Create Aperture / depth of field effect

How can I create a function that will replicate the effects of different aperture settings. I want the user to be able to click on different 'focal points' of their picture and see how the aperture/开发者_JAVA百科depth of field would change depending on which focal point is in focus.

Also I was curious if anyone knows how to create a slider bar that would create the blurring effect of a low aperture.

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Why not go the simplest route? Set a camera on a tripod, take your pictures with different aperture and focal distance settings. When the user of your app choses a different aperture or focal distance, just swap out the picture to show the depth of field effects. This will save you a lot of trouble, will be authentic, and look much nicer.

You can do this all with 16 pictures (4 focal distances, and 4 aperture settings). Have a slider for the aperture value, and a slider for the focal distance.

If you try to let the user select a point on the picture you'll need to have 3D information available for the scene, and I think this just ramps up the complication of your app. Keep things as simple as possible, because it doesn't take too much to convey the information for your students.

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You need a convolution filter. To get the coefficients for the filter, you can look at the impulse response. If you take an out-of-focus picture of a bright point of light, you get a nearly perfect circle - if you generate a circle and average every pixel inside of it, you'll get a good approximation to an unfocused image.

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That sounds like something you could do with a configurable pixel shader. WPF and Silverlight are capable of that, as well as other open-source image editing libraries.

Read up on High Level Shader Language for more info. There is also a .NET ImageTools library that may help.