Programming LED fixtures with more than 3 colour sources

[James]

[split from 'Attending PLASA' thread]

It felt a lot better to me in Olympia than it did in Excel but not as good as the Earls Court days.

 

This was the first year I can remember Strand (Phillips) not having a presence.

 

It also clashed completely with IBC this year which may have led to some people not exhibiting here (Sony for example I remember doing PLASA last year but I don't think they were here this year)

 

I also took a quick look at the new little Zero 88 desk and was amused to see the demo with it connected to some RGBA fixtures with it unable to produce RGBA control. The demonstrator proceeded to argue with me that RGB control was far more accurate than RGBA and any other desk that offers RGBA is doing it wrong.

 

James.

[alistermorton]

That's an "interesting" view on RGBA - wonder if the same applies to RGBW RGBAW RGBAWL etc

 

:-^

[jonhole]

Hi James,

 

I've spoken to the person who demonstrated this. Maybe we didn't clearly explain our stance. We (and most other console manufactures) suggest putting fixtures into a standard colour mode (RGB, CMY, or HSI/V), and to let the fixture create it's own colour mixing based on the chips it has available. If you choose not to do that, we still give you access to all the direct channels, just via encoders / palettes / faders etc, not the colour picker.

 

Our colour pickers supports RGBW, CMY and HSI/V. There's far too much variation in Amber across fixtures to accurately build support in for this. Most fixtures aren't calibrated out of the factory, so we can't even take measurements and build in our own calibration. This is an industry problem, not just ours. PLASA/ESTA tried solving this with ANSI E1.54, which, in theory, standardises the colour output when RGB is received from the console (just as we do). Arri have build that into their SkyPanel fixtures as part of their 3.0 firmware, as have many other manufactures.

 

Without taking a calibration of each and every fixture in your rig, it really has to be down to the fixture manufactures, and not the console manufactures, to truly get accurate colours across fixture types and manufactures.

[timsabre]

We (and most other console manufactures) suggest putting fixtures into a standard colour mode (RGB, CMY, or HSI/V), and to let the fixture create it's own colour mixing based on the chips it has available. If you choose not to do that, we still give you access to all the direct channels, just via encoders / palettes / faders etc, not the colour picker.

 

This is one approach but I don't think it is common across console manufacturers as you suggest - a lot of lower-end fixtures don't support "smart white" or "smart amber" modes so you'd be stuck with just using the RGB emitters.

 

I know Avo desks actively control up to 6 direct colour channels from the colour picker. I'm less familiar with ETC but I think that is the same. Chamsys was just RGB from the picker last time I checked.

[jonhole]

I know Avo desks actively control up to 6 direct colour channels from the colour picker. I'm less familiar with ETC but I think that is the same. Chamsys was just RGB from the picker last time I checked.

Interesting, I wonder how Avo define these 6 colours when there’s such variation in fixtures. I’ve spoken to 3 ETC employees over the past few months who all separately tell me they don’t suggest most customers use their 7 colour fixtures in “direct” mode, but in their calibrated modes

[timsabre]

Interesting, I wonder how Avo define these 6 colours when there's such variation in fixtures.

 

It is slightly mindboggling but I believe it is in the fixture personality somehow. Niclights would know as he writes them but it may be a trade secret...

[James]

Jon - I understand what you are saying but the current lighting desk I use does support RGBA etc and whilst there might be technical differences between amber to do this accurately it's certainly good enough to get a sensible look (and one that looks better to my eyes for use of A than without)

 

 

- Do I also assume from this that the fixtures you had on the stand connected to the demo didn't support a pure RGB mode?

[jonhole]

I've just read the v10 Titan manual, and you're right - Avo claim their colour picker works with amber, lime and UV. I'm happy to be corrected, but as far as I can see the only way of doing this would be to approximately define where colours such as "amber" and "lime" sit on the spectrum, and hope the fixtures vaguely match. There's a whole separate argument on how you can possibly place "UV" onto a visible colour spectrum. This isn't something we'd be comfortable doing, as the results would be hit and miss dependent on the fixture.

 

Do I also assume from this that the fixtures you had on the stand connected to the demo didn't support a pure RGB mode?

To be honest - I'm not sure. The up lighters around the stand were meant to be purely stand lighting in an Eaton blue, but then it started getting used for demos!

[niclights]

Regarding Avo you are correct that it is currently an approximation for each of the components from a number of predefined options. If necessary it is possible to deliberately include or exclude components from the colour picker in the personality file but normally they're all included.

 

The output colour might not be a perfect match but I would suggest this is true for just RGB (and CMY) in the same way. For example RGB at full will typically be white in a colour picker but in the real world the majority tend to be red biased and therefore appear lavender. Perhaps it will be possible to calibrate in the future and I have proposed some concepts regarding this but in reality I'm not sure how many fixtures we would have the data for unless it was achieved with user colaboration/feedback (which might then introduce concerns about standardisation).

[timsabre]

I've just read the v10 Titan manual, and you're right - Avo claim their colour picker works with amber, lime and UV. I'm happy to be corrected, but as far as I can see the only way of doing this would be to approximately define where colours such as "amber" and "lime" sit on the spectrum, and hope the fixtures vaguely match. There's a whole separate argument on how you can possibly place "UV" onto a visible colour spectrum. This isn't something we'd be comfortable doing, as the results would be hit and miss dependent on the fixture.

 

As Nic confirms it is only rough, but it works quite well in practice. On a colour picker you're normally moving your finger around till you get the colour you want on stage, you don't look at the colour on screen and expect to get exactly that on the stage.

UV in 6-led fixtures is not really UV, it's just very deep blue, whereas the blue is greener. The Avo system seems to use it effectively to get congoblue type colours.

[James]

Jon - I use lightfactory (originally purchased via Zero88) which allows you to define where each of the colour attributes sit on the colour spectrum from within the fixture profile.

 

James.

[alistermorton]

Hi James,

 

I've spoken to the person who demonstrated this. Maybe we didn't clearly explain our stance. We (and most other console manufactures) suggest putting fixtures into a standard colour mode (RGB, CMY, or HSI/V), and to let the fixture create it's own colour mixing based on the chips it has available. If you choose not to do that, we still give you access to all the direct channels, just via encoders / palettes / faders etc, not the colour picker.

 

Our colour pickers supports RGBW, CMY and HSI/V. There's far too much variation in Amber across fixtures to accurately build support in for this. Most fixtures aren't calibrated out of the factory, so we can't even take measurements and build in our own calibration. This is an industry problem, not just ours. PLASA/ESTA tried solving this with ANSI E1.54, which, in theory, standardises the colour output when RGB is received from the console (just as we do). Arri have build that into their SkyPanel fixtures as part of their 3.0 firmware, as have many other manufactures.

 

Without taking a calibration of each and every fixture in your rig, it really has to be down to the fixture manufactures, and not the console manufactures, to truly get accurate colours across fixture types and manufactures.

 

So if you connect say a S4 LED lustr series 2 to a FLX S, do you ignore everything but the red green and blue channels, or do you map the RGB/HSI/CMY picker onto the full gamut of the fixture?

[jonhole]

So if you connect say a S4 LED lustr series 2 to a FLX S, do you ignore everything but the red green and blue channels, or do you map the RGB/HSI/CMY picker onto the full gamut of the fixture?

 

Neither. As I said earlier, we've had several conversations with the ETC team on how best to control their fixtures. If you put a Lustr into "direct" mode, you're choosing to bypass the individual fixture's unique calibration which is created in the factory, and all the clever maths developed over many years by the manufacture of the fixture. Therefor, for the vast majority of users, a better option is to choose one of the fixture's calibrated modes, send a colour value from the console, and allow the fixture to choose how to best create that colour using it's available chipset. Lustr's then have the "+7" option to allow you to manually tweak these values for use on specific surfaces / costumes etc. In this situation, the FLX uses the Colour Picker for the overall colour, and encoder wheels to access these direct calibration tools.

[alistermorton]

OK, that makes some sort of sense and is clearer (to me) than what you said before.

[J Pearce]

Essentially, fixtures should ideally support receiving an HSI value, and work out how best to create that colour. This would make touring and morphing a new rig a piece of cake.

 

However, this requires calibration and more processing on board compared to simply exposing each channel to DMX. Thus, it costs more - compare the price of an ETC D40 Lustr to a Qtx 6 colour PAR.