SPIE: Deconvolution allows Recovery of Full Resolution in Light Field Images

Figure 1. Restoration of a blurred image (simulated data) through deconvolution associated with a plenoptic wavefront sensor. Top left: Original object. Top right: Degraded (blurred) image. Bottom left: Plenoptic acquisition. Bottom right: Restored image. This simulation shows that it is possible to recover an image (obtained with a 512×512-pixel sensor) with only 32 × 32 microlenses. (Image: Rodriguez-Ramos et al., 2015) One of the most limiting hardware factors in light field photography is the loss of image resolution by use of microlens arrays: In Lytro’s light field cameras, the effective image resolution is a factor of 10 below the sensor resolution (i.e. 4 Megapixel images from a 40 Megaray sensor in the Lytro Illum). Raytrix, on the other hand, has managed to achieve up to 25% of sensor resolution using multi-focus plenoptic arrays.

In a recent article on SPIE.org, the Society for Optics and Photonics Technology, researchers José Manuel Rodriguez-Ramos and colleagues discuss a new deconvolution approach which allows recovery of full image resolution from a raw light field picture.

In their experiments, they used a 512×512 pixel plenoptic wavefront sensor with 32×32 microlenses to restore the recorded image to the original sensor resolution, except for interstitial regions between the microlenses.

Figure 2. Left: Optical arrangement of components used to experimentally confirm the simulations illustrated in Figure 1. Right: Restoration of the imaged object. The original resolution of the object is completely restored, except for the interstitial regions between the microlenses. (Image: Rodriguez-Ramos et al., 2015)

While the process is still computationally very demanding, the researchers believe that improvements in microlens manufacturing – square-shaped microlenses retain more information than circular ones – will allow existing graphics processors to perform these calculations in real-time.

We have successfully demonstrated that a deconvolution approach can be used to restore lost resolution of images that are obtained with plenoptic sensors. Although our technique requires a large amount of processing power, this can be achieved with existing graphics processors. We now plan to implement a CUDA (compute unified device architecture) system to work in real time. We will also use square-shaped microlens arrays for plenoptic acquisition to address the loss of information from interstitial regions between microlenses.

More information: Rodríguez-Ramos J.M., Trujillo Sevilla J.M. and Rodríguez-Ramos L.F. 2015. Restoring lost resolution of plenoptic images. SPIE Newsroom. DOI: 10.1117/2.1201503.005848

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