Radiographic image processing method wherein small variation of density is selectively made clear
First Claim
1. A method for processing a radiographic image, comprising:
- generating and transmitting X-rays through a body using an X-ray generator to produce original image data;
calculating an average (Sm) of the original image data of an averaging area around each pixel of said radiographic image;
transforming the original image data of each pixel of said radiographic image to obtain a processed image data of each pixel in accordance with an equation,
space="preserve" listing-type="equation">Q=S+ƒ
(S-S.sub.m)where Q is the processed image data, S is the original image data, and ƒ
(S-Sm) is a function of the difference between the original image data S and the average Sm, and has a characteristic in at least one of first and second ranges of the difference between the original image data S and the average Sm, the difference between the original image data S and the average Sm is positive in said first range and negative in said second range, and according to said characteristic, the absolute value |Q-S| of the difference between the processed image data Q and the original image data S varies in accordance with an increasing monotonic function of the absolute value |S-Sm | of the difference between the original image data S and the average Sm when the absolute value |S-Sm | of the difference between the original image data S and the average Sm is less than a predetermined value, and the absolute value |Q-S| of the difference between the processed image data Q and the original image data S varies in accordance with a decreasing monotonic function of the absolute value |S-Sm | of the difference between the original image data S and the average Sm when the absolute value |S-Sm | of the difference between the original image data S and the average Sm is more than the predetermined value; and
outputting the processed image data to output device.
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Abstract
A method for processing a radiographic image, containing: a step for calculating an average Sm of original image data of an averaging area around each pixel of the radiographic image; and a step for transforming the original image data S of each pixel of the radiographic image to obtain a processed image data Q of each pixel in accordance with an equation, Q=S+ƒ(S-Sm), where ƒ(S-Sm) has a characteristic in at least one of first and second ranges of the difference S-Sm, the difference S-Sm is positive in the first range and negative in the second range, and according to the above characteristic, the absolute value |Q-S| varies in accordance with an increasing monotonic function of the absolute value |S-Sm | when the absolute value |S-Sm | is less than a predetermined value, and the absolute value |Q-S| varies in accordance with a decreasing monotonic function of the absolute value |S-Sm | when the absolute value |S-Sm | of the difference S-Sm is more than the predetermined value. The above function ƒ(S-Sm) may be a non-odd function of the difference S-Sm.
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Citations
20 Claims
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1. A method for processing a radiographic image, comprising:
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generating and transmitting X-rays through a body using an X-ray generator to produce original image data; calculating an average (Sm) of the original image data of an averaging area around each pixel of said radiographic image; transforming the original image data of each pixel of said radiographic image to obtain a processed image data of each pixel in accordance with an equation,
space="preserve" listing-type="equation">Q=S+ƒ
(S-S.sub.m)where Q is the processed image data, S is the original image data, and ƒ
(S-Sm) is a function of the difference between the original image data S and the average Sm, and has a characteristic in at least one of first and second ranges of the difference between the original image data S and the average Sm, the difference between the original image data S and the average Sm is positive in said first range and negative in said second range, and according to said characteristic, the absolute value |Q-S| of the difference between the processed image data Q and the original image data S varies in accordance with an increasing monotonic function of the absolute value |S-Sm | of the difference between the original image data S and the average Sm when the absolute value |S-Sm | of the difference between the original image data S and the average Sm is less than a predetermined value, and the absolute value |Q-S| of the difference between the processed image data Q and the original image data S varies in accordance with a decreasing monotonic function of the absolute value |S-Sm | of the difference between the original image data S and the average Sm when the absolute value |S-Sm | of the difference between the original image data S and the average Sm is more than the predetermined value; andoutputting the processed image data to output device. - View Dependent Claims (2, 3, 4, 5, 6, 10)
- 6. A method according to claim 5, wherein said functions F1 (P) and F2 (P) are respectively determined in accordance with equations,
- space="preserve" listing-type="equation">F.sub.1 (P)=A+B+C
space="preserve" listing-type="equation">F.sub.2 (P)=A×
P.sup.2 +B×
P+Cwhere A, B, and C are each a constant, determined for a range wherein P>
1 and a range wherein P<
1, respectively.
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10. A method according to claim 1, wherein said function ƒ
- (S-Sm) is respectively determined for a plurality of anatomical regions of said radiographic image.
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7. A method for processing a radiographic image, comprising:
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generating and transmitting X-rays though a body using an X-ray generator to produce original image data; calculating an average (Sm) of the original image data of an averaging area around each pixel of said radiographic image; transforming the original image data of each pixel of said radiographic image to obtain a processed image data of each pixel in accordance with an equation,
space="preserve" listing-type="equation">Q=S+ƒ
(S-S.sub.m)where Q is the processed image data, S is the original image data, and ƒ
(S-Sm) is a non-odd function of the difference S-Sm between the original image data S and the average Sm ; andoutputting the processed image data to output device. - View Dependent Claims (8, 9)
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11. An apparatus for processing a radiographic image, comprising:
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an X-ray generator generating X-rays through a body to produce original image data; a memory in which original image data is stored; an image processor comprising; averaging means for calculating an average Sm of the original image data of an averaging area around each pixel of said radiographic image, and transforming means for transforming the original image data of each pixel of said radiographic image to obtain a processed image data of each pixel in accordance with an equation
space="preserve" listing-type="equation">Q=S+ƒ
(S-S.sub.m)where Q is the processed image data, S is the original image data, and ƒ
(S-Sm) is a function of the difference between the original image data S and the average Sm, and has a characteristic in at least one of first and second ranges of the difference between the original image data S and the average Sm, the difference between the original image data S and the average Sm is positive in said first range and negative in said second range, and according to said characteristic, the absolute value |Q-S| of the difference between the processed image data Q and the original image data S varies in accordance with an increasing monotonic function of the absolute value |S-Sm | of the difference between the original image data S and the average Sm when the absolute value |S-Sm | of the difference between the original image data S and the average Sm is less than a predetermined value, and the absolute value |Q-S| of the difference between the processed image data Q and the original image data S varies in accordance with a decreasing monotonic function of the absolute value |S-Sm | of the difference between the original image data S and the average Sm when the absolute value |S-Sm | of the difference between the original image data S and the average Sm is more that the predetermined value;storing means for storing said processed image data; and a display device displaying said processed image data. - View Dependent Claims (12, 13, 14, 15, 16, 17)
- 16. An apparatus according to claim 15, wherein said functions F1 (P) and F2 (P) are respectively determined in accordance with equations,
- space="preserve" listing-type="equation">F.sub.1 (P)=A+B+C
space="preserve" listing-type="equation">F.sub.2 (P)=A×
P.sup.2 +B×
P+Cwhere A, B, and C are each a constant, determined for a range wherein P>
1 and a range wherein P<
1, respectively.
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17. An apparatus according to claim 16, further comprising third storing means for storing values of said functions F1 (P) and F2 (P) which are determined in advance for respective values of the original image data S and the average Sm, for a range wherein P>
- 1 and a range wherein P<
1, respectively; andsaid transforming means reads the values stored in the third storing means corresponding to the original image data S, the average Sm, and said range, for obtaining the processed image data Q in accordance with the equation,
space="preserve" listing-type="equation">Q=S×
{F.sub.1 (P)/F.sub.2 (P)}/{F.sub.2 (1)/F.sub.1 (1).
- 1 and a range wherein P<
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18. An apparatus for processing a radiographic image, comprising:
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an X-ray generator generating X-rays through a body to produce original image data; a memory in which original image data is stored; an image processor comprising; averaging means for calculating an average Sm of the original image data of an averaging area around each pixel of said radiographic image, and transforming means for transforming the original image data of each pixel of said radiographic image to obtain a processed image data of each pixel in accordance with an equation,
space="preserve" listing-type="equation">Q=S+ƒ
(S-S.sub.m)where Q is the processed image data, S is the original image data, and ƒ
(S-Sm) is a non-odd function of the difference S-Sm between the original image data S and the average Sm ;storing means for storing said processed image data; and a display device displaying said processed image data. - View Dependent Claims (19, 20)
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Specification