UHD vs HDR | Comparison of 4K UHD and HDR of a Display

Next generation televisions and monitors are really exciting with crazy resolutions and stunning picture quality. OLEDs are slowly becoming the dominating display technology, thanks to the latest developments from Samsung Display in the form of QD-OLED display. LCDs with IPS panels and Nano Cell Technology and full array local dimming are an affordable alternative. Even though high-definition televisions, monitors and projectors are available for a long time, the technical jargon behind these displays such as Full HD, UHD, HDR, 4K etc. can be a little difficult to understand. If you are a novice to such terminology, then it can be daunting while make a new purchase. So, in this guide, let us explore the two important display terminologies: UHD and HDR in detail. We will compare UHD vs HDR and find out the differences between them.

The reason we chose UHD and HDR for this discussion is that these two technologies are the dominating factors while purchasing a modern TV, Monitor or Projector. We hope that with the help of this guide, you will be able to understand the differences between UHD vs HDR and make a better buying decision.

What is UHD?

Let us begin the comparison starting with UHD. It is short for Ultra High Definition and represents the resolution of a display. Resolution is nothing but the number of horizontal and vertical pixels in a display while a pixel is the smallest controllable display element.

You might be familiar with Full HD. It has a resolution of 1920 × 1080 pixels i.e., it has 1920 horizontal pixels and 1080 vertical pixels. So, a Full HD display has 2,073,600 or 2 million pixels. We sometime call a Full HD display as 1080P display, representing its vertical pixels.

When it comes to UHD, the pixel count will increase by 4 times as it has a resolution of 3840 × 2160 pixels i.e., it has 3840 horizontal pixels and 2160 vertical pixels. Similar to 1080P, we also call the UHD simply as 2160P.

UHD has 4 times the number of pixels than a 1080P display i.e., 3840 × 2160 = 8,294,400 or 8 million pixels. Hence, it is often called as a 4K display (technically, a 4K UHD display).

Due to this high resolution, the display will produce more crisp, clear and sharper images. This resolution is independent to the size of the display. For example, consider two popular TV sizes: 55” and 65”. Both these display sizes can have UHD resolution.

What changes is the Pixel Density of display that is often represented as pixels per inch or PPI of the display. It is the ratio of the resolution of the display to the screen size. So, a 65” 4K UHD TV will have slightly less pixel density than a 55” 4K UHD TV.

What is HDR?

Even though there is HD in HDR, it is completely different to UHD. HDR stands for High Dynamic Range. It is a technology associated with the dynamic range of an image which is associated with the brightest and darkest spots of an image.

HDR optimizes the contrast, brightness, sharpness and color of an image to make it more life-like and realistic. A HDR display will clearly differentiate a bright spot in an image and also, they will not dominate the rest of the image.

In order to do this, an image or video must be shot in HDR format, where each frame of the image/video contains additional metadata related to the brightness and contrast of the frame. Based on this data, the display will dynamically optimize each frame in the video rather than setting a static brightness and contrast values.

The display must have additional hardware capabilities in order to decode and display an HDR video. Some popular HDR Formats are:

• Dolby Vision
• HLG
• HDR10
• HDR10+

Of these, Dolby Vision is becoming the main stream HDR format with support from different TV manufacturers (LG, Sony, Panasonic, TCL, Vizio, etc.), content and streaming services (Ultra HD Blu-Ray Discs, Netflix, Disney+, HBO Max etc.). Game developers are also releasing popular AAA titles with support for HDR.

Comparison of UHD vs HDR

It is not ideal to compare UHD and HDR as they are completely different concepts with respect to displays. While 4K UHD represents the number of pixels of a display, HDR represents how those pixels are optimized for color, brightness and contrast.

UHD is a significant jump in image/video quality from a Full HD resolution. HDR takes this already beautiful video and dynamically adjusts the important parameters such as brightness and contrast for each frame.

A 4K UHD TV can have HDR capabilities or omit them completely depending on the type of display. For example, as OLED TVs are self-emissive, it is very easy to control the brightness of each pixel. So, the contrast of an image can also be adjusted dynamically to easily differentiate/isolate white/bright spots from darker spots. Hence, almost all 4K UHD OLED TVs have HDR feature.

Coming to LCD Displays, since they have a backlight, it is slightly difficult to control the brightness of various spots of the display. But some advanced LCD TVs have full-array local dimming feature, where the back light is divided into multiple zones so that we can control those zones individually rather than all the backlight at a time.

If an LCD TV has the feature of full-array local dimming, then it is easy to implement HDR feature. So, high-end LCD TVs from LG and Sony with full-array local dimming have HDR capabilities.

4K UHD LCD TVs with partial dimming also have HDR feature but the overall experience is not that great when we compare it to LCD displays with full-array local dimming or OLED TVs.

HDR vs UHD, which is better?

Simple answer: the combination of 4K UHD with HDR is the best display technology right now. If your budget permits, we recommend an OLED Display as you get excellent colors, contrast and wide viewing angles. Combine this with HDR you can experience the best possible video quality in the market.

Apart from TVs, computer monitors and laptop displays are also coming with 4K UHD resolution and HDR capability. Latest 4K projectors from reputed brands are now featuring HDR feature.

The cost of a 4K UHD Display (or projector) with HDR will be definitely more when we compare it to regular UHD displays. Since HDR dynamically adjusts the brightness of the video frame-by-frame, the power consumption of a HDR compatible TV (display) will be more especially when we play HDR content.

Conclusion

Although UHD and HDR are two completely different aspects of a display, people often confuse between these two. UHD is an indication of the resolution of the display (number of pixels) while HDR is the ability of a display to dynamically adjust the image parameters such as brightness, color and contrast. We saw the basic of UHD and HDR in this guide and also compared UHD vs HDR.