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copied!<p>Okay, the added info helps. The problem is not that your program uses too much memory, it uses <em>too little</em>. The garbage collected heap has very little data in it. That's not uncommon for a program that manipulates bitmaps. The Bitmap class is a very small wrapper around GDI+ functions, it uses only a handful of bytes in the GC heap. So you can create an enormous amount of bitmaps before you fill up the gen #0 heap and trigger a garbage collection. This is also visible from Perfmon, you want to look at the .NET CLR Memory, Gen 0 Collections counter. A healthy program triggers a collection about 10 times per second when it is doing work.</p> <p>Not getting collections is fine, but there's something else that doesn't work when there are no collections. The finalizer thread never runs. Finalizers are important to release unmanaged resources other than memory. Like operating system handles and any unmanaged memory pointers held by managed objects. Bitmap has those.</p> <p>First thing to do is to run Taskmgr.exe, Processes tab. Click View + Select Columns and tick Handles, USER objects and GDI objects. Observe these counters while your program is running. If you see one climbing up without bound then you have a problem that could cause GDI+ to generate an OOM exception. GDI objects being the common cause.</p> <p>Carefully review your code and check that you are calling Dispose() on any Image or Bitmap that you no longer use. Beware of the subtle ones, like assigning the Image property of a PictureBox. You'd have to dispose the old one if it isn't null. That's painful of course and it is too easy to miss one. So use a simple strategy, count the number of bitmaps you created and, say, on the hundredth call GC.Collect + GC.WaitForPendingFinalizers() to trigger a collection and a finalizer sweep.</p>

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