CODEWITHSUNDEEP
androidimage-processingrenderscript
InquisitiveCoder
InquisitiveCoder

Reputation: 171

Need help getting pixel location for Android Renderscript

I am working with Android Renderscript to analyze preview frames received from Camera2API. I intend to analyze each pixel and based on some rules(dependent on intensity and location of the pixel) I need to update a counter. I intend to use a ForEach loop but how do I get the pixel coordinates.

An example java loop would be.

 for (int i = 0; i < 240; i++)
        {
            for (int j = 0; j < 320; j++)
            {
                tempPixelIntensity =  image.getPixel(i,j);
                x = i;
                y = j ;
                if(tempPixelIntensity=zzz&x<zzzandy<zzz)
                {
                     counter++;
                }
            }
        }

How would I go about doing the same in a renderscript? Thanks

Upvotes: 0

Views: 405

Answers (1)

sakridge
sakridge

Reputation: 578

You might try something like this:

#pragma rs_fp_relaxed   // needed for some GPUs
uint32_t counter;
void RS_KERNEL process(uchar tempPixelIntensity, uint32_t x, uint32_t y)
{
    if(tempPixelIntensity=zzz&x<zzzandy<zzz)
    {
        rsAtomicInc(&counter);
    }
}

RS kernels are SPMD (single program multiple data). So you write only the inner part of your loop for a single pixel element and the framework does the looping.

In the java side you will do something like:

 Type.Builder tb = new Type.Builder(rs, Element.U8(rs));
 tb.setX(320);
 tb.setY(240);
 Allocation input = Allocation.createTyped(rs, tb.create(), Allocation.USAGE_SCRIPT);
 script.forEach_process(input);

So the dimensions of the input allocation determines the bounds that the kernel will operate over. In this case x will vary from [0,319] and y will vary from [0,239]. The x,y parameters to the kernel are special parameters that are filled in by the RS runtime, similarly the tempPixelIntensity value will be populated by the value of the input allocation pixel at the given x,y coordinate.

Upvotes: 3

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