Lossless sending of precompressed data, with adjusted printing parameters, for very large fine-resolution images

摘要

Printing is based on lossy-precompressed nontext raster-image data (24, 43), using a Windows® operating system (65). One invention aspect adjusts (44) data without lossy recompression to match file formats the printing device (83) expects. Another aspect passes (55) data to a driver (74) via a "Postscript passthrough" (67) in Windows® . In either case data then go on through Windows to the device, still without lossy recompression. If data (61, 62) are not compressed nontext raster data, these steps are omitted (Fig. 5) and the image sent (61, 63, 66, 71; 62, 64, 68, 72) to the device per steps of an application (32). When used, adjusting also best accommodates (45) desired print parameters, e. g. image rotation, trimming and sizing; number of color planes; and (by color plane) image height and width, and resolution per unit distance. Passing the image to the device best includes sending adjusted precompressed data (53) directly to a printing-device driver (74) and thence to the device. Lossless decompression (41) is best applied to received data, and lossless recompression (51) applied after the transformation and before going to the device. Here if data are JPEG data (DCT coefficients and quantization tables), then between the two lossless applying steps the data (44) are best stored in a temporary file that is not a system swap file. This step best includes exploiting (45) data symmetry to effect an exchange among coefficients, to rotate the printed image. Other aspects are a printing device (83) and driver (74).