A presenter steps up and there are black bars down both sides of a screen you specified to be nine metres wide. Or the logo is stretched. Building presentation slides for an LED wall, meaning a screen built from light emitting diode panels, is a different job from building them for a projector or a meeting room television. A projector gives you a fixed rectangle. An LED wall gives you whatever shape the panels make. The fix is a number, handed over early.
In short
Ask your audio visual (AV) supplier for two things before anyone opens a deck: the pixel dimensions of the screen canvas, and the proportion those pixels make. Build the slides to that proportion, keep anything that has to be read inside a margin of about 5% all round, and size the type for the furthest seat in the room.
Your screen is whatever shape the panels make
A modular LED video wall is built from cabinets, each carrying a fixed number of pixels. Tile them into a rectangle and the pixel canvas, meaning the total picture area the wall can display, is the panel count multiplied out. Nine cabinets across by three high gives one shape. Ten by three gives another. Neither is chosen from a menu, neither is likely to be 16:9, and the shape exists as soon as the wall is drawn on the stage plan.
Two numbers settle it. The pixel dimensions of the canvas, and what the processor feeding the wall will actually accept, which is not always the same thing. A scaler usually sits between the desk and the panels, and it is that input resolution your content has to match. Our earlier piece on sizing a screen for a conference covers how the wall itself gets specified.
Where presentation slides for an LED wall go wrong
PowerPoint and Keynote both offer two standard shapes and a custom option. The custom option is where the trouble starts, because it is measured in physical units, not pixels.
Microsoft’s documentation for changing slide size sets out the limits: width and height can be typed in inches, centimetres or pixels, with a stated maximum of 56 in, 142.24 cm or 720 px. A wide stage canvas of 5,760 by 1,080 pixels cannot be typed in as pixels at all.
You do not need to. The proportion is what matters. A slide set to 40 cm wide by 7.5 cm high has exactly the same proportion as 5,760 by 1,080, so it maps onto the wall without letterboxing or stretching. Set the shape correctly and export at the highest resolution the software will give you. The processor handles the scaling.
The margin that keeps content on the screen
Broadcast has a usable answer to how much room to leave at the edges. The European Broadcasting Union’s recommendation on safe areas for widescreen production defines two zones: an action safe area with a margin of 3.5% at the top, bottom and sides, and a graphics and title safe area with a margin of 5%. Anything that has to be read sits inside the tighter one.
Those figures were written for television, but the reasoning travels. Processing and a scenic surround both eat into the edges of a picture. On a live stage there is also a second kind of safe area that the broadcast standards do not address: the part of the wall the room hides. On a flat floor the bottom of a tall screen disappears behind seated heads, and a lectern will take a corner with it. Keep anything that has to be read above that line.
How big the type has to be
The test is whether a slide reads from the worst seat in the room. Your monitor will not tell you that, and the AV trade has a standard for working it out.
The Audiovisual and Integrated Experience Association (AVIXA) publishes a display image size standard known as DISCAS, short for Display Image Size for 2D Content. It expresses the answer as element height: the height of the smallest thing that has to be legible, as a percentage of the picture height. That is tied to a viewing ratio, which is the furthest viewer’s distance divided by the image height. The further back the last row sits relative to the picture, the larger the percentage has to be. Where the viewing ratio reaches 10, the standard puts the minimum element height at 5% of the picture height.
Measure the furthest seat and divide by the picture height. That number gives you your smallest usable type size.
Video and images break in different ways
A logo built as a vector redraws cleanly at any size. The same logo saved as a small bitmap and dragged wider turns to mush on a wall taller than a person. Ask for vector artwork from whoever owns the brand, and ask early, because artwork requests sit in a queue and the build date does not move.
Video needs the same treatment. Supply it at the canvas resolution and send the file separately alongside the deck. Embedded video is a common reason a presentation plays in the office and stalls on a show machine. If the event is also being streamed, the same content has to survive a second path: our piece on what the room needs before the stream does covers that side.
Somebody owns the deck, and there is a date
The canvas number is useless if it reaches the people building slides two days before the doors open. It has to go out in writing, with the pixel dimensions and a deadline, to every presenter and every designer working on content.
Sponsor and agency decks are where this falls down. They arrive in 16:9 because that is what the sponsor’s brand kit contains, and somebody has to decide whether they get rebuilt or centred on the canvas with the surround treated as part of the design. Make it a decision in good time.
We work the shape out at proposal stage, because specifying equipment before we understand what an event is for produces the wrong equipment. Our proposals include 3D visual renders of a design where they help. For the MLE fashion show and exhibition at Event City, our proposal carried 3D visuals of the catwalk design, and we ran vision equipment, audio, lighting and staging across the conference area alongside it.
Frequently asked questions
What aspect ratio should we build our slides in?
Whichever one the wall actually is. Ask your supplier for the pixel dimensions of the screen canvas and build the deck to that proportion. Do not assume 16:9. If it is an ultrawide stage canvas, a 16:9 deck will either sit in the middle with dead space around it or be stretched, and neither reads as planned.
Can we use our existing 16:9 deck on a wider screen?
Yes, and on some events that is the right call. The deck gets centred on the canvas at its correct proportion, with the remaining width treated deliberately: a flat colour or part of the set. Do not let it be stretched to fill the width, because every face and every chart in it will be distorted.
When do the slides have to be finished?
Agree a cut-off with your supplier. If content is going through a playback system it needs loading and rehearsing on the actual canvas, so the working deadline usually lands a day or two before the event. Agree a change route for the genuine late edits as well, so a presenter with a corrected figure knows who to hand it to on the day.
Sources
- Microsoft Support · Change the size of your slides
- European Broadcasting Union · R 95, Safe areas for 16:9 television production
- AVIXA · Display Image Size for 2D Content, DISCAS
If you have a wall drawn and nobody has told your presenters what shape it is, that is the next thing to fix. We are happy to send the canvas dimensions and a slide template before anyone starts designing, whether it is a conference main screen or a set-wide backdrop. Tell us about the room and the running order through the contact page or by email at hire@eventproductiongroup.co.uk, and we will tell you what your content needs to be while there is still time to change it.
