Image resizing efficiency in C# and .NET 3.5

Question

I have written a web service to resize user uploaded images and all works correctly from a functional point of view, but it causes CPU usage to spike every time it is used.

Answer 1

I know that the DirectX being released with Windows 7 is said to provide 2D hardware acceleration. Whether this implies it will beat out GDI+ on this kind of operation, I don't know. MS has a pretty unflattering description of GDI here which implies it is slower than it should be, among other things.

If you really want to try to do this kind of stuff yourself, there is a great GDI Tutorial that shows it. The author makes use of both SetPixel and "unsafe blocks," in different parts of his tutorials.

As an aside, multi-threading will probably help you here, assuming your server has more than one CPU. That is, you can process more than one image at once and probably get faster results.