Creating an NSImage from bitmap data - objective-c

Question

Ok, it appears that the I'm creating a PDFDocument where pixelWidth is incorrect in the images that I created. So the question becomes: How do I get the correct resolution into the image?
I start with bitmap data from a scanner. I'm doing this:
CGDataProviderRef provider= CGDataProviderCreateWithData(NULL (UInt8*)data, bytesPerRow * length, NULL);
CGImageRef cgImg = CGImageCreate (
width,
length,
bitsPerComponent,
bitsPerPixel,
bytesPerRow,
colorspace,
bitmapinfo, // ? CGBitmapInfo bitmapInfo,
provider, //? CGDataProviderRef provider,
NULL, //const CGFloat decode[],
true, //bool shouldInterpolate,
kCGRenderingIntentDefault // CGColorRenderingIntent intent
);
/* CGColorSpaceRelease(colorspace); */
NSData* imgData = [NSMutableData data];
CGImageDestinationRef dest = CGImageDestinationCreateWithData
(imgData, kUTTypeTIFF, 1, NULL);
CGImageDestinationAddImage(dest, cgImg, NULL);
CGImageDestinationFinalize(dest);
NSImage* img = [[NSImage alloc] initWithData: imgData];
there doesn't appear to be anywhere in there to include the actual width/height in inches or points, nor the actual resolution, which I DO know at this point... how am I supposed to do this?

Answer 1

If you've got a chunk of data, the easiest way to turn it into an NSImage is to use NSBitmapImageRep. Specifically something like:
NSData * byteData = [NSData dataWithBytes:data length:length];
NSBitmapImageRep * imageRep = [NSBitmapImageRep imageRepWithData:byteData];
NSSize imageSize = NSMakeSize(CGImageGetWidth([imageRep CGImage]), CGImageGetHeight([imageRep CGImage]));
NSImage * image = [[NSImage alloc] initWithSize:imageSize];
[image addRepresentation:imageRep];
...use image

Answer 2

Hope this will be helpful
size_t bufferLength = width * height * 4;
CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, data, bufferLength, NULL);
size_t bitsPerComponent = 8;
size_t bitsPerPixel = 32;
size_t bytesPerRow = 4 * width;
CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedLast;
CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault;
CGImageRef iref = CGImageCreate(width,
height,
bitsPerComponent,
bitsPerPixel,
bytesPerRow,
colorSpaceRef,
bitmapInfo,
provider, // data provider
NULL, // decode
YES, // should interpolate
renderingIntent);
_image = [[NSImage alloc] initWithCGImage:iref size:NSMakeSize(width, height)];

Answer 3

version with channel not 4:
size_t bufferLength = width * height * channel;
CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, data, bufferLength, NULL);
size_t bitsPerComponent = 8;
size_t bitsPerPixel = bitsPerComponent * channel;
size_t bytesPerRow = channel * width;
CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedLast;
if(channel < 4) {
bitmapInfo = kCGBitmapByteOrderDefault | kCGImageAlphaNone;
}
CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault;
CGImageRef iref = CGImageCreate(width,
height,
bitsPerComponent,
bitsPerPixel,
bytesPerRow,
colorSpaceRef,
bitmapInfo,
provider, // data provider
NULL, // decode
YES, // should interpolate
renderingIntent);
_image = [[NSImage alloc] initWithCGImage:iref size:NSMakeSize(width, height)];