Bilateral alpha omega: calculating LUT argument with few arithmetic operations

US11233994B2 · kind B2 · utility

Assignee

• Telefonaktiebolaget LM Ericsson (Publ) · SE

Inventors

• Jacob Ström · Stockholm, SE
• Per Wennersten · Kramfors, SE
• Jack Enhorn · Sollentuna, SE
• Du LIU · Solna, SE

Key dates

• Filing date: Jul 9, 2019
• Grant date: Jan 25, 2022
• Expiry date: Jul 9, 2039

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04N19/86
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

According to a first aspect, a method is provided. The method includes obtaining an M×N array of pixel values an image; determining a weight selection value for position x,y in the M×N array; and using the weight selection value to obtain a weight value for use in a filter for filtering the image. Determining the weight selection value for position x,y (omegax,y) includes: a) retrieving a previously determined weight selection value for position x,y−1 (omegax,y−1); b) retrieving a previously determined alpha value (a) for position x,y−1; c) calculating a delta value (d); and d) calculating omegax,y=omegax,y−1−a+d. Calculating d includes: i) retrieving a first previously determined value (omega_row); i) retrieving a second previously determined value (alpha_row); and ii) calculating d=omega_row−alpha_row+abs(Ax+1,y+1−Ax+1,y+2), wherein Ax+1,y+1 is the value stored in position x+1,y+1 of the array and Ax+1,y+2 is the value stored in position x+1,y+2 of the array.