As shown in the block diagram in Fig. 1(a), multispectral reflectance images were separated spectrally with dichroic mirrors (475DCLP, 560DCLP, Omega Optical, Inc., Brattleboro, Vermont) and bandpass filters (FB460-10, FB530-10, FL632.8-10, Thorlabs, Inc., Newton, New Jersey). Filtered images were detected using three 12-bit charge-coupled device cameras (Flea2G, Point Grey, Richmond, BC, Canada). Images from the three cameras were co-registered with one another using a fiducial marker (reflective sticker, 1-mm diameter) on a solid tissue-simulating phantom.15 A crossed linear polarizer (Edmund Optics, Barrington, New Jersey) was also placed before the cameras to reduce the effect of specular reflectance from the sample. The input–output curve (gamma function) of the projector was determined empirically by sequentially projecting 256 grayscale level images on spectralon (Labsphere) and recording the average pixel intensity from the camera, normalized to the brightest projection (Fig. 2). We found that the nonlinear gamma function of the projector distorts a sine wave image input from the computer to appear as a square wave. We adjusted the computer image input levels, based on the gamma function, such that the actual projected image was sinusoidal when detected (Fig. 2). The projector and cameras were connected to a personal computer and controlled by custom LabVIEW software (National Instruments, Austin, Texas).