Frequently Asked Questions

What is Edge Blending?

In the context of multi-projector display systems, edge blending is possible when the projected channels are arranged to have overlapping regions on the display surface, within which regions the projected content is identical from each contributing projector.  If the relative intensity of each channel image is faded out in a controlled fashion within the overlap regions, then it is possible to result in a seamless join between projected images to form a continuous larger field of view. Edge blending is an essential function when forming immersive projected environments for a wide range of applications.

What is Optical Edge Blending?

Optical Blending uses physical masking techniques to provide managed fading of multiple partially-overlapped projected images so that their images are blended together to form a larger, continuous, image.

What are the benefits of Optical Blending and why do we need it?

Optical blending operates on the entire projected light flux by attenuating the optical transmission in a controlled way within the overlapping blend regions between projected images.  In doing so, when a dark scene is being projected that includes the unwanted leakage light “offset” from each projector, all of this light is being attenuated, so there will be no unwanted addition of leakage light in the overlap regions.  When blended with high-performance optical blend masks, a seamless image is then achieved for all scene content.

What projector types and technologies can be optically blended?

In principle any large-format projectors may be supported, depending on lens selection primarily. Chronos has been successfully implemented on WUXGA, WQXGA and 4K single-chip DLP, WUXGA and 4K 3-chip DLP and 8K LCoS projectors, including lamp, laser-phosphor and LED illuminated models. We continually adapt to projector technologies as they evolve and develop. It can be applied to most projection configurations: Simple single-level arrays, Complex multi-level arrays, Domes and partial domes, Front and rear projection and Collimated displays.

Does Optical Blending impact display resolution or brightness?

Chronos Greyscale blending plates have an optical transmission of greater than 97%, so ~3% loss should be allowed for when calculating display luminance performance. Foil provides 100% transmission through the clear aperture.

Chronos Glass Greyscale preserves full resolution in the blend regions and throughout the projected image.

With patterned masks (Foil), while there is no impact on display resolution in the unblended regions, there will be a slight blurring effect visible within the blend regions, owing to diffraction at the pattern edges. GBvi’s blending algorithms have been specifically developed to minimise this effect while still providing high-quality blends.

What is the maximum number of projectors you can work with?

We have no set maximum. To date Chronos has been successfully implemented on dome displays with up to 16 channels each. The alignment processes significantly ease the installation and setup efforts, so even higher channel counts can certainly be supported.

Can you help with display design and layout?

Yes. GBvi has extensive projection display design experience and a standard component of our service is to review your display design primarily for compatibility with optical blending.

However, if you would like help with display layout or performance analysis, we would be happy to offer this service.

How is the blend mask positioned?

A set of Chronos Mechanics is comprised of an adjustable rig that positions a glass/film mask at the precise distance in front of the projector.

We recommend the use of Chronos Mechanics, since this serves as a carefully designed solution optimised to fit with Chronos blend masks.

Chronos Mechanics are available in two forms: static and actuated:

Static: fully adjustable by hand, and once it set up, is left permanently. Requires no further action!

Actuated: motorised (moveable) mask to remove the blend from the light path. A solution optimised for systems which show both light and dark scenes for prolonged periods.

What is the difference between your blend masks and alternatives?

GBvi is the leading independent developer and manufacturer of high-performance optical blending systems. We have invested heavily in our own in-house manufacturing facility and have developed system design tools, mask generation algorithms and alignment processes to enable us to support the most demanding requirement, customised to each display design.

Our blending solutions give you high-performance blending, superior to any plain-edge, layered or sawtooth mask solutions that are also used – and it can withstand high light flux without degradation.

What is the lead time?

An overall project timescale is typically 6-8 weeks, depending on the design complexity.

However, with advanced notice and with quick provision of customer design data we can often turn systems around significantly faster.

Can we ask our integrator to use your blending?

Yes, of course. Just put the integrator in touch with us and we would be happy to work with them.

GBvi does not offer complete display system solutions and integration; our normal mode of operation is to work with integrators and to develop good working relationships.

Why would we need Optical Blending instead of software / electronic blending?

Very good performance blending can be achieved with electronic (also software) blending, for bright scenes.

However, for darker scenes, the overlap region will quickly become visible as the leakage light from adjacent channels sums together.

While this could be compensated with ‘infill’, where a deliberate grey scale value is added to video signals to try to match this overlap, this significantly degrades the overall system dynamic range, making dark scenes appear washed out and lacking ‘blackness’.

Quality optical blending can completely eliminate this issue, so that dynamic range is optimised and transitions between ‘day’ and ‘night’ scenes do not need to be carefully managed.

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