4K - beyond the pixels

When determining the video quality of visualization assets, resolution is always top of mind. But it is important to remember that resolution is only a piece of the image quality puzzle. A great 4K experience goes beyond the number of pixels displayed... Here are some parameters to put in equal consideration. 

Matching inputs and outputs

Having a 4K display or projector might be cool and all but remember that this is only relevant when the content you play also has as at least the 4K resolution! If your input signals have a lower resolution that does not match the same 4K quality, the image will be upscaled and you won’t be able to enjoy your extra pixels. The visual quality is not on par with content natively produced in 4K. This is also why the lack of 8K mainstream content is holding back the boom of 8K visualization systems.

The same logic applies the other way around. Most projectors accept a resolution input that’s higher than their native resolution. However, to cope with the higher resolution, the projectors will compress and adapt the image that is received into fewer pixels. So, you can project 4K content with an HD projector, but it does not make much sense, as you will never see the 4K result projected…

So, in short, to have the best 4K experience, the inputs and outputs of your system should both support this 4K resolution. 

P.S. The same rule goes for aspect ratios. The aspect ratio of your content must match the size of your screen. If they do not correspond, it will try to compensate by either having black bars appear around your content or stretching it to fit the screen.

Contrast ratio

The sensitivity to detail also depends on the contrast of the image, so the perceived resolution will also be impacted by the room ambient levels and the system’s brightness and contrast ratio.

Projectors with higher contrast ratios reproduce your content with deeper black levels and shadow details. Whereas, with low contrast, blacks or dark areas appear more like grey. The higher the contrast ratio, the sharper the details and the more subtle shades you will be able to see. It really boasts the depth of an image and makes it easier to see/recognize objects in darker scenes. 

To benefit from that high contrast ratio provided by the projector, the ambient lighting is of utmost importance. With a high ambient lighting, you ‘wash out’ the dark scenes and you lose the details.

Refresh rates

Refresh rate is the number of times per second (written in hertz, or Hz) a visualization system refreshes its image. With traditional televisions, this was 60 times each second, or "60Hz."

The refresh rate is especially noticeable when watching sports or showing content with a lot of action and quick movement. One benefit of a higher refresh rate is to reduce the motion blur.

And so, it might seem counterintuitive, but a HD television with a refresh rate of 120Hz might give a better viewing experience than a 4K unit that only refreshes at 60Hz.

Read more about the Barco framerates in this article.

Viewing distance

High resolutions allow for the optimal viewing distance to be shorter. Clearly, if viewers are seated close to the screen, you don’t want them to see a pixelated image, so increasing resolution may make sense in such situations.

Lower resolutions with lower pixel density, on the other hand, are perfect for long distance viewing experiences like digital signage advertisements on buildings. So, when viewers are further back, they can’t see the resolution, which makes paying for high-resolution solutions and/or content less useful.

Conclusion

So 4K is not simply a matter of getting more pixels on the screen? No! If you look at 4K as a tool to bring extra value and premium experiences, consider the other parameters that make up the visual experience. Many of them are quantified in the product spec sheets (brightness, contrast ratio, uniformity …) and worth comparing to make your assessment of the best technology.

At Barco we believe that the bigger picture counts and that means taking the broader content-to-display chain into account and ensuring that all the conditions are met to deliver content as intended.