It is obvious that HTC simply exactly the same screen as used in the M8, but that is not the case. For reasons we do not understand is the manufacturer went for another panel that produces noticeably less beautiful picture. For example, the brightness is lower, although the difference is not large. With a maximum brightness of 474cd / m² of M9 screen is fortunately still bright enough to be still visible in the air.
If we look at the contrast ratio of the screen, we see a big difference. Where the M8 a ratio of 1624: 1 makes note, an excellent score for an LCD, the M9 does not exceed 911: 1. That is to see if you like both devices side by side; the image of the M8 look more impressive. Especially in a dark environment can be seen that the black on the M8 is much deeper; the M9 tends a bit more to very dark gray with a blue touch. Look you then even at an oblique angle to the screen, we see clear color shifting, something we expected earlier in cheaper phones.