Apparatus and method for implementing transformations in grayscale image processing

Claim 1

An image processor for processing a digital signal representative of a grayscale image made up of a matrix of points, the digital signal being a plurality of serial multibit words each corresponding to one of the image points, said processor including a logic unit through which the digital signal is passed, said logic unit comprising: input port means for receiving the digital signal; delay means for delaying the digital signal to produce a delayed signal; memory means for storing a dynamically selectable constant enhancement value and a dynamically selectabel constant limit value; control means for dynamically selecting the enhancement value and the limit value; an arithmetic logic unit (ALU) means including means for adding or subtracting the constant enhancement value to each word in the delayed signal to produce an enhanced signal, said ALU means further including a first status flag indicative of whether overflow occurred as a result of said addition or subtraction, said ALU means further including means for subtracting each word of one of the enhanced and digital signals from each corresponding word of the other of the enhanced and digital signals, said ALU means further including a second status flag indicative of whether overflow occurred as a result of said subtraction; and output means for outputting an output signal, said output means including selector means responsive to the first and second status flags for selecting each word of the output signal from one of the constant limit value, the corresponding word from the digital signal, and the corresopnding word from the enhanced signal.

Claim 9

A method of processing a digital signal representative of a grayscale image made up of a matrix of points, the digital signal being a plurality of serial multibit words each corresponding to one of the image points, said method comprising: receiving the digital signal; delaying the digital signal to produce a dealyed signal; dynamically selecting a constant enhancement value and a constant limit value; adding or subtracting the constant enhancement value to each word in the delayed signal to produce an enhanced signal noting whether overflow occurs; subtracting each word in one of the enhanced and digital signals from the corresponding word in the other of the enhanced and digital signals noting whether overflow occurs; selecting the constant limit value, the enhanced signal word, or the digital signal word depending on whether overflow occurred on either or both of the preceding steps; and outputting the selected values as a serial output signal.

Claim 10

A method of processing a digital signal representative of a grayscale image made up of a matrix of points, the digital signal being a plurality of serial multibit words each corresponding to one of the image points, said method comprising: receiving the digital signal; delaying the digital signal to produce a dealyed signal; dynamically selecting a constant enhancement value and a constant limit value; adding or subtracting the constant enhancement value to each word in the delayed signal to produce an enhanced signal noting whether overflow occurs; subtracting each word in one of the enhanced and digital signals from the corresponding word in the other of the enhanced and digital signals noting whether overflow occurs; selecting the constant limit value, the enhanced signal word, or the digital signal word depending on whether overflow occurred on either or both of the preceding steps; and outputting the selected values as a serial output signal.