當麻許的超技八

/// <summary>

/// 純紅濾鏡

/// </summary>

/// <param name="bitmap">Bitmap</param>

/// <param name="threshold">門檻值 -255~255</param>

/// <returns></returns>

public System.Drawing.Bitmap AdjustToRed(System.Drawing.Bitmap bitmap, int threshold)

{

    for (int y = 0; y < bitmap.Height; y++)

    {

        for (int x = 0; x < bitmap.Width; x++)

        {

            // 取得每一個 pixel

            var pixel = bitmap.GetPixel(x, y);

            var pR = pixel.R + threshold;

            pR = Math.Max(pR, 0);

            pR = Math.Min(255, pR);

            // 將改過的 RGB 寫回

            // 只寫入紅色的值 , G B 都放零

            System.Drawing.Color newColor = System.Drawing.Color.FromArgb(pixel.A, pR, 0, 0);

            bitmap.SetPixel(x, y, newColor);

        }

    }

    // 回傳結果

    return bitmap;

}