What does 4K mean in photography

4K - Maximum brilliance for your pictures

Markus Mizgalski

Ultra-high-resolution images are no longer a utopia, even for less demanding photographers; any system camera can do this. It is different with videos: 4K is only slowly taking off here

EnlargeThe future belongs to 4K: We reveal what the technology will bring and how to prepare for it.
© Artur Marciniec @ Fotolia.com

HD, Full HD, 3D and now Ultra HD or 4K - the future of film and television has had many faces in recent years and still has many faces. The latest is that ominous 4K, a video resolution that overshadows everything that has been known so far. Around 4,000 pixels in width are available, although there are differences with regard to the exact number. More on that later. First of all, the question arises as to what the advantages are compared to Full HD, which most viewers already consider to be quite brilliant.

Which camera is right for you?

Quadruple resolution

Both in terms of width and height, 4K offers twice the resolution compared to Full HD, i.e. 3,820 x 2,160 pixels compared to 1,920 x 1,080 pixels. In relation to the total amount of pixels, this means four times the resolution and thus another significant increase in color space, brilliance, depth, dynamics - in short: simply an even better picture. Even an HDR mode is implemented. So far so good. However, the first question to be answered is what exactly we are talking about here. Because 4k and UltraHD (UHD) are often used synonymously, which is also correct with regard to televisions and peripherals. However, the Ultra HD standard, as defined by the manufacturers of consumer electronics, can also appear in the form of 8K UHD, i.e. with four times the 4K resolution. At the same time, the definition of the Digital Cinema Initiatives Consortium exists. Here the native resolution is 4,096 x 2,160 pixels because the aspect ratio is 19:10. In contrast, Ultra HD works with a 16: 9 aspect ratio. Youtube, on the other hand, also offers the option of streaming in 4: 3 format, i.e. with a resolution of 4,096 x 3,072 pixels.

EnlargeThe diagram shows very clearly what a quantum leap Ultra HD means. The Full HD resolution is shown in red, the difference to HD (yellow) can be seen, but is far less clear than between Full HD and Ultra HD 4K (blue) or 8K (green).

More color

The Ultra HD standard also includes a larger color space than Full HD (Rec. 2020), because while Full HD covers around 55 percent of the reference color space, UHD is around 75 percent. Incidentally, the pixels are square with a bit depth of 10 or 12 bits.

The maximum frame rate available is 120 images per second, which means extremely fluid and fast image changes. Rec. 2020 is supported by both the H.264 / MPEG-4 AVC and Google's HEVC codec; Youtube uses the latter for streaming.

Affordable devices

While UHD televisions were very expensive in the early days, the devices have now become affordable. Devices from premium brands such as Samsung, Philips or LG are theoretically available from just under 800 euros, for around 900 euros you can get the brand new Philips 42PUS7809, which also offers 3D and Ambilight. The situation with projectors is not quite as positive, because here the offer starts at around 3,500 euros for the cheapest model from JVC. With Blu-ray players, on the other hand, you have to differentiate between what the devices are supposed to do. Models with 4K upscaling are available from around 120 euros, but only extrapolate full HD content to UHD. For players that can play UHD natively, you have to estimate 400 euros or more, if devices are available at some point. With the BDT700, Panasonic has brought a model onto the market that can technically reproduce 4K natively, but at the moment there is simply a lack of data carriers with native content. Because a 4K standard for Blu-rays is currently not yet certified, allegedly there are still discussions about layers, technical details and the codes to be used. Rumors also say that with Sony, one of the driving forces behind Blu-ray in recent years, it could lose interest in physical media for financial reasons, which would at least slow down the development of 4K discs.

Watch UHD on TV

If you bought the flat screen TV last year (2013), it belongs to the first generation of Ultra HD devices. Although they are designed for 4K content, they have a few peculiarities: the TV's media players can often display content from an external memory in full HD at most. If you connect a USB hard drive with an Ultra HD video, the TV will recognize the drive but not the content. In contrast to this, current Ultra HD TVs with content from external media generally have no playback problems. Their processors, interfaces and media players are powerful enough for 4K content.

You can, however, use a computer or notebook as a player - it then takes on the role of the media player on the television. The PCs must not be too old and must have the latest graphics cards with HDMI output - for example from the GTX 600 and 700 series from Nvidia or R9 from AMD. At the same time, the computer needs a media player that can play Ultra HD content, such as the VLC player. Connect the computer to the TV via HDMI and set the correct resolution under Windows or in the graphics card driver. Then nothing should stand in the way of enjoying the film.

EnlargeHDMI remains HDMI even with version 2.0. If the shielding of the cable is good enough, you can continue to use it for 4K. This copy, for example, creates the necessary data rate.

A little pitfall

It is important that anyone who wants to be future-proof will at some point need both a player and a television that support the new HDMI 2.0 standard, because HDMI 1.4 cannot transmit UHD without technical tricks; the bandwidth of 10.4 GBit / s is not sufficient. UltraHD requires 18 GBit / s. This means that the inexpensive televisions are out of the running, models with HDMI 2.0 cost from around 1,100 euros upwards. The cheaper models compress the signal, so to speak, but not without loss. After all, if you call high-quality cables their own, you don't need any new ones when switching to 4K. There is no physical difference and the data rate that can be transmitted depends primarily on the quality of the shielding.

EnlargeOne or two years ago, UHD TVs were only available in the upper price segment, but even such a model with a curved panel costs “only” a good 2,000 euros, a 55-inch model, mind you.

And the content?

In the case of data carriers, the problem of the specifications for the 4K Blu-ray that have not yet been approved also applies here. The 4K remastered Blu-rays that can now be bought only contain Full HD material that was downscaled by a 4K master, i.e. is of high quality, but not 4K resolution. After all - originals with Ultra HD resolution exist and Netflix also wants to offer 4K material for streaming based on them. There are also numerous videos on YouTube, and there are also special sites such as 4ktv.de that have various material available, many of which are trailers or non-commercial videos.

And so you still have the opportunity to produce your 4K material yourself. In fact, you don't need any sinfully expensive cameras for this. Apart from the fact that there is an open source project for a UHD camera with Apertus, a few high-quality photo cameras have now also mastered the high-resolution video format. Among them are the Sony Alpha 7 and also the brand new Panasonic FZ-1000. Both manufacturers also offer affordable 4K camcorders for end customers.

EnlargeTheoretically, Panasonic's Blu-ray player BDT700 is probably able to play 4K videos natively. Alone there is a lack of suitable data carriers.