We describe reversible modulation of 4D light field by inserting a patterned planar mask in the optical path of a lens based camera. We can reconstruct the 4D light field from a 2D camera image without any additional lenses as required by previous light field cameras. The patterned mask attenuates light rays inside the camera instead of bending them, and the attenuation recoverably encodes the ray on the 2D sensor. Our mask-equipped camera focuses just as a traditional camera might to capture conventional 2D photos at full sensor resolution, but the raw pixel values also hold a modulated 4D light field. The light field can be recovered by rearranging the tiles of the 2D Fourier transform of sensor values into 4D planes, and computing the inverse Fourier transform.

We also show how a broad-band mask placed at the lens enables us to compute refocusing at full sensor resolution for images of layered Lambertian scenes. This partial encoding of 4D ray-space data enables editing of image contents by depth to remove or suppress unwanted occluders, yet does not require computational recovery of the complete 4D light field.

Additional Results:   [Refocussing Movie 1]   [Refocussing Movie 2]   [Refocussing Movie 3]

[1] Ashok Veeraraghavan, Ramesh Raskar, Amit Agrawal, Rama Chellappa, Ankit Mohan and Jack Tumblin. "Non-refractive modulators for encoding and capturing scene appearance and depth", Accepted for presentation at IEEE Computer Society Conference on Computer Vision and Pattern Recognition (CVPR), 2008. [pdf] NEW

[2] Ashok Veeraraghavan, Ramesh Raskar, Amit Agrawal, Ankit Mohan, Jack Tumblin. "Mask Based Modulation For Light Field Capture by Conventional Cameras" in ACM SIGGRAPH 2007. [LowResPDF] [HighResPDF] [SlideShow] [Project Page] [Movie of SIGGRAPH Talk]  NEW

	Errata: Equations 11 and 12 have error in published version which has been corrected in online pdfs. 
	Detailed Derivation of equations 10,11 and 12 (NOT IN PAPER)

[3] Ashok Veeraraghavan, Ramesh Raskar, Amit Agrawal, Ankit Mohan, Jack Tumblin. "Frequency Domain capture of light fields using Heterodyning: Analysis of Aliasing" UMIACS Tech Report, 2007. [LowResPDF]