Reflection and Transparency Separation Method using EPI analysis
The aim of research is to remove reflection from images taken indoors. For example, when taking a photograph of a painting inside a picture frame ,it is desireble to seperate the glass from the picture behind the glass.
A space-time image(EPI image) is generated by taking one epipolar line over the whole imagesequence. See image below in this work,the camera is translated horizontally, so the epipolar line is an image row.
All pixels on the epipolar line that belong to the image behind glass will produce the same type of track in the EPI image.
Any pixelsthat are due to reflection will produce a track at a different angle, depending upon the apparant distance to the reflected object. By looking at the color of inconsistant tracks, the reflection can be removed.
Here is an example.


Left picture: Original picture image, right picture: EPI






Left picture: Transparency, right picture: Reflection layer


In case where large reflections are present or reflections that cover entire epipolar lines are present, this method will fail. However, by using the mean RGB value a good seperation can still be acheved:


Left picture: Wide reflection, right picture: All of the one line in side reflection



Publications
  • Thanda Oo, Hiroshi Kawasaki, Yutaka Ohsawa, Katsushi Ikeuchi, "Separation of Reflection and Transparency using Epipolar Plane Image Analysis", LNCS3851, the 7th Asian Conference on Computer Vision (ACCV06), Vol.1, pp.908-917, 1.2006
  • Thanda Oo, Kawasaki Hiroshi, Ohsawa Yutaka, Ikeuchi Katsushi, "The separation of reflected and transparent layers from real-world image sequence", Journal Machine Vision and Applications, Vol.18, No.1, pp.17-24, 2.2007
Kawasaki Laboratory