Hewlett-Packard Development Company, L.p.

Ronny Kimmel

Doron Shaked

Renato Keshet

Irwin E Sobel

Michael Elad

Danny Barash

A system and a method solve the estimation problem of finding reflectance R and illumination L. The system and method to solve a functional of the unknown illumination L such that a minimum of the functional is assumed to yield a good estimate of the illumination L. Having a good estimate of the illumination L implies a good estimate of the reflectance R. The functional uses a variational framework to express requirements for the optimal solution. The requirements include: 1) that the illumination L is spatially smooth; 2) that the reflectance values are in the interval [0,1] &#x2014;thus, when decomposing the image S, the solution should satisfy the constraint L&#x3e;S; 3) that among all possible solutions, the estimate of the illumination L should be as close as possible to the image S, so that the contrast of the obtained R is maximal; and 4) that the reflectance R complies with typical natural image behavior (e.g., the reflectance is piece-wise smooth).

System and method for image enhancement, dynamic range compensation and illumination correction

Demosaicing convolution kernels are incorporated into the framework of bilateral filtering in order to reduce artifacts at abrupt intensity transitions when a color mosaic pattern is converted to an output image. As a consequence of the bilateral filtering within a window that is selected without intensity considerations, intensity values of pixels that are physically close are given greater weight than intensity values of more distant pixels and, simultaneously, intensity values that are quantitatively similar (i.e., photometrically similar) are given greater weight than intensity values that are quantitatively dissimilar. Using photometric similarity in a demosaicing operation reduces the effects of pixels on one side of an abrupt intensity transition in determining interpolated intensity values for pixels on the opposite side of the abrupt intensity transition.

Bilateral filtering in a demosaicing process

An array of n-bit words representing an image is filtered to produce a corresponding array of higher precision m-bit words representing the image. During the filtering, upper and lower bounds for the m-bit words are identified, and values for the m-bit words are selected between the upper and lower bounds. There is at least some spatial smoothness between the selected values. For example, the values may be selected at sample points of a curve or surface between the upper and lower bounds.

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Haifa, Israel

Ronny Kimmel