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HC720 Projector Measurements and Calibration

Posted on October 5, 2008 by Art Feierman
The Epson HC720 is a bit of an odd projector. Overall, in most modes, color temperature (grayscale balance) is very tight from white (100 IRE) down to dark gray (30 IRE). That's a very good thing, and it does this better than almost all of its direct competition. Countering that, however, is that the color temperatures are typically not exactly where they should be. You should expect modes for movie watching to be at D65 (6500K), while modes for TV and sports more in the 7500K to 8000K range. This Epson's color temps were not where they should be.

The first thing to note, however, is that there is a color temperature mode in the menus and directly accessible from the remote. In most cases (Living Room being the noteworthy exception), adjusting the color temperature setting took care of most of the inaccuracy. Of course, I still tuned the individual red green and blue to get even better results. Here's what I found:


Theater Black 1 mode: default settings except color temp dropped from default 7000K to 6500K.

White (100 IRE) 6797K
Light gray (80 IRE) 6938K
Medium gray (50 IRE) 6869K
Low gray (30 IRE) 6963K

All numbers are very close to each other (about as close as any projector gets), but still on avearage over 400K too high.

I then tried dropping color temp to 6000 and that lowered the average temperature to a little more than 6300K. Very good, but a tad warm. My personal belief is that most prefer (for movie watching), that if their projector's color temp is a little off, that it be cooler (blue) rather than too red.

Theater Black 1 final adjustments: Color Temperature 6500K,

Offset Red 5, Green 0, Blue -1
Gain Red 5, Green 0, Bule -1 (yes both sets are the same)

And here are my final measurements for Theater Black 1 based on those settings:

White (100 IRE) 6675K
Light gray (80 IRE) 6524K
Medium gray (50 IRE) 6458K
Low gray (30 IRE) 6522K

I should also note, that green was almost perfect across the whole range.


Theater (I did not adjust)

White (100 IRE) 6982K
Light gray (80 IRE) 6581K
Medium gray (50 IRE) 6380K
Low gray (30 IRE) 6508K

Note, green was a a bit weak on white, shifting to a bit strong in dark gray, not a serious shift, and easily correctable.


White (100 IRE) 6457K
Light gray (80 IRE) 6429K
Medium gray (50 IRE) 6388K
Low gray (30 IRE) 6345K

And again, green balance was excellent.

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