With ordinary HDTVs, achieving high resolution is an expensive process. The part of the TV that generates the pixels – the spatial light modulator (SLM) – is one of the priciest parts of a projection system. But TVs with wobulation technology are able to double the number of pixels in the image without doubling the pixel on the modulator, so there’s no need for a more expensive SLM – and no need to spend nearly twice as much for the same high-quality picture.
How is it possible to double the resolution with the same number of pixels? By thinking about light the same way you think about ink. HP research had already shown it was possible to create higher resolution prints by carefully overlapping drops of ink on paper.
By applying the same thinking to projection, wobulation overlaps points of light. It actually projects two independent, overlapping images, so that one pixel is replaced by two – but it all happens so precisely and quickly that all the human eye notices is a smoother, more natural-looking image. Wobulation virtually eliminates the distracting “screen door” effect of a grid of pixels. In HP testing, viewers have actually preferred wobulated images over non-wobulated images created with a double pixel count spatial light modulator.
WobulationÂ’s inventor is Will Allen, chief scientist in HPÂ’s Display Technolgy and Products group. After focusing on ink-based technologies, Allen redirected his creative energy to digital image projection. Rather than thinking about ink, Allen thought about light.
“As I learned how digital projectors worked, I realized they had a striking number of similarities with inkjet printers,” explains Allen. “Both devices create a color picture from a matrix of points composed of primary colors. I discovered, to my surprise, that light was the ‘ink’ of our dreams. Being easier to control, light allowed us to accomplish in weeks what had ta ken years to accomplish with inks.”
HPÂ’s research with inkjet printers showed that to increase print quality you need to place more and more overlapping ink droplets within the same size grid on a small area on the page. This yields better image quality, even if dot size is not reduced. Allen surmised that applying this concept to projection systems would improve resolution of projected images.
To test the idea, Allen and his team modified a projector and used an aerospace mirror to rapidly and accurately shift a projected image in a way that overlapped the pixels. Two specially constructed images were projected. When they first projected the test images on the wall everyone was stunned by crisp quality. Wobulation had been born.
