Originally Posted by Doug Blackburn
Filters never had a time or place.
Sure they did ... my point was that there has been a significant change of *philosophy* in the "art" of calibration since the "blue filter" method was devised. That change has rendered the method "obsolete" on modern digital sets with at least a rudimentary CMS.
Back in the the blue filter's day, you lived with the phosphors you had, not the ones you wished you had (i.e. SMPTE-C.) Maintaining linearity was considered more important than reaching specific x,y points. Furthermore, in most cases, there wasn't anything you could do beyond getting the green-yellow-red side of the gamut "correct" - a task that the blue filter was specifically designed to do. I've never seen a set that "failed" this task (even really bad ones,) provided you knew what the filter method was meant to do, how to use it *and* how to cross check it with red and green. I never had to go back and "re-adjust anything by eye," that appears to be something you've appended to the method ... I've never seen that in *any* instruction material.
It's really only been in the past five(ish) years or so, that we've had the tools and, most importantly, the display controls
that allow us to go beyond what was the common practice for the first 45-50 years of (NTSC) color TV. (OK, actually for a lot of that time the common practice was to tell viewers to adjust their (Color/Tint) controls until the color bars looked right. The "BFM" was an attempt to remove the subjective "looks right" element and replace it with an objective method. Perhaps you've melded the two methodologies in your memory? )
PS: I'm all for squeezing as much accuracy as we can out of our modern digital displays, but I don't think we really need to shun the past in the process; on the contrary, if more people understood what the SMPTE bar chart and "filter" method represents mathematically, they might better understand what they're doing when they start playing around with their newfangled CMS controls ...
Calibration wasn't always about being perfect (and anything less just won't do,) it was about getting the best performance you could out of less than perfect displays ... while sometimes having to use stone knives and bear-skins to do it. I think in our obsessions with trying to achieve higher and higher levels of "perfection," we may have lost sight of that.