https://www.microsoft.com/en-us/download/details.aspx?id=8279
<system.diagnostics>
<sources>
<source name="System.ServiceModel" switchValue="Information, ActivityTracing" propagateActivity="true">
<listeners>
<add name="traceListener" type="System.Diagnostics.XmlWriterTraceListener" initializeData="C:\temp\Traces.svclog"/>
</listeners>
</source>
</sources>
</system.diagnostics>
using (Bitmap bmp = new Bitmap(img))
{
if (File.Exists(string.Format(@"{0}\{1}", txtDest.Text, filename)))
{
File.Delete(string.Format(@"{0}\{1}", txtDest.Text, filename));
}
//CodecInfo para imagens Jpeg
ImageCodecInfo codec = ImageCodecInfo.GetImageEncoders().First(enc => enc.FormatID == ImageFormat.Jpeg.Guid);
//EncoderParameters que vai setar o nível de qualidade (compressão)
EncoderParameters imgParams = new EncoderParameters(1);
//Qualidade em 0L = máximo de compressão
imgParams.Param = new[] { new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, Convert.ToInt64( ((ComboboxItem) cmbCompress.SelectedItem).Value) )};
//Salvar a imagem a imagem
bmp.Save(string.Format(@"{0}\{1}", txtDest.Text, filename), codec, imgParams);
txtUpdate.Text += string.Format(PADRAOUPDATE, Path.GetFileNameWithoutExtension(img) , filename);
}