我需要从用户那里得到一张带有不同格式扩展名的图片,并且我想始终将其保存为“jpg”,以便于处理。有没有在c#中做到这一点而不提高质量的好方法?
问问题
68773 次
4 回答
27
来自:http: //msdn.microsoft.com/en-us/library/system.drawing.imaging.encoderparameter.aspx
private void VaryQualityLevel()
{
// Get a bitmap.
Bitmap bmp1 = new Bitmap(@"c:\TestPhoto.jpg");
ImageCodecInfo jpgEncoder = 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", jpgEncoder,
myEncoderParameters);
myEncoderParameter = new EncoderParameter(myEncoder, 100L);
myEncoderParameters.Param[0] = myEncoderParameter;
bmp1.Save(@"c:\TestPhotoQualityHundred.jpg", jpgEncoder,
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", jpgEncoder,
myEncoderParameters);
}
...
private ImageCodecInfo GetEncoder(ImageFormat format)
{
ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();
foreach (ImageCodecInfo codec in codecs)
{
if (codec.FormatID == format.Guid)
{
return codec;
}
}
return null;
}
于 2012-06-05T09:47:14.597 回答
18
我使用这个简单的扩展来转换流,它所做的只是转换它并且对质量没有任何作用。
public static Stream ConvertImage(this Stream originalStream, ImageFormat format)
{
var image = Image.FromStream(originalStream);
var stream = new MemoryStream();
image.Save(stream, format);
stream.Position = 0;
return stream;
}
用法:
var outputStream = gifStream.ConvertImage(ImageFormat.Png);
于 2013-07-29T11:08:28.717 回答
2
Windows GDI+ 提供了Image 类和Bitmap 类,用于在内存中存储图像和在内存中操作图像。GDI+ 借助图像编码器将图像写入磁盘文件,并借助图像解码器从磁盘文件加载图像。
检查Image.Save 方法重载以实现您的功能。它支持ImageFormat Class类型的各种图像格式。
遵循Image.Save Method (String, ImageCodecInfo, EncoderParameters)上的示例,它可以让您Jpg
使用编码等保存文件。
代码片段:
using System;
using System.Drawing;
using System.Drawing.Imaging;
class Example_SetJPEGQuality
{
public static void Main()
{
Bitmap myBitmap;
ImageCodecInfo myImageCodecInfo;
Encoder myEncoder;
EncoderParameter myEncoderParameter;
EncoderParameters myEncoderParameters;
// Create a Bitmap object based on a BMP file.
myBitmap = new Bitmap("Shapes.bmp");
// Get an ImageCodecInfo object that represents the JPEG codec.
myImageCodecInfo = GetEncoderInfo("image/jpeg");
// Create an Encoder object based on the GUID
// for the Quality parameter category.
myEncoder = 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.
myEncoderParameters = new EncoderParameters(1);
// Save the bitmap as a JPEG file with quality level 25.
myEncoderParameter = new EncoderParameter(myEncoder, 25L);
myEncoderParameters.Param[0] = myEncoderParameter;
myBitmap.Save("Shapes025.jpg", myImageCodecInfo, myEncoderParameters);
// Save the bitmap as a JPEG file with quality level 50.
myEncoderParameter = new EncoderParameter(myEncoder, 50L);
myEncoderParameters.Param[0] = myEncoderParameter;
myBitmap.Save("Shapes050.jpg", myImageCodecInfo, myEncoderParameters);
// Save the bitmap as a JPEG file with quality level 75.
myEncoderParameter = new EncoderParameter(myEncoder, 75L);
myEncoderParameters.Param[0] = myEncoderParameter;
myBitmap.Save("Shapes075.jpg", myImageCodecInfo, myEncoderParameters);
}
// 编解码器信息
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;
}
}
希望这有帮助..
于 2012-06-05T09:53:21.840 回答
2
试试这个:
public static class BitmapExtension
{
public static void Save(this Bitmap bitmap, String fileName, ImageFormat imageFormat, long quality = 75L)
{
using (var encoderParameters = new EncoderParameters(1))
using (encoderParameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality))
{
ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();
bitmap.Save(fileName, codecs.Single(codec => codec.FormatID == imageFormat.Guid), encoderParameters);
}
}
}
...
Bitmap bitmap = new Bitmap("myImage.bmp");
bitmap.Save("myImage.jpg", ImageFormat.Jpeg, 50L);
于 2015-09-10T14:31:26.273 回答