Better HD Comes Into Focus at FutureSPORT Event
When it comes to creating better HD images, the often overlooked craft of lighting, continued commitment to quality lenses and cameras in an age of cellphone video, and a willingness to embrace video formats that require higher bitrates are just a few of the important considerations laid out during a session at SVG’s FutureSPORT event on Wednesday.
SMPTE fellow Mark Schubin kicked off the discussion with a quick overview of the importance of higher contrast ratios, illustrated with a slide featuring the same black-and-white–striped pattern but only a 3% difference in contrast. The result? The one with less contrast appeared to have less detail, demonstrating the simple relationship between higher contrast and higher perceived resolution.
Larry Thorpe, senior fellow, Imaging Technologies & Communications Group, Professional Engineering & Solutions Division, Canon USA, agreed on the importance of contrast, noting that lenses that have higher contrast ratios can allow more sharpness and detail.
“HD image quality still needs a lot of help, and the frontend is ever so important,” he said of the need for quality cameras and lenses.
As a signal passes through production and distribution, he pointed out, the high-quality parts of the signal are degraded with each successive step in compression. But artifacts and distortions do not get smaller and, thus, become more pronounced and noticeable by the time the signal gets to the home viewer.
“You have got to get the best-quality signal going into the system,” he added. “A cheap lens on a good camera compromises a lot of things, and a really good lens on a cheap camera is a compromise. The only way to not compromise is to get a good lens and a good camera.”
The Importance of Light
With field lenses having as many as 36 lens elements, Thorpe noted, there is the potential for hundreds of millions of variables in performance. And then there is the use of up to 20 glass materials.
“You can have the best glass and optical coatings, but, if they are not precisely aligned, things will move and chew away at optical performance in [excessively cold or hot] temperatures,” he explained. “For example, a piece of glass will let in 100% of the light but will have 4% of refraction, so you lose 8% of the light. When you have eight elements working in tandem, you lose 52% of the light.”
Lighting designer Alan Adelman discussed the importance of having a good lighting director involved with studio and other operations and also focused on two key decisions for any project: what will the exposure be and what is the desired color temperature.
“Those are basic decisions, but they affect all of the colors on the set. If you balance for tungsten lighting or for daylight, all of the colors will be different,” he said, “and, in different situations, you may want a different look.”
Those looks, ideally, are part of a conversation between the lighting director, the director of photography, and the director of the production. “They need to meet on a regular basis because how you light impacts the style of the shoot,” Adelman added.
Another consideration for lighting is the massive numbers of LED screens that are now part of nearly every set. Consideration has to be given to ensure that the displays look great without affecting how the hosts look.
“And you have to be more careful about how everything in the frame looks,” he explained, “because cameras are more sensitive and viewers can see more detail in dark areas.”
Adelman also advised that, if possible, material that will be edited later should be recorded in RAW format.
“Recording in RAW opens up new possibilities of what can be done in post,” he said, “and we are seeing a lot of movies, for example, doing color balance and effects in post. It is an enormous change for what is possible when shooting HD video.”
One word of caution: be careful when using LED lighting since LED lights can cause flicker in the video because not all lights are manufactured to the same standard. He recommends making sure there is no flicker in the image before making any multimillion-dollar lighting commitments.
Steve Mahrer, senior technology alliance manager, Panasonic Systems Communications Co. of North America, laid out Panasonic’s vision of an HD-acquisition environment where customers have ultimate flexibility and can use the resolution that best suits the need. But the challenge in all that choice is that the eventual need for transcoding and crossconversion leads to compromised image quality.
“Crossconversion is not a good idea, so a neutral format, like 1080p/60, which is quite possible and feasible today, can allow for easy conversion to 1080i and lossless and full-resolution 720p,” he explained. “It’s a win-win as you can originate beautiful 1080i or 720p images.”
He cited the new AVC Ultra format as offering Class 200 recording for visually lossless acquisition suitable for master-quality–content needs. His company’s Varicam 3, he suggested, can be an important workhorse for sports production, offering wide dynamic range and powerful color management.