Cmp中的Bmp到jpg / png

7 回答

• 0

  你可以试试：

  Bitmap.InterpolationMode = InterpolationMode.HighQualityBicubic;
  

  和

  Bitmap.CompositingQuality = CompositingQuality.HighQuality;
  

  这确实保持了相当高的质量，但不是最高的 .

  回复于 2024-04-29T05:00:08+08:00
• 0

  我正在开发一个费用报告应用程序，从Bitmap对象保存时，我对JPG（和PNG）的默认质量设置非常满意 .

  https://msdn.microsoft.com/en-us/library/9t4syfhh%28v=vs.110%29.aspx

  Bitmap finalBitmap = ....; //from disk or whatever
  finalBitmap.Save(xpsFileName + ".final.jpg", ImageFormat.Jpeg);
  finalBitmap.Save(xpsFileName + ".final.png", ImageFormat.Png);
  

  我在使用.NET 4.6 ......也许后续框架版本的质量有所提高 .

  回复于 2024-04-29T05:00:08+08:00
• 53

  var qualityEncoder = Encoder.Quality;
  var quality = (long)<desired quality>;
  var ratio = new EncoderParameter(qualityEncoder, quality );
  var codecParams = new EncoderParameters(1);
  codecParams.Param[0] = ratio;
  var jpegCodecInfo = <one of the codec infos from ImageCodecInfo.GetImageEncoders() with mime type = "image/jpeg">;
  bmp.Save(fileName, jpegCodecInfo, codecParams); // Save to JPG
  

  回复于 2024-04-29T05:00:08+08:00
• 32

  public static class BitmapExtensions
  {
      public static void SaveJPG100(this Bitmap bmp, string filename)
      {            
          EncoderParameters encoderParameters = new EncoderParameters(1);
          encoderParameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
          bmp.Save(filename, GetEncoder(ImageFormat.Jpeg), encoderParameters);
      }
  
      public static void SaveJPG100(this Bitmap bmp, Stream stream)
      {
          EncoderParameters encoderParameters = new EncoderParameters(1);
          encoderParameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
          bmp.Save(stream, GetEncoder(ImageFormat.Jpeg), encoderParameters);
      }
  
      public static ImageCodecInfo GetEncoder(ImageFormat format)
      {
          ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();
  
          foreach (ImageCodecInfo codec in codecs)
          {
              if (codec.FormatID == format.Guid)
              {
                  return codec;
              }
          }
  
          return null;
      }
  }
  

  回复于 2024-04-29T05:00:08+08:00
• 1

  由jestro提供的BitmapExtensions很棒，我用它们 . 但是想要显示更正的版本 - 适用于Image父类，这比我想象的更方便，并提供了一种提供质量的方法：

  public static class ImageExtensions
  {
      public static void SaveJpeg(this Image img, string filePath, long quality)
      {
          var encoderParameters = new EncoderParameters(1);
          encoderParameters.Param[0] = new EncoderParameter(Encoder.Quality, quality);
          img.Save(filePath, GetEncoder(ImageFormat.Jpeg), encoderParameters);
      }
  
      public static void SaveJpeg(this Image img, Stream stream, long quality)
      {
          var encoderParameters = new EncoderParameters(1);
          encoderParameters.Param[0] = new EncoderParameter(Encoder.Quality, quality);
          img.Save(stream, GetEncoder(ImageFormat.Jpeg), encoderParameters);
      }
  
      static ImageCodecInfo GetEncoder(ImageFormat format)
      {
          ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();
          return codecs.Single(codec => codec.FormatID == format.Guid);
      }
  }
  

  回复于 2024-04-29T05:00:08+08:00
• 1

  从根本上说，你将无法保持相同的质量，因为即使有最高质量设置，jpg（据我所知）总是有损 .

  如果位精确质量非常重要，请考虑使用png，它有一些无损模式 .

  回复于 2024-04-29T05:00:08+08:00
• 10

  只是想说JPEG本质上是一种有损格式 . 因此，即使在最高设置下你也会有一些信息丢失，但它在很大程度上取决于图像 . 但是png是无损的 .

  回复于 2024-04-29T05:00:08+08:00