I have issues with the 100% view in PS CC (currently 2015.1.2) on iMac 5k: images in 100% view seem to be visibly less sharp than they really are, e.g. when viewing that same image in other viewers or photo editors including Apple's Preview, Affinity Photo or Capture One Pro 9 (used to display a JPEG image, of course).
issue seems to be with Photoshop, as even in its own dialog boxes the
100% previews are visibly sharper than the main image window. For example "Image Size" or the sharpen dialogs with "preview"
active - the small previews in the dialogs are different (sharper) from
the main window.
zooming in to 200% and viewing from a little bit farther away also
gives the fully sharp impression, so the information is there, it's just
Seems like PS does not really do a 1:1 pixel mapping in
100% view but some kind of pixel doubling or interpolation. This makes it difficult to assess sharpness in PS.