Abstract: One embodiment of the present invention provides a system for applying a bilateral filter to an image. During operation, the system selects a first region within the image which is associated with a first pixel. Next, the system constructs a first histogram using pixel values within the first region. The system then computes a new value for the first pixel using the current value of the first pixel and the first histogram. The system then selects a second region within the image which is associated with a second pixel. Next, the system determines a non-overlapping region between the first region and the second region. The system then constructs a second histogram using the first histogram and pixel values in the non-overlapping region. Next, the system computes a new value for the second pixel using the current value of the second pixel and the second histogram.

Abstract: One embodiment of the present invention provides a system for applying a bilateral filter to an image. During operation, the system selects a first region within the image which is associated with a first pixel. Next, the system constructs a first histogram using pixel values within the first region. The system then computes a new value for the first pixel using the current value of the first pixel and the first histogram. The system then selects a second region within the image which is associated with a second pixel. Next, the system determines a non-overlapping region between the first region and the second region. The system then constructs a second histogram using the first histogram and pixel values in the non-overlapping region. Next, the system computes a new value for the second pixel using the current value of the second pixel and the second histogram.

Abstract: Methods and apparatus, including computer program products, for filtering an image. A filter kernel is received to determine one or more filtered values for each pixel in a sequence of pixels, where adjacent pixels are separated by a characteristic distance in the image. A difference kernel is defined based on local differences between a first kernel and a second kernel that are defined by the filter kernel centered at a first location and a second location, respectively. The second location is separated from the first location by the characteristic distance separating adjacent pixels in the sequence. The difference kernel is used to determine a difference between filtered values of adjacent pixels in the sequence. For depth of field filtering, the filter kernel can include a blur filter kernel that is based upon depth values of pixels in the sequence.

Abstract: One embodiment of the present invention provides a system for applying a filter to an image whose pixel values can span a large range of values. During operation the system receives an image to which the filter is to be applied. The system then selects a first region within the image which is associated with a first pixel. Next, the system generates a first histogram using pixels within the first region whose values are within a first range of pixel values. Next, the system determines a new value for the first pixel using the first histogram. The system then selects a second region within the image which is associated with a second pixel. Next, the system determines if the second pixel value is within a second range of pixel values. If the second pixel value is within the second range of pixel values, the system determines a non-overlapping region between the first region and the second region.

Abstract: Methods and apparatus, including computer program products, for filtering an image. A filter kernel is received to determine one or more filtered values for each pixel in a sequence of pixels, where adjacent pixels are separated by a characteristic distance in the image. A difference kernel is defined based on local differences between a first kernel and a second kernel that are defined by the filter kernel centered at a first location and a second location, respectively. The second location is separated from the first location by the characteristic distance separating adjacent pixels in the sequence. The difference kernel is used to determine a difference between filtered values of adjacent pixels in the sequence. For depth of field filtering, the filter kernel can include a blur filter kernel that is based upon depth values of pixels in the sequence.

Abstract: Briefly, in accordance with one embodiment of the invention, a higher dynamic range image sensor may be implemented by comparing a voltage across the sensor to a threshold voltage during image capture. At the threshold voltage, a count may be registered and the image sensor may be reset for continued image capture until an exposure is complete. A final image signal may be obtained by multiplying the threshold voltage by the number of counts registered and adding the final image sensor voltage.

Abstract: Methods and apparatus that generate data structures representing the frequency with which colors occur in a collection of colors, such as occurs in a raster image. The invention provides a list consisting essentially of first generation entries and combines first generation entries to form a list consisting essentially of second generation entries. Each first generation entry has an associated color set of one or more colors. Each first generation entry represents the frequency with which colors in the associated color set appear in the image. The color sets for all of the first generation entries are mutually non-intersecting. Particular embodiments have the following features. Each second generation color set corresponds to a volume of the color space. All second generation color sets have the same size. The second generation entries can be combined to form a list of third generation entries.