Abstract: A method of reconstructing an image from a dithered image. A predefined set of filters having different regions of support is established. Each filter is defined by a number of filter coefficients and an impulse response function which defines the filter response for a region of support outside of which the impulse response is zero. Filters are organized according to indexes and this organization represents the order in which the filters are considered during a filter selection process. The filter selection process selects a filter constrained by the rule that the filter selected must only perform low-pass filtering on a region of support that does not contain edges of an image. Due to the organization of the filter set, the filter selection process first selects the largest filter from the filter set that fits within the region about the current processed pixel. If there is an edge of an image within the support region of the first selected filter, the next smaller filter is selected.
Type:
Grant
Filed:
January 30, 1998
Date of Patent:
February 6, 2001
Assignee:
Compaq Computer Corporation
Inventors:
Shiufun Cheung, Robert A. Ulichney, Robert MacNamara, Giridharan Iyengar
Abstract: An apparatus is provided for determining an average number of instructions entering a stage of a processor pipeline of a computer system during a clock cycle of a processor clock. The number of instructions entering a particular stage of the pipeline are stored in a queue during each of a predetermined number (N) of clock cycles. The total number of instructions processed over the last P clock cycles is computed, where P is less than or equal to N. The total number of instructions processed is divided by the last P processor cycles to yield the instantaneous average number of instructions processed for each processor cycle. This average number of instructions processed is communicated to software.
Type:
Grant
Filed:
November 26, 1997
Date of Patent:
January 16, 2001
Assignee:
Compaq Computer Corporation
Inventors:
George Z. Chrysos, Jeffrey Dean, James E. Hicks, Jr., Carl A. Waldspurger, William E. Weihl
Abstract: Entries are cached in a function cache by statically assigning a primary key to each cache entry, and first grouping entries having identical primary keys, and dynamically assigning a secondary key to each cache entry, and then second grouping entries in each primary key group into sub-groups according to their secondary keys. The function cache is first accessed with a particular primary key to get the primary key group. Second, the primary key group is accessed with a particular secondary key to get a sub-group, and third, the sub-group is accessed with the same particular secondary key to get a matching cache entry.
Type:
Grant
Filed:
June 8, 1998
Date of Patent:
November 7, 2000
Assignee:
Compaq Computer Corporation
Inventors:
Clark Allan Heydon, Roy Levin, Butler Lampson