Image (Distance) is Everything: 4K and HiDPI Displays

Since I launched it, over 5,000 people have used my 4K Calculator to see if they will benefit from a 4K display. What many people have found is that in a common living room setup, with a 50” display around 10’ away from the couch, you may not see any benefit at all. If you do see one, it is probably slight in nature. I’m sure some 4K vendors are not fans of this, but it helps readers realize what they might not be missing.

I often hear from people that the calculator is wrong. That they see a huge difference with 4K in a showroom and I’m obviously blind. Or they mention that their iPad or smartphone have HiDPI (Higher Dots-Per-Inch) screens and they can see the difference.  When it comes to a smartphone, or tablet, or even a computer monitor, they’re right. You can see a difference. Which is why this article has a simple point to make: High resolution is about the distance from the display just as much as the size of the display.

To show this, I did the math on a number of displays, assuming you have 20/20 vision. If you are better or worse, you can adjust accordingly for all these numbers. What I want to show is how close you need to be to see pixels with common displays. From a 4” iPhone 5 display to a 15” Retina MacBook Pro, up to an 84” 4K LCD, this distance varies. This is essential to understanding why 4K and HiDPI are great for some applications but not all.

Product

Resolution

Minimum Distance to see Pixels

iPad Mini

1024×768

1’ 9”

iPad Retina

2048×1536

1’ 1”

iPhone 5

1136×640

0’ 11”

Galaxy S4

1920×1080

0’ 8”

13” MacBook Air

1440×900

2’ 3”

13” MacBook Pro Retina

2560×1600

1’ 3”

Dell U3014 30” LCD

2560×1600

2’ 10”

Asus PQ321Q 32” 4K LCD

3840×2160

2’ 1”

50” 1080p TV

1920×1080

6’ 6”

50” 4K TV

3840×2160

3’ 3”

Sony 4K 84” LCD

3840×2160

5’ 6”

100” 1080p Projector

1920×1080

13’ 0”

100” 4K Projector

3840×2160

6’ 6”

Tablets and Smartphones

galaxy-s-4What do you see here? For items that are held close to your face, like a phone or tablet, HiDPI pays off. You need to have the iPad Retina or iPhone 5 a scant foot away from your eyes before you’ll see a pixel. On the iPad Mini, you begin to see pixels closer to 2’ away. I’m reasonably tall, and with my arms fully extended holding a tablet or phone, it is barely 2’ away from my eyes. More often it is closer to 12”-15” away, where the high-resolution pays off. Here the combination of higher resolution and small screen size are a benefit because of the distance.

Laptops and Monitors

387562-asus-4k-monitorWith laptops there is a benefit as well. Pixels are hidden from 1’3” and greater instead of 2’3” away. Desktop LCDs show similar benefits for reasonable distances. I can sit 2’10” away from a 30” Dell LCD without seeing pixels, but can get as close as 2’1” away from a 32” 4K LCD Monitor from Asus without seeing them. On a computer this allows a larger work space, or crisper fonts and icons. All of this at distances that are common for people to be using their laptop or desktop.

TVs

sony 4k lcdWhen this extra resolution starts to be less beneficial is in the home entertainment system. I asked friends, family and fellow reviewers about their viewing environment. The most common setup is a 50” TV that is around 10’ away from the seats. Sometimes closer or larger, sometimes a little further or smaller, but this is the median. As you see on the chart, you would have to move the couch over 3 feet closer to the TV to start to see pixels on the screen. Replacing a 1080p set with a 4K set is going to offer nothing unless you sit uncommonly close.

Projectors

sony 4k projectorWith a projector, the benefits are more likely to be seen. With a 100” screen, you can sit 13’ away and not see pixels with a 1080p projector. With a 4K projector you can move those seats up to 6’ 6” away if you want. I have a screen close to this size (96” for 16×9 content), and I currently sit 11 feet away. This is closer than most people sit, though it isn’t uncommon to be closer. Many people have a screen larger than 100” in a dedicated theater room. These situations all can benefit from 4K projection.

One more area where 4K can help with projectors is with CinemaScope content. With my 122”, 2.40 ratio screen, it is equivalent to a 130” 16×9 screen for pixel density. If I zoom in the projector and watch Star Wars on my screen, I can see pixels from 16’ 11” away. With a 4K projector and a 4K copy of Star Wars, I’d only see pixels if my seat was 8’ 6” away or closer. That is a real scenario where 4K can benefit.

Great Benefits in the Correct Situation

4K and HiDPI displays can benefit you by making images sharper and hiding pixels from view. The revolution to HiDPI screens in computers, smartphones, and tablets is welcome. It makes working and reading on a display much more pleasant. There are also benefits in larger home theaters that use a projector and screen.

Where we don’t see much real-world benefit is with 50”-70” 4K TVs. Most people sit too far away to see a difference at all. When people transitioned from SDTV to HDTV, they often replaced their 27” CRT with a much larger flat screen, but didn’t move the couches closer. With 4K I don’t expect people to move their seats closer, or to double the screen size again. 4K TVs look great in a showroom from 4’ away, but at home you won’t really see a difference.

So check those distances before you consider a 4K UltraHD TV. You might not need it and you can put that money towards a HiDPI computer monitor, or a 4K projector, where you will see the benefits.

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  • Gh0st

    While this is true in regards to seeing pixels, high resolutions offer more than just pixel density itself. Borders around objects can be smaller on higher resolutions, causing the image to look crisper. On top of that, more shades of colors can be drawn within an area causing the eye to see the colors as more brilliant.