The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 04, 2006
Filed:
Apr. 20, 2001
Xuemei Zhang, Mountain View, CA (US);
Robert W. Jones, Corvallis, OR (US);
Izhak Baharav, San Jose, CA (US);
Donald M. Reid, Corvallis, OR (US);
Xuemei Zhang, Mountain View, CA (US);
Robert W. Jones, Corvallis, OR (US);
Izhak Baharav, San Jose, CA (US);
Donald M. Reid, Corvallis, OR (US);
Agilent Technologies, Inc., Palo Alto, CA (US);
Abstract
An adaptive image tone mapping curve based on perceptual preference guidelines is generated as a sigmoidal function, in which the sigmoidal function parameters (slope and shift) are determined by original image statistics. Tone curves generated for different images each have a smooth sigmoidal shape, so that the tone mapping process does not change the image histogram shape drastically. The sigmoidal function has the form:where α is the slope parameter and β is the shift parameter. The input value x in the sigmoidal function varies in the range [0, 100], because the tone curve is generated on an L* scale, which has values from 0 to 100. The sigmoidal tone curve calculation can be implemented efficiently using simple arithmetic operations by pre-calculating and storing various factors used in the calculation of α and β and by pre-generating a pair of fixed tone curves with two extreme slopes and interpolating between the curves.