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In what is good news for consumers, many modern televisions include energy-saving features as standard. We wanted to explore the physical properties of displays, to see if adapted Â鶹ԼÅÄ content could take deliberate advantage of these characteristics, and reduce energy consumption.

Modern screens often include 'local dimming' features, enabling light level management for individual parts of an image, sometimes even at the individual pixel level. Older TVs did not necessarily behave this way. Modern dimming features are able to adjust backlight power accordingly in specific parts of the screen. Therefore, reducing luminance wherever possible in parts of an image should also decrease energy usage.

We wanted to understand this luminance vs energy relationship further, in order to experiment with adapted graphics and understand any graphics 'rules' that could then trigger energy saving behaviour in these screens.

Understanding TV lighting

Modern screens can use a variety of different backlight technologies. We wanted to test our hypothesis on three types that we felt represented the UK market at that moment in time:

• Direct LED: Lighting 'zones' are made by individual LEDs lighting a group of pixels from behind. Tending to have larger LEDs, and therefore fewer zones, Direct LED TVs can be slightly reactive to luminance vs energy changes.

• Full Array, Local Dimming (FALD): As above, but smaller LEDs are used in higher numbers, resulting in many more individually controlled zones. We considered these as highly reactive.

• Organic LED (OLED): Each individual pixel is also its own independent light source. OLEDs are therefore'100%' reactive.

Testing methodology

For our tests, we used 55" TVs from 2021, that represented each lighting technology. Using a smart meter connected to each screen, our intention was to measure energy while displaying various full-screen colours, bars, or shapes, all at varying brightness levels.

To fairly test our hypothesis, we sought a 'medium' power level for each display. Considering our nationwide ambition for any LCGfx changes, we had to account for households with older non-reactive TVs, or those who set brightness deliberately high. Therefore, we intentionally deactivated many built-in energy-saving features in modern screens, including default low-power modes, timers for screen dimming, and pop-up alerts. Indeed, turning off so many built-in power-saving features evidences the positive trend of TV manufacturers making such settings standard.

We set TV picture profiles to 'standard' or 'neutral', and adjusted all other picture settings (such as 'colour' or 'contrast') to 50% of their given range. We ran each set of image tests twice, once with the backlight at 50% strength, and again at 100%.

This approach ensured our tests were not about comparing different TVs or backlight technologies against each other - rather comparing LCGfx test images against each other to understand which changes triggered the most savings.

Our tests quickly validated the wider luminance vs energy hypothesis. All the screens saved some energy with darker images. However, we were surprised by just how reactive the FALD and OLED screens were, with even a few luminance changes in relatively small parts of the image.

Testing energy impacts on modern TVs, using smart energy meters

Our next challenge was to identify a large-scale use-case for this idea, one that wouldn't require the Â鶹ԼÅÄ to start filming everything in the dark! We knew that graphics (such as menus, interfaces, and holding screens) would have the least narrative impact, and be easiest to implement. It was here where my Blue Room colleague, Alison Hunter, suggested looking at radio graphics on TV.

Radio on TV

showed that UK audiences listen to 58 million hours annually via DTV radio. While these audiences concentrate on the audio, placeholder 'slates' for each station appear on screen. Not surprisingly, this makes TVs the most energy-inefficient 'radio' devices.

Market data also suggests that 3 million (11%) of the 27 million UK TV households own a FALD or OLED TV. As a'reactive' group of TV households, they would also gain from any LCGfx changes to DTV Radio, while the remaining 89% may also find smaller energy savings. Therefore, regardless of the screen type, any new LCGfx-style radio slates would have the potential to save energy in millions of DTV radio homes.

It's important to note here that the original DTV slates were designed in an era of mostly non-reactive TV screens, which reduced brightness by filtering an 'always-on' light. Our LCGfx idea was not about considering older images as wrong in any way - they were right for their time. Rather, an LCGfx approach is about optimising and future proofing graphics to take advantage of the advanced dimming and backlight technologies of today - and tomorrow!

With DTV radio identified as our use-case, we mocked up a redesigned series of LCGfx slates, which meant reducing larger areas of luminance or vibrant colour, while still allowing text and the station brand to be prominent.

LCGfx radio slates

Fortunately, our work coincided with a Â鶹ԼÅÄ-wide rebranding project, which meant we combined LCGfx principles with the latest guidelines when producing the prototypes. Once compared with the original slates under our test conditions, we found the results to be astounding! In our tests, at 100% backlight strength, averaging across all the Â鶹ԼÅÄ radio station graphics, the savings were:

• 64% on OLED
• 47% on FALD
• 22% on Direct LED

Updating the Radio 4 Extra slate produced the largest individual saving on the OLED display, moving from 263W to just 63W - a saving of 76%!

Â鶹ԼÅÄ Station measurements (averaged across HbbTV and MHEG systems) when measured at 100% backlight on OLED.

Many modern televisions offer features such as dimming or screensavers whenever static or audio-only content is played. This means it would be unlikely that an OLED would display a DTV graphic for too long anyway - but these LCGfx changes would still make a huge difference during any pre-screensaver time, when applied to the millions of screens in use.

Â鶹ԼÅÄ Station measurements (averaged across HbbTV and MHEG systems) when measured at 100% backlight on FALD.

Our tests also revealed that the 'press green' function on Â鶹ԼÅÄ DTV radio, which hides the station logo and makes the screen almost completely black, also works in an LCGfx way! While not necessarily the green button's original purpose, we were pleased to discover bonus functionality that really does mean the green button is 'green'!

Once we had the results for each station documented, we approached our colleagues in radio and branding with our moon-shot request: would they be able to change the original radio slates over to our new LCGfx alternatives?

Making the change

The ongoing Â鶹ԼÅÄ rebranding meant colleagues were already primed for a graphics change, although a sustainability-focused one was a pleasant surprise for them! Our live demonstrations and test data won immediate support. The teams collectively embraced the idea and did all they could to quickly roll out new LCGfx radio slates based on our prototypes. Notably, they adjusted the concept to work on both older MHEG systems and newer HbbTV equipment, so that all audience members would benefit.

Averaged energy consumption readings, across all stations, HbbTV & MHEG, and backlight technologies. The red line shows the original graphic's energy use, versus the new 'LCGfx' alternatives.

Once we were notified of the roll-out, Alison and I quickly switched on as many TVs as we could find to check! It was an amazing feeling to be greeted by new lower-carbon images, broadcasting live, nationwide! What began as a casual thought-experiment between two colleagues was now an energy-saving reality. We were incredibly moved in that moment, knowing that from very the moment of switch-on, the graphics were instantly saving energy in potentially millions of homes - in fact, anywhere a TV was being used to listen to Â鶹ԼÅÄ radio.

What's next for lower carbon graphics?

The success of the radio slates has spurred further LCGfx thinking within Â鶹ԼÅÄ, and beyond. Many Â鶹ԼÅÄ radio studios now use LCGfx principles on internal displays. Technology colleagues in collaboration with BT are developing LCGfx'bars and tone' graphics, commonly used by broadcasters throughout Europe. We hope these developments will be showcased to the European Broadcasting Union to be considered in future energy-saving standards. While these initiatives are not focused on audiences, they will still reduce energy at a 'local' level, and any industry adoption will also hopefully inspire even more LCGfx projects.

The Â鶹ԼÅÄ's new LCGfx radio slates are making a real impact for audiences right now - saving energy at a local level, and collectively, potentially, preventing hundreds of tonnes of CO2e or more from entering the atmosphere, had the original slates not changed.

To summarise:

• Audiences: We would encourage audiences to reduce their backlight setting! Without going so far as to turning the TV off, dialling down the light is the most effective way to reduce energy!

• Manufacturers: We'll continue to explore and highlight energy-saving features built into modern screens, while also encouraging manufacturers to continue their efforts in making these settings even more accessible by default.

• Content makers: We invite all content creators, especially those working in user experience or graphic design, to consider appropriate and effective places where they could deploy LCGfx.

Collectively, these actions can significantly reduce television energy usage, not only in individual screens and homes, but also at a much wider UK-wide scale.

We hope that this introduction to Lower Carbon Graphics has been inspiring. We particularly look forward to seeing how our creative colleagues in the broadcasting industry may adopt these ideas and push the boundaries of energy-saving graphics even further. Our experiment proved that even a little change can go a long way, and we can't wait to see where these ideas may go next.