Hi everyone,
My first test of CoreImage does not seem to go well. I
tried the motion blur filter using the code bellow;
the camera simulation movement seems correct however
there is an inexplicable (to me of course) shift of
colors: black and red appear blue, green becomes pink,
etc. The image is an RGB with an alpha constant
everywhere (value 255). What am I doing wrong please?
Many thanks
JJ
=================
{
size_t imageWidth, imageHeight; // Known
unsigned char ioData = NULL;
NSBitmapFormat bitmapFormat = NSBitmapFormat(
NSAlphaFirstBitmapFormat +
NSAlphaNonpremultipliedBitmapFormat);
int bitsPerSample = 8;
size_t samplesPerPixel = 4;
size_t bytesPerRow = imageWidth*samplesPerPixel;
size_t bitmapByteCount = bytesPerRow*imageHeight;
ioData = new unsigned char[ bitmapByteCount];
// set ioData here as interleaved ARGB.
CGColorSpaceRef colorSpaceRef =
CGColorSpaceCreateWithName( kCGColorSpaceGenericRGB);
CIImage* inCIImage = [[CIImage alloc]
initWithBitmapData: [NSData dataWithBytesNoCopy:
ioData length: bitmapByteCount freeWhenDone: NO]
bytesPerRow: bytesPerRow size: CGSizeMake(
imageWidth, imageHeight)
format: kCIFormatARGB8 colorSpace:
colorSpaceRef];
CGColorSpaceRelease( colorSpaceRef);
CIFilter* motionBlur = [CIFilter filterWithName:
@"CIMotionBlur"];
[motionBlur setDefaults];
[motionBlur setValue: [NSNumber numberWithFloat:
radius] forKey: @"inputRadius"];
[motionBlur setValue: [NSNumber numberWithFloat:
angleInRadians] forKey: @"inputAngle"];
[filter setValue: inCIImage forKey: @"inputImage"];
CIImage* outCIImage = [filter valueForKey:
@"outputImage"];
// Create a bitmap rep
NSBitmapImageRep* bitmapImageRep = [
[NSBitmapImageRep alloc] initWithBitmapDataPlanes:
NULL
pixelsWide: imageWidth pixelsHigh:
imageHeight
bitsPerSample: bitsPerSample
samplesPerPixel: samplesPerPixel
hasAlpha: YES isPlanar: NO colorSpaceName:
NSDeviceRGBColorSpace
bitmapFormat: bitmapFormat
bytesPerRow: bytesPerRow bitsPerPixel:
(bitsPerSample*samplesPerPixel)
];
// Draw on the bitmapImageRep
NSGraphicsContext* nsgContext = [NSGraphicsContext
graphicsContextWithBitmapImageRep: bitmapImageRep] ;
CGContextRef cgContext = (CGContextRef)[nsgContext
graphicsPort];
CIContext* myCIContext = [CIContext
contextWithCGContext: cgContext options: nil];
[myCIContext drawImage: outCIImage atPoint:
CGPointZero fromRect: CGRectMake( 0, 0, imageWidth,
imageHeight)];
unsigned char* ioData = (unsigned
char*)[bitmapImageRep bitmapData];
// When I do the drawing from ioData here I get this
strange color shift!
[bitmapImageRep release];
[inCIImage release];
}
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