I have a c# program that opens a .tif image and later offers the option to save it. However, there is always a drop in quality when saving the image.
I passed some parameters while saving the image so that the quality is at 100 % and there is no compression, but the number of actual unique colors go from 254 (in the original image) to 16(in the saved image) with a clear loss in quality/information, even though the image properties show 8bpp. Displaying the image in a picturebox also shows reduced quality, so I am thinking that the problem is opening the image but so far, I haven't been able to resolve the issue
How do I avoid this?
Here's the code for opening the image:
public Image imageImport(){
Stream myStream = null;
OpenFileDialog openTifDialog = new OpenFileDialog();
openTifDialog.Title = "Open Desired Image";
openTifDialog.InitialDirectory = @"c:\";
openTifDialog.Filter = "Tiff only (*.tif)|*.tif";
openTifDialog.FilterIndex = 1;
openTifDialog.RestoreDirectory = true;
if (openTifDialog.ShowDialog() == DialogResult.OK)
{ try
{
if ((myStream = openTifDialog.OpenFile()) != null)
{
using (myStream)
{
String tifFileName= openTifDialog.FileName;
imgLocation = tifFileName;
Bitmap tifFile = new Bitmap(tifFileName);
return tifFile;
}
}
}
catch (Exception ex)
{
MessageBox.Show("Error: Could not read file from disk. Original error: " + ex.Message);
}
}
return null;
}
This is the way I save the image:
private void saveImage(Image img){
SaveFileDialog sf = new SaveFileDialog();
sf.Title = "Select File Location";
sf.Filter = " bmp (*.bmp)|*.bmp|jpeg (*.jpg)|*.jpg|tiff (*.tif)|*.tif";
sf.FilterIndex = 4;
sf.RestoreDirectory = true;
sf.ShowDialog();
// If the file name is not an empty string open it for saving.
if (sf.FileName != "")
{
// Saves the Image via a FileStream created by the OpenFile method.
System.IO.FileStream fs =
(System.IO.FileStream)sf.OpenFile();
// Saves the Image in the appropriate ImageFormat based upon the
// File type selected in the dialog box.
// NOTE that the FilterIndex property is one-based.
switch (sf.FilterIndex)
{
case 1:
img.Save(fs,
System.Drawing.Imaging.ImageFormat.Bmp);
break;
case 2:
img.Save(fs,
System.Drawing.Imaging.ImageFormat.Jpeg);
break;
case 3://only one i am currently using
ImageCodecInfo codecInfo = ImageClass.GetEncoderInfo(ImageFormat.Tiff);
EncoderParameters parameters = new EncoderParameters(2);
parameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality,100L);
parameters.Param[1] = new EncoderParameter(System.Drawing.Imaging.Encoder.Compression, (long)EncoderValue.CompressionNone);
img.Save(fs,codecInfo, parameters);
break;
}
fs.Close();
}
}
Even if I don't resize or change the image in any ways, I experience a loss in quality. any advice?
