THX 1138 "preservations" + the 'THX 1138 Italian Cut' project (Released) — Page 74

Yes, of course, you don't want your end result to be NTSC broadcast standard of my previously-posted colorbars' RGB numbers (16-235). Rather, you're shooting for the full color spectrum (0-255).

The capture is fairly noisy. Smoothing the image first (or using a larger pixel-sample for your eye-dropper tool) would make readings easier. The RGB numbers look fine ... except where there's Blue.

Overlaying R-G-B channel-separation strips (each outlined in it's color for easy identification), you see of your colorbars as if using those blue & red filters for TV adjustment. Red and Green filtered are nice and uniform. Blue is not.

It seems Blue mixed with all colors (grey) is okay. Mixed with only an individual color, and even alone, it varies significantly brighter or darker. Some kind of analogue blue-timing issue? Can your equipment make the specific analogue adjustments to correct this?

Across the various color combinations, it looks like Blue averages out to the norm. Maybe that's good enough if you can't take it any further.

Always glad to help where I can, and sorry about the confusion (of duplicating the color-bars limits for the broader capture limits). Which stirred me to thinking ...

The color-bars are a good relative guide but perhaps not representative of the included content. I mean, often I check and constantly see "professional" DVDs & Blu-rays crushing and blowing-out their spectrum limits. (That doesn't include Lucas or Jackson, BTW; they're allowed with their "license to kill" colors [cue 007 theme].)

Do you check that you never actually hit 0 or 255 during the entire stretch of the capture? Not that it's "illegal" to do just that. But we'd never know if such pixels were at 0 or 255 or actually beyond those limits.

Therefore, should your working safe-area be 1 thru 254, at minimum?

From what I see, it looks fine. Your breakdown graphic (above) is right and your last shown capture/adjustment (top page) reads fine.

My eye-dropper (averaging 5x5 area) reads (RGB):

WHITE - 253,253,253 [±1]
BLACK - 3,3,3 [±1]
GREY - 191,191,191 [±1]

The only problem I see (and I don't know if that's fixable) is the blue's wide variation in the mixed colors -- demonstrated in my above color-separation strips analysis. The other colors vary, too, but that seems to be the nature of the analogue beast (more so with consumer equipment).  :)

Aside form all that, I noted my concern to not get too close to the bottom & top limits (0 and 255) to assure the media proper doesn't go out -- unless you can easily test it throughout the length of the movie(s). Of course, any stray pixels that differ from frame to frame shouldn't be a bother and should be allowed to be clipped at those limits.

In reviewing the RGB-seps, I noticed that color variation of one affected the other color(s). It's almost like one color putting a drain on the other, when displayed at their maximum brightnesses. Weak electronic circuits? Maybe. Also, maybe, tint or/and color controls not at their optimum settings.

I'm new to the details of analogue TV theory, but this little snippet I found ..

"They combined red (R), green (G), and blue (B) into a luminance, or brightness, channel (called Y for historical reasons), a B-Y channel (called U or Cb depending on the context), and a R-Y channel (called V or Cr). On the other end, the television would convert B-Y to B by adding Y to it, and R-Y to R the same way. Then G could be recovered because Y is a simple weighted combination of R, G, and B, so G is just Y minus a small amount of R and B. ... [They] put Color and Tint controls on the display to allow users to correct for mismatches in overall amplitude of the three channels. Broadly speaking, the Color control raises and lowers the level of the Cb and Cr channels relative to the Y channel. This can correct errors where Cb and Cr are both too high or too low by the same amount. The Tint control rotates the Cb and Cr values around the origin of a 2D space." - http://www.spearsandmunsil.com/portfolio/setting-color-and-tint-2/

.. leads me to think the TV errors mentioned therein might be the "impossible" variations in your color-bars capture.

If you're not sure how to proceed, I suggest making multiple captures and taking careful records. Work from the controls' default settings. Vary each control to create all possible control-step combinations for tint and color. Take your sample and make an RGB-sep analysis (like mine) for each one.

This should give you an actual setting to even out the color-bar variations. If not, at least you should get a feel for direction where to vary the controls in half or quarter steps for better results.

ColorPic is a nice and free one I've been using. (They also sell a "Pro" version and have some other graphics-related products.)
http://www.iconico.com/colorpic/

SilverWook said:

Recent photo of a corridor at LAX. I'm fairly certain the row of Unichapel phone booths were shot here, as was one shot of the monks. The wall mural can clearly be seen in the film. It's been in many other films since then as well.

Bonus points if you know what 1980 movie also shot here. ;)

 Airplane! ?

"The white zone is for loading and unloading of passengers only. There is no parking in the white zone..."

SilverWook said:

Recent photo of a corridor at LAX. ... Bonus points if you know what 1980 movie also shot here. ;)

 I hate hard questions! Can I cheat (w/ StartPage.com searches)?  :D

EDIT (after cross-posting):
Okay, let me think.
Think. Think. Think.
Is it ... "Ariplane"?

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AntcuFaalb said:

... I have nothing like "color" and "tint" capture-side ... so I might as well make use of the extra headroom and save this headache for post-production.

 Considering the info on analogue processes of TV, I tested my imagined correlation to a digital equivalent for your colorbar capture. Looks like it was right ... with the "hue wheel".

Your posted colorbar is shown here with my color separation strips (B&W w each's color as a border) superimposed. The paint program has a Hue/Saturation/Lightness adjuster with a color wheel that turns a full 360° to shift the hue of the spectrum.

At it's default settings of "no adjustment", each separation strip should have uniform intensity of areas where it is "on". But, here, Red and Green vary somewhat and Blue varies significantly.

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To test this approach, I arbitrarily chose a -5° spectrum shift. The R-G-B separations showed worse variation. Success!  :D

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Now, going in the opposite direction for spectrum shift, this time +5° from the default position, Red and Green variations all but disappeared! Blue improved but still varied:

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Testing further (+10°), to try for Blue improvement, resulted in everything pushed too far -- creating worse uniformity for all R-G-B. Trying an additional shift of just the Blue part of the spectrum (from a drop-down menu selecting degree-range pre-sets) was ineffective. I'll try more testing along that line for improvement in Blue (maybe manually setting more effective degree-range endpoints?).

SHUT YOUR MOUTH!

poita said:

(We don't have airplanes here, only aeroplanes)

 Yes, airplanes, like air-guitars, are an entirely different beast: