video-projector

Video Projection

INDUSTRY STANDARDS FOR LIGHT OUTPUT

The only requirement for commercial cinema projector systems is light output, with cinemas requiring 16 ft lamberts of screen brightness. This same standard applies to all domestic applications and is often not calculated. The calculation of screen brightness given a projector light output combined with your screen gain, is simple enough to calculate. Additional factors are the distance from the screen, losses passing through glass and whether a zoom method is being utilised for anamorphic widescreen. All these factors mean that your system should be engineered by an industry expert, like Cogworks.

HDR further complicates these standards as a much higher light output delivers the dynamics required by HDR signals on the latest 4K UHD discs. For the ultimate picture quality, we recommend 32 ft lamberts of screen brightness.

USING ACOUSTICALLY TRANSPARENT SCREENS IN CINEMAS

Whenever you go to commercial cinemas the speakers and acoustic treatments are hidden behind an acoustically transparent screen. Speakers placed under the screen often can’t be seen from the rear row of seating and if you can’t see the speaker, you are not hearing the speaker directly, which is a problem. Imagine listening to stereo speakers and putting a pot plant in front of of the speakers, the resulting the sound quality is not going to be very good. The same applies in this situation.

The screen is the perfect place to hide room acoustics and hearing the voice coming from a speaker behind the screen, is always more convincing.
Using incorrect screen materials in a home cinema can lead to voice intelligibility problems, hot spotting and screen distortions.

Contact a Cogworks professional to learn more about our screen solutions.

BENEFITS OF VIDEO CALIBRATION AND PROCESSING

All video systems for mastering movies are completed on monitors and projectors calibrated to industry standards. These are the same standards used in commercial cinemas and should be used in any system where the original intent of the director is paramount.

Projector and TV manufacturers can’t afford to hand calibrate each product and the reality is that the room affects the contrast ratio and colour reproduction, or any product put into that room. The colours of the room such as paint, leathers, rugs are reflected to the screen and even the colour temperature of light sources can affect the colour of a TV.

Some brands have quite good calibration tools but often we need to use external products to achieve the best outcomes. Of these products, Lumagen is by far the most superior product on the market for both video calibration and general video processing of low resolution and compressed images.

Video Calibration should be carried out by professional video calibrators. Please contact Cogworks to find out more.

DEALING WITH HDR

High Dynamic Range (HDR) has introduced a significant set of problems for most projection systems. The reality is that most projector systems are not producing any more than 50 nits, however the HDR standard requires systems to be able to handle over 2,500 nits. This requires a conversion process to be applied to the signal and that HDR settings potentially need to be turned off in the projector/ TV system. While Blu-Ray players such as Sony and Panasonic have this conversion, the quality of the conversion is not ideal, and we highly recommend using a Lumagen to correct this and other problems in any high-end video system. Please contact Cogworks for more information.

ANAMORPHIC LENS

The issue with making an image larger using anamorphic widescreens is that the image is not going to be as bright. One way to increase screen brightness while making the image larger is to use an anamorphic lens. The image is stretched vertically in the projector to maximise light output and then passes into the anamorphic lens which expands the image to fill the entire screen. By doing this, we can increase the screen size by 33% with approximately a 10% drop in brightness.
We highly recommend using cylindrical anamorphic lenses which is the only way to correct for distortions in the image. We also recommend using sealed optical systems as multiple glass surfaces will collect dust that diffuse light and drops the screen contrast ratio.
It is a misnomer in the industry that curved screens are good for anamorphic widescreen. Like most technologies, curved screens have their place but only as a tool to eliminate specific distortions in projection. Most cinemas do not require curved screens.

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