shuiyin/ShuiYinCSharp/Com/Lmc/ShuiYin/Two/Utils/WaterMarkDFT.cs

using System.Collections.Generic;
using OpenCvSharp;

namespace Com.Lmc.ShuiYin.Two.Utils
{
    public class WaterMarkDFT
    {
        public static void Embed(string imagePath, string watermark, string outputPath)
        {
            Mat image = Cv2.ImRead(imagePath);
            List<Mat> allPlanes = new List<Mat>();
            Cv2.Split(image, out Mat[] splitPlanes);
            allPlanes.AddRange(splitPlanes);

            Mat processImage = allPlanes[0];
            processImage.ConvertTo(processImage, MatType.CV_32F);
            
            List<Mat> planes = new List<Mat>();
            planes.Add(processImage);
            planes.Add(Mat.Zeros(processImage.Size(), MatType.CV_32F));
            
            Mat complexImage = new Mat();
            Cv2.Merge(planes.ToArray(), complexImage);
            
            Cv2.Dft(complexImage, complexImage);
            
            Scalar scalar = new Scalar(2, 2, 2);
            Point point = new Point(40, 40);
            
            Cv2.PutText(complexImage, watermark, point, HersheyFonts.HersheyComplex, 1.5, scalar, 3, LineTypes.Link8, false); // Java: 20 -> bottomLeftOrigin? No, putText last arg is bottomLeftOrigin. Java code says 20?? 
            // Java putText signature: (img, text, org, fontFace, fontScale, color, thickness, lineType, bottomLeftOrigin)
            // Java code: putText(complexImage, watermark, point, FONT_HERSHEY_COMPLEX, 1.5, scalar, 3, 20);
            // Wait, 20 is not boolean.
            // Check Java params: 
            // putText(Mat img, String text, Point org, int fontFace, double fontScale, Scalar color, int thickness)
            // or
            // putText(Mat img, String text, Point org, int fontFace, double fontScale, Scalar color, int thickness, int lineType, boolean bottomLeftOrigin)
            // The code has 8 arguments. 
            // putText(complexImage, watermark, point, FONT_HERSHEY_COMPLEX, 1.5, scalar,3, 20);
            // Arg 8 is 20? 20 is not boolean.
            // Maybe they mean lineType=20? But lineType is usually 8, 4, CV_AA (16).
            // Maybe it is calling a different overload?
            // Actually, in the Java code: `putText(complexImage, watermark, point, FONT_HERSHEY_COMPLEX, 1.5, scalar,3, 20);`
            // If I assume 20 is lineType? CV_AA? No.
            // Let's assume standard parameters: thickness=3, lineType=20?
            // I will use standard LineTypes.Link8 and false for bottomLeftOrigin.
            
            Cv2.Flip(complexImage, complexImage, FlipMode.XY); // -1
            Cv2.PutText(complexImage, watermark, point, HersheyFonts.HersheyComplex, 1.5, scalar, 3, LineTypes.Link8, false);
            Cv2.Flip(complexImage, complexImage, FlipMode.XY); // -1
            
            Mat invDFT = new Mat();
            Cv2.Idft(complexImage, invDFT, DftFlags.Scale | DftFlags.RealOutput);
            
            invDFT.ConvertTo(invDFT, MatType.CV_8U);
            
            allPlanes[0] = invDFT;
            
            Cv2.Merge(allPlanes.ToArray(), invDFT);
            Cv2.ImWrite(outputPath, invDFT);
        }

        public static void Extract(string targetImage, string outputWatermark)
        {
            Mat image = Cv2.ImRead(targetImage);
            List<Mat> allPlanes = new List<Mat>();
            Cv2.Split(image, out Mat[] splitPlanes);
            allPlanes.AddRange(splitPlanes);
            
            Mat processImage = allPlanes[0];
            processImage.ConvertTo(processImage, MatType.CV_32F);
            
            List<Mat> planes = new List<Mat>();
            planes.Add(processImage);
            planes.Add(Mat.Zeros(processImage.Size(), MatType.CV_32F));
            
            Mat complexImage = new Mat();
            Cv2.Merge(planes.ToArray(), complexImage);
            
            Cv2.Dft(complexImage, complexImage);
            
            List<Mat> newPlanes = new List<Mat>();
            Mat mag = new Mat();
            Cv2.Split(complexImage, out Mat[] splitComplex);
            newPlanes.AddRange(splitComplex);
            
            Cv2.Magnitude(newPlanes[0], newPlanes[1], mag);
            Cv2.Add(Mat.Ones(mag.Size(), MatType.CV_32F), mag, mag);
            Cv2.Log(mag, mag);
            
            // Crop
            mag = mag.SubMat(new Rect(0, 0, mag.Cols & -2, mag.Rows & -2));
            int cx = mag.Cols / 2;
            int cy = mag.Rows / 2;
            
            Mat q0 = new Mat(mag, new Rect(0, 0, cx, cy));
            Mat q1 = new Mat(mag, new Rect(cx, 0, cx, cy));
            Mat q2 = new Mat(mag, new Rect(0, cy, cx, cy));
            Mat q3 = new Mat(mag, new Rect(cx, cy, cx, cy));
            Mat tmp = new Mat();
            q0.CopyTo(tmp);
            q3.CopyTo(q0);
            tmp.CopyTo(q3);
            q1.CopyTo(tmp);
            q2.CopyTo(q1);
            tmp.CopyTo(q2);
            
            mag.ConvertTo(mag, MatType.CV_8UC1);
            Cv2.Normalize(mag, mag, 0, 255, NormTypes.MinMax, (int)MatType.CV_8UC1);
            Cv2.ImWrite(outputWatermark, mag);
        }
        
        private static Mat OptimizeImageDimensions(Mat image)
        {
            Mat padded = new Mat();
            int addPixelRows = Cv2.GetOptimalDFTSize(image.Rows);
            int addPixelCols = Cv2.GetOptimalDFTSize(image.Cols);
            Cv2.CopyMakeBorder(image, padded, 0, addPixelRows - image.Rows,
                0, addPixelCols - image.Cols, BorderTypes.Constant, Scalar.All(0));
            return padded;
        }
    }
}