Posted on October 5, 2020 By Phil Jones
The topic of this month’s sponsored article is video processing and its impact on a projector’s SDR and HDR picture quality. Video processing separates one video display from another because it impacts so many factors like 4K upscaling, visual contrast, color reproduction, and motion performance. Processing is the reason why two OLED TVs which utilize the same panel can look completely different.
No matter what content you’re watching – HDR movies, HDTV broadcast, web videos, it’s the video display processor that analyzes, cleans, and refines the image.
It takes more than specs and fancy parts to guarantee exceptional picture quality. The quality of the 4K panel, DCI-P3 color filters, dynamic iris, or laser source are less important than how they are used. Many projectors/TVs with “better” specs are outperformed by a less-equipped display with a better brain.
Sony has always stressed that superior processing separates its 4K video displays from the competition. While the processing in Sony flat panels has continued to evolve, it has been a while since they updated their home theater projectors’ brains.
HDR content is the current hot topic in home theater entertainment. However, it is exceptionally challenging to reproduce HDR content on a projector. HDR content contains information that far exceeds a standard home theater projector’s capabilities, so a huge leap in video processing horsepower is required.
In 2016, Sony introduced the flagship Z9D flat panel TV with a powerful new processor called the X1. This year, two Sony projector models, the VW915ES and the VW715ES feature a version of that X1 processor optimized for projectors. Thanks to the power of that X1 processor, these projectors feature Sony’s exclusive Reality Creation technology that analyzes HD, 4K, and HDR content frame by frame to enhance detail, colors, and detail. The X1 processor ensures that Full HD is upscaled close to 4K quality.
Manufacturers like Sony also use these powerful video processors in their home theater projectors for dynamic analysis and HDR content tone mapping. The X1 processor powers a new feature called Dynamic HDR Enhancer that combines scene by scene HDR tone mapping with a dynamic iris and precisely modulated laser light source to deliver a massive improvement in HDR reproduction. The lamp-based Sony VPL-VW715ES uses the same X1 processor so also benefits from Dynamic HDR Enhancer.
During my review, I took several photos of the new VW715ES and the predecessor model VW615ES side by side on the same screen. As you can see from the image above, Dynamic HDR Enhancer powered by the X1 processor makes a noticeable improvement in the HDR performance of the VW715ES compared to the previous Sony projector. While it is difficult to capture all the differences in a photo, you can see that the newer model has brighter HDR content, more vibrant color, and deeper black levels, while still maintaining brighter highlight detail.
Today’s projectors just don’t have enough brightness or color volume to accurately reproduce all the information in HDR content. So, how does a projector manufacturer cram the most color and brightness possible into a projector’s more limited capability? It is my continued belief that dynamic tone mapping is essential to extract the maximum image quality from HDR10 content.
HDR consumer content (4K Blu-ray and streaming) is mastered for playback on a flat panel display monitor, not a projector, so it’s produced at a variety of brightness levels ranging from 1,000 nits (292 fL) to 10,000 (2919 fL) nits. To generate over 10,000 nits on a 100-inch screen would require approximately 87,000 ANSI lumens while 1,000 nits would require 8,700 ANSI lumens.
No home theater projector can deliver that massive amount of brightness while maintaining deep blacks. Most 4K HDR capable projectors can only deliver between 100 nits (29 fL) and 200 nits (58 fL). Now you see why no HDR compatible home theater projector can reproduce all the brightness and color volume found in consumer HDR content.
As a result, HDR projectors utilize tone mapping which is a compromise between maintaining bright highlight details and delivering higher screen brightness. There are a couple of pieces of information embedded in HDR10 content that an HDR display uses to make picture adjustments.
There is an HDR infoframe that tells the video display to switch to the appropriate HDR mode. When the HDR infoframe is detected, many HDR projectors switch to HDR mode with a fixed tone map. It is basically “one size fits all” which hurts HDR performance.
Auto tone mapping uses the static metadata found in HDR10 content to automatically adjusts the projector’s HDR settings (tone mapping curves) in an attempt to optimize image quality. Last year, companies like JVC began offering auto tone mapping on their projectors. The goal was to better utilize the projector’s brightness and contrast capabilities based on the HDR movie or TV episode being shown. The two pieces of metadata that the projector’s video processor uses for HDR tone mapping are:
The average brightness of most HDR video frames is usually much less than 300 nits with a few peak highlights (sparks, flame tips, reflections) reaching up to 10,000 nits. While using the static metadata can improve a projector’s HDR performance, it is not enough to fully optimize the picture quality.
This year, companies like Sony and JVC are further improving tone mapping by giving their projectors the ability to do it dynamically.
Sony has a habit of hiding major improvements under obscure names. The VW915ES, along with the VW715ES and the GTZ380, has a new feature called Dynamic HDR Enhancer. By utilizing a version of Sony’s X1 processor optimized for projection, these are the first Sony projectors that can analyze HDR content scene by scene for precise dynamic tone mapping of HDR10 content.
First, let’s discuss why it is better to measure the HDR content dynamically instead of using the static metadata included in the content.
Since the MaxFALL/MaxCLL metadata is based on the brightest frame’s average brightness and brightest pixel in the movie, certain scenes with lower than average frame levels can still look way too dark.
In many cases, the metadata is missing or incorrect, so the projector might not have the right information to work with. Also, since the same embedded metadata (MaxCLL/MaxFALL) is applied throughout the movie, sometimes the projector’s tone mapping decisions can be very inaccurate.
Many LCD and OLED TVs have measured the HDR content frame-by-frame and generated accurate metadata dynamically for years. Last summer, JVC added the capability to dynamically measure HDR metadata to their NX and RS Series home theater projectors. This year, Sony is introducing that capability as well.
Unlike most projectors, Sony has years of experience with HDR tone mapping since Sony 4K TVs have had the capability since 2017.
Powered by the new X1 for projector processor, each frame is analyzed, and Dynamic Tone Mapping is applied. In the VW915ES, this is combined with a dynamic laser and a dynamic iris to greatly improve the look of HDR content.
The new projector optimized X1 processor not only improves detail and resolution, but it also makes a noticeable improvement in the VW915ES Sony HDR performance compared to the VW885ES. HDR content is brighter, colors are richer, black levels are deeper, and bright highlight detail is visible.
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