Background:
Noise can be a major component of file size when using AVC/HEVC compression.
Other components include the amount of detail in the frame, and the amount of new
image area revealed on each new frame. At high levels of compression,
the contribution of noise diminishes because the encoder acts as a filter,
but at the expense of some loss in sharpness and subtle details.
When improved compression quality is chosen, noise is better preserved, but preserving high noise levels result in much larger file sizes.
There are two types of noise commonly encountered in video frames:
(1) film grain, and (2) "shot noise" in solid state camera sensors.
Shot noise always occurs as a statistical consequence of the discrete nature of
photons and electrons in image sensors. Shot noise is inevitably an increasing problem
as video frame sizes increase to UHD and beyond, because more pixels normally equates to a smaller light collection area per sensor, and reduced electric current flows.
Unlike film grain, shot noise has no aesthetic appeal, so reducing it without
sacrificing image quality is becoming increasingly critical in today's bandwidth-constrained world.
Noise Reduction:
Noise can be a major component of file size when using AVC/HEVC compression.
Applying noise reduction is not really equivalent to reducing file-size.
If there is no noise, then noise reduction should do nothing to each image.
For a given encoder, low-noise file sizes therefore cannot be further reduced without reducing detail.
Typical noise reduction techniques applies spectral or spatial
filtering to each frame separately. These techniques are limited in their
ability to distinguish noise from fine detail, resulting in image blur and washed-out low-level details.
Benefits Viarte MC Noise Reduction:
Viarte MC noise reduction can reduce film and shot noise without impacting detail.
The results look much sharper than
other denoise methods. When combined with scaling, viewers can enjoy a much cleaner and more immersive viewing experience, particularly not normally achieved with SD sources.
The Viarte deinterlacer produces less flicker and noise than other deinterlacers, allowing MC
noise reduction to be even more effective.
The latest Viarte HDR/SDR MC noise reduction has made substantial advancement.
For example on HDR test material, at 50dB PSNR, the bit-rate reduction is over 80%, dropping
to 65% at 45dB on average. The PSNR gain at 3Mbps or higher is over 3.5dB.
In general, the latest processing bests the previous version by 1-3dB,
reducing HEVC/AVC bit-rates by 50% on average, and up to 5x on lower CQP values,
while maintaining very subtle details and sharpness.
For more information, please refer to our latest paper
"HEVC Results from MC Noise Reduction of HDR Content",
April 2016.
Other benefits of Viarte NR include:
Demonstrations of the latest isovideo HDR noise reduction were given at NAB 2016
#SU14608,
and could be made available upon request.
Please
contact us
if you need more information, or want a free trial.
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