US4950894A
Expired / Lapsed
US
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Radiation image read-out method
Assignee: Fujifilm Holdings Corp
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Filing: 1989-03-22
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Granted: 1990-08-21
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Expires: 2009-03-22
Abstract
Abstract In a method of reading out a radiation image stored in a stimulable phosphor sheet, preliminary read-out for approximately detecting the image is conducted. A cumulative histogram of the image information is created, read-out conditions in the final read-out are corrected based on a characteristic value of the cumulative histogram, then the final read-out is conducted using the corrected conditions. Alternatively, a standard image information range is determined from the characteristic value, and the read-out conditions are adjusted so that the standard range corresponds to a predetermined electronic signal range. In addition, in the read-out method where gradation processing is performed for electronic image signals obtained by photoelectrically detecting the phosphor light emitted by the sheet, histogram of the image signals is created, and a desired image signal range is determined therefrom. A cummulative histogram then is created, the desired range is corrected based on a characteristic value of the cumulative histogram, and gradation processing conditions are adjusted so that the corrected desired signal range corresponds to a predetermined electronic signal range. Alternatively, a standard signal range is determined based on the characteristic value, and gradation processing conditions are adjusted so that the standard range corresponds to a predetermined electronic signal range.
Inventors
- 👤 Makoto Hara
- 👤 Yuuma Adachi
- 👤 Masamitsu Ishida
- 👤 Nobuyoshi Nakajima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:46
CPC Classifications
G; G01; G01T; G01T1/00; G01T1/16; G01T1/20; G01T1/2012; G01T1/2014; G06; G06T; G06T5/00; G06T5/40; G06T5/90; G06T5/92
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
242 words
A radiation image read-out method including final read-out conducted by scanning a stimulable phosphor sheet carrying a radiation image stored therein with stimulating rays which cause the stimulable phosphor sheet to emit light in proportion to the stored radiation energy, photoelectrically detecting the emitted light by use of predetermined read-out conditions, and obtaining an electronic image signal for reproducing a visible image, wherein the improvement comprises the steps of: (i) prior to said final read-out, conducting preliminary read-out for detecting the radiation image stored in said stimulable phosphor sheet by use of stimulating rays of a level lower than the level of stimulating rays used in said final read-out; (ii) predetermining a desired image information range having lower and upper boundaries as one of said predetermined read-out conditions, (iii) creating a cumulative histogram image information obtained by said preliminary read-out, (iv) selecting a characteristic value of said cumulative histogram which provides an indication of the frequency distribution of the light emission amounts from the scanned stimulable phosphor sheet; (v) correcting said predetermined read-out conditions in accordance with the selected characteristic value of said cumulative histogram, including reducing said lower boundary of said desired image information range when said selected characteristic value is below a first threshold amount, and increasing said upper boundary of said desired image information range when said selected characteristic value is above a second threshold amount; and (vi) conducting said final read-out by use of said corrected read-out conditions.
Claim 2
Dependent Claim
242 words
A radiation image read-out method including final read-out conducted by scanning a stimulable phosphor sheet carrying a radiation image stored therein with stimulating rays which cause the stimulable phosphor sheet to emit light in proportion to the stored radiation energy, photoelectrically detecting the emitted light by use of predetermined read-out conditions, and obtaining an electronic image signal for reproducing a visible image, wherein the improvement comprises the steps of: (i) prior to said final read-out, conducting preliminary read-out for detecting the radiation image stored in said stimulable phosphor sheet by use of stimulating rays of a level lower than the level of stimulating rays used in said final read-out; (ii) predetermining a desired image information range having lower and upper boundaries as one of said predetermined read-out conditions, (iii) creating a cumulative histogram image information obtained by said preliminary read-out, (iv) selecting a characteristic value of said cumulative histogram which provides an indication of the frequency distribution of the light emission amounts from the scanned stimulable phosphor sheet; (v) correcting said predetermined read-out conditions in accordance with the selected characteristic value of said cumulative histogram, including reducing said lower boundary of said desired image information range when said selected characteristic value is below a first threshold amount, and increasing said upper boundary of said desired image information range when said selected characteristic value is above a second threshold amount; and (vi) conducting said final read-out by use of said corrected read-out conditions.
Claim 3
Dependent Claim
50 words
A method as defined in claim 1 wherein said cumulative histogram is created only for a desired image information range (maximum light emission amount Smax to minimum light emission amount Smin) which is determined based on the image information obtained by said preliminary read-out when said read-out conditions are predetermined.
Claim 4
Dependent Claim
30 words
A method as defined in claim 2 wherein a 50% image information value at which the cumulative frequency is 50% in said cumulative histogram is selected as said characteristic value.
Claim 5
Dependent Claim
140 words
A method as defined in claim 2 wherein a ratio of the image information range between said characteristic value and said lower boundary (which corresponds to minimum light emission amount Smin) to said desired image information range (Smax to Smin) is calculated, the lower end of said desired image information range (Smax to Smin) is shifted towards the small light emission amount region when said ratio is smaller than said first threshold value, the upper end of said desired image information range (Smax to Smin) is shifted towards the large light emission amount region when said ratio is larger than a second threshold value, and said predetermined read-out conditions are corrected so that the desired image information range obtained by said shifting corresponds to a correct density range (maximum density Dmax to minimum density Dmin) in said reproduced visible image.
Claim 6
Dependent Claim
21 words
A method as defined in claim 4 wherein said first threshold value is 1/3 and said second threshold value is 2/3.
Claim 7
Dependent Claim
225 words
A radiation image read-out method including final read-out conducted by scanning a stimulable phosphor sheet carrying a radiation image stored therein with stimulating rays which cause the stimulable phosphor sheet to emit light in proportion to the stored radiation energy, photoelectrically detecting the emitted light, and obtaining an electronic image signal for reproducing a visible image, said electronic image signal having a predetermined electronic image signal range, wherein the improvement comprises the steps of: (i) prior to said final read-out, conducting preliminary read-out for detecting the radiation image stored in said stimulable phosphor sheet by use of stimulating rays of a level lower than the level of stimulating rays used in said final read-out; (ii) predetermining read-out conditions for said final read-out; (iii) creating a cumulative histogram of image information obtained by said preliminary read-out; (iv) selecting a characteristic value of said cumulative histogram which provides an indication of the frequency distribution of the light emission amounts from the scanned stimulable phosphor sheet; (v) correcting said predetermined read-out conditions in accordance with the selected characteristic value of said cumulative histogram, including determining a standard image information range based on said characteristic value, and adjusting said read-out conditions so that said standard image information range corresponds to said predetermined electronic image signal range; and (vi) conducting said final read-out by use of said adjusted read-out conditions.
Claim 8
Dependent Claim
225 words
A radiation image read-out method including final read-out conducted by scanning a stimulable phosphor sheet carrying a radiation image stored therein with stimulating rays which cause the stimulable phosphor sheet to emit light in proportion to the stored radiation energy, photoelectrically detecting the emitted light, and obtaining an electronic image signal for reproducing a visible image, said electronic image signal having a predetermined electronic image signal range, wherein the improvement comprises the steps of: (i) prior to said final read-out, conducting preliminary read-out for detecting the radiation image stored in said stimulable phosphor sheet by use of stimulating rays of a level lower than the level of stimulating rays used in said final read-out; (ii) predetermining read-out conditions for said final read-out; (iii) creating a cumulative histogram of image information obtained by said preliminary read-out; (iv) selecting a characteristic value of said cumulative histogram which provides an indication of the frequency distribution of the light emission amounts from the scanned stimulable phosphor sheet; (v) correcting said predetermined read-out conditions in accordance with the selected characteristic value of said cumulative histogram, including determining a standard image information range based on said characteristic value, and adjusting said read-out conditions so that said standard image information range corresponds to said predetermined electronic image signal range; and (vi) conducting said final read-out by use of said adjusted read-out conditions.
Claim 9
Dependent Claim
30 words
A method as defined in claim 6 wherein a 50% image information value at which the cumulative frequency is 50% in said cumulative histogram is selected as said characteristic value.
Claim 10
Dependent Claim
35 words
A method as defined in claim 6 wherein predetermined ranges are taken from said characteristic value respectively towards greater and smaller light emission amounts, and together said predetermined ranges form said standard image information range.
Claim 11
Dependent Claim
66 words
A method as defined in claim 6 wherein a desired input signal level range (maximum signal level Qmax to minimum signal level Qmin), for input to a means for processing said electronic image signals to produce said visible image, corresponds to a correct density range (maximum density Dmax to minimum density Dmin) in said visible image, and is selected as said predetermined electronic image signal range.
Claim 12
Dependent Claim
56 words
A method as defined in claim 7 wherein a desired input signal level range (maximum signal level Qmax to minimum signal level Qmin) in an image processing means, which corresponds to a correct density range (maximum density Dmax to minimum density Dmin) in said reproduced visible image, is selected as said predetermined electronic image signal range.
Claim 13
Dependent Claim
56 words
A method as defined in claim 8 wherein a desired input signal level range (maximum signal level Qmax to minimum signal level Qmin) in an image processing means, which corresponds to a correct density range (maximum density Dmax to minimum density Dmin) in said reproduced visible image, is selected as said predetermined electronic image signal range.
Claim 14
Independent Claim
166 words
A method of processing a radiation image in which a stimulable phosphor sheet carrying a radiation image stored thereon is scanned by stimulating rays which cause the stimulable phosphor sheet to emit light in proportion to the stored radiation energy, the emitted light is detected photoelectrically to obtain electronic image signals and gradation processing is performed for the electronic image signals, a predetermined electronic image signal range of said image signals being used for reproducing a visible image, wherein the improvement comprises the steps of: (i) creating a histogram of said image signals; (ii) determining a desired image signal range on the basis of said histogram; (iii) creating a cumulative histogram of said image signals; (iv) correcting said desired image signal range in accordance with a characteristic value of said cumulative histogram; (v) adjusting gradation processing conditions so that the corrected desired image signal range corresponds to said predetermined electronic image signal range; and (vi) performing said gradation processing by use of said gradation processing conditions.
Claim 15
Independent Claim
166 words
A method of processing a radiation image in which a stimulable phosphor sheet carrying a radiation image stored thereon is scanned by stimulating rays which cause the stimulable phosphor sheet to emit light in proportion to the stored radiation energy, the emitted light is detected photoelectrically to obtain electronic image signals and gradation processing is performed for the electronic image signals, a predetermined electronic image signal range of said image signals being used for reproducing a visible image, wherein the improvement comprises the steps of: (i) creating a histogram of said image signals; (ii) determining a desired image signal range on the basis of said histogram; (iii) creating a cumulative histogram of said image signals; (iv) correcting said desired image signal range in accordance with a characteristic value of said cumulative histogram; (v) adjusting gradation processing conditions so that the corrected desired image signal range corresponds to said predetermined electronic image signal range; and (vi) performing said gradation processing by use of said gradation processing conditions.
Claim 16
Dependent Claim
27 words
A method as defined in claim 12, wherein said cumulative histogram is created only for said desired image signal range determined on the basis of said histogram.
Claim 17
Dependent Claim
30 words
A method as defined in claim 13 wherein a 50% image signal level at which the cumulative frequency is 50% in said cumulative histogram is selected as said characteristic value.
Claim 18
Dependent Claim
91 words
A method as defined in claim 13 wherein said correction of said desired image signal range is performed by calculating a ratio of the image signal range between said characteristic value and a minimum image signal level of said desired image signal range to said desired image signal range, reducing the minimum level of said desired image signal when said ratio is smaller than a first threshold value, and increasing a maximum image signal level of said desired image signal range when said ratio is larger than a second threshold value.
Claim 19
Dependent Claim
23 words
A method as defined in claim 15 wherein said first threshold value is approximately 1/3, and said second threshold value is approximately 2/3.
Claim 20
Dependent Claim
48 words
A method as defined in claim 12 wherein an input signal level range, for input to a means for reproducing said visible image from the electronic image signals, corresponds to a correct density range in said visible image, and is selected as said predetermined electronic image signal range.
Claim 21
Independent Claim
145 words
A method of processing a radiation image in which a stimulable phosphor sheet carrying a radiation image stored thereon is scanned by stimulating rays which cause the stimulable phosphor sheet to emit light in proportion to the stored radiation energy, the emitted light is detected photoelectrically to obtain electronic image signals, and gradation processing is performed for the electronic image signals, a predetermined electronic image signal range of said image signals being used for reproducing a visible image, wherein the improvement comprises the steps of: (i) creating a cumulative histogram of said image signals; (ii) determining a standard image signal range on the basis of a characteristic value of said cumulative histogram; (iii) adjusting gradation processing conditions so that said standard image signal range corresponds to the predetermined electronic image signal range; and (iv) performing said gradation processing by use of said gradation processing conditions.
Claim 22
Independent Claim
145 words
A method of processing a radiation image in which a stimulable phosphor sheet carrying a radiation image stored thereon is scanned by stimulating rays which cause the stimulable phosphor sheet to emit light in proportion to the stored radiation energy, the emitted light is detected photoelectrically to obtain electronic image signals, and gradation processing is performed for the electronic image signals, a predetermined electronic image signal range of said image signals being used for reproducing a visible image, wherein the improvement comprises the steps of: (i) creating a cumulative histogram of said image signals; (ii) determining a standard image signal range on the basis of a characteristic value of said cumulative histogram; (iii) adjusting gradation processing conditions so that said standard image signal range corresponds to the predetermined electronic image signal range; and (iv) performing said gradation processing by use of said gradation processing conditions.
Claim 23
Dependent Claim
30 words
A method as defined in claim 18 wherein a 50% image signal level at which the cumulative frequency is 50% in said cumulative histogram is selected as said characteristic value.
Claim 24
Dependent Claim
47 words
A method as defined in claim 18 wherein predetermined ranges are taken from said characteristic value respectively towards the high image signal level side and towards the low image signal level side, and the sum of said predetermined ranges is determined as said standard image signal range.
Claim 25
Dependent Claim
39 words
A method as defined in claim 18 wherein an input signal level range in an image reproduction means, which corresponds to a correct density range in said reproduced visible image, is selected as said predetermined electronic image signal range.
Claim 26
Dependent Claim
20 words
A method as defined in claim 6 wherein said read-out conditions are predetermined on the basis of said preliminary read-out.
Claim 27
Dependent Claim
20 words
A method as defined in claim 1 wherein said read-out conditions are predetermined on the basis of said preliminary read-out.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-08-20 | 1994-02-19 | 1994-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-20 | 1998-02-19 | 1998-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-20 | 2002-02-19 | 2002-08-21 | $7700.00 | Window Closed / Lapsed |