Re: [londroid] Android NDK & Image processing

From: Paul de la W.
Sent on: Monday, March 19, 2012 6:24 PM
Hi Neil,

The NDK is one way of doing it. Qualcomm has an library ( https://developer.qualcomm.com/develop/mobile-technologies/computer-vision-fastcv ). I haven't used it extensively, but there must be something to change the colour space, do some changes, and then change it back.

Another way would be to use OpenGL ( http://code.google.com/p/libgdx/ is my favourite here, pure java also) specifically OpenGL 2.0 to use shaders, this would only be applicable if your interested in rendering as there isn't a fast way to read data back from the GPU to the CPU.

I hope those give you a couple of options, if you need any more help I feel free to message me back directly, good luck buddy!

Paul

On Mon, Mar 19, 2012 at 6:16 PM, Neil Glenister <[address removed]> wrote:
Hi all,


I've been pulling my hair out over some problems with an image processing app and wondered if any of you would be able to help/give advice...

The app essentially takes the live camera feed and applies a simple filter to it (e.g. yellow tint). The problem is that it runs far too slow. The app MUST run without any lag at all for it to be usable.

I've been told that the only viable option is to use the NDK (based on info from tight lipped companies who have achieved this) which I have tried and so far I haven't managed to get it to work. What I'm currently trying to do is push the two intensive parts through the NDK:

1/ Converting the camera image format from YUV to RGB
2/ Applying the filters

The filters and YUV>RGB is readily available in Java so it's "simply" a case of porting it to the NDK. I've tried http://nhenze.net/?p=253 but it doesn't work and I can't get a hold of the developer.

I guess my questions are:

a) Has anyone ever used the NDK with image processing?
b) Is there another way that's been tested and proven?

Thanks a lot in advance for any feedback!


Neil

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