Until a few years ago, there were only two options for achieving a cinemaScope image:
An externally mounted lens slides in front of the projector (and back out of the way when not needed) The projector must vertically stretch the image and thereafter the lens will optically stretch the image horizontally to fill the screen. This system is complex, time consuming to install and has potential mechanical drift issues.
Using memory zoom results in a disruptive experience as multiple user interactions are required.
The projector must zoom the image out to fill the screen whilst adjusting focus and shift. This approach is slow, taking up to 20 seconds before the image is displayed correctly.
The premise of the memory zoom option is that the projector needs a zoom range that can accommodate a 16:9 film and then a 2.39:1 movie by zooming the image as far as the edges of the black bars.
1. Anamorphic lenses and the ‘constant height’ option can be problematic, because the integrator has to return to the site to adjust the inaccuracy in the anamorphic lens or the lens memory positioning.
2. The image quality will be negatively impacted when using an anamorphic lens by such things as chromatic aberration, pincushion distortion, focus uniformity and a softening of the image.
3. Finally it’s worth noting that a 2.39:1 image will be 32% less bright then an image in 16:9 when using memory zoom. Compare this to the Barco Residential approach which offers Constant Light Output and which, for the installer, means: no extra lenses, no fuss and no need for repeat calibration checks.
This is where Barco’s technology comes in: on Barco projectors, the image is scaled diagonally, using simulation grade processing power – a uniform process that maintains perfect geometry while utilizing more pixels, almost 2.7 million. The result is an image that fills the entire 5120x2160 space available – real CinemaScope! We refer to this as ‘cropping’, and there are several features under the cropping function in the menu. The procedure crops off the black bars over and under the image and changes the aspect ratio to CinemaScope. At Barco, we scale an image so that it fills the complete height of 3840x2160 pixels; and then, to maintain the aspect ratio, the image is scaled sideways to fill tthe full width. We do this in one step, as diagonal stretch.