Integral imaging is a technique capable of displaying 3D images with continuous parallax in full natural color. Since micro-lens sheet is used in recording

only one recording is necessary in containing 3D information. The paper presents a method for extracting depth information directly from lenticular integral images. The method involves first extracting viewpoint images from the lenticular integral image. The approach starts with the constructions of special viewpoint-images from the integral image. A viewpoint-image is constructed by extracting one pixel from each micro-lens rather than a macro-block of pixels corresponding to a micro-lens unit. Each viewpoint-image contains a 2D parallel recording of the 3D scene from one particular view direction. A new mathematical expression giving the relationship between object depth and the corresponding viewpoint image pair displacement is derived by geometrically analyzing the 3D image recording process. The depth information for any object point can be calculated with its disparity between corresponding viewpoint images. The method is validated and applied to measure the thickness of a matchbox in the experiment

The results can not only be applied on the area of integral image data processing but also be expected to provide theory foundation for a novel depth extraction technique.