c# - 穿越 BMP 中的像素

Question

您好，我有一个 bmp 加载到 BMP 对象，我需要像上图那样从 (1,1) 像素到 (100,100) px 。使用 getpixel() 方法。我使用的是 ONE 循环，但没有成功。

如果我使用多维数组的概念，变量值应该是什么？

Answer 1

When you want to doing image processing on huge images GetPixel() method takes long time but I think my algorithm takes less time than other answers , for example you can test this code on 800 * 600 pixels image.

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Bitmap bmp = new Bitmap("SomeImage");

// Lock the bitmap's bits.  
Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);
BitmapData bmpData = bmp.LockBits(rect, ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);

// Get the address of the first line.
IntPtr ptr = bmpData.Scan0;

// Declare an array to hold the bytes of the bitmap.
int bytes = bmpData.Stride * bmp.Height;
byte[] rgbValues = new byte[bytes];
byte[] r = new byte[bytes / 3];
byte[] g = new byte[bytes / 3];
byte[] b = new byte[bytes / 3];

// Copy the RGB values into the array.
Marshal.Copy(ptr, rgbValues, 0, bytes);

int count = 0;
int stride = bmpData.Stride;

for (int column = 0; column < bmpData.Height; column++)
{
    for (int row = 0; row < bmpData.Width; row++)
    {
        b[count] = (byte)(rgbValues[(column * stride) + (row * 3)]);
        g[count] = (byte)(rgbValues[(column * stride) + (row * 3) + 1]);
        r[count++] = (byte)(rgbValues[(column * stride) + (row * 3) + 2]);
    }
}