Re: Bit of a Con Really - Follow-up ...

[William Sommerwerck]

How? The film's color response is basically set by the choice of sensitizers.

You can adjust the balance, but that's not the same thing.

[Bob Larter]

It does. One specifies that with colour temperature. Eg; direct sunlight is about 5000K, while shade is up around 6500K, & tungsten light bulbs are down around 2400K. Higher temperatures are biased towards blue, lower are biased towards red. The white balance of a screen or an image is specified in the same way.

There is: 6500K, which is what I have my monitors calibrated to. Traditionally, the print (CMYK) media use 5500K.

In general, that's true, although it's common for LCD monitors to have a factory WB of as much as 8000K, as it makes the image zappier.

[dennis]

Its only confusing to people that don't understand that backlit LCDs, like CRTs, add three primary colours together to make a colour image. The source (phosphors or white light tubes/LEDs with colour filters) of the primary colours may vary but the process is the same.

It is not the same as a slide which filters each pixel (that's picture element to the one who claimed slides don't have pixels) through several coloured layers or prints that do it with inks of various shades.

[Bob Larter]

Colour transparencies aren't printed images.

[Bob Larter]

You're completely missing the point. Once again, projected colour transparencies are nothing like printed images.

[Bob Larter]

Yeah, okay, you can, but it's rarely done.

[Bob Larter]

That's true, but it's a joke compared to being able to directly tune the black level & amptitude of RGB levels on an LCD panel or CRT.

[Bob Larter]

Nothing like to the degree that you can with CRTs or LCDs.

[Bob Larter]

One of 5500-6500K, typically.

[Bob Larter]

That's exactly correct. The colour temperature of the reference white (ie; the WB) is vitally important for correct colour rendition. The eye will adjust to an incorrect WB, but it will still be incorrect.

It's just as likely that, as you said, a salesbunny wound up the colour control to make the image "look better". Go knows that it's common practice in showrooms.

[Bob Larter]

Not at all:

[William Sommerwerck]

And the Spyder will let me set up my Pioneer Kuro correctly? Because that's what we were discussing.

I already have a huey, which did a decent job on my computer monitor.

[Leonard Caillouet]

The overlap is caused by the shape of the standard observer curves and is part of the very reason that using a narrow band RGB device may not produce color properly. The CIE standard observer curves are precisely attempts at modeling the response of the human visual system. For decades, cameras have been calibrated to match them, and phosphors designed to do the same, to the degree possible. Now, with narrow spectrum devices, we have to consider the implications of those assumptions. It may be that in the future, we should simplify the system and use a narrow band response in cameras and reproduce the RGB in the same manner at the display. Then we can more easily predict the output of RGB systems using a standard matrix.

Leonard

[Leonard Caillouet]

My experience with the spyder products and other tristimulus colorimeters such as those from xrite and sencore (really just a version of the xrite products) is that they are a poor choice for anything other than gray scale. If you want to adjust a CMS properly, you need a spectrophotometer. The minimum useful would be the i1 pro.

Leonard

[Andy Champ]

Thinking about this offline leads me to realise that there is a fundamental difference between the operation of a slide and the operation of an LCD display.

A slide consists of a series of coloured dots (CMY) mixed together in such a way that they filter out some of the colour, and leave the rest. A red dot will be produced where the G and B have been filtered out, and only the R left.

An LCD consists of ADJACENT (not overlaid) coloured filters. So a red dot is produced by having the B and G pixels opaque, and only the R one (which always has no G or B) letting light through.

Andy

[Bob Larter]

In that case, you might be able to rig up some way of using it on your Pioneer.

[Bob Larter]

The problem with LCD monitors is they typically only have 6 bits (64 levels) of resolution for each colour channel, so you don't have a lot of scope for tweaking the WB via the LUTs. Do it that way, & you'll lose tonal detail, resulting in posterisation.

[William Sommerwerck]

Uh-huh.

[Bob Larter]

There's no such thing as a 5000K LCD display, sans backlight. Until you put light through it, an LCD doesn't have a colour temperature at all.

Yes, it does. It drastically reduces the number of transmission levels available to the pixels of that colour, causing posterisation & colour distortion. The more out of whack the colour temperature of the backlight is in comparison to the desired colour temperature of the image, the worse the problem will get. Unlike CRTs, the transmission value of an LCD pixel isn't infinitely variable, they only work in steps.

[Bob Larter]

Exactly. It's why CRTs are better than LCDs for editing photos, for example.