Integral imaging is a technique capable of displaying images with continuous parallax in full natural color. This paper presents a modified multi-baseline method for extracting depth information from unidirectional integral images. The method involves first extracting sub-images from the integral image. A sub-image is constructed by extracting one pixel from each micro-lens rather than a macro-block of pixels corresponding to a micro-lens unit. A new mathematical expression giving the relationship between object depth and the corresponding sub-image pair displacement is derived by geometrically analyzing the three-dimensional image recording process. A correlation- based matching technique is used fo find the disparity between two sub-images. In order to improve the disparity analysis, a modified multi-baseline technique where the baseline is defined as the distance between two corresponding pixels in different sub-images is adopted. The effectiveness of this modified multi-baseline technique in removing the mismatching caused by similar patterns in object scenes has been proven by analysis and experiment results. The developed depth extraction method is validated and applied to both photographic and computer generated unidirectional integral images. The depth estimation solution gives a precise description of object thickness with an error of less than 1.0% from the photographic image in the example.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.