如何在C#中识别黑色或暗色图像？

Question

如何识别C#中的黑/暗图像.有没有API来检查图像可见度或暗度比？在我的应用程序中,在复制图像时,我想检查每个图像并想要丢弃黑色图像.

任何想法如何实现这一目标？

Answer 1

// For fast access to pixels        
public static unsafe byte[] BitmapToByteArray(Bitmap bitmap) { 
    BitmapData bmd = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height), ImageLockMode.ReadOnly,
                                     PixelFormat.Format32bppArgb);
    byte[] bytes = new byte[bmd.Height * bmd.Stride];
    byte* pnt = (byte*) bmd.Scan0;
    Marshal.Copy((IntPtr) pnt, bytes, 0, bmd.Height * bmd.Stride);
    bitmap.UnlockBits(bmd);
    return bytes;
}

public bool IsDark(Bitmap bitmap, byte tolerance, double darkProcent) {
    byte[] bytes = BitmapToByteArray(bitmap);
    int count = 0, all = bitmap.Width * bitmap.Height;
    for (int i = 0; i < bytes.Length; i += 4) {
        byte r = bytes[i + 2], g = bytes[i + 1], b = bytes[i];
        byte brightness = (byte) Math.Round((0.299 * r + 0.5876 * g + 0.114 * b));
        if (brightness <= tolerance)
            count++;
    }
    return (1d * count / all) <= darkProcent;
}

public void Run(Bitmap bitmap) { // Example of use
    // some code
    bool dark = IsDark(bitmap, 40, 0.9); 
    // some code
}

Answer 2

获得图像暗度/亮度的想法可以是:

Bitmap bitmap = // the bitmap
var colors = new List<Color>();
for (int x = 0; x < bitmap.Size.Width; x++)
{
    for (int y = 0; y < bitmap.Size.Height; y++)
    {
        colors.Add(bitmap.GetPixel(x, y));
    }
}

float imageBrightness = colors.Average(color => color.GetBrightness());

也许将暗图像视为亮度小于0.1(或任何其他相关值)的图像