When it comes to display technologies, projection systems have been around for a very long time. There have been many improvements in the technology, but nearly all of them apply to the projector. There have been variations in projector imaging systems, such as three-gun CRT, LCD, DLP engines; as well as light engine improvements from the electron gun to UHP and Xenon bulbs. So as a system projection grew, but the screens stayed similar being some form of coated vinyl, particulate bead, or a mix of both. Around 2004, screen technologies that factored in ambient light rejection started to emerge in the market, and that enabled projection to really progress. This is because optical projection screens remove ambient light without removing the projected light. Projection systems can now be used in areas where only light-emitting technologies were capable of being used.
To understand how this is possible when using optical projection screens, a return to the basics of imaging is required. The basic part of any image is contrast: Contrast is King! Any color in its full saturated form is black (minimum light point) and any color fully bright reaches white (maximum light point). So, whether it’s a black and white or color-rich image, contrast remains one of the primary factors. The Image Contrast Ratio (ICR), simply put, is just the total image white level divided by the total image black level (ICR = w/b). The important thing to note here is that black is the primary focus and denominator, and therefore, it is the black value that changes an image the most. Adding to the white level has an effect as seen in table A, but is not nearly as effective as reducing the black level, as seen in Table B below. Stay tuned for our next blog post regarding The Race to Black.