EP0409206A2
Expired / Lapsed
EP
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Digital image display apparatus
Assignee: Toshiba Corp
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Filing: 1990-07-18
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Granted: —
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Expires: 2010-07-18
Abstract
Abstract A digital image display apparatus for converting a pixel value of medical digital image data such as MRI image data or CT image data into brightness in accordance with a display window including a window level and a window width of a display unit, determines the optimum window level and width for each image as follows. The apparatus obtains a histogram of pixel values from the digital image data and calculates brightness data of a pixel value having a highest frequency, brightness data of a pixel value at a boundary between a background and an image, area data of a portion having middle brightness within a display brightness range, area data of a portion having maximum brightness, and data indicating a ratio between an area of a portion having higher brightness than the middle brightness and an area of a portion having lower brightness than that obtained, when the digital image is to be displayed by a given display window on the basis of the histogram. The apparatus obtains image quality indicating clarity of the image displayed by the given window on the basis of the above data by using arithmetic operations or by using a neural network, thereby determining the optimum display window which provides a maximum image quality.
Inventors
- 👤 Akinami C/O Intellectual Property Div. Ohhashi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 16:51
CPC Classifications
G; G06; G06T; G06T5/00; G06T5/90; G06T5/92; G06T5/40; G06T5/60; G06T2207/00; G06T2207/20; G06T2207/20084; G06T2207/30; G06T2207/30004
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
98 words
A digital image display apparatus for displaying digital image data by converting a pixel value of the digital image data into brightness of a display, characterized by comprising: means for calculating a frequency distribution of the pixel value of the digital image data; means for calculating a plurality of image qualities indicating clarity of a display image when the digital image data is to be displayed in accordance with a plurality of pixel value-to-brightness conversion modes; and means for selecting one of said plurality of pixel value-to-brightness conversion modes on the basis of said plurality of image qualities.
Claim 2
Dependent Claim
98 words
A digital image display apparatus for displaying digital image data by converting a pixel value of the digital image data into brightness of a display, characterized by comprising: means for calculating a frequency distribution of the pixel value of the digital image data; means for calculating a plurality of image qualities indicating clarity of a display image when the digital image data is to be displayed in accordance with a plurality of pixel value-to-brightness conversion modes; and means for selecting one of said plurality of pixel value-to-brightness conversion modes on the basis of said plurality of image qualities.
Claim 3
Dependent Claim
25 words
An apparatus according to claim 1, characterized in that said selecting means comprises means for selecting a pixel value-to-brightness conversion mode indicating maximum image quality.
Claim 4
Dependent Claim
105 words
An apparatus according to claim 1, characterized in that said conversion mode is a display window of a display unit, and said image quality calculating means comprises: first means for calculating the image qualities in the display window set as a candidate and the display window shifted from the candidate by a predetermined amount; second means for inputting, when the image quality in the display window different from the candidate is maximum, the display window having the maximum image quality as a new candidate; and third means for decreasing, when the image quality of the candidate is maximum, the predetermined amount of said first means.
Claim 5
Dependent Claim
70 words
An apparatus according to claim 1, characterized in that said image quality calculating means comprises: first means for calculating first data indicating brightness of the display image, second data indicating contrast of the display image, and third data indicating a balance of brightness, in accordance with the frequency distribution of the pixel value; and second means for calculating the image quality on the basis of the first to third data.
Claim 6
Dependent Claim
43 words
An apparatus according to claim 4, characterized in that said second means comprises means for adding data which are obtained by converting the first to third data with a nonlinear function and are weighted by a predetermined value to calculate the image quality.
Claim 7
Dependent Claim
31 words
An apparatus according to claim 4, characterized in that said second means comprises a neural network for inputting normalized data of the first to third data and outputting the image quality.
Claim 8
Dependent Claim
108 words
An apparatus according to claim 4, icharacterized in that the first data includes brightness data of a pixel value having a highest frequency and brightness data of a pixel value at a boundary between a background and an image on a histogram indicating the frequency distribution, the second data includes area data of a portion having middle brightness within a display brightness range and area data of a portion having maximum brightness within the range, and the third data includes data indicating a ratio between an area of a portion having brightness higher than the middle brightness and an area of a portion having brightness lower than that.
Claim 9
Dependent Claim
46 words
An apparatus according to claim 1, characterized in that said image quality calculating means comprises means for calculating the image quality indicating clarity of each portion to be observed of one image, and said selecting means comprises means for selecting one conversion mode for each portion.
Claim 10
Dependent Claim
24 words
An apparatus according to claim 8, characterized in that said each portion is a portion corresponding to each peak frequency of the frequency distribution.
Claim 11
Dependent Claim
22 words
An apparatus according to claim 1, characterized in that the conversion mode is defined by a window width and a window level.
Claim 12
Dependent Claim
116 words
A digital image conversion apparatus for converting a first digital image data into a second digital image data, characterized by comprising: means for displaying the first digital image data by converting a pixel value of the first digital image data into a brightness of a display; means for calculating a frequency distribution of the pixel value of the digital image data; means for calculating a plurality of image qualities indicating clarity of a display image when the digital image data is to be displayed in accordance with a plurality of pixel value-to-brightness conversion modes; and means for selecting one of said plurality of pixel value-to-brightness conversion modes on the basis of said plurality of image qualities.
Claim 13
Dependent Claim
116 words
A digital image conversion apparatus for converting a first digital image data into a second digital image data, characterized by comprising: means for displaying the first digital image data by converting a pixel value of the first digital image data into a brightness of a display; means for calculating a frequency distribution of the pixel value of the digital image data; means for calculating a plurality of image qualities indicating clarity of a display image when the digital image data is to be displayed in accordance with a plurality of pixel value-to-brightness conversion modes; and means for selecting one of said plurality of pixel value-to-brightness conversion modes on the basis of said plurality of image qualities.
Claim 14
Dependent Claim
25 words
An apparatus according to claim 11, characterized in that said selecting means comprises means for selecting a pixel value-to-brightness conversion mode indicating maximum image quality.
Claim 15
Dependent Claim
105 words
An apparatus according to claim 11, characterized in that said conversion mode is a display window of said display means, and said image quality calculating means comprises: first means for calculating the image qualities in the display window set as a candidate and the display window shifted from the candidate by a predetermined amount; second means for inputting, when the image quality in the display window different from the candidate is maximum, the display window having the maximum image quality as a new candidate; and third means for decreasing, when the image quality of the candidate is maximum, the predetermined amount of said first means.
Claim 16
Dependent Claim
70 words
An apparatus according to claim 11, characterized in that said image quality calculating means comprises: first means for calculating first data indicating brightness of the display image, second data indicating contrast of the display image, and third data indicating a balance of brightness, in accordance with the frequency distribution of the pixel value; and second means for calculating the image quality on the basis of the first to third data.
Claim 17
Dependent Claim
44 words
An apparatus according to claim 14, characterized in that said second means comprises means for adding data which are obtained by converting the first to third data with a nonlinear conversion function and are weighted by a predetermined value to calculate the image quality.
Claim 18
Dependent Claim
31 words
An apparatus according to claim 14, characterized in that said second means comprises a neural network for inputting normalized data of the first to third data and outputting the image quality.
Claim 19
Dependent Claim
108 words
An apparatus according to claim 14, characterized in that the first data includes brightness data of a pixel value having a highest frequency and brightness data of a pixel value at a boundary between a background and an image on a histogram indicating the frequency distribution, the second data includes area data of a portion having middle brightness within a display brightness range and area data of a portion having maximum brightness within the range, and the third data includes data indicating a ratio between an area of a portion having brightness higher than the middle brightness and an area of a portion having brightness lower than that.
Claim 20
Dependent Claim
46 words
An apparatus according to claim 11, characterized in that said image quality calculating means comprises means for calculating the image quality indicating clarity of each portion to be observed of one image, and said selecting means comprises means for selecting one conversion mode for each portion.
Claim 21
Dependent Claim
24 words
An apparatus according to claim 18, characterized in that said each portion is a portion corresponding to each peak frequency of the frequency distribution.
Claim 22
Dependent Claim
22 words
An apparatus according to claim 11, characterized in that the conversion mode is defined by a window width and a window level.
Claim 23
Dependent Claim
107 words
A digital image display apparatus for converting a pixel value of digital image data into a brightness value such that only pixel values within a predetermined range are converted into continuously changing brightness values, characterized by comprising: means for calculating a frequency distribution of the pixel value of the digital image data; neural network means for receiving a plurality of predetermined parameters in the frequency distribution and outputting an image quality indicating clarity of the image displayed with said brightness value; and means for determining an optimum value of said predetermined range in accordance with the output from said neural network obtained when said predetermined range varies.
Claim 24
Dependent Claim
107 words
A digital image display apparatus for converting a pixel value of digital image data into a brightness value such that only pixel values within a predetermined range are converted into continuously changing brightness values, characterized by comprising: means for calculating a frequency distribution of the pixel value of the digital image data; neural network means for receiving a plurality of predetermined parameters in the frequency distribution and outputting an image quality indicating clarity of the image displayed with said brightness value; and means for determining an optimum value of said predetermined range in accordance with the output from said neural network obtained when said predetermined range varies.
Claim 25
Dependent Claim
98 words
An apparatus according to claim 21, characterized in that said optimum value determining means comprises: means for determining a candidate of said predetermined range; means for calculating the image quality of the candidate and the image quality obtained when the center of said predetermined range varies or when said predetermined range varies; and means for changing the candidate such that the image quality of the candidate is maximized and repeatedly calculating and comparing the image quality of the candidate and the image quality obtained when the center of said predetermined range varies or when said predetermined range varies.
Claim 26
Dependent Claim
78 words
An apparatus according to claim 22, characterized in that said neural network means comprises at least two neural networks each having at least three layers and learning a different data in precision, and said optimum value determining means determines an optimum value by using said neural networks sequentially from a neural network learning a low precision data, so that an output from each neural network is used as a candidate in processing performed by the next neural network.
Claim 27
Dependent Claim
46 words
An apparatus according to claim 21, characterized in that said neural network means receives first data indicating brightness of a display image, second data indicating contrast of the display image, and third data indicating a balance of brightness, on the basis of of the frequency distribution.
Claim 28
Dependent Claim
108 words
An apparatus according to claim 24, characterized in that the first data includes brightness data of a pixel value having a highest frequency and brightness data of a pixel value at a boundary between a background and an image on a histogram indicating the frequency distribution, the second data includes area data of a portion having middle brightness within a display brightness range and area data of a portion having maximum brightness within the range, and the third data includes data indicating a ratio between an area of a portion having higher brightness than the middle brightness and an area of a portion having lower brightness than that.
Claim 29
Dependent Claim
54 words
An apparatus according to claim 25, characterized in that said neural network means produces the image quality indicating clarity of each portion to be observed in one image, and the brightness data of a pixel value having a highest frequency includes brightness data of a pixel value at each peak in the frequency distribution.
Claim 30
Dependent Claim
194 words
A digital image display apparatus for converting pixel values within a window width centering a window level of digital image, in which each pixel value is represented by a digital signal, into continuously changing brightness values and displaying the digital image data by the brightness values, for setting an optimum window level and width, characterized by comprising: first means for calculating image quality indicating, by means of an index, clarity of an image displayed when the window level and the window width are set to be predetermined candidate values; second means for calculating the image quality when at least one of the window level and the window width is shifted from the candidate values by a predetermined value; third means for comparing the image quality calculated by said first means and the image quality calculated by said second means; and means for changing the candidate values and decreasing said predetermined value in accordance with the comparison result, repeatedly operating said first, second, and third means so that a maximum image quality is obtained by said first means, and setting the candidate values set in said first means as the optimum window level and width.
Claim 31
Dependent Claim
194 words
A digital image display apparatus for converting pixel values within a window width centering a window level of digital image, in which each pixel value is represented by a digital signal, into continuously changing brightness values and displaying the digital image data by the brightness values, for setting an optimum window level and width, characterized by comprising: first means for calculating image quality indicating, by means of an index, clarity of an image displayed when the window level and the window width are set to be predetermined candidate values; second means for calculating the image quality when at least one of the window level and the window width is shifted from the candidate values by a predetermined value; third means for comparing the image quality calculated by said first means and the image quality calculated by said second means; and means for changing the candidate values and decreasing said predetermined value in accordance with the comparison result, repeatedly operating said first, second, and third means so that a maximum image quality is obtained by said first means, and setting the candidate values set in said first means as the optimum window level and width.
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