Re: What is CIImageAccumulator?

I have not used CIAccumulator for painting specifically, but it is very useful for feedback effects, where you can draw over a frame many times. You can do this sans the CIAcumulator, but (at least when I have done it) its resulted in rapid loss of Vram for whatever reasons, due to the inner workings of Core Image and I suspect its garbage collection (this is a guess).

I use a CIAcumulator here to provide feedback (this is in Quartz Composer). The output of the effect is fed back into a mixer where the it is fed back into the input of the effect, creating a feedback loop responsible for much of the distortions.

http://www.vimeo.com/3951567

You can also peruse

/Developer/Examples/Quartz Composer/Compositions/Feedback/ yourself to get a handle on how a CIAccumulator is used, and play with the results in realtime using QC.

On Apr 1, 2009, at 5:34 PM, Carmen Cerino Jr. wrote:

I stumbled upon this guy in a few example projects, but his documentations is sort of vague. I get that he would be useful in situations where you would want to iteratively edit an image, ie a paint canvas. I guess the issue I am struggling with is why not just use a CIImage?  The pattern in most examples goes: get your image out of the accumulator, apply your filters, place it into the accumulator, using a CIContext draw the image stored in the accumulator in a view. Why do you need to stuff the image into an accumulator in between iterations? There is probably something I am missing about the Core Image pipeline that makes him crucial to this process. Clarification would be much appreciated.

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