Hi,

If you are using Leopard (10.5), you could do something like this:

CIImage* imageBlurred = .....
NSBitmapImageRep* bitmap = [[[NSBitmapImageRep alloc] initWithCIImage: imageBlurred] autorelease];

// Getting pixels data
// this returns a pointer to the pixel data
[bitmap bitmapData]

regards
Nikolai Hellwig


Am 13.05.2008 um 03:06 schrieb Bridger Maxwell:

Hey,
I am trying as hard as I can to get pixel data from a CIImage, but am
failing, pretty miserably. I am using
render:toBitmap:rowBytes:bounds:format:colorSpace: from CIContext and
it seems to work, but doesn't really. I get data in my int*
pointer, but it never changes! What am I doing wrong? I posted my
code. The part in need of assistance is near the bottom of
(void)captureOutput. I would greatly appreciate your help.


Thank You,
Bridger Maxwell



- (void)captureOutput:(QTCaptureOutput *)captureOutput
didOutputVideoFrame:(CVImageBufferRef)videoFrame
withSampleBuffer:(QTSampleBuffer *)sampleBuffer
fromConnection:(QTCaptureConnection *)connection

{

CIImage* image = [CIImage imageWithCVImageBuffer:videoFrame];



[monoChromeFilter setValue:image forKey:@"inputImage"];  //First we
monochrome it (only black and white

//[smoothingFilter setValue:[monoChromeFilter
valueForKey:@"outputImage"] forKey:@"inputImage"];



if (needsNewBackground) { //If the flag has been raised we will
capture a new background

[backgroundFilter setValue:[monoChromeFilter
valueForKey:@"outputImage"] forKey:@"inputBackgroundImage"];

if (videoDeviceInput) {

needsNewBackground = NO;

}

}



[backgroundFilter setValue:[monoChromeFilter
valueForKey:@"outputImage"] forKey:@"inputImage"]; //Now we subtract
the background from the monochrome image

[colorCorrectionFilter setValue:[backgroundFilter
valueForKey:@"outputImage"] forKey:@"inputImage"];

CIImage* finalImage = [colorCorrectionFilter valueForKey:@"outputImage"];

size_t rowBytes = [self optimalRowBytesForWidth:[finalImage
extent].size.width bytesPerPixel:4];

int* imageData;

[[[NSGraphicsContext currentContext] CIContext] render:finalImage

  toBitmap:imageData rowBytes:rowBytes

bounds:[finalImage extent]

format:kCIFormatARGB8

colorSpace:CGColorSpaceCreateWithName(kCGColorSpaceGenericGray)];



blobDetector->computeBlobs(imageData);

NSLog(@"On Frame %i there are %i blobs. Sample byte 5:
%i",frameCount++,blobDetector->getBlobNb(),imageData[19]);



[outputView setImage:finalImage];

[outputView setNeedsDisplay:YES];

//CIContext* theContext = [outputView ciContext];

}




- (void) drawBlobsOnCIImage:(CIImage *)image {

for (int n=0 ; n< blobDetector->getBlobNb() ; n++)

{

*blob = blobDetector->getBlob(n);

if (blob->isOk())

{

NSRect rectangle = NSMakeRect(blob->xMin, blob->yMin, blob->xMax -
blob->xMin , blob->yMax - blob->yMin);

}

}



}




- (size_t)optimalRowBytesForWidth: (size_t)width bytesPerPixel:
(size_t)bytesPerPixel

{

   size_t rowBytes = width * bytesPerPixel;



   //Widen rowBytes out to a integer multiple of 16 bytes

   rowBytes = (rowBytes + 15) & ~15;



   //Make sure we are not an even power of 2 wide.

   //Will loop a few times for rowBytes <= 16.

   while( 0 == (rowBytes & (rowBytes - 1) ) )

       rowBytes += 16;



   return rowBytes;

}
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