Pseudo HDR
How To Deliver HDR-Like Video In An SDR Package
Click the orange play button to see how you could have HDR-like video quality delivered in an SDR package with Visionular's Pseudo HDR.
More about Pseudo HDR
What Visionular is doing is providing HDR-like quality video but keeping it in SDR format. We refer to this as Pseudo HDR. You can input your HDR source footage, but your output is delivered as an SDR stream with “HDR-like” quality. This means you no longer have to deal with the typical HDR limitations.
Deliver HDR content in an SDR package
Now non-HDR devices can deliver HDR content in an SDR package to support more devices. Slower networks aren’t an issue. You can deliver HDR-like footage over networks that can’t support high bitrates, traditionally needed to deliver HDR. UGC – User-generated content by nature varies widely in quality. That used to make encoding and color matching a painstaking process. Now scene identification and pre-processing are widely used to address this variance.
Technology
Adaptive Histogram Equalization
We use something called Adaptive Histogram Equalization (AHE). We extract multiple histograms from localized regions of a single frame and then use those local histograms to achieve boosted contrast levels resulting in a significantly enhanced dynamic range.
Cap Limit
We also apply a contrast limit to address other artifacts, such as noise that can surface during the histogram transformation process. This contrast limit clips the enhanced histogram to prevent these artifacts and make them less noticeable. The value at which the histogram is clipped is called “Clip Limit.”
YUV Domain
We have proposed a direct YUV histogram transformation by leveraging the theory behind probability distribution, considering the conversion matrix between RGB and YUV channels. By deriving such nonlinear probability functions, we directly apply Pseudo HDR in the YUV domain without the YUV to RGB conversion.
Skin Tone Mapping
We combine the output of the Pseudo HDR with the original source video through the use of adaptive weighted sum. This allows us to address problem areas such as skin tones that, when subjected to a histogram transformation, can produce undesirable artifacts.
Behind The Curtain
High Dynamic Range Frame Beautification
With audiences accustomed to the vibrant, true-to-life colors of HDR photos and videos, they have little tolerance for flat or poor color reproduction. As most videos were originally captured in standard dynamic range (SDR), our Pseudo HDR solution was developed by using our HDR Frame Beautification (HDR-FB) technology.
After analyzing a video’s color range and brightness, HDR-FB converts standard dynamic range video to a simulated high dynamic range, with deep, balanced colors across the spectrum for a beautifully natural look. We call the end result “Pseudo HDR.”
Smart Tone Mapping
For devices that do not support HDR video decoding or where the connected display cannot correctly represent high dynamic range video, Smart Tone Mapping converts HDR video to SDR video.
HDR images and videos have higher brightness, deeper bit depth, and wider color gamut, meaning in many cases they cannot be displayed correctly on non-HDR displays. To be compatible with HDR images and videos, SDR devices make it necessary to apply tone mapping technology to map HDR images and videos to SDR only displays and devices.
Because the brightness range of SDR display devices is much smaller than that of HDR images, and with the brightness range seen in nature including the relationship between the human eye’s perception of brightness and brightness intensity as perceived by the human eye, non-linear processing is required when designing tone mapping algorithms.