US 11,863,788 B2
Encoders and decoders employing log-polar coordinate system
Mikko Strandborg, Hangonkylä (FI); and Ville Miettinen, Helsinki (FI)
Assigned to Varjo Technologies Oy, Helsinki (FI)
Filed by Varjo Technologies Oy, Helsinki (FI)
Filed on Apr. 8, 2022, as Appl. No. 17/716,714.
Prior Publication US 2023/0328283 A1, Oct. 12, 2023
Int. Cl. H04N 19/60 (2014.01); G06F 3/01 (2006.01); H04N 19/167 (2014.01)
CPC H04N 19/60 (2014.11) [G06F 3/013 (2013.01); H04N 19/167 (2014.11)] 15 Claims
OG exemplary drawing
 
1. An encoder for encoding images, the encoder comprising at least one processor configured to:
transform a given input pixel of an input image having (x, y) coordinates in a Cartesian coordinate system into a given transformed pixel of a transformed image having (ρ, θ) coordinates in a log-polar coordinate system, using a log-polar transformation in which a radial distance (ρ) of the given transformed pixel is a logarithm of a distance of the given input pixel from an origin in the Cartesian coordinate system, and an angular distance (θ) of the given transformed pixel is a sum of an arctangent of a slope of a line connecting the given input pixel to the origin and a function of the radial distance;
encode the transformed image, by employing a compression algorithm, into an encoded image; and
send the encoded image to a display apparatus for subsequent decoding thereat;
wherein the function of the radial distance is equal to a half of the radial distance.