Modified pseudo-cylindrical mapping of spherical video using linear interpolation of empty areas for compression of streamed images

摘要

A panoramic video stream is compressed. Sinusoidal projection is performed on spherical input images to generate pseudo-cylindrical projection images. A lower-left region and a lower-right region of the image are cut and moved to upper corners of the rectangular bounding box around the pseudo-cylindrical projection image. These upper corners are non-effective areas of default dark pixels with no image pixels. A bottom one-third of the rows of pixels from the image that contained the moved regions are deleted, compressing the image by 33%. Default dark pixels in interface regions between the moved regions and the pseudo-cylindrical projection image are linear interpolated to provide gradual changes in pixel values across the remaining formerly non-effective regions, preventing encoding artifacts caused by abrupt changes in pixel values. Functions may be implemented using lookup tables. Non-focus image areas may be downsampled for additional compression using multi-resolution mapping and adaptive view streaming.