CMYK NSImage gets pixel data
I am loading a CMYK jpeg image into NSImage, How can I extract the c, m, y, k values for a specific pixel? How can I get a byte array with all CMYK pixel data. in RGB images I use .bitmapData but it seems for CMYK images it's all 0xff.
I tried to convert NSImage to RGB color space but didn't like the results .. and I really want c, m, y, k values, not rgb equivalent values
NSImage *image = [[NSImage alloc] initWithContentsOfFile:inputImageString];
NSBitmapImageRep* rep = [NSBitmapImageRep imageRepWithData:[image TIFFRepresentation]];
bool isCMYK = [rep.colorSpaceName isEqualToString: NSDeviceCMYKColorSpace];
const unsigned char *bytes = rep.bitmapData;
// all values at bytes are not weird and does not represent CMYK values
ps I cant use main graphics as this cocoa code is compiled using GNUStep.
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I haven't tested this, but does this code return the correct values?
NSImage *image = [[NSImage alloc] initWithContentsOfFile:inputImageString];
NSBitmapImageRep* rep = [NSBitmapImageRep imageRepWithData:[image TIFFRepresentation]];
bool isCMYK = [rep.colorSpaceName isEqualToString: NSDeviceCMYKColorSpace];
if(isCMYK){
NSColor* aColor = [raw_img colorAtX:0 y:0];
NSString* theColorSpace = [aColor colorSpaceName];
if ([theColorSpace isEqualToString: NSDeviceCMYKColorSpace]){
NSLog(@"C:%f,M%f,Y:%f,K%f",
aColor.cyanComponent,
aColor.magentaComponent,
aColor.yellowComponent,
aColor.blackComponent);
}
}
This should be a good starting point if you want what you want.
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Have you seen this site? Is this close to what you want?
http://oleb.net/blog/2011/05/using-cocoa-to-convert-images-from-rgb-to-cmyk/
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