Angry About Contrast
"Angry Man/Neutral Woman," copyright 1997, Aude Oliva, MIT, and Philippe G. Schyns, University of Glasgow
If you are looking at the above picture on a nominally sized screen at a nominal viewing distance, you probably see an angry man on the left. What’s an “angry man”? Me, when I think about technical descriptions of HDTV.
Think about it. Maybe you hear HDTV described as being 1080i or 720p. Maybe it’s 1920 x 1080 or 1280 x 720. Maybe it’s 2 megapixels or 1. An engineer who remembers such things as analog bandwidths might refer to 30 MHz or 37 MHz. Someone concerned with lenses might talk about 100 line-pairs per millimeter. Someone describing visual acuity, screen sizes, and viewing distances might offer 30 cycles per degree.
Someday, I’ll probably get around to explaining how all of those are related and how many of them are pretty much the same thing. But, when it comes to the sharpness perceived by viewers, they’re all pretty bogus because they’re all missing something of vital importance.
Of course, that isn’t the only silly spec. Look at “sensitivity,” or, one of my all-time favorites, “minimum sensitivity.” I just went to a web site of someone called an “expert” and found a sensitivity figure of 1 lux. More »
Tags: angular frequency, aperture, contrast, gain, hdtv, heynacher, mtf, schade, sensitivity, sharpness, spatial frequency
