Remedy: Video Geometry Nightmares - AvNetwork.com

Remedy: Video Geometry Nightmares

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“Image and display screen geometry continues to be a major headache for our industry,” maligned Tom Kopin, Global Engineering Specialist at Kramer Electronics. He shares some tips and insights so you don’t feel all alone.

For years, computer monitors and televisions had the same aspect ratio—4:3, or 1.33:1. With the advent of HDTV, the 16:9 (1.77:1) aspect ratio came into being, and it was expected that the manufacturers of computer monitors and projectors would follow suit.

Except they didn’t, adopting instead widescreen variations of older 4:3 computer display formats. While HDTV embraced the 1280 x 720 and 1920 x 1080 video standards, laptop computer and computer manufacturers started rolling out Wide XGA (1280 x 800), SXGA+ (1400 x 1050), and Wide UXGA (1920 x 1200) formats—all of which use a 16:10 aspect ratio, or 1.6:1.

As video moves from traditional broadcast to streaming formats, 1080p/60 has become the default standard for everything from tablets and smartphones to Apple TV, Roku, and a host of media players. Meanwhile, the computer industry is stubbornly hanging on in their 16:10 world, although there are laptops available with 16:9 screens (e.g., 1366 x 768 resolution).

SCREEN CHOICE HEADACHES

This makes choosing a projection screen a major headache: Do you settle for black bars on the left and right, or top and bottom? Simply fitting the width of a 16:9 image onto a 16:10 screen will result in a “letterboxed” presentation, with black areas observed above and below the actual image.

Conversely, fitting the height of a 16:10 image onto a 16:9 screen will result in a “pillarboxed” presentation, with black areas on the sides of the image. Neither of these is pleasing aesthetically, and in many cases it’s not practical to install manual or automatic side/top drapes to mask the unlit screen area.

Obviously, a compromise is needed. In general, conference and meeting room projectors use a 16:10 aspect ratio, so we’ll need to manipulate 16:9 images to fill the screen. Installing a video scaler with full image geometry adjustments ahead of the projector will permit you to re-scale a 16:9 source to a target resolution of 1920 x 1200, and zoom slightly to fill the height of the screen.

If the screen has a large black matte border or frame, any image that overshoots the width will not be noticed. You can also define an input on the scaler for 16:9 video sources and change the blanking to create a 16:10 image so that there is no overshoot. Assuming the content being shown doesn’t have important detail running right to the edges of the image, this is an acceptable solution as you’ll lose only 10 percent of the total 16:9 screen area.

Another approach is to use the scaler to compress the image slightly in the horizontal plane. This will create some image distortion, as objects will appear thinner than they should. If the 16:9 source is a computer showing documents, spreadsheets, and slides, most observers won’t notice anything askew.

AN END TO THE CONUNDRUM?

The emergence of 4K may solve this problem once and for all, as it appears that both computer and display manufacturers are finally converging on a common image size, rendering most 4K images with 3840 x 2160 pixels (16:9). Can we at last end, once and for all, the aspect ratio conundrum? Don’t get your hopes up. Cinema 4K (4096 x 2160, 1.85:1) and wide 5K (5120 x 2160, 2.37:1) displays are already being exhibited at trade shows. Given current market trends, you can be certain that we’ll see even more unusual pixel counts and aspect ratios. Sigh…

THREE DIRECTIONS TO SOLVE THE ASPECT RATIO ISSUES

1: With conference and meeting room projectors use a scaler and zoom slightly to fill the height of the screen
2: Create a custom border around the source image to fill the width or height of the screen
3: Wait for 4K!

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Kramer VSM−4x4HFS Matrix Switcher/Multi−Scaler

The What: Kramer’s VSM−4x4HFS Matrix Switcher/Multi−scaler with video wall and multi−viewing modes offers the fast and clean switching and scaling. Designed for presentation environments, the switcher/scaler features a 4x4 matrix switcher, as well as video wall (2x2), dual display (PIP/P&P) and quad display modes.

The What Else: Video wall mode comes with Bezel correction options. VSM−4x4HFS includes PixPerfect scaling, Kramer’s high−precision pixel mapping and scaling technology. The VSM−4x4HFS has four HDMI inputs and four scaled HDMI outputs and offers flexible control options, e.g., front panel buttons, IR remote control with OSD (On−Screen Display), RS−232, and a built−in Web browser.

More Info:www.kramerav.com

This remedy is part of our special AV TECHNOLOGY 10 Remedies ebook.

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