Abstract: Image coding methods and apparatus employing discrete cosine transforms for supressing and/or reducing blocking artifacts using a JPEG file format. The methods can be implemented on JPEG hardware slightly modified to provide access to discrete cosine transform coefficients. Filtering techniques by which an overlap procedure for implementing the inventive methods are also disclosed.

Abstract: A method for processing color mapping data includes the steps of performing a discrete cosine transform on color descriptors resulting in a set of corresponding discrete cosine transform (DCT) coefficients. Selected discrete cosine transform coefficients are set to zero in order to produce a revised set of coefficients including a compressed smaller set of coefficients. The smaller set is more readily manipulated and facilitates interpolation. In one embodiment an inverse DCT is performed on the revised set of coefficients to produce a revised map in color space including a revised set of corresponding device dependent color descriptors. Discrete standard color descriptors are interpolated in the revised map by linear interpolation. In another embodiment of the invention, interpolation is included within an inverse cosine continuous transform (ICCT) of the revised set of coefficients employing an ICCT interpolator.

Abstract: A method and apparatus are presented for processing a set of image data points representing an image and being detected by a detector array having array elements wherein each array element is responsive to only one of a first or a second color.

Abstract: The invention concerns a method for rendering scene information in images having a large dynamic range, i.e. sunny and shady areas. The method takes particular advantage of image segmentation and computations employed in compression of images for electronic still photography. In distinguishing large areas, the method selectively adjusts the brightness of all portions of the area without necessarily preserving contrast which avoids halo artifacts. Those portions in areas of intermediate size are subjected to a smoothing feature which avoids the production of artifacts in the form of a line at the boundary.

Abstract: A method for processing a field of image data samples to provide for one or more of the functions of decimation, interpolation, and sharpening is accomplished by use of an array transform processor such as that employed in a JPEG compression system. Blocks of data samples are transformed by the discrete even cosine transform (DECT) in both the decimation and interpolation processes, after which the number of frequency terms is altered. In the case of decimation, the number of frequency terms is reduced, this being followed by inverse transformation to produce a reduced-size matrix of sample points representing the original block of data. In the case of interpolation, additional frequency components of zero value are inserted into the array of frequency components after which inverse transformation produces an enlarged data sampling set without an increase in spectral bandwidth.

Abstract: A narrow divergence, single quantum well, separate confinement, AlGaAs laser of the type which includes the following sequentially grown epitaxial layers: (a) an n-AlGaAs cladding layer; (b) an AlGaAs waveguide layer; (c) a GaAs quantum well layer; (d) an AlGaAs waveguide layer; (e) a p-AlGaAs cladding layer; and is improved to provide a far-field angular divergence in the order of thirty degrees (30.degree.), full width at half maximum (FWHM) with a reduced threshold current temperature sensitivity for use in electronic imaging printers.