While looking at the new ilumo ZOOM LED Spot, On Stage Lighting considers the future of colour in stage lighting control and revisits an old problem with a possible solution that leads to further questions.

The Colour Mixing Problem

In a past article, we looked at a specific problem concerning the crossfading of colour mixing lighting units and the possible visual hideousness that can be the stopping off point between one colour and another.

Briefly, the principle of channel value controlled colour mixing and state based lighting create an problem. When channel levels create a mixed light colour based on the intensity of individual colours like Red, Green and Blue (RGB) sources, a fade between these colours sends the values through a series of colours including what might be termed Dull White.

Colour Mixing and Crossfades suggests ways in which these transitions can be managed, either by hand or using additional cues as stopping off points that create an A-road bypass around the Dull White and avoid unwanted colours between two lighting looks.

The Colour Control Problem

The way we currently run colour mixing fixtures using additive RGB, RGBW et al and subtractive CMY uses control channels for each colour component intensity. This used to simply translate to a series of 8-bit values on an encoder (or even earlier, a fader) but lighting console makers wanted to give us more. They created ways in which we could pick the colour or align it to a simplified colour model that might approximate, say, a Lee filter. By somewhat crudely mashing up a series of values, a colour was produced that didnt involve wheely-wheelying each individual colour emitter to its desired intensity.

But crudely is the key. The actual resulting colour output is, of course, very much based on the light source it is being used with, what colour temperature discharge lamp, the colour of the Magenta flag or which Red LED. This mashing of values and the variable nature of the light source depending on fixture type, has always led me to create my colours while avoiding things like colour pickers and any adjustments made are directly controlled by said wheely-wheelying the specific colour channel.

Some professional consoles give the programmer the option to use Hue, Saturation and Intensity (HSI) or some similar model to set the exact colours. These systems dont really address the issue that a lighting console doesnt actually see the colours it thinks its outputting and cant really judge if the Cheapo-LED Pro is actually the same steel blue as the Lari*lite 2000 Wash.

The CIE Colour Space

Before we go anywhere, you should probably know about the CIE colour space. Its extremely interesting and science-y if you are extremely interested in science-y things. If not, its basically a mathematical way of describing a particular colour, based on coordinates and can be visualised with a lovely rainbow thing shaped like, well, something. The important bit is that, using these coordinates we can describe colour. Handy.

The ilumo Zoom LED Spot

I recently took a look at the ilumo ZOOM LED Spot, following its formal outing at the Frankfurt show. The last time I saw the prototype, it was more of a non-working model, but this time Lumonics baby was full of life and I had plenty of questions for the designer of the ZOOM Spot.

Well, ok, so its not really a spot. If you expect it act like a projector or profile spot, it doesnt.

The Zoom LED from Lumonic is a fixed PAR style colour mixing fixture, with a remote motorised zoom. Its based on OSRAM high brightness LEDs in an array and goes from pretty darn tight to nice n wide. The ilumo is DMX controllable, has all the things youd expect from a professional level colour mixing PAR-like and a load of other things too. Well let you head over to the website to mug up on all these things, but notice that the design pedigree of this fixture is not insignificant, having a heritage with the orginal JTE Pixel range of LED kit including the famous 1044. If you know your MAX2s from your RGB DMX modes, hold that thought.

There is much to talk about in this LED fixture, but this article isnt a product review. We are more concerned with the concepts for colour mixing control , of which the Zoom Spot flags up.

Fixture Personality

The ilumo ships with range of possibilities regarding the way the unit is controlled via DMX (or similar: Artnet, sACN etc.) and these possibilities are wrangled into what they call personalities but you might consider simlar to fixture modes. These have been put together by the designers to give the user a single point of access to a specific setup, a bit like a stored series of settings, rather than what we think of as modes, which seem to be most manufacturers way of making sure you end with a fixture that will Pan and Tilt, but wont open its dimming shutter!!

Within this personality, one channel of DMX control may be given over to what the ilumo call Colour Control, which in reality sets up the unit to behave in certain ways regarding its use of colour. Remember, this is controlled remotely from the console using ranges on a single 8-bit channel, effectively giving you control over the colour model at any given time, right there in your cues. In P6 (Personality 6) the channel map looks like:

• 0-40 RGBW (raw)
• 41-80 RGB (calibrated)
• 81-120 CIE x & y
• 121 – 160 CIE Colour Temperatures 2000K to 10000K
• 161-200 Palette Selection
• 201-255 HSI (& Colour Temperature)

The first part of this channel range simple sets the fixture to a standard RGBW model, in which a Red at full equals all the Red emitters are full pelt. But take a moment to look at the other models, all interesting in their own right. HSI is there and is what is says on the tin, plus something called calibrated. There is mention of the CIE coordinates x and y, but more on that in a moment.

Colour Calibration

With all the mention of colour temperatures and the problems outlined at the start of this article regarding the somewhat vague nature of colour mixing, its worth looking at how calibration works within the ilumo. For a start, what you are looking at is the fixture itself designating what colour it is, based on things such as your chosen CT or calibrated Red, Green and Blue sources.

What this means is that you can set the Red at the fixture to be LEE 106 or LEE 027 and other possibilities, customisable or standard. Obviously, the LED units themselves dont swap out for new ones, the fixture creates the base colours with a combination of its given raw material and an uplift in this calibrated Red might involve a change in all RGBW LEDs. You can see why this is called a Colour Engine already. We are pretending to control this RGB fixture in a simplistic way, and its busy doing stuff under the hood.

CIE X and Y Coordinates

As we now know, you can pick a colour using the CIE colour space using numbers, and this is where the CIE x & y comes in. Again, we are now looking at taking out the vagaries of the console colour picker and identifying exactly a colour that the engine will attempt to reproduce. I have to say at this point, that these in-fixture calcs presumably dont take into account the age of the LEDs themselves or the batch, possibly not even the model generation of the ilumo range. Anyone that has worked with a large quantity of JTE 1044 Pixelline of different ages, from different hire companies, will know the shenanigans involved in putting all that that sort next to those other ones when it came to getting and even colour. Now, of course, LED technology has advanced and perhaps such variance is less common.

But keep the CIE model in your mind as we move on to…

Palette Control

In lighting programming, we know what palettes are with regard to consoles. They are a preset thing, including colour, that we can save away for later use and update centrally. They are the centre of our world. The ilumo uses the term palette accurately, but not in the way we moving light programmers think of it. So lets call them Stored Colours for the minute.

These stored colours are recalled by one of two DMX controlled channels, I didnt get if they stored the same colours or different ones on each channel, to be honest. The key thing is that the two channels act like an A/B buss, like a DJ mixer. One channel sets up one colour, the other, another a second colour. The final piece of this puzzle is the third X-Fade channel – its the sideways slider-y thing that DJs like to fiddle with. It fades between the two colours, loaded up on the A and B busses.

But why? I hear you ask. Surely, we dont need to set up a colour on a channel and another on another channel, and upload and store it in the LED fixture to then crossfade between them. I spent good money on a lighting console that does that for me and without so much faffing about!! Well, its a good point.

The interesting thing about the ilumo ZOOM Spot is the reason it bothers with all this in the first place. The colour engine goes out of its way, to, well, go out of its way!

What I mean is, the crossfade from colour A to colour B deliberately doesnt take the path that leads through Dull White or other colour nasties. The fixture finds a route from one side of the CIE colour space to the other, while trying to avoid Yuckville around the middle.

Im not entirely clear how the routing decisions are taken but tested it out and it does actually work, presumably the engine interpolates between the two colours, rather than simple changing intensities in a linear fashion. The acid test for an RGB fixture is something like a Red to Cyan crossfade, taking the LEDs at their extremes and crossing them over. The colour route wasnt half bad and there was no discernible dips or bulges in intensity during the transition.

The Questions

All these interesting solutions and options for more accurate colour control create some interesting questions, which probably dont have one answer for everyone:

Are colour mixing fixtures expected to make a better job of their colour business within the fixtures themselves, making it easier on the end user and the lighting console?

Is it better that the dumb kit just takes instruction from a calculating console, which in turn needs a lot more information about the light source than it currently has? (Cue minor rant about the nature of console fixture personalities)

Is the additional effort of creating and storing colours in a fixture, in order to make use of its colour cross fading engine, offset by the benefits to the lighting designer of better transitions?

Can I ever think in CIE coordinates? And if I do start with a CIE colour, can I edit in them or do I need to return bumping up the Green a bit? I dont mean Can the kit do this?, can my brain?

Are we happy to simply create console colour palettes up for various fixture types, adjusting them and matching them by eye, and putting up with dealing with transition issues using the various workarounds we have at the moment?

How does a fixture with such proprietary colour control fit onto the consoles of today and tomorrow, with their current colour setting arrangements? If other colour mixing kit doesnt use such a control system, does it even matter?

Are we finally seeing the limits of DMX and other dumb channel based one-way control for complex fixtures? And are workarounds like the A/B Colour buss just pandering to an old system when we should just get up to speed with our controls?

The ilumo ZOOM LED Spot is a very interesting piece of technology and control implementation, as well as being a very nice piece of kit from the lighting designers point of view. Lumonic says their mission is to challenge the status quo and there are elements within their patent pending Colour Crossfade Engine that certainly does that. It also asks questions of us as programmers and those that design our interfaces.

Do you have any thoughts on the subject? Let us know in the comments below as usual.

Appendix for DMX chart nerdery – Personality P6 channel mapping:

1. Red (or Red calibrated or Hue)
2. Green (or Green calibrated or Saturation)
3. Blue (or Blue calibrated or Intensity)
4. White (or White CT)
5. Zoom
6. Dimmer Speed
7. Master Intensity
8. Strobe
9. Colour Control (mentioned above)
10. Colour Temperature
11. CIE x coordinate
12. CIE y coordinate
13. Palette A (colour buss discussed above)
14. Palette B
15. Palette Crossfade (A/B)

If this has helped you, consider buying me a beer and CLICK HERE to donate a few bucks to On Stage Lighting (why should I donate?). Thanks, - Rob

You May Also Like:

• LED Lighting and Colour Output
• LED Light Control – DMX Controllers for LED Stage Lighting
• LEDs, Colour Mixing and Crossfades

In a world where both traditional lighting and digital visual media are the domain of the modern lampie, On Stage Lighting considers the forthcoming release of media software Resolume 4 Arena which looks like it has potential in the small to mid scale show visual market.

Here at OSL, we dont really do product reviews and the following piece continues that tradition. In order to give you a look around the software, we finish up with a video poke about under the hood.

This article simply looks at Resolume 4, which is in Beta 2 at the time of writing, from the point of view of a Lighting Designer/Programmer and asks if we should give the new Arena offering our attention. If you have some experience of media servers or the complexities of current projection and mapping trends, youll find some ideas on using Resolume 4 instead of your more familiar Arkatalyst Hippo Box software (see what I did there?). If you didnt get that joke and have little experience of media servers in show production, read on anyway after checking this media server primer from a few years ago.

What might we want from our media server?

To precis, media servers are used on all kinds of show to play digital media which is then either projected on screens, the set, the floor, or even pixel mapped to starcloths or other low resolution outputs. They come as hardware/software or simply as software that you run on your own machine such as a decent spec laptop or desktop PC/Mac. Resolume is in the software camp and the interesting thing for us about Resolume 4 Arena is that they have added features to their Avenue VJ platform that are relevant to what we do. We will completely ignore the fact that it does quantised audio playback for simplicity today. Resolume has a setting to Hide Audio Controls, which clears thing up for us.

So what do us lampies really want from a media server and how does Resolume stack up? Well start with our typical Lampie Demands and see where it gets us.

Content playback

The ability to pick and mix video files and play them back whole, or in loops, or backwards or in a specific order.

Resolume 4 Arena plays stuff back as you would expect. Unlike some other lampie media servers, its a little different to simply picking a media folder between 0 and 255, the picking a clip between 0 and 255. It does have the usual Play Modes: Forward, Backward, Bounce, Loop etc. plus Pause, Stop,yadda yadda yadda.

The thing that is different is the way it organises content, something you do at the terminal, not from the lighting desk, as its extremely flexible which is code for saying You are likely to get yourself into a muddle.

Composition:

The file/workspace you are working on at the time and the final output of your combined content.

Decks:

Within the Composition, a collection of layers and clips youve set up, that you can toggle between from the desk if you like. You could use a different desk per song, for example.

Layers:

If you are into media servers, you know what layers are. You can set the number of layers and drag and drop clips from your media folder onto slots on the layer. The difference with these layers, is that although they are numbered by default, the layer order is not set in stone and you can bump order around so a different one is on top.

The layers have the usual Opacity and other manipulation controls such as scale, size, rotation and a whole bunch of others.

Columns:

The slots that you drag content in live in Layers on the X axis, but in columns on the Y axis. Now you might be starting to see that Resolume differs from things like Catalyst. Columns can be triggered ie. all the clips in all the layers of that column can be Goed at once, firing off your final look of combined layers. You can also set the columns to auto fire along the line in a time you specify. You can bump the order of the columns…. uh oh…. so much choice….

Clips:

These are the slots where your media file is put ready to play, in the Layer you choose and in the relevant column to taste. The file can be triggered by a Column or individually and get this, you can move the clip around within the Layer. Holy confusion, Batman. Fortunately, I dont think you can do this from the console by default.

So, unlike some media servers, Resolume Arena doesnt so much have a timeline in the conventional sense but it does have options for the firing of cues, using pre set up columns is probably your best way. Either way, the flexibility in this means that you should decide on some kinda ordered system of how you use your layers and columns and clips and decks. And stick to it.

Along with conventional video content, Resolume can also deal with Flash and Quartz Composer stuff, which is fandabbydozey because that kind of realtime rendered content is just loverly and opens up huge possibilities that dont rely on particular videos of particular resolutions.

Content Manipulation

To be able to layer, mix and generally mess about with video content, to come up with something original and fitting the visual look of the show. We want to be able to muck up the 4 loop clips we have in so many ways, so that it looks like we have endless content hidden back there.

OMG. Forget scaling and rotating, the tools you have for manipulating content at every level, Composition (output level), Layer and Clip are like having real time After Effects that you can plug in wherever you like.

With the standard manipulations such as scale, you have constant access to them from the console but the fun starts when you look at plugging in your effects such as Colour Shift or Waves. These effects can hit any level, can be applied in different orders and you can assign certain parameters to the eight Dials at the top of the Clip, Layer or Composition tab. This translates to dials on the console, meaning that in one instance, an encoder could be controlling Red level of a Layer, the next could be tweaking the Noise or Mask across the whole Composition.

If you cant get a whole show outta 4 clips and all this visual trickery, you aint trying. The key point is, again, you need a structured approach and to spend some time setting up what you want to be able to control. And keep it simple. My suggestion would be to assign Add/Subtract Colours Red, Green and Blue at Layer Level to your dials, giving you the option to blend your visuals into the rest of your stage look.