Image.FromFile alternative

[AdeHall]

Im trying to load multiple jpegs from disk to create thumbnails. Ive 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]

Youre 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 cant 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]

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

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

Dont 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?