生成 16 位灰度 BitmapData 并保存到文件

Generate 16-bit grayscale BitmapData and save to file(生成 16 位灰度 BitmapData 并保存到文件)

问题描述

我正在尝试从随机数据中生成 C# 中的 16 位灰度位图.但它在 Marshal.Copy 上崩溃了.

I am trying to generate 16bit grayscale Bitmap in C# from a random data.But it crashed on Marshal.Copy.

这是我的代码:

   Bitmap b16bpp;
    private void GenerateDummy16bitImage()
    {

        b16bpp = new Bitmap(IMAGE_WIDTH, IMAGE_HEIGHT, System.Drawing.Imaging.PixelFormat.Format16bppGrayScale);

        var rect = new Rectangle(0, 0, IMAGE_WIDTH, IMAGE_HEIGHT);
        var bitmapData = b16bpp.LockBits(rect, ImageLockMode.WriteOnly, b16bpp.PixelFormat);
        // Calculate the number of bytes required and allocate them.
        var numberOfBytes = bitmapData.Stride * IMAGE_HEIGHT * 2;
        var bitmapBytes = new short[numberOfBytes];
        // Fill the bitmap bytes with random data.
        var random = new Random();
        for (int x = 0; x < IMAGE_WIDTH; x++)
        {
            for (int y = 0; y < IMAGE_HEIGHT; y++)
            {

                var i = ((y * IMAGE_WIDTH) + x) * 2; // 16bpp

                // Generate the next random pixel color value.
                var value = (short)random.Next(5);

                bitmapBytes[i] = value;         // BLUE
                bitmapBytes[i + 1] = value;     // GREEN
                bitmapBytes[i + 2] = value;     // RED
              //  bitmapBytes[i + 3] = 0xFF;      // ALPHA
            }
        }
        // Copy the randomized bits to the bitmap pointer.
        var ptr = bitmapData.Scan0;
        Marshal.Copy(bitmapBytes, 0, ptr, numberOfBytes);//crashes here

        // Unlock the bitmap, we're all done.
        b16bpp.UnlockBits(bitmapData);

        b16bpp.Save("random.bmp", ImageFormat.Bmp);
        Debug.WriteLine("saved");
    }

例外是:

mscorlib.dll 中发生类型为System.AccessViolationException"的未处理异常

这不是我的代码.我发现它与 32 位位图相关并进行了修改.但我想我错过了一些东西，因为我对 C# 还很陌生.

This is not my code.I found it in relation to 32bit Bitmaps and modified.But I guess I have missed something as I am pretty new to C#.

基本上，我需要的只是将一个短裤数组包装到 BitmapData 中.

Basically,all I need is to wrap into BitmapData an arrays of shorts.

推荐答案

这适用于 System.Drawing.Imaging.PixelFormat.Format16bppGrayScale:

This works for System.Drawing.Imaging.PixelFormat.Format16bppGrayScale:

    private static void SaveBmp(Bitmap bmp, string path)
    {
        Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);

        BitmapData bitmapData = bmp.LockBits(rect, ImageLockMode.ReadOnly, bmp.PixelFormat);

        var pixelFormats = ConvertBmpPixelFormat(bmp.PixelFormat);

        BitmapSource source = BitmapSource.Create(bmp.Width,
                                                  bmp.Height,
                                                  bmp.HorizontalResolution,
                                                  bmp.VerticalResolution,
                                                  pixelFormats,
                                                  null,
                                                  bitmapData.Scan0,
                                                  bitmapData.Stride * bmp.Height,
                                                  bitmapData.Stride);

        bmp.UnlockBits(bitmapData);


        FileStream stream = new FileStream(path, FileMode.Create);

        TiffBitmapEncoder encoder = new TiffBitmapEncoder();

        encoder.Compression = TiffCompressOption.Zip;
        encoder.Frames.Add(BitmapFrame.Create(source));
        encoder.Save(stream);

        stream.Close();
    }

    private static System.Windows.Media.PixelFormat ConvertBmpPixelFormat(System.Drawing.Imaging.PixelFormat pixelformat)
    {
        System.Windows.Media.PixelFormat pixelFormats = System.Windows.Media.PixelFormats.Default;

        switch (pixelformat)
        {
            case System.Drawing.Imaging.PixelFormat.Format32bppArgb:
                pixelFormats = PixelFormats.Bgr32;
                break;

            case System.Drawing.Imaging.PixelFormat.Format8bppIndexed:
                pixelFormats = PixelFormats.Gray8;
                break;

            case System.Drawing.Imaging.PixelFormat.Format16bppGrayScale:
                pixelFormats = PixelFormats.Gray16;
                break;
        }

        return pixelFormats;
    }

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