Image.FromFile alternative

[AdeHall]

I'm trying to load multiple jpegs from disk to create thumbnails. I've tried various ways but the Image.FromFile( path ) or Bitmap aBitmap = new Bitmap( path ) methods seem very slow.

 

The jpegs are about 750k each but it is taking approx 30-40 seconds to load 100.

 

Are there any faster ways to load the data?

Thanks

Ade

[divil]

You're probably running out of memory and having to swap to disk. Are you disposing of each image and any intermediate bitmaps and graphics objects before loading the next?

[AdeHall]

This is a little benchmark prog I tried, to make sure that it was the IO that was taking the time before I do anything with the image.

I ended up forcing the garbage collector because as you say I was running out of memory.

 

When you use one of the commercial photo apps out there they seem to be able to read in and convert the same images in a fraction of the time. Surely .NET can't be making that much difference can it?

 

if ( openFileDialog1.FileNames != null )
			{
				DateTime StartTime = DateTime.Now;
				System.Diagnostics.Debug.WriteLine( "Start:" + StartTime.ToLongTimeString());
									int i=0;
				foreach ( string FileName in openFileDialog1.FileNames )
				{
					i++;
					Bitmap _bitmapNew;
					 _bitmapNew = (Bitmap)Image.FromFile( FileName, false );
										_bitmapNew = null;
					GC.Collect();
					GC.WaitForPendingFinalizers();
				}
				DateTime EndTime = DateTime.Now;
				System.Diagnostics.Debug.WriteLine( "End:" + EndTime.ToLongTimeString());
				System.Diagnostics.Debug.WriteLine( "Loading " + i.ToString() + " Photos took " + (EndTime - StartTime) ) ;
			}
}

[divil]

There's no need to invoke the garbage collector like that. In my last post I said you need to dispose of objects when you're done with them. In that example you're still not doing this.

 

Bitmap _bitmapNew;
_bitmapNew = (Bitmap)Image.FromFile( FileName, false );
_bitmapNew.Dispose();
_bitmapNew = null;

 

Don't worry too much if you see your memory usage increasing - if it becomes a problem, or after a short delay, the garbage collector will collect.

[AdeHall]

Thanks Divil

 

The memory as you say is looking after itself better.

However, it is still taking 45 seconds to load and dispose of 145 jpgs.

 

Do you think 1/3 of a second is a long time to open and load a 700k file from disk?