Google Research

Geometry-driven quantization for omnidirectional image coding

  • Francesca De Simone
  • Pascal Frossard
  • Paul Wilkins
  • Neil Birkbeck
  • Anil Kokaram
Picture Coding Symposium (PCS) (2016)


In this paper we propose a method to adapt the quantization tables of typical block-based transform codecs when the input to the encoder is a panoramic image resulting from equirectangular projection of a spherical image. When the visual content is projected from the panorama to the viewport, a frequency shift is occurring. The quantization can be adapted accordingly: the quantization step sizes that would be optimal to quantize the transform coefficients of the viewport image block, can be used to quantize the coefficients of the panoramic block. As a proof of concept, the proposed quantization strategy has been used in JPEG compression. Results show that a rate reduction up to 2.99% can be achieved for the same perceptual quality of the spherical signal with respect to a standard quantization.

Research Areas

Learn more about how we do research

We maintain a portfolio of research projects, providing individuals and teams the freedom to emphasize specific types of work