當麻許的超技八

/// <summary>
/// 增加或減少亮度
 /// </summary>
/// <param name="img">System.Drawing.Image Source </param>
/// <param name="valBrightness">0~255</param>
/// <returns></returns>
public System.Drawing.Bitmap AdjustBrightness(System.Drawing.Image img, int valBrightness)
{
    // 讀入欲轉換的圖片並轉成為 Bitmap
    System.Drawing.Bitmap bitmap = new System.Drawing.Bitmap(img);
    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);

            // 判斷 如果處理過後 255 就設定為 255 如果小於則設定為 0
            var pR = ((pixel.R + valBrightness > 255) ? 255 : pixel.R + valBrightness) < 0 ? 0 : ((pixel.R + valBrightness > 255) ? 255 : pixel.R + valBrightness);
            var pG = ((pixel.G + valBrightness > 255) ? 255 : pixel.G + valBrightness) < 0 ? 0 : ((pixel.G + valBrightness > 255) ? 255 : pixel.G + valBrightness);
            var pB = ((pixel.B + valBrightness > 255) ? 255 : pixel.B + valBrightness) < 0 ? 0 : ((pixel.B + valBrightness > 255) ? 255 : pixel.B + valBrightness);

            // 將改過的 RGB 寫回
            System.Drawing.Color newColor = System.Drawing.Color.FromArgb(pixel.A, pR, pG, pB);

            bitmap.SetPixel(x, y, newColor);

        }
    }
    // 回傳結果
     return bitmap;
}

var resultBitmap = AdjustBrightness((img), -100);

var resultBitmap = AdjustBrightness((img), -50);

var resultBitmap = AdjustBrightness((img), 50);

var resultBitmap = AdjustBrightness((img), 100);