Mark S, thanks for posting the notice about the Aardenburg Imaging MonitorChecker target.
I've beeen following this thread to see if there was any improvement that could be made to this latest version of the Aardenburg MonitorChecker PSD File. I built it in PSCC thinking it would also be compatible with PS6. In view of some of the comments about warnings popping up in non PSCC versions of photoshop, I went back to a CS6 copy of photoshop I still have on an older Mac in my studio to see check out the backwards compatibility issues. As others have noted a warning sign did pop up, which if navigated with the appropriate choice gives a fully functional MonitorChecker PSD file with the needed layers, but the other choice offered does flatten the file rendering it useless.
Conversely, by saving the MonitorChecker PSD file in CS6, the file still opens seamlessly into PSCC, so I've gone ahead and replaced the MonitorChecker PSD download file on the Aardenburg website with a copy that is more seamlessly backwards compatible to PS CS6. Such is life in this rapidly evolving digital age! For website link consistency reasons, I did not iterate the version name, but for those on PS CS6, if you download again, you should now get a file that opens without any warning. For folks using photoshop versions older than CS6, there are indeed likely to be some text substitution issues as well, but you still may be able to get the file to work correctly even if the text is altered somewhat. I can't easily test for any PS versions older than PSCS6.
Also, for anyone using Photoshop Elements, you are out of luck since the Elements doesn't fully support LAB and will insist on converting LAB to RGB thus requiring a flattening move
Lastly, don't expect pure perfection in the gamma square layer, but on a high-end monitor it's going to be really really close when you back away far enough from the screen so as not be able to resolve the interlace lines in the target. On a lesser display like a Macbook Pro Retina laptop that is nevertheless instrument calibrated (e.g. i1 display Pro 2, Spyder 5, basicColor, etc), it will also be quite good but definitely not quite as good as a high-end monitor. This role of overall monitor quality is what motivated me to create the first version of the MonitorChecker PSD file in the first place over ten years ago. Essentially, I wanted to know how calibrated is calibrated. Trust but verify
cheers,
Mark
http://www.aardenburg-imaging.com