Abstract
High dynamic range (HDR) displays are enabling new advances in visual psychophysics, but commercial HDR displays are both expensive, and difficult to calibrate colorimetrically. Homebrew HDR displays incorporating LCD panels and digital projectors are relatively inexpensive and can be calibrated, but building such displays requires sophisticated technical skills. We have developed a low-cost, color-calibrated HDR display for vision research that can be constructed and used by researchers without the need for specialized equipment or advanced engineering abilities. Inspired by the work of Bimber et al., this reflective HDR display incorporates an inkjet printer, a digital video projector and a digital camera. To display an HDR image, the image is first processed through the iCAM06 image appearance model to produce a standard dynamic range (SDR) image that is sent to the printer. The digital video projector is then roughly positioned so its image field covers the print. Custom camera-based structured-light image registration software then automatically aligns the projected and printed images. A color calibration module then measures the print colors and determines the values to send to the projector to achieve the best possible reproduction of the original HDR image. This iCAM-based approach to HDR color reproduction goes substantially beyond prior work in terms of its colorimetric accuracy. With respect to intensity and dynamic range, because the print area is substantially smaller than a projector's typical field size, the maximum intensity in the combined image can be quite high, and the current display has a peak luminance around 2000 cd/m2 with a dynamic range greater than 20,000:1. While the print-based nature of this display does limit its usefulness for interactive studies, its low-cost, do-it-yourself design, and its ability to be calibrated should make it a valuable addition to the vision researcher's laboratory.