Brightness vs. Grayscale
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"I've been meaning to get to this for a while, but like everything, real life
often decides differently.
I had some time to take another look at the interaction between the grayscale and some
of the user controls on the TV. While the settings and numbers are by no means absolute,
they should provide an idea of how things work and your experiences should be similar if
you try the same thing regardless of the TV set that you have.
First off, Dean R. had wondered about the interaction of the contrast on the grayscale,
but at the lower end of the scale. I have finished those tests and here are the updated
figures using both 100 ire and 30 ire window patterns.
Contrast 100 ire 30 ire
25 6780 6400
30 7170 6490
35 7620 6450
40 7960 6450
45 8230 6490
50 8390 6520
55 8390 6490
60 8400 6500
Max 8420 6530
Interesting how the contrast only really affects the upper end of the ire scale. This
is consistent with what Joel Silver said at the ISF Seminar. Now what is more interesting
is the brightness item. JS said that it should affect the dark end of the IRE scale more.
Here are the results. Note that 50 represents the optimized brightness point for the TV.
Black lvl 100 ire 30 ire
50 6780 6400
55 7000 6500
60 7060 6570
65 7280 6590
70 7410 6600
75 7550 6670
80 7680 6660
85 7780 6660
90 7920 6700
95 8070 6700
100 8170 6700
So contrary to what JS said, the brightness seems to have more of an effect on the
brightend of the grayscale as well. The changes seem to be more uniform than with the
contrast control. The temperature seems to go up by 100 K for every 5 notch increase. The
changes to the dark end are much less although there are changes here too.
The below 50 readings were taken more out of curiosity since the brightness level is
below the VE/AVIA optimum and the user would never take the brightness down like that. You
can see the temp dropping more significantly, but the point is moot since you cannot see
the image anyway.
Conclusions ... both the brightness and the contrast have more effect on the bright end
of the grayscale than the dark end. Pumping up the brightness will result in a more
uniform / slower increase in the colour temp than the contrast control.
More stuff to file away in the back of your mind.
Next up ... Grayscale versus Grayscale ... Or something to that effect. Testing AVIA's
Grayscale against VE."