Although I supplied a bitmapFormat =
NSAlphaFirstBitmapFormat +
NSAlphaNonpremultipliedBitmapFormat when I created the
NSBitmapImageRep the returned data after drawing on
the CIContext seems to be of the form RGBA! Any
explanation for this?
Thanks
JJ
--- Joran Joran <email@hidden> wrote:
> 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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