Folks,
I'm having an issue where CMYK images aren't being recognized by my
quartz compositions, so I need to convert them to RGB for display.
I've written a routine to do it, but its causing problems.
NSImageRep* theImageRep = [inputImage bestRepresentationForDevice:
[NSDictionary dictionaryWithObject: NSDeviceRGBColorSpace
forKey
: NSDeviceColorSpaceName]];
NSString* theColorSpace = [theImageRep colorSpaceName];
if ([theColorSpace isEqualToString: NSDeviceCMYKColorSpace])
{
NSBitmapImageRep* theRGBImageRep = [[[NSBitmapImageRep alloc]
initWithBitmapDataPlanes: NULL
pixelsWide
: [theImageRep pixelsWide]
pixelsHigh
: [theImageRep pixelsHigh]
bitsPerSample
: 8
samplesPerPixel
: 4
hasAlpha
: YES
isPlanar
: NO
colorSpaceName
: NSDeviceRGBColorSpace
bytesPerRow
: 0
bitsPerPixel
: 0] autorelease];
[inputImage lockFocus];
NSGraphicsContext* theContext = [NSGraphicsContext
graphicsContextWithBitmapImageRep: theRGBImageRep];
[NSGraphicsContext saveGraphicsState];
[NSGraphicsContext setCurrentContext: theContext];
NSRect theBoundsRect = NSMakeRect(0.0, 0.0, [theRGBImageRep
pixelsWide], [theRGBImageRep pixelsHigh]);
[[NSColor clearColor] set];
NSRectFill(theBoundsRect);
[theImageRep drawInRect: theBoundsRect];
[NSGraphicsContext restoreGraphicsState];
[inputImage unlockFocus];
ASSIGNOBJECT(rgbImage, [[[NSImage alloc] initWithSize:
[theImageRep size]] autorelease]);
[rgbImage addRepresentation: theRGBImageRep];
}
else
{
ASSIGNOBJECT(rgbImage, inputImage);
}
The resulting image is correct, but somewhere along the line, my
original image (inputImage) is being modified - the CMYK
representation is being removed, and replaced with a downsampled RGB
representation. The goal here was to leave inputImage unmodified, so
that when it is finally sent to the printer, the CMYK representation
would be used.
inputImage before creating the RGB version.
NSImage 0x12313dd0 Size={340.08, 340.08} Reps=(
NSBitmapImageRep 0xd8201c0 Size={340.08, 340.08}
ColorSpace=NSDeviceCMYKColorSpace BPS=8 BPP=32 Pixels=1417x1417
Alpha=NO Planar=NO Format=0
)
inputImage after creating the RGB version.
NSImage 0x12313dd0 Size={340.08, 340.08} Reps=(
NSCachedImageRep 0xd824530 Size={340, 340}
ColorSpace=NSCalibratedRGBColorSpace BPS=8 Pixels=340x340 Alpha=NO
)
Clearly, I'm doing something wrong. I added calls to [inputImage
lockFocus] and [inputImage unlockFocus] in order to resolve a multi-
thread problem, but that seems to have caused this problem.
So, what's the best way for me to convert an NSImage of unknown
pedigree to a simple RGB representation?
Thanks,
Ron Aldrich
Software Architects, Inc.
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