/src/imageutil.cpp
new file mode 100644
index 0000000..3fd8a94
--- /dev/null
+++ b/xsig/src/imageutil.cpp
@@ -0,0 +1,131 @@
+//Chris Xiong 2022
+//License: MPL-2.0
+#include <algorithm>
+#include <cmath>
+#include <fstream>
+#include <iterator>
+#include <limits>
+//#include <cstdio>
+
+#include <opencv2/imgcodecs.hpp>
+
+#include "imageutil.hpp"
+
+//libpuzzle uses a contrast-based cropping, and clamps the cropped area to a given percentage.
+cv::Range image_util::crop_axis(cv::InputArray s, int axis, double contrast_threshold, double max_crop_ratio)
+{
+    //axis: 0=x (returns range of columns), 1=y (returns range of rows)
+    //input matrix must be continuous
+    cv::Mat m = s.getMat();
+    cv::Size sz = m.size();
+    if (axis == 0)
+        sz = cv::Size(m.rows, m.cols);
+    int innerstride = axis == 0 ? m.cols : 1;
+    int outerstride = axis == 0 ? 1 - m.cols * m.rows : 0;
+    std::vector<double> contrs;
+    const float *data = m.ptr<float>(0);
+    const float *dp = data;
+    double total_contr = 0.;
+    for (int i = 0; i < sz.height; ++i)
+    {
+        double accum = 0.;
+        float lastv = *data;
+        for (int j = 0 ; j < sz.width; ++j)
+        {
+            data += innerstride;
+            //printf("%d %d\n", (data - dp) / m.cols, (data - dp) % m.cols);
+            if (data - dp >= sz.height * sz.width)
+                break;
+            accum += fabsf(*data - lastv);
+            lastv = *data;
+        }
+        //printf("---\n");
+        data += outerstride;
+        contrs.push_back(accum);
+        total_contr += accum;
+    }
+    //printf("======\n");
+    //for (size_t i = 0; i < contrs.size(); ++i) printf("%.4f ",contrs[i]/total_contr);
+    //printf("\n%f====\n",total_contr);
+    double realth = total_contr * contrast_threshold;
+    int l = 0, r = sz.height - 1;
+    total_contr = 0;
+    for (; l < sz.height; ++l)
+    {
+        total_contr += contrs[l];
+        if (total_contr >= realth) break;
+    }
+    total_contr = 0;
+    for (; r > 0; --r)
+    {
+        total_contr += contrs[r];
+        if (total_contr >= realth) break;
+    }
+    int crop_max = (int)round(sz.height * max_crop_ratio);
+    return cv::Range(std::min(l, crop_max), std::max(r, sz.height - 1 - crop_max) + 1);
+}
+
+cv::Mat image_util::crop(cv::InputArray s, double contrast_threshold, double max_crop_ratio)
+{
+    //input matrix must be continuous
+    cv::Range xr = crop_axis(s, 0, contrast_threshold, max_crop_ratio);
+    cv::Range yr = crop_axis(s, 1, contrast_threshold, max_crop_ratio);
+    //printf("%d,%d %d,%d\n",yr.start,yr.end,xr.start,xr.end);
+    return s.getMat()(yr, xr);
+}
+
+double image_util::median(std::vector<double> &v)
+{
+    if (v.empty())
+        return std::numeric_limits<double>::quiet_NaN();
+    if (v.size() % 2)
+    {
+        int m = v.size() / 2;
+        std::vector<double>::iterator mt = v.begin() + m;
+        std::nth_element(v.begin(), mt, v.end());
+        return *mt;
+    }
+    else
+    {
+        int m = v.size() / 2;
+        int n = m - 1;
+        std::vector<double>::iterator mt, nt;
+        mt = v.begin() + m;
+        nt = v.begin() + n;
+        std::nth_element(v.begin(), mt, v.end());
+        std::nth_element(v.begin(), nt, v.end());
+        return (*mt + *nt) / 2.;
+    }
+}
+
+cv::Mat image_util::blend_white(cv::Mat m)
+{
+    //input must be a continuous, CV_32FC4 matrix
+    cv::Mat ret;
+    ret.create(m.size(), CV_32FC3);
+    size_t p = m.size().width * m.size().height;
+    float *d = m.ptr<float>(0);
+    float *o = ret.ptr<float>(0);
+    for (size_t i = 0; i < p; ++i)
+    {
+        float a = d[3];
+        o[0] = d[0] * a + (1. - a);
+        o[1] = d[1] * a + (1. - a);
+        o[2] = d[2] * a + (1. - a);
+        d += 4;
+        o += 3;
+    }
+    return ret;
+}
+
+cv::Mat image_util::imread_path(const std::filesystem::path &p, int flags)
+{
+    auto size = std::filesystem::file_size(p);
+    std::fstream fst(p, std::ios::binary | std::ios::in);
+    std::vector<char> dat;
+    dat.resize(size);
+    fst.read(dat.data(), size);
+    fst.close();
+    cv::Mat img = cv::imdecode(dat, flags);
+    return img;
+}
-- 
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