Canon Kabushiki Kaisha

Manish Kulkarni

Moshe Broudo

Timothy Louis Kohler

Jonathan Hui

Ron Barzel

Heidi M Schoolcraft

A method for deriving a reverse model look-up table whose entries represent device dependent colors as a function of device independent colors, based on a forward model look-up table whose entries represent device independent colors obtained in response to printout of corresponding device dependent colors. For each device independent target color, a binary search of the forward model look-up table is performed so as to locate a cell that contains the device independent target color. The grid points from the forward model look-up table that define the cell are interpolated so as to obtain device dependent colors corresponding to the device independent target color. The device dependent color is stored at the grid point for the reverse model look-up table at a position corresponding to the device independent target color.

Determining color mappings for a color printer

A configurable color and image management system which allows a developer to create customized color and image management for a color-related application operating in a specified environment. A configurator is provided which has access to a library of plural classes of color and image management functionality, with each class including plural different modules of varying complexity and processing quality. The classes pertain to different aspects of color and image management functionality, such as a class to perform linearization and gamma correction, a class to perform color space transformation, a class to perform image correction, a class to perform gray color component replacement, a class to perform image expansion, and a class to perform halftone processing. The developer provides design parameters which define the operating environment within which the target color and image management system is designed to operate. Based on the design parameters, the configurator selects the highest quality modules in whichever classes of color and/or image management functionality are needed, all within the constraints defined by the parameters of the operating environment. Thereafter, a list of the selected modules are provided to a core module which provides a framework from which the selected modules can be invoked to realize the target color and image management system.

Modularized architecture for color and image management system

A streamlined technique for obtaining interpolated color output values from corresponding color input values based on color output values stored in a color look-up table, with tetrahedral interpolation being applied so as to dissect each cubic grid of the color look-up table into plural tetrahedrons. According to the invention, processing efficiency is increased by avoiding the use of conditional branches when making a determination as to which of the plural dissected tetrahedrons a particular color input value falls. Preferably, rather than making such a determination, weights for all possible tetrahedrons for one cube are stored in a temporary look-up table, and an index into the temporary look-up table is calculated based on the magnitude of component values for each color input value. The index is calculated in a block of code that does not include conditional branches that are conditioned on the relative magnitude of the component values of the color input value. Most preferably, the block of code calculates the index through use of arithmetic operations, such as subtractions, which throw off a condition code that can be used to build the index into the temporary look-up table of weights. Because conditional branches are avoided, processing of such tetrahedral interpolation is speeded, particularly for processors such as a Pentium&reg; processor that employ dual processor pipelines together with branch prediction.

Streamlined tetrahedral interpolation

Determining a skew angle of a bitmap image comprising of background and image pixels and de-skewing the bitmap image by the determined skew angle. The bitmap image skew angle is determined by calculating plural estimates of the skew angle with corresponding reliability indicators and thereafter selecting the estimate skew angle with the best reliability indicator as the bitmap image skew angle and then de-skew the bitmap image by the determined skew angle. Thereafter, auto-cropping the de-skewed image around a rectangle defined by a first and last column and first and last row of pixels which are not all white.

Method for determining a skew angle of a bitmap image and de-skewing and auto-cropping the bitmap image

Compression for color values of pixels in a raster image of pixels, in which pixels are selected in a checkerboard-like pattern. Pixels selected by the checkerboard are not compressed at all, whereas pixels not selected by the checkerboard are compressed by using the color of the closest one of adjacent selected pixels and of a few predetermined colors.

Growing community of inventors

Sunnyvale, CA, United States of America

Manish Kulkarni