C#给图片加水印文字后整个图片质量上降

C#给图片加水印文字后整个图片质量下降
我在ASP.NET中动态给JPG图片加水印 文字，这个目标已经实现，但是保存之后发现，加了水印的图片对比原图片模糊很多，本来的图片层次分明，很漂亮，加了水印后只能用凑合来形容，虽然能看清，但是不能满足视觉需要。

网上找了很多资料，大部分都是说怎么保证缩略图的质量，可我的图片处理前后大小没有改变，所以不存在缩略图

相信肯定有让图片处理后质量不下降 的高招，恳请大虾们赐教！！谢谢！

目标：C#处理JPG图片前后，保持图片质量不降低[size=16px][/size]

[解决办法]
C#图片水印类 
using System; 
using System.Collections.Generic; 
using System.Text; 
using System.Drawing; 
using System.IO; 
using System.Drawing.Drawing2D; 
using System.Drawing.Imaging; 
namespace ECHX.BLL 
{ 
/// <summary> 
/// WaterMark 的摘要说明 
/// </summary> 
/// 
/// <param name="strCopyright">要加入的文字 </param> 
/// <param name="strMarkPath">水印图片路径 </param> 
/// <param name="strPhotoPath">要加水印的图片路径 </param> 
/// <param name="strSavePath">处理后的图片路径 </param> 
/// <param name="iMarkRightSpace">水印在修改图片中距左边的宽度 </param> 
/// <param name="iMarkButtomSpace">水印在修改图片中距底部的高度 </param> 
/// <param name="iDiaphaneity">水印图片的透明度 </param> 
/// <param name="iFontRightSpace">文字 </param> 
/// <param name="iFontButtomSpace">文字 </param> 
/// <param name="iFontDiaphaneity">文字 </param> 
/// <param name="bShowCopyright">是否显示文字 </param> 
/// <param name="bShowMarkImage">是否显示水印图片 </param> 

public class WaterMark 
{ 
#region param 
private string strCopyright,strMarkPath,strPhotoPath,strSavePath; 
private int iMarkRightSpace, iMarkButtomSpace, iDiaphaneity; 
private int iFontRightSpace = 0, iFontButtomSpace = 0, iFontDiaphaneity=80; 
private int iFontSize = 10; 
private bool bShowCopyright=true, bShowMarkImage=true; 
#endregion 

#region WaterMark 
public WaterMark() 
{ 
this.strCopyright = ""; 
this.strMarkPath = null; 
this.strPhotoPath = null; 
this.strSavePath = null; 
this.iDiaphaneity = 70; 
this.iMarkRightSpace = 0; 
this.iMarkButtomSpace = 0; 
} 

/// <summary> 
/// 主要用两样都加的 
/// </summary> 
public WaterMark(string copyright,string markPath,string photoPath,string savePath) 
{ 
this.strCopyright = copyright; 
this.strMarkPath = markPath; 
this.strPhotoPath = photoPath; 
this.strSavePath = savePath; 
this.iDiaphaneity = 70; 
this.iMarkRightSpace = 0; 
this.iMarkButtomSpace = 0; 
} 
#endregion 

#region property 

/// <summary> 
/// 设置是否显示水印文字 
/// </summary> 
public bool ShowCopyright 
{ 
set { this.bShowCopyright = value; } 
} 

/// <summary> 
/// 设置是否显示水印图片 
/// </summary> 
public bool ShowMarkImage 
{ 
set { this.bShowMarkImage = value; } 
} 

/// <summary> 
/// 获取或设置要加入的文字 
/// </summary> 
public string Copyright 
{ 
set { this.strCopyright = value; } 
} 

/// <summary> 
/// 获取或设置加水印后的图片路径 
/// </summary> 
public string SavePath 
{ 
get { return this.strSavePath; } 
set { this.strSavePath = value; } 
} 

/// <summary> 
/// 获取或设置水印图片路径 
/// </summary> 
public string MarkPath 
{ 
get { return this.strMarkPath; } 
set { this.strMarkPath = value; } 
} 

/// <summary> 
/// 获取或设置要加水印图片的路径 
/// </summary> 
public string PhotoPath 
{ 
get { return this.strPhotoPath; } 
set { this.strPhotoPath = value; } 
} 

/// <summary> 
/// 设置水印图片的透明度 
/// </summary> 
public int Diaphaneity 
{ 
set { 
if(value > 0 && value <= 100) 
this.iDiaphaneity = value; 
} 
} 

/// <summary> 
/// 设置水印字体的透明度0-255 
/// </summary> 
public int FontDiaphaneity 
{ 
set 
{ 
if (value >= 0 && value <= 255) 
this.iFontDiaphaneity = value; 
} 
} 

/// <summary> 
/// 设置水印图片在修改图片中距左边的高度 
/// </summary> 
public int MarkRightSpace 
{ 
set { this.iMarkRightSpace = value; } 
} 

/// <summary> 
/// 设置水印图片在修改图片中距底部的高度 
/// </summary> 
public int MarkButtomSpace 
{ 
set { this.iMarkButtomSpace = value; } 
} 

/// <summary> 
/// 设置水印字体在修改图片中距左边的距离 
/// </summary> 
public int FontRightSpace 
{ 
set { iFontRightSpace = value; } 
} 

/// <summary> 
/// 设置水印字体在修改图片中距底部的高度 
/// </summary> 
public int FontButtomSpace 
{ 
set { iFontButtomSpace = value; } 
} 

#endregion 


/// <summary> 
/// 生成水印图片 
/// </summary> 
/// <returns> </returns> 
public void createMarkPhoto() 
{ 
Bitmap bmWatermark = null; 
Image gPhoto = Image.FromFile(this.strPhotoPath); 
int PhotoWidth = gPhoto.Width; 
int PhotoHeight = gPhoto.Height; 
Bitmap bitPhoto = new Bitmap(PhotoWidth, PhotoHeight,PixelFormat.Format24bppRgb); 
bitPhoto.SetResolution(gPhoto.HorizontalResolution,gPhoto.VerticalResolution); 

try 
{ 
if (bShowCopyright) 
{ 
Graphics grPhoto = Graphics.FromImage(bitPhoto); 
grPhoto.SmoothingMode = SmoothingMode.AntiAlias; 

grPhoto.DrawImage(gPhoto, new Rectangle(0, 0, PhotoWidth, PhotoHeight), 0, 0, PhotoWidth, PhotoHeight, GraphicsUnit.Pixel); 

Font crFont = new Font("楷体", iFontSize, FontStyle.Bold); 
SizeF crSize = grPhoto.MeasureString(strCopyright, crFont); 

//设置字体在图片中的位置 
float yPosFromBottom = PhotoHeight - iFontButtomSpace - (crSize.Height); 

//float xCenterOfImg = (phWidth/2); 
float xCenterOfImg = PhotoWidth - iFontRightSpace - (crSize.Width / 2); 
//设置字体居中 

StringFormat StrFormat = new StringFormat(); 
StrFormat.Alignment = StringAlignment.Center; 

//设置绘制文本的颜色和纹理 (Alpha=153) 
SolidBrush semiTransBrush2 = new SolidBrush(Color.FromArgb(this.iFontDiaphaneity, 0, 0, 0)); 

//将版权信息绘制到图象上 
grPhoto.DrawString(strCopyright, crFont, semiTransBrush2, new PointF(xCenterOfImg, yPosFromBottom), StrFormat); 

gPhoto = bitPhoto; 
grPhoto.Dispose(); 
} 



if (bShowMarkImage) 
{ 
//创建一个需要填充水银的Image对象 
Image imgWatermark = new Bitmap(strMarkPath); 
int iMarkWidth = imgWatermark.Width; 
int iMarkmHeight = imgWatermark.Height; 

Graphics grWatermark = null; 
if (bShowCopyright) 
{ 
//在原来修改过的bmPhoto上创建一个水银位图 
bmWatermark = new Bitmap(bitPhoto); 
bmWatermark.SetResolution(gPhoto.HorizontalResolution, gPhoto.VerticalResolution); 
} 
else 
{ 
bmWatermark = new Bitmap(gPhoto); 
} 

//将位图bmWatermark加载到Graphics对象 
grWatermark = Graphics.FromImage(bmWatermark); 
ImageAttributes imageAttributes = new ImageAttributes(); 

ColorMap colorMap = new ColorMap(); 

colorMap.OldColor = Color.FromArgb(255, 0, 255, 0); 
colorMap.NewColor = Color.FromArgb(0, 0, 0, 0); 

ColorMap[] remapTable = { colorMap }; 

imageAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap); 

float[][] colorMatrixElements = { 
new float[] {1.0f, 0.0f, 0.0f, 0.0f, 0.0f}, 
new float[] {0.0f, 1.0f, 0.0f, 0.0f, 0.0f}, 
new float[] {0.0f, 0.0f, 1.0f, 0.0f, 0.0f}, 
new float[] {0.0f, 0.0f, 0.0f, (float)iDiaphaneity/100f, 0.0f}, 
new float[] {0.0f, 0.0f, 0.0f, 0.0f, 1.0f}}; 
ColorMatrix wmColorMatrix = new ColorMatrix(colorMatrixElements); 

imageAttributes.SetColorMatrix(wmColorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap); 

grWatermark.DrawImage(imgWatermark, new Rectangle((PhotoWidth - iMarkRightSpace - (iMarkWidth / 2)), (PhotoHeight - iMarkButtomSpace - (iMarkmHeight/2)), iMarkWidth, iMarkmHeight), 0, 0, iMarkWidth, iMarkmHeight, GraphicsUnit.Pixel, imageAttributes); 

gPhoto = bmWatermark; 
grWatermark.Dispose(); 

imgWatermark.Dispose(); 
} 
gPhoto.Save(strSavePath, ImageFormat.Jpeg); 
} 
finally 
{ 

if (bitPhoto!=null) 
bitPhoto.Dispose(); 

if (bmWatermark != null) 
bmWatermark.Dispose(); 

gPhoto.Dispose(); 
} 

} 
} 
} 

[解决办法]
帮顶
[解决办法]
到我的资源里下一个，bitmap -> int[,,], int[,,] -> image,在数组中对水印进行操作，然后再转换成 Image,效果应该好得多，我BLOG上的内容全是这样操作出来然后转换成最终图像的，如果内容不变，它的质量没有损失
[解决办法]
没有做过这方面的东西，顶一个吧
[解决办法]
没有见过加了水印就变模糊的.
你把加水印的源代码发出来看看.
[解决办法]
一般的加水印就直接是在原图上画东西，应该不会变模糊吧
[解决办法]
不会C#
grPhoto.SmoothingMode = SmoothingMode.AntiAlias
这句代码的作用是让合成模式为自动反锯齿,也就是所谓的"模糊"
你把这句去掉.
另外,在定义新画布时不要定义位深度,这样才能保持原图的色彩.
就是这句里面的加粗地方也去掉:
Bitmap bitPhoto = new Bitmap(PhotoWidth, PhotoHeight,PixelFormat.Format24bppRgb)；

代码其他地方没什么异常.
[解决办法]
bitPhoto.Save(Response.OutputStream, ImageFormat.Jpeg)；
图像保存的问题，默认的质量是60%

EncoderParameter p;
EncoderParameters ps;

ps = new EncoderParameters(1);

p = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
ps.Param[0] = p;

ImageCodecInfo ii = GetCodecInfo("image/jpeg");
bitPhoto.SaveResponse.OutputStream,ii,ps);

private ImageCodecInfo GetCodecInfo(string mimeType)
{
ImageCodecInfo[] CodecInfo = ImageCodecInfo.GetImageEncoders();
foreach (ImageCodecInfo ici in CodecInfo)
{
if (ici.MimeType == mimeType) return ici;
}
return null;
}