UHD Picture Quality: More Than Just Pixels
As the Ultra HD (UHD or 4K) TV bandwagon gains momentum, it is important to keep in mind that delivering excellent video quality requires much more than just increasing the picture resolution from 1920×1080 to 3840×2160 pixels. The expanded detail of 4K also creates new demands on the video signal processing chips that make it all happen.
Key considerations for 4K displays & chipsets
For starters, it’s important to recognize that not all 4K displays are the same. Plainly stated, some are better than others in key parameters such as contrast range, frame rate, and the number of bits per pixel (determining color depth). For all display models and input signal characteristics, it is absolutely critical that the video processing chips driving that display are custom tuned, or tweaked, to best compensate for any deficiencies in either the incoming source or the display itself.
Moreover, excellence in picture quality does not stop at eliminating the deficiencies, but also enhancing the picture to conform to the viewer’s preferences. Sigma Designs incorporates proprietary compensation algorithms into its 4K technology to tune the processing, and facilitate adjustments by TV manufacturers to enable each particular display model to look its very best.
Most high-end 4K displays operate at a 120 Hz frame rate, while most content for 4K TV is delivered at either 60 frames per second (live TV and sports) or 24 fps (movies). Motion Estimation and Motion Compensation (MEMC) frame rate conversion, a technology which Sigma Designs leads the industry in developing and deploying, is essential for interpolating “in between” frames to optimally reduce the inherent motion blur of LCD displays.
The bottom line is that making a great 4K television requires quite a bit more than just a 4K display.
Upscaling existing content & enhancing color
Scaling today’s lower resolution content, such as from cable-TV or DVD/Blu-ray, to 4K “super resolution” is another area where the chipset makes a difference. Merely duplicating pixels will result in blurry-looking pictures, a problem avoided using Sigma Designs’ advanced non-linear interpolation, which does the best job scaling lower resolution (HD and SD) content to look its best on 4K screens.
Achieving high dynamic range, meaning the widest possible contrast between the darkest blacks and the whitest whites is another area where Sigma Designs works closely with TV set manufacturers to take fullest advantage of display features such as local dimming and dynamic backlight controls, achieving the widest possible color range along with smooth, continuous-appearing brightness gradations. This is important, as 4K incorporates a broader color range (10 bit) as compared to previous generations of HD technology (8 bit).
The bottom line is that making a great 4K television requires quite a bit more than just a 4K display, and Sigma Designs provides much of the “secret sauce” in video processing that enables today’s most sophisticated, and best-performing 4K UHD-TVs further enhancing a rich tradition of delivering excellence at the cutting edge of video technology. This heritage includes the acquisition of Trident Microsystems which itself had acquired the DTV and set top box (STB) divisions of NXP (itself a spinoff of Philips.) The acquisition of Gennum’s award-winning VXP image processing unit has further contributed to Sigma Designs’ world-renowned expertise in video processing.Filed under: 4K / UHD, Smart TV, Technology Briefs