Abstract: A data processing system of the type in which a first program interacts with a second lower level language program is provided, the system includes a lower level language subroutine for generating objects within the second program, a memory for storing the objects, and an interface, object surrogates and surrogate references for associating the objects with one or more slots allocated to the first program. The interface is generated between the first and second programs by the first program, the interface residing within the first program. The object surrogates are then contained within the interface, each object surrogate containing an identifier for a given object. To associate one or more of the slots with a particular object surrogate, the surrogate references identifying the object surrogates are stored by the first program in those slots. During operation of the first program slots may be redefined by erasing old surrogate references and replacing them with different ones.

Abstract: A system and method are disclosed for handling errors in a state-free manner. A digital data processing system is provided which is operable in a state-free manner and has an output generator for generating an output manifestation of a model. An object generator within the system is used to generate objects describing the model, each object being then stored in an object memory. If an error occurs during generation of an object, an error reference is then generated within that object. This error reference provides identifying information for an error object, the error object being stored in an error memory and containing error details for that object. By such an approach the errors are handled in a state-free manner and can be readily retrieved when required.

Abstract: An image processor has image processing logic for detecting pixel data representing stepped chrominance or luminance transitions characteristic of staircase aliasing in a source image and for producing an output image including selective antialiasing on the detected stepped transitions. The image processing logic operates as a post processor, but is able to give much better results than conventional convolution filtering.

Abstract: A method of generating a two-dimensional (2-D) image of a transform of a three-dimensional (3-D) solid object involves sub-dividing a 3-D box defining viewing space into sub-boxes, generating test-cells in object space by performing an inverse transform on the sub-boxes and determining which of the test-cells intersect the object. Thus, the need to transform the object itself is avoided. A particular application of the method is the generation of 2-D perspective images of a 3-D solid object. A graphics processing system including means for performing the method is defined.

Abstract: Saturation problems are alleviated, when displaying image data on a device capable only of displaying pixel intensity values between a minimum value (Imin) and a maximum value (Imax), by smoothly mapping source intensity values greater than a threshold value (T), which is intermediate the minimum and maximum values, to output intensity values (Io) in a range between the threshold value (T) and the maximum value (Imax). Intensity values darker than the threshold value are not altered by the image generator with the result that image detail in the lower range of values is not lost. In order to maintain the correct color balance where separate color component intensities are defined in the source image data, each color component is mapped in accordance with a mapping determined for the largest color component value.