Yasumasa Iwamura

Combination Photometric Stereo Using Compactness of Albedo and Surface Normal in the Presence of Shadows and Specular Reflection

We present a novel combination photometric stereo which can estimate surface normals precisely even for images including shadows and specular reflection. We can use photometric stereo if there are more than three input images. Therefore we can employ photometric stereo with \(_n C_3\) combinations for n input images. We make 3D distribution of albedos and surface normals estimated from pixel intensities of \(_n C_3\) pixel combinations. In the distribution, we define a novel value “compactness” to distinguish pixels which are included in neither shadows nor specular reflection from pixels which are included in shadows or specular reflection. Through experimental results, we demonstrate that the proposed method can estimate surface normals in the presence of shadows and specular reflection. Moreover the proposed method is superior to previous works in better accuracy.

A New Optical System for Holographic Memory Applying a Finite Objective Lens

We have developed a new objective lens for a holographic storage system to increase areal density. To balance focal length and working distance, we adopted a finite objective lens. By incorporating phase conjugate reproduction into the finite objective lens, we obtained practically applicable and adequate signal quality. We measured shift selectivity and the effect of crosstalk and evaluated book size, which was reduced by ca. 0.8. The areal density was estimated to increase by about 1.6 times when using the new objective lens.