我创建了一个小的C#应用程序以生成.jpg格式的图像。
pictureBox.Image.Save(name,ImageFormat.Jpeg);
图片已成功创建。我输入一个原始图片,对它进行了一些处理并保存了下来。然而,这张新图片的质量比原始图片低。
有没有办法设置所需的质量?
我创建了一个小的C#应用程序以生成.jpg格式的图像。
pictureBox.Image.Save(name,ImageFormat.Jpeg);
图片已成功创建。我输入一个原始图片,对它进行了一些处理并保存了下来。然而,这张新图片的质量比原始图片低。
有没有办法设置所需的质量?
private void VaryQualityLevel()
{
// Get a bitmap.
Bitmap bmp1 = new Bitmap(@"c:\TestPhoto.jpg");
ImageCodecInfo jgpEncoder = GetEncoder(ImageFormat.Jpeg);
// Create an Encoder object based on the GUID
// for the Quality parameter category.
System.Drawing.Imaging.Encoder myEncoder =
System.Drawing.Imaging.Encoder.Quality;
// Create an EncoderParameters object.
// An EncoderParameters object has an array of EncoderParameter
// objects. In this case, there is only one
// EncoderParameter object in the array.
EncoderParameters myEncoderParameters = new EncoderParameters(1);
EncoderParameter myEncoderParameter = new EncoderParameter(myEncoder,
50L);
myEncoderParameters.Param[0] = myEncoderParameter;
bmp1.Save(@"c:\TestPhotoQualityFifty.jpg", jgpEncoder,
myEncoderParameters);
myEncoderParameter = new EncoderParameter(myEncoder, 100L);
myEncoderParameters.Param[0] = myEncoderParameter;
bmp1.Save(@"c:\TestPhotoQualityHundred.jpg", jgpEncoder,
myEncoderParameters);
// Save the bitmap as a JPG file with zero quality level compression.
myEncoderParameter = new EncoderParameter(myEncoder, 0L);
myEncoderParameters.Param[0] = myEncoderParameter;
bmp1.Save(@"c:\TestPhotoQualityZero.jpg", jgpEncoder,
myEncoderParameters);
}
private ImageCodecInfo GetEncoder(ImageFormat format)
{
ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();
foreach (ImageCodecInfo codec in codecs)
{
if (codec.FormatID == format.Guid)
{
return codec;
}
}
return null;
}
参考:http://msdn.microsoft.com/en-us/library/system.drawing.imaging.encoderparameter.aspx
这是一个更加简洁的代码块,可以用于以特定质量保存为JPEG格式:
var encoder = ImageCodecInfo.GetImageEncoders().First(c => c.FormatID == ImageFormat.Jpeg.Guid);
var encParams = new EncoderParameters() { Param = new[] { new EncoderParameter(Encoder.Quality, 90L) } };
image.Save(path, encoder, encParams);
或者,如果每行120个字符对你来说太长了:
var encoder = ImageCodecInfo.GetImageEncoders()
.First(c => c.FormatID == ImageFormat.Jpeg.Guid);
var encParams = new EncoderParameters(1);
encParams.Param[0] = new EncoderParameter(Encoder.Quality, 90L);
image.Save(path, encoder, encParams);
请确保质量是long
,否则会触发ArgumentException
异常!
这是一个旧的线程,但我已经重写了微软(根据Dustin Getz的答案)使其更加实用 - 缩小了GetEncoderInfo并在Image上进行了扩展。总之没有什么新东西,但可能会有用:
/// <summary>
/// Retrieves the Encoder Information for a given MimeType
/// </summary>
/// <param name="mimeType">String: Mimetype</param>
/// <returns>ImageCodecInfo: Mime info or null if not found</returns>
private static ImageCodecInfo GetEncoderInfo(String mimeType)
{
var encoders = ImageCodecInfo.GetImageEncoders();
return encoders.FirstOrDefault( t => t.MimeType == mimeType );
}
/// <summary>
/// Save an Image as a JPeg with a given compression
/// Note: Filename suffix will not affect mime type which will be Jpeg.
/// </summary>
/// <param name="image">Image: Image to save</param>
/// <param name="fileName">String: File name to save the image as. Note: suffix will not affect mime type which will be Jpeg.</param>
/// <param name="compression">Long: Value between 0 and 100.</param>
private static void SaveJpegWithCompressionSetting(Image image, string fileName, long compression)
{
var eps = new EncoderParameters(1);
eps.Param[0] = new EncoderParameter(Encoder.Quality, compression);
var ici = GetEncoderInfo("image/jpeg");
image.Save(fileName, ici, eps);
}
/// <summary>
/// Save an Image as a JPeg with a given compression
/// Note: Filename suffix will not affect mime type which will be Jpeg.
/// </summary>
/// <param name="image">Image: This image</param>
/// <param name="fileName">String: File name to save the image as. Note: suffix will not affect mime type which will be Jpeg.</param>
/// <param name="compression">Long: Value between 0 and 100.</param>
public static void SaveJpegWithCompression(this Image image, string fileName, long compression)
{
SaveJpegWithCompressionSetting( image, fileName, compression );
}
社区维基的答案被接受,它引用了微软的一个例子。
然而,为了节省您的时间,我概括了其要点并
IDisposable
。我在其他任何答案中都没有看到using (...) {
。为了避免内存泄漏,最佳做法是处理所有实现IDisposable
的内容。public static void SaveJpeg(string path, Bitmap image)
{
SaveJpeg(path, image, 95L);
}
public static void SaveJpeg(string path, Bitmap image, long quality)
{
using (EncoderParameters encoderParameters = new EncoderParameters(1))
using (EncoderParameter encoderParameter = new EncoderParameter(Encoder.Quality, quality))
{
ImageCodecInfo codecInfo = ImageCodecInfo.GetImageDecoders().First(codec => codec.FormatID == ImageFormat.Jpeg.Guid);
encoderParameters.Param[0] = encoderParameter;
image.Save(path, codecInfo, encoderParameters);
}
}
使用无类型的GDI+样式(https://msdn.microsoft.com/zh-cn/library/windows/desktop/ms533845(v=vs.85).aspx)属性来设置JPEG质量显得有些过度。
直接的方式应该是这样的:
FileStream stream = new FileStream("new.jpg", FileMode.Create);
JpegBitmapEncoder encoder = new JpegBitmapEncoder();
encoder.QualityLevel = 100; // "100" for maximum quality (largest file size).
encoder.Frames.Add(BitmapFrame.Create(image));
encoder.Save(stream);
该文档介绍了JpegBitmapEncoder类的Rotation属性,该属性用于设置图像的旋转角度。旋转角度可以是0度、90度、180度或270度。
encoder.QualityLevel = 100
。 - ToolmakerSteve请查看MSDN关于如何设置JPEG压缩级别的文章:http://msdn.microsoft.com/en-us/library/bb882583.aspx
你需要使用另一个Save()重载,该重载接受一个ImageEncoder及其参数。
image.Save(filename, ImageFormat.Png);