OpencvSharp 的使用 以及配合 BitMiracle.LibTiff.NET 从内存读取多页的TIF

需要同时安装 OpenCvSharp4 和 OpenCvSharp4 runtime，作者 shimat，地址: https://github.com/shimat/opencvsharp

using OpenCvSharp;

Mat image1 = Cv2.ImRead("..\272b4318-9a46-ac9d-1675-e7696b9087d1_1.tif", ImreadModes.Color);

 cv::Mat 在可以直接转换为 C# Bitmap，速度极快，4ms

var bitmap = new Bitmap(image1Result.Cols, image1Result.Rows, (int)image1Result.Step(), System.Drawing.Imaging.PixelFormat.Format24bppRgb, image1Result.Data);

使用 BitMiracle.LibTiff.NET 从上传文件读取多页 TIF

using System.IO;
using System.Web;
using BitMiracle.LibTiff.Classic;
using OpenCvSharp;

class Program
{
    static void Main(HttpPostedFileBase httpPostedFile)
    {
        // 从 HttpPostedFile 对象获取图像数据流
        Stream stream = httpPostedFile.InputStream;

        // 将图像数据流读取为字节数组
        byte[] imageData;
        using (var memoryStream = new MemoryStream())
        {
            stream.CopyTo(memoryStream);
            imageData = memoryStream.ToArray();
        }

        // 使用 BitMiracle.LibTiff.NET 加载多页 TIFF 文件
        using (var tiff = Tiff.ClientOpen("in-memory", "r", new MemoryStream(imageData), new TiffStream()))
        {
            if (tiff != null)
            {
                // 获取 TIFF 文件的页数
                int pageCount = tiff.NumberOfDirectories();

                // 加载所有页面的图像
                Mat[] images = new Mat[pageCount];
                for (int i = 0; i < pageCount; i++)
                {
                    tiff.SetDirectory((short)i);
                    int width = tiff.GetField(TiffTag.IMAGEWIDTH)[0].ToInt();
                    int height = tiff.GetField(TiffTag.IMAGELENGTH)[0].ToInt();
                    int bitsPerPixel = tiff.GetField(TiffTag.BITSPERSAMPLE)[0].ToInt();
                    int samplesPerPixel = tiff.GetField(TiffTag.SAMPLESPERPIXEL)[0].ToInt();
                    int bytesPerLine = width * bitsPerPixel / 8;
                    int imageSize = height * bytesPerLine;
                    byte[] buffer = new byte[imageSize];
                    tiff.ReadScanline(buffer, 0);
                    Mat image = new Mat(height, width, MatType.CV_8UC(samplesPerPixel));
                    Marshal.Copy(buffer, 0, image.Data, imageSize);
                    images[i] = image;
                }

                // 在这里可以使用 OpenCvSharp 对多页 TIFF 文件进行处理
                // ...

                // 释放图像资源
                foreach (var image in images)
                {
                    image.Dispose();
                }

                tiff.Close();
            }
            else
            {
                Console.WriteLine("无法加载 TIFF 文件");
            }
        }
    }
}

 保存图像位深度为1：

var inputMat = OpenCvSharp.Cv2.ImRead(@"6622df65-c19d-184a-d47f-be2fdf7d72ce_01.tif", OpenCvSharp.ImreadModes.Color);

            // 将图像转换为灰度
            OpenCvSharp.Cv2.CvtColor(inputMat, inputMat, OpenCvSharp.ColorConversionCodes.BGR2GRAY);

            // 将图像二值化为黑白图像
            OpenCvSharp.Cv2.Threshold(inputMat, inputMat, 128, 255, OpenCvSharp.ThresholdTypes.Binary);

            // 将位深度从8位转换为1位
            OpenCvSharp.Cv2.ConvertScaleAbs(inputMat, inputMat, 1.0 / 255.0, 0);

            // 现在inputMat是一个位深度为1的黑白Mat对象

            var saveParams = new OpenCvSharp.ImageEncodingParam[]
                    {
                        new OpenCvSharp.ImageEncodingParam(OpenCvSharp.ImwriteFlags.PngCompression, 3), // 设置 PNG 压缩方式，3 表示 PNG_COMPRESSION_3
                        new OpenCvSharp.ImageEncodingParam(OpenCvSharp.ImwriteFlags.PngBilevel, 1), // 设置 PNG 位深度为 1
                    };

            // 要将其保存到磁盘，请使用以下代码：
            inputMat.ImWrite(Server.MapPath("output.png"), saveParams);

 

 转换 Bitmap 为灰度图像：

private Bitmap ConvertToGrayscale(Bitmap bmp)
        {
            // Convert input bitmap to Mat object
            OpenCvSharp.Mat src = OpenCvSharp.Extensions.BitmapConverter.ToMat(bmp);

            // Create grayscale output mat
            OpenCvSharp.Mat gray = new OpenCvSharp.Mat();

            // Convert input mat to grayscale
            OpenCvSharp.Cv2.CvtColor(src, gray, OpenCvSharp.ColorConversionCodes.BGR2GRAY, 1);

            // Convert output mat back to bitmap
            return OpenCvSharp.Extensions.BitmapConverter.ToBitmap(gray);
        }