使用Aforge.net进行颜色替换

string filePath = Server.MapPath("~/...");//你的图片地址

Bitmap bmp = new Bitmap(filePath);

string htmlColor= "#"+Request.QueryString["color"];

Color newColor = System.Drawing.ColorTranslator.FromHtml(htmlColor);

///Old color

IntRange red= new IntRange(217,217);

IntRange green = new IntRange(20,20);

IntRange blue = new IntRange(31,31);

ColorFiltering colorFilter = new ColorFiltering(red, green, blue);

colorFilter.FillOutsideRange = false;//表示替换的是选中的颜色。如果false的话则表示替换外部的哪些颜色

colorFilter.FillColor = new AForge.Imaging.RGB(newColor);

Bitmap bitmap = colorFilter.Apply(bmp.Clone(new Rectangle(0,0,bmp.Width,bmp.Height) ,PixelFormat.Format24bppRgb));

Encoder enc = Encoder.Quality;

EncoderParameters eps = new EncoderParameters(1);

EncoderParameter ep = new EncoderParameter(enc, 90L);
eps.Param[0] = ep;

ImageCodecInfo codecInfo = ImageCodecInfo.GetImageEncoders()[0];

bitmap.Save(Response.OutputStream,codecInfo,eps);
Response.ContentType = "image/jpeg";
Response.End(); 
图片高质量保存