Apparatus for enhancing image data using a monotonously decreasing function

Claim 1

An apparatus for dynamic range compression of an image, comprising: an image readout device which reads an image off of a recording medium by projecting a laser beam onto said recording medium; a photomultiplier connected to said readout device and receiving the read-out image and converting it into an analog electrical signal; an A/D converter connected to said photomultiplier and receiving said analog electrical signal and converting it into a digital electrical signal Sorg; and an image processing device connected to said A/D converter and receiving said digital electrical signal Sorg; wherein said image processing device further comprises: a first calculator which receives the signal Sorg as an input and which calculates the value of an unsharp mask signal Sus corresponding to each of a plurality of picture elements in said signal Sorg by averaging the values of image signal components of said signal Sorg, which image signal components represent the picture elements belonging to a predetermined region surrounding each said picture element; and a second calculator which is connected to said first calculator and which receives the unsharp mask signal Sus and calculates values of a processed image signal Sproc with the formula Sproc=Sorg+f1(Sus) where f1(Sus) represents a function, the value of which decreases monotonously as the value of said unsharp mask signal Sus increases.

Claim 2

An apparatus for dynamic range compression of an image, comprising: an image readout device which reads an image off of a recording medium by projecting a laser beam onto said recording medium; a photomultiplier connected to said readout device and receiving the read-out image and converting it into an analog electrical signal; an A/D converter connected to said photomultiplier and receiving said analog electrical signal and converting it into a digital electrical signal Sorg; and an image processing device connected to said A/D converter and receiving said digital electrical signal Sorg; wherein said image processing device further comprises: a first calculator which receives the signal Sorg as an input and which calculates the value of an unsharp mask signal Sus corresponding to each of a plurality of picture elements in said signal Sorg by averaging the values of image signal components of said signal Sorg, which image signal components represent the picture elements belonging to a predetermined region surrounding each said picture element; and a second calculator which is connected to said first calculator and which receives the unsharp mask signal Sus and calculates values of a processed image signal Sproc with the formula Sproc=Sorg+f1(Sus) where f1(Sus) represents a function, the value of which decreases monotonously as the value of said unsharp mask signal Sus increases.

Claim 3

An apparatus for dynamic range compression of an image, comprising: an image readout device which reads an image off of a recording medium by projecting a laser beam onto said recording medium; a photomultiplier connected to said readout device and receiving the read-out x-ray image and converting it into an analog electrical signal; an A/D converter connected to said photomultiplier and receiving said analog electrical signal and converting it into a digital electrical signal Sorg; and an image processing device connected to said A/D converter and receiving said digital electrical signal Sorg; wherein said image processing device further comprises: a first calculator which receives the signal Sorg as an input and which calculates the value of an unsharp mask signal Sus corresponding to each of a plurality of picture elements in said signal Sorg by averaging the values of image signal components of said signal Sorg, which image signal components represent the picture elements belonging to a predetermined region surrounding each said picture element, and a second calculator which is connected to said first calculator and which receives the unsharp mask signal Sus and calculates values of a processed image signal Sproc with the formula Sproc=Sorg+f2(Sus) where f2(Sus) represents a function, the value of which decreases monotonously as the value of said unsharp mask signal Sus increases, and the differential coefficient of which is continuous.

Claim 4

An apparatus for dynamic range compression of an image, comprising: an image readout device which reads an image off of a recording medium by projecting a laser beam onto said recording medium; a photomultiplier connected to said readout device and receiving the read-out x-ray image and converting it into an analog electrical signal; an A/D converter connected to said photomultiplier and receiving said analog electrical signal and converting it into a digital electrical signal Sorg; and an image processing device connected to said A/D converter and receiving said digital electrical signal Sorg; wherein said image processing device further comprises: a first calculator which receives the signal Sorg as an input and which calculates the value of an unsharp mask signal Sus corresponding to each of a plurality of picture elements in said signal Sorg by averaging the values of image signal components of said signal Sorg, which image signal components represent the picture elements belonging to a predetermined region surrounding each said picture element, and a second calculator which is connected to said first calculator and which receives the unsharp mask signal Sus and calculates values of a processed image signal Sproc with the formula Sproc=Sorg+f2(Sus) where f2(Sus) represents a function, the value of which decreases monotonously as the value of said unsharp mask signal Sus increases, and the differential coefficient of which is continuous.