System for manipulating noise in digital images
AssigneeAdobe Systems Incorporated
InventorJonathan Martin Shekter
Life of this patent
Estimating the term…
Abstract
An apparatus for analyzing the broadband noise content of a digital image comprising the following: a means of automatically identifying regions of originally constant color in the image by analysis of the variance of pixel values of regions of the image; a means of automatically detecting and discarding regions deemed to be unrepresentative of the true noise content of an image, including under- and over- exposed regions; a means of allowing the user to manually select some or all required constant color regions if desired; and, a means of analyzing such constant color regions to generate a parametric or non-parametric model of the noise in the image, including frequency characteristic within and between channels and other characteristics such as phase which might describe structured noise.
Claims23
A method for analyzing noise content in a digital image, comprising:
- using a computer to perform:
- sampling regions of the digital image;
- discarding sampled regions that do not satisfy a pre-specified condition, wherein said discarding sampled regions that do not satisfy the pre-specified condition involves:
- discarding sampled regions that are underexposed or overexposed;
- computing the variance of the pixel values in each remaining sampled region;
- and
- discarding sampled regions where the variance is above a pre-specified value;
- extracting noise information from each remaining sampled region;
- and
- generating a mathematical model of the noise using the noise information.
A method for analyzing noise content in a digital image, comprising:
- using a computer to perform:
- sampling regions of the digital image;
- discarding sampled regions that do not satisfy a pre-specified condition;
- extracting noise information from each remaining sampled region, wherein said extracting noise information from each remaining sampled region involves:
- for each remaining sampled region:
- computing the mean of the pixel values for the remaining sampled region to generate a mean pixel value;
- and
- subtracting the mean pixel value from the remaining sampled region, thereby generating sampled regions containing noise information, but no image content;
- and
- generating a mathematical model of the noise using the noise information.
A method for analyzing noise content in a digital image, comprising:
- using a computer to perform:
- sampling regions of the digital image;
- discarding sampled regions that do not satisfy a pre-specified condition;
- extracting noise information from each remaining sampled region;
- and
- generating a mathematical model of the noise using the noise information, wherein said generating a mathematical model of the noise using the noise information involves:
- applying a discrete Fourier transform to each remaining sampled region and to an auto correlation function of the noise;
- taking the square of the discrete Fourier transforms;
- averaging the squares of the discrete Fourier transforms;
- and
- selecting a best-fit linear-combination of the averages to generate the power spectral density of the noise for the digital image.
A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for analyzing noise content in a digital image, the method comprising:
- sampling regions of the digital image;
- discarding sampled regions that do not satisfy a pre-specified condition, wherein said discarding sampled regions that do not satisfy the pre-specified condition involves:
- discarding sampled regions that are underexposed or overexposed;
- computing the variance of the pixel values in each remaining sampled region;
- and
- discarding sampled regions where the variance is above a pre-specified value;
- extracting noise information from each remaining sampled region;
- and
- generating a mathematical model of the noise using the noise information.
A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for analyzing noise content in a digital image, the method comprising:
- sampling regions of the digital image;
- discarding sampled regions that do not satisfy a pre-specified condition;
- extracting noise information from each remaining sampled region, wherein said extracting noise information from each remaining sampled region involves:
- for each remaining sampled region:
- computing the mean of the pixel values for the remaining sampled region to generate a mean pixel value;
- and
- subtracting the mean pixel value from the remaining sampled region, thereby generating sampled regions containing noise information, but no image content;
- and
- generating a mathematical model of the noise using the noise information.
A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for analyzing noise content in a digital image, the method comprising:
- sampling regions of the digital image;
- discarding sampled regions that do not satisfy a pre-specified condition;
- extracting noise information from each remaining sampled region;
- and
- generating a mathematical model of the noise using the noise information, wherein said generating a mathematical model of the noise using the noise information involves:
- applying a discrete Fourier transform to each remaining sampled region and to an auto correlation function of the noise;
- taking the square of the discrete Fourier transforms;
- averaging the squares of the discrete Fourier transforms;
- and
- selecting a best-fit linear-combination of the averages to generate the power spectral density of the noise for the digital image.
An apparatus for analyzing noise content in a digital image, comprising:
- a noise analysis mechanism configured to:
- sample regions of the digital image;
- discard sampled regions that do not satisfy a pre-specified condition;
- wherein to discard sampled regions that do not satisfy the pre-specified condition, the noise analysis mechanism is further configured to:
- discard sampled regions that are underexposed or overexposed;
- compute the variance of the pixel values in each remaining sampled region;
- and
- discard sampled regions where the variance is above a pre-specified value;
- extract noise information from each remaining sampled region;
- and
- generate a mathematical model of the noise using the noise information.
Dependencies are inferred from the claim text.