A system for electronically storing revisions or modifications to documents which are already electronically stored in unrevised or unmodified form. The system compares, at the pixel-by-pixel level, a modified document bit map with a stored document bit map and determines from the differences between the two bit maps, at the pixel-by-pixel level, which differences are significant and which are insignificant. A revised document bit map is then formed from the portions of the stored-document bit map exhibiting no significant bit map differences and the significant differences bit map. The result is a revised document bit map in which no unnecessary changes have been introduced into the initial stored-document bit map. The system also includes steps for defining, on a pixel-by-pixel basis, a significant region bit map from the significant difference bit map and for forming the revised document bit map using the significant region bit map.

Unprocessed video signals from an optical scanner are processed in accordance with a transfer function which adjusts the gain of the unprocessed video to produce processed video which better represents the form of the object scanned. The transfer function is selected from a memory including a plurality of such functions by a signature signal which characterizes the entire scanner system including the optical system, the illumination system and the sensor system. The signature signal is developed from an initial value of signature which is updated by processing with the unprocessed video.

A system for use with large libraries of existing technical drawings for permitting the drawings to be electronically captured and digitally stored in a central data base. As needed, the documents can be retrieved, displayed, electronically revised, and printed out. The system includes scanners which scan existing drawings to generate a bit stream of pixel data which is then compressed and stored in a mass storage unit. A drawing revisory subsystem is provided capable of operating in a DRAWING REVISION MODE and a DRAWING REDISPLAY MODE. When operating in the DRAWING REVISION MODE, as the operator inputs revisory commands, the revisory subsystem generates primitives which modify the displayed drawing in real time by changing a bit map stored in a dedicated pixel memory driving a display monitor. Additionally, however, the revisory subsystem automatically caches the primitives defining the desired drawing revisions. At the completion of a revisory session, the cached primitives are grouped as a designated REVISION LEVEL and stored in the mass storage unit. When operating in the DRAWING REDISPLAY MODE, the compressed pixel data is expanded and stored in the pixel memory to cause the monitor to display the original drawing. The redisplayed drawing is then revised through its successive REVISION LEVELS in an incremental or cinematic manner by successively revising the bit map in the pixel memory.

An image data filing system capable of facilitating an easy and accurate modification on the image filed in the system, without demanding a cumbersome operation for an operator. In the system, the image is modified by specifying an image to be modified among images filed in the system; displaying the specified image to be modified; specifying a region to be modified on the displayed image to be modified; obtaining a hard copy of the specified region to be modified; making a modification on the obtained hard copy of the specified region to be modified to obtain an modified image; and entering the modified image obtained on the hard copy into the system.

A system for electronically storing revisions or modifications to documents which are already electronically stored in unrevised or unmodified form. The system compares, at the pixel-by-pixel level, a modified document bit map with a stored document bit map and determines from the differences between the two bit maps, at the pixel-by-pixel level, which differences are significant and which are insignificant. A revised document bit map is then formed from the portions of the stored-document bit map exhibiting no significant bit map differences and the significant differences bit map. The result is a revised document bit map in which no unnecessary changes have been introduced into the initial stored-document bit map. The system also includes steps for defining, on a pixel-by-pixel basis, a significant region bit map from the significant difference bit map and for forming the revised document bit map using the significant region bit map.