Abstract: The invention discloses a method and apparatus for an improved digital film recorder. The improved recorder is capable of quantizing and recording high resolution images, in order to reduce recording time, without adding, or displaying appreciable quantization error artifacts. An image processor is provided which takes an image value at a select one of M input levels and quantizes the image value down to a select one of N output levels where M>N. The image processor of the invention then generates an error value which is related to the deviation between an idealized input signal and the quantized output signal. This error signal is then added back into the next input signal in order to smooth, or diffuse the error across a large area. Finally, in order to further reduce visible artifacts associated with the repetitive errors accompanying image areas having little or no change in image value, noise may be intentionally injected in order to break up any "bunching" of errors.

Abstract: A video computer system and methods are disclosed for displaying video graphics on a video display screen. The video computer system employs two alternative video graphics controllers. A first graphics controller is typically one that has been previously available to consumers and which also has a substantial library of graphics programs which are designed to be executed compatibly thereon. The second graphics controller is typically not compatible with the first graphics controller, and accordingly executes a second type of graphics programs which also may not be compatibly executed on the first controller. A select circuit and methods are disclosed which automatically determine the type of graphics program presented to the system, and correspondingly selects the compatible graphics controller to execute the program.

Abstract: Methods and apparatus are disclosed for inhibiting the unauthorized copying of ROM-resident computer software or the like, for example, the audio-visual display of an electronic video game. A protection circuit including encryption/decryption means is coupled between the microprocessor and the ROM-memory and is operable in a first mode to properly encrypt/decrypt the program information according to a first algorithm and in a second mode to prevent proper encryption/decryption. The address-data buses are monitored by the protection circuit to detect an invalid program event, such as may occur when a microprocessor emulator is used to attempt an unauthorized copying or "dumping" of the program information. Upon detection of the invalid program event or "trap condition", the protection circuit switches to its second operating mode thereby to prevent copying of the decrypted program information.