NSImage *picture = [[NSImage alloc] initWithContentsOfFile:@"bais2.tif"]; //file is located in resoureces folder.
NSBitmapImageRep *imageRep = [[picture representations] objectAtIndex:0];

NSColor* color = [imageRep colorAtX:10 y:10];
NSLog(@"%f %f, %f", [color redComponent], [color blueComponent], [color greenComponent]);

NSBitmapImageRep* imageRep = [[NSBitmapImageRep alloc] initWithData:[picture TIFFRepresentation]];

NSImage *picture = [[NSImage alloc] initWithContentsOfFile:@"bais2.tif"];
-------------------------------------------------------------------^^^^

NSImage *picture= [NSImage imageNamed:@"bais2.tiff"];

NSImage *picture = [[NSImage alloc] initWithContentsOfFile:@"bais2.tiff"];

NSData *someNSData = [Image TIFFRepresentation];
 NSBitmapImageRep *someNSBitmapImageRepData = [[NSBitmapImageRep alloc] initWithData:someNSData];
 NSSize imageSizee = [someNSBitmapImageRepData size];

 CGFloat y = imageSize.height - 100.0;
 NSColor* color = [someNSBitmapImageRepData colorAtX:100.0 y:y];

 NSLog(@"color = %@",color);

[yourImage lockFocus]; // yourImage is just your NSImage variable
NSColor *pixelColor = NSReadPixel(NSMakePoint(1, 1)); // Or another point
[yourImage unlockFocus];