在图像上设置水印，并将其保存在原有的品质 [英] Set watermark on an image and save it in an original quality

问题描述

我上传的网站上的照片，我想设置就可以了水印并将其保存在原有的品质。为了测试我创建C＃应用程序。

I upload a photo on web site and I want to set a watermark on it and save it in original quality. For testing I create C# application.

class Class1
    {
        public static string GetContentType(String path)
        {
            switch (Path.GetExtension(path))
            {
                case ".bmp": return "Image/bmp";
                case ".gif": return "Image/gif";
                case ".jpg": return "Image/jpeg";
                case ".png": return "Image/png";
                default: break;
            }
            return String.Empty;
        }

        public static ImageFormat GetImageFormat(String path)
        {
            switch (Path.GetExtension(path).ToLower())
            {
                case ".bmp": return ImageFormat.Bmp;
                case ".gif": return ImageFormat.Gif;
                case ".jpg": return ImageFormat.Jpeg;
                case ".png": return ImageFormat.Png;
                default: return null;
            }
        }

        public static void AddWaterMark(string sourceFile, string destinationPath)
        {

            // Normally you’d put this in a config file somewhere.
            string watermark = "http://mysite.com/";

            Image image = Image.FromFile(sourceFile);

            Graphics graphic;
            if (image.PixelFormat != PixelFormat.Indexed &&
                image.PixelFormat != PixelFormat.Format8bppIndexed &&
                image.PixelFormat != PixelFormat.Format4bppIndexed &&
                image.PixelFormat != PixelFormat.Format1bppIndexed)
            {

                graphic = Graphics.FromImage(image);
            }
            else
            {

                Bitmap indexedImage = new Bitmap(image);
                graphic = Graphics.FromImage(indexedImage);

                // Draw the contents of the original bitmap onto the new bitmap.
                graphic.DrawImage(image, 0, 0, image.Width, image.Height);
                image = indexedImage;
            }
            graphic.SmoothingMode = SmoothingMode.AntiAlias & SmoothingMode.HighQuality;

            Font myFont = new Font("Arial", 20);
            SolidBrush brush = new SolidBrush(Color.FromArgb(80, Color.White));

            //This gets the size of the graphic 

            SizeF textSize = graphic.MeasureString(watermark, myFont);

            // Code for writing text on the image. 

            PointF pointF = new PointF(430, 710);
            graphic.DrawString(watermark, myFont, brush, pointF);
            image.Save(destinationPath, GetImageFormat(sourceFile));
            graphic.Dispose();
        }

    }

//And using
class Program
    {

        private static string file1 = "C:\\1.JPG";
        private static string file1_withwatermark = "C:\\1_withwatermark.JPG";
        static void Main(string[] args)
        {
            Class1.AddWaterMark(file1, file1_withwatermark);
        }
}

文件1的分辨率为为3648x2736 ，大小 - 的4Mb

我不明白的第一件事就是为什么有水印 file1_withwatermark 是不是？

The first thing I don't understand is why does the file1_withwatermark isn't with watermark?

和第二个是为什么的大小 file1_withwatermark 是的1Mb ，但它的分辨率为为3648x2736 呢！我想保存 file1_withwatermark 在原有的品质，那就是大小 file1_withwatermark 必须约为 4MB 。

And the second one is why does the size of the file1_withwatermark is 1Mb, however the resolution of it is 3648x2736 too! I want to save file1_withwatermark in original quality, that is the size of file1_withwatermark must be about 4Mb.

推荐答案

两个感想：1）尝试更换保存和处理线;您可能必须保存之前未完成挂起的图形操作。 2）如果它是一个JPEG IMG，你需要指定的质量水平。见<一href=\"http://stackoverflow.com/questions/1669850/jpeg-com$p$pssion-with-high-quality-in-c-sharp\">Jpeg COM pression在C＃高品质

Two thoughts: 1) Try swapping the save and dispose lines; you might have a pending graphics operation that is not completed before you save. 2) If it's a jpeg img, you need to specify the quality level. See Jpeg compression with high quality in c#

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