Talking about colour gamut range

[Aussie Bloke]

I've been reading the responses to the 15GP22 Owner Pole and been interested with the talk about the gamut range of a 15GP22 opposed to a modern CRT so thought I'd continue the thread as a separate topic.

Reading Pete's response and looking at the gamut chart on his site with the ranges of the early colour TV sets opposed to a modern CRT, I'm amazed how much less gamut range todays CRTs have.

I am wondering why is it with todays technology do we not make CRTs/plasma/LCD screens with at least the gamut of a 15GP22???

Also one thing that has bugged me years ago I remember is I was noticing I'm not seeing emerald greens when I scan pictures with those colours, they turn out to be more yellowed than emerald, and a good example was the UK 12p queen head stamp http://paulreed.me.uk/Images/stamps/12p%20-1.jpg . This stamp has very very nice emerald green colour too it but comes up as more of a yellowish green when scanned! And with aqua colours they don't show up as a nice strong blue green on a computer monitor either.

I can imagine that 12p stamp if displayed on a 15GP22 CRT would come up with its original emerald green coloul. This would be a good experiment for CT-100 owners to try out, displaying a 12p queen head stamp on their sets and see if they can see the original emerald greens.

[yagosaga]

Hi Aussie Bloke,

Originally Posted by Aussie Bloke

I am wondering why is it with todays technology do we not make CRTs/plasma/LCD screens with at least the gamut of a 15GP22???

There are practical reasons. A picture with the original NTSC gamut is very dim in comparison to modern television gamut. The emerald green is too dark. A yellowish green is much brighter. People want bright pictures, no dim pictures. And they don't want to watch television in darkened rooms.

Another reason are the correct fleshtones: with a yellowish green, it is easier to adjust the tint or hue control for correct flesh tones. The flesh or face skin colors looks like a lich or like the skin of an alcoholic when they are not absolutely well adjusted with the tint control. It is easier to get a natural fleshtone with a yellowish green and an orange-red.

Kind regards,
Eckhard

[old_tv_nut]

Originally Posted by Aussie Bloke

This stamp has very very nice emerald green colour too it but comes up as more of a yellowish green when scanned! And with aqua colours they don't show up as a nice strong blue green on a computer monitor either.

I can imagine that 12p stamp if displayed on a 15GP22 CRT would come up with its original emerald green coloul. This would be a good experiment for CT-100 owners to try out, displaying a 12p queen head stamp on their sets and see if they can see the original emerald greens.

There are several fine points to this experiment. When you use a scanner without any special setup, it and the softwaree you use for photo-editing and viewing is normally setup for the modern phosphors, "sRGB". In this case, even if the scanner is capable of correctly sensing the color, it is adjusted to fall within the sRGB gamut. Programs like Photoshop can be set to operate in the NTSC or even larger color spaces. However, your scanner may not be adjustable to operate this way. Digital cameras used in "raw" mode can produce a raw file that Photoshop can then import and process in NTSC color space. An NTSC picture displayed on an sRGB monitor will appear desaturated and with an exaggerated range of hues between red and green [caution, that is a simplified statement]- but if the RGB outputs could be sent to a 15GP22, not only would the colors be correct, but the emerald green would be correctly reproduced.

An important point is, if the range is limited at any point of the end-to-end system, you cannot get it back. Also, if the scanner/camera doesn't sense the dyes the same way as the eye, you will never get the right result even if the device is capable of an extended range.

The main reason that CRT displays with yellower green came into use is that brighter pictures were much more appealing to buyers than dimmer pictures with the wider range. Today, common flat panel displays (for example computer LCD monitors in the few hundreds of dollars) have a range similar to sRGB. (However, they are not always specified to even do that - laptop displays are typically worse.) Some extended gamut displays are being manufactured, both for computers and HDTV, at higher prices. These usually are LCDs with LED backlights or other special technology to get purer spectra for the primary colors.

As another note, diagrams of the range of colors on the 1931 CIE diagram distort how much gamut is lost, exaggerating the loss in the green region and under-representing it in the blue region. The NTSC blue is actually quite a bit less violet and more cyan than the modern blue, and this reduces the saturation of purple and magenta colors similar to the way the modern phosphors limit cyans and true greens. This comparison is better viewed in a "Uniform Chromaticity Diagram" or even a 3-dimensional "L*ab" plot.

[Aussie Bloke]

Just recently been to a friends house, he recently got himself an highly priced large LCD screen for his PC and it happens to be an extended gamut range type and it reproduced the emerald greens on this 12p stamp very nicely http://paulreed.me.uk/Images/stamps/12p%20-1.jpg . He also had a standard LCD screen to one side and his PC is set up so the Windows Vista area is extended to two screens which you can click n drag windows/icons etc across from the left monitor to the right and I did a comparison check of that 12p stamp by dragging the Firefox window displaying the pic across between the two monitors and it was real interesting seeing how it looks mint/grass green on the standard monitor and original emerald on the extended gamut monitor.