1. Geometry adjustments for seamless edge blending
(1-1) Optical Alignment, adjustment of the Lens Shift and Zoom of lens increases the precision and flexibility of projection locations. There are two ways to adjust them, the first one is manual adjustment, which is a knob for Lens Shift, and a ring for Zoom, the second one is automatic adjustment. By comparison, automatic adjustment offers not only higher precision and reliability, but also speedy geometry adjustment, which is convenient and saves time.
(1-2) In terms of geometry positioning, there are two methods in general, external software or built-in image warping/edge blending processor. Aside from basic adjustment of the four corners, it also need to be able to freely adjust any regions within the projection, that way, it would be able to support edge blending of not only regular rectangle outputs, but also irregular shaped outputs such as arcs, columns etc. The higher the warping resolution (more grid blocks), the higher the amount of precision one can achieve, for a better seamless effect.
2. Image consistency (i.e. consistency of brightness and color)
(2.1) Prior to image blending apply basic configurations to each projector, including setting the same picture mode, color temperature and brightness, and measures color parameters to lower the optical parameter differences between projectors.
(2.2) After image blending make brightness and color adjustments, including increasing the white level of the overlapping region, decreasing the black level at the non-overlapping region as well as adjusting RGB color parameters, so that the overall projection has both even brightness and color.
Accurate geometry positioning and consistent imagery would be able to satisfy the performance requirements of multi-projection.
Compared to other (LCD) projection technologies, DLP projection can produce dark (black) levels with much lower brightness. Other technologies cannot output relatively low brightness for black images, which is already visible in a single projection setting; In a multi-projection setting, projection overlap would amplify the brightness of black images, which cause them to be visually not black enough. Since DLP projections have low brightness for black images, they can offer higher contrast in multi-projection settings.