C# 保存的jpeg失真??

WM_JAWIN 2014-04-10 02:41:30

Image 对像保存为jpg时,怎么把质量调到最高?,参看了网上说的100L也是没效果,100L也多也就是等于80品质,达不到真正的100
测试了几条线,几个字,除了黑色,其它几种色,几乎都是有毛边,且颜色不正.偏暗

这个是我的代码:

public class Imagetest : IHttpHandler

{

    HttpRequest Request { get; set; }

    public void ProcessRequest(HttpContext context)

    {

        context.Response.ContentType = "image/jpeg";

        Request = context.Request;

        using (var img = new Bitmap(256, 256))

        {

            PrintLogo(img);

            //var ics = GetEncoderInfo("image/png");

            var ics = GetEncoderInfo("image/jpeg");

            var ptrs = new EncoderParameters();

            ptrs.Param[0] = new EncoderParameter(Encoder.Quality, 100L);

            img.Save(context.Response.OutputStream, ics, ptrs);

        }

    }



    void PrintLogo(System.Drawing.Image src)

    {

        using (var g = Graphics.FromImage(src))

        {

            g.Clear(Color.White);

            g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;

            g.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;



            g.DrawLine(Pens.Red, new Point(0, 0), new Point(256, 256));

            g.DrawLine(Pens.Green, new Point(64, 0), new Point(256, 256));

            g.DrawLine(Pens.Blue, new Point(0, 64), new Point(256, 256));

            g.DrawLine(Pens.Black, new Point(0, 128), new Point(256, 256));

            g.DrawLine(Pens.Yellow, new Point(128, 0), new Point(256, 256));

            g.DrawString("Png效果", new Font("新宋体", 12), Brushes.Red, new Point(192, 8));

            g.DrawString("Png效果", new Font("新宋体", 12), Brushes.Green, new Point(192, 32));

            g.DrawString("Png效果", new Font("新宋体", 12), Brushes.Blue, new Point(192, 56));

            g.DrawString("Png效果", new Font("新宋体", 12), Brushes.Black, new Point(192, 80));

        }

    }



    public bool IsReusable { get { return false; } }



    private static ImageCodecInfo GetEncoderInfo(String mimeType)

    {

        int j;

        ImageCodecInfo[] encoders;

        encoders = ImageCodecInfo.GetImageEncoders();

        for (j = 0; j < encoders.Length; ++j)

        {

            if (encoders[j].MimeType == mimeType)

                return encoders[j];

        }

        return null;

    }

}