The imaging depth of field (DOF) of white-light illuminated objects is extended by carefully integrating two image-processing techniques, one optical and one digital. The optical technique makes use of a tailored phase mask positioned at the pupil of the imaging system to cause different color channels to have different focal lengths; accordingly, the phase-mask equipped imaging system acquires a high resolution and reasonably focused image in at least one of the three, red, green, blue (RGB), color channels at any location within the specified DOF. The digital processing comprises fusing the separate RGB images with an original technique that implements principal component analysis to deliver the overall sharpest grayscale composite image throughout the DOF region. The obtained experimental results agree well with the theoretical predictions and demonstrate the capability of the integrated technique to extend the DOF.