C# 图片压缩 。

[mc_dv]

/// <summary>
/// 无损压缩图片
/// </summary>
/// <param name="sFile">原图片</param>
/// <param name="dFile">压缩后保存位置</param>
/// <param name="dHeight">高度</param>
/// <param name="dWidth"></param>
/// <param name="flag">压缩质量 1-100</param>
/// <returns></returns>
public static bool GetPicThumbnail(string sFile, string dFile, int dHeight, int dWidth, int flag, string newname, int hid)
{
System.Drawing.Image iSource = System.Drawing.Image.FromFile(sFile);
ImageFormat tFormat = iSource.RawFormat;
int sW = 0, sH = 0;
//按比例缩放
Size tem_size = new Size(iSource.Width, iSource.Height);
if (tem_size.Width > dHeight || tem_size.Width > dWidth) //将**改成c#中的或者操作符号
{
if ((tem_size.Width * dHeight) > (tem_size.Height * dWidth))
{
sW = dWidth;
sH = (dWidth * tem_size.Height) / tem_size.Width;
}
else
{
sH = dHeight;
sW = (tem_size.Width * dHeight) / tem_size.Height;
}
}
else
{
sW = tem_size.Width;
sH = tem_size.Height;
}
Bitmap ob = new Bitmap(dWidth, dHeight);
Graphics g = Graphics.FromImage(ob);
g.Clear(Color.WhiteSmoke);
g.CompositingQuality = CompositingQuality.HighQuality;
g.SmoothingMode = SmoothingMode.HighQuality;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.DrawImage(iSource, new Rectangle((dWidth - sW) / 2, (dHeight - sH) / 2, sW, sH), 0, 0, iSource.Width, iSource.Height, GraphicsUnit.Pixel);
g.Dispose();
//以下代码为保存图片时，设置压缩质量
EncoderParameters ep = new EncoderParameters();
long[] qy = new long[1];
qy[0] = flag;//设置压缩的比例1-100
EncoderParameter eParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, qy);
ep.Param[0] = eParam;
try
{
ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();
ImageCodecInfo jpegICIinfo = null;
for (int x = 0; x < arrayICI.Length; x++)
{
if (arrayICI[x].FormatDescription.Equals("JPEG"))
{
jpegICIinfo = arrayICI[x];
break;
}
}
if (!System.IO.Directory.Exists(dFile))
{
System.IO.Directory.CreateDirectory(dFile);
}
if (jpegICIinfo != null)
{
if (hid == 0)
{
if (File.Exists(sFile))
{
iSource.Dispose();
File.Delete(sFile);
}
}
ob.Save(dFile + newname);
//ob.Save(dFile, jpegICIinfo, ep);//dFile是压缩后的新路径
}
else
{
ob.Save(dFile, tFormat);
}
return true;
}
catch (Exception ex)
{
return false;
throw new Exception(ex.Message);
}

finally
{
iSource.Dispose();
ob.Dispose();
}
}

用这个算法, 把552*400的图片压缩成114*89 挺完美,然后体积也小了10多倍 . 但把1650*616 压缩成1200*545 图片体积由130多K变成1.12MB. 图片都是JPG格式. 求解!!!!!

[mc_dv]

压缩质量设什么值都一样 .

[我是飞云]

确定是正常的？连EncoderParameter参数都没进去

//ob.Save(dFile, jpegICIinfo, ep);//dFile是压缩后的新路径 

这句才是关键

[娃都会打酱油了]

你保存的是bmp矢量图啊，你指定下保存结果是jpg呢 Bitmap ob = new Bitmap(dWidth, dHeight);

[myhope88]

估计是存成bmp的了