c# - 获取图像的RGB值并可能在C#中移动图像文件

Question

我正在考虑用 C# 做一个项目，该项目查看一个尚未确定扩展名的图像文件，并记下 RGB 值，如果它太暗则将其移动到另一个文件夹供我稍后查看

所以这里是 block 形式

从目录加载多个图像 > 检查每个文件的 RGB 值 > 如果太暗 > 移动到不同的文件夹。如果不忽略(保留在原始文件夹中)

我知道基本知识，例如从目录获取文件，但检查整张图片的 RGB 值，然后移动它或忽略它，我很困惑。

我有这个代码:

    private void button1_Click(object sender, EventArgs e)
    {
        CompareImages(Environment.GetFolderPath(Environment.SpecialFolder.MyPictures),
            Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory), "checked"), 127.0, new string[] {"*.jpg", "*.png"});
    }

    private void CompareImages(string sourceFolder, string disposedImgFolder, double threshold, string[] extensions)
    {
        if (Directory.Exists(sourceFolder))
        {
            DirectoryInfo dir = new DirectoryInfo(sourceFolder);
            List<FileInfo> pictures = new List<FileInfo>();

            foreach (string ext in extensions)
            {
                FileInfo[] fi = dir.GetFiles(ext);
                pictures.AddRange(fi);
            }


            Directory.CreateDirectory(disposedImgFolder);

            int j = 0;

            if (pictures.Count > 0)
            {
                for (int i = 0; i < pictures.Count; i++)
                {
                    Image img = null;
                    Bitmap bmp = null;

                    try
                    {

                        img = Image.FromFile(pictures[i].FullName);
                        bmp = new Bitmap(img);
                        img.Dispose();

                        double avg = GetAveragePixelValue(bmp);

                        bmp.Dispose();


                        if (avg < threshold)
                        {
                            string dest = Path.Combine(disposedImgFolder, pictures[i].Name);

                            if (File.Exists(dest) == false)
                            {
                                pictures[i].MoveTo(dest);
                                j++;
                            }
                            else
                            {

                            }
                        }
                        else
                        {

                        }
                    }
                    catch
                    {
                        if (img != null)
                            img.Dispose();
                        if (bmp != null)
                            bmp.Dispose();
                    }
                }

                MessageBox.Show("Done, " + j.ToString() + " files moved.");
            }
        }
    }

    private unsafe double GetAveragePixelValue(Bitmap bmp)
    {
        BitmapData bmData = null;

        try
        {
            bmData = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);

            int stride = bmData.Stride;
            IntPtr scan0 = bmData.Scan0;
            int w = bmData.Width;
            int h = bmData.Height;

            double sum = 0;
            long pixels = bmp.Width * bmp.Height;

            byte* p = (byte*)scan0.ToPointer();

            for (int y = 0; y < h; y++)
            {
                p = (byte*)scan0.ToPointer();
                p += y * stride;

                for (int x = 0; x < w; x++)
                {

                    double i = ((double)p[0] + p[1] + p[2]) / 3.0;
                    sum += i;


                    p += 4;
                }

            }

            bmp.UnlockBits(bmData);

            double result = sum / (double)pixels;

            return result;
        }
        catch
        {
            try
            {
                bmp.UnlockBits(bmData);
            }
            catch
            {

            }
        }

        return -1;
    }

如何定义阈值？

Answer 1

如果要读取图像的每个像素，必须将其转换为位图。然后您可以使用 GetPixel 方法。但是，这个过程非常慢并且需要大量的 CPU。如果这样做，您确实应该先进行一些测试。

        using (var m = new MemoryStream())
        {
            using (var img = Image.FromFile(args[0]))
            {
                img.Save(m, ImageFormat.Bmp);
            }

            m.Position = 0;

            using (var bitmap = (Bitmap)Bitmap.FromStream(m))
            {
                for (var x = 0; x < bitmap.Width; x++)
                {
                    for (var y = 0; y < bitmap.Height; y++)
                    {
                        var color = bitmap.GetPixel(x, y);

                        // TODO: Do what ever you want
                    }
                }
            }
        }