Originally Posted by mailiang
The article was written in 2001, but it does offer some good observations. Since you feel the author falls short, maybe you should write one of your own.
I suppose I could, and it could be used as a sleep aid
In re-reading this, it does contain a lot of good information. It points out the effect of frequency vs. outline thickness, and that it occurs both horizontally and vertically. I disagree with the premise that all detail enhancement, including aperture correction, is bad. Used properly it can effectively compensate for some detail losses. Fixed pattern imagers, such as CCDs, have inherent high frequency roll off with near full fill factors. Also it states that transfers are heavily filtered to reduce flicker. There were techniques to increase the scan line thickness by carefully misadjusting the astigmatism (ScanDal) which used with higher amounts could soften the vertical detail. I found that was more useful for transfers in 525, while the extra scan lines in 625 didn't really need it as much. In the SD days transfers commonly needed to be delivered in both 525 and 625, and transferring in 625 and converting to 525 (using slow PAL) to me looked better than a native 525 transfer.
Using film test patterns allowed objective settings for aperture and enhancement settings. Flyspot scanners usually needed little if any vertical enhancement, other than perhaps matching excessive horizontal enhancement. In more current times, film scanning at higher resolutions have replaced real time transfers, and much of the enhancement issues are disappearing. As far as enhancement outlines being baked in permanently on existing video, filtering out excessive mid frequencies can effectively minimize them. The limitation is on areas with clipping, whether that be the enhancement peaks or the video itself.
Live camera video seems to still have the enhancement set subjectively, and settings seem to vary widely. Letterman's show (CBS) to me has heavy enhancement, and from what I gather is using older cameras. Sports also often seems to have heavy enhancement. Hopefully as UHD gains usage that some of this will disappear. I was hoping that was going to be the case with HD, and to an extent it was. The Today show in SD was extremely enhanced, but the HD era is far better. In the past detail enhancement was also called contours, and a pejorative term I remember for those who added excessive enhancement was 'Contour Kings'.
The term 'ringing' is commonly used, but to me it's not an accurate description. Ringing, at least in the past, referred to damped oscillation such as how a bell vibrates when struck and fades. With enhancement, there can be overshoots from excessive emphasis of some frequencies which create the outlines but they are not typically oscillating between positive and negative after a transition.
Better stop here before even I fall asleep reading this.