EP0280412A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Image processing
Assignee: Philips Nuclear Medicine Inc
•
Filing: 1988-01-29
•
Granted: —
•
Expires: 2008-01-29
Abstract
Abstract An imaging method and apparatus wherein an MRI or other scanner (A) generates image data d(x,y) which has a Gaussian noise distribution for reconstruction by an imager into an electronic image representation comprising an array of pixel values [p(i,j)] which may have a Gaussian or Rayleigh noise distribution. An image processing circuit replaces each image pixel vlaue [P(i,j)] from an image reconstruction means (32) with an improved pixel value p*(i,j) defined as follows: P*(i,j) = G (i,j)[P(i,j) - @(i,j)]+@(i,j) - @, where G(i,j) is a weighting function uniquely defined for each pixel (i,j), @ is the mean of pixel values of neighboring pixels and @ is the mean image noise. The weighting function is based on an image data noise variance and a pixel value variance V(i,j) corresponding to the same pixel. The data noise variance is derived by comparing a data value difference between each data value d(x,y) and its neighboring data values in a data memory (30). The smallest data value difference is indicative of the image noise variance. Each pixel variance is indicative of the difference between a corresponding pixel value and the neighboring pixel values. Preferably, the weighting function is: <MATH> For a Gaussian image noise distribution: <MATH> For a Rayleigh image noise distribution: <MATH> o
Inventors
- 👤 Kenneth S. Denison
- 👤 William Sattin
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 11:30
CPC Classifications
G; G06; G06T; G06T5/00; G06T5/20; G06V; G06V10/00; G06V10/20; G06V10/30
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
118 words
A method of imaging comprising: collecting image data; converting the collected data into an electronic image representation which includes an array of pixel values; for each pixel value determining (i) a variance between the pixel value and neighboring pixel values and (ii) an average of the neighboring pixel values; and replacing each pixel value of the array by a weighted combination of the replaced pixel value and the average of pixel values neighboring the replaced pixel value; and characterised in that the method further includes determining noise statistics of the collected data; and in that the weighting is in accordance with the determined noise statistics and the variance between the replaced pixel value and its neighboring pixel values.
Claim 2
Independent Claim
118 words
A method of imaging comprising: collecting image data; converting the collected data into an electronic image representation which includes an array of pixel values; for each pixel value determining (i) a variance between the pixel value and neighboring pixel values and (ii) an average of the neighboring pixel values; and replacing each pixel value of the array by a weighted combination of the replaced pixel value and the average of pixel values neighboring the replaced pixel value; and characterised in that the method further includes determining noise statistics of the collected data; and in that the weighting is in accordance with the determined noise statistics and the variance between the replaced pixel value and its neighboring pixel values.
Claim 3
Dependent Claim
90 words
A method according to Claim 1 wherein the noise statistics of the collected data are determined by: digitizing the collected data and storing the digitized data in a data memory; determining a data variance between each of a plurality of data values stored in the data memory and its neighboring data values; and comparing each determined data variance with previously determined data variances to determine a minimum data variance, the minimum data variance being indicative of the noise statistics, whereby the noise variance of the collected diagnostic data is determined.
Claim 4
Dependent Claim
45 words
A method according to Claim 2 wherein the data variance is determined only for selected data values whose surrounding data values have a higher probability of representing substantially no signal such that the data variance is primarily indicative of noise variance rather than imaged structure.
Claim 5
Dependent Claim
53 words
A method according to Claim 2 or Claim 3 further including: generating the data with a magnetic resonance imager; orgnaizing the digitized data values in the data memory in a rectangular matrix array; and. in the noise variance determination, determining the variance of data values disposed generally around the periphery of the matrix.
Claim 6
Independent Claim
38 words
A method according to any one of the preceding claims wherein the weighting is proportional to the ration of the corresponding data value variance to a sum of the corresponding pixel value variance and the determined noise statistics.
Claim 7
Independent Claim
61 words
A method according to any one of the preceding claims wherein the replacing step includes subtractively combining replaced pixel values with the average of neighboring pixel values and multiplying the difference with a weighting function, the weighting function being determined in accordance with the determined noise statistics and the pixel value variance between the replaced pixel and its neighboring pixel values.
Claim 8
Dependent Claim
30 words
A method according to Claim 6 wherein the weighting function is proportional to a ratio of the pixel value variance corresponding to the replaced pixel and the determined noise statistics.
Claim 9
Dependent Claim
33 words
A method according to Claim 7 wherein the replacing step further includes summing the average of pixel values neighboring the replaced pixel value with the product of said difference and said weighting function.
Claim 10
Dependent Claim
35 words
A method according to Claim 8 further including: determining a mean noise level value from the determined noise statistics; and wherein the replacing step further includes subtracting the mean noise level value from said product.
Claim 11
Independent Claim
84 words
A method of imaging comprising: collecting image data; converting the collected data into an electronic image representation which includes an array of pixel values; combining each pixel value with an average of its neighboring pixel values; and weighting the combination with a weighting value: characterised in that the method further includes measuring a data noise statistic from the collected data; and said weighting value is determined from the determined data noise statistic and a variance between the pixel value and its neighboring pixel values.
Claim 12
Independent Claim
84 words
A method of imaging comprising: collecting image data; converting the collected data into an electronic image representation which includes an array of pixel values; combining each pixel value with an average of its neighboring pixel values; and weighting the combination with a weighting value: characterised in that the method further includes measuring a data noise statistic from the collected data; and said weighting value is determined from the determined data noise statistic and a variance between the pixel value and its neighboring pixel values.
Claim 13
Independent Claim
89 words
A method of imaging comprising: collecting image data; converting the collected data into an electronic image representation which includes an array of pixel values; and replacing each pixel value with a new pixel value; characterised in that the method further includes determining a data noise statistic of the collected data and determining an image mean noise from said data noise statistic; and in that each pixel value is replaced with a combination of the replaced pixel value itself, the average of its neighboring pixel values, and the mean noise.
Claim 14
Independent Claim
89 words
A method of imaging comprising: collecting image data; converting the collected data into an electronic image representation which includes an array of pixel values; and replacing each pixel value with a new pixel value; characterised in that the method further includes determining a data noise statistic of the collected data and determining an image mean noise from said data noise statistic; and in that each pixel value is replaced with a combination of the replaced pixel value itself, the average of its neighboring pixel values, and the mean noise.
Claim 15
Dependent Claim
36 words
A method according to Claim 11 wherein the step of determining the data noise statistic includes determining a data value variance between at least one data value of the collected data and its neighboring data values.
Claim 16
Dependent Claim
23 words
A method according to Claim 12 wherein the image mean noise is proportional to a square root of the determined data value variance.
Claim 17
Dependent Claim
163 words
An imaging apparatus comprising: data generating apparatus (A) for generating image data indicative of at least a selected region of a body; a data memory means (30) for storing image data from the data generating apparatus (A); a transform means (32, 34, 36) for converting the data from the data memory means (30) into an electronic image representation which includes an array of pixel values; an average pixel value determining means (38, 70, 72) for determining an average pixel value of pixel values neighboring each pixel value; and combining means (82, 84, 86, 88) for adjusting each pixel value, in accordance with the corresponding said average pixel value; characterised in that the apparatus further includes a data noise statistic determining means (40, 76) for determining a noise statistic from the data stored in said data memory means (30); and in that said combining means (82, 84, 86, 88) combines each pixel value with the corresponding average pixel value and the data noise statistic.
Claim 18
Dependent Claim
163 words
An imaging apparatus comprising: data generating apparatus (A) for generating image data indicative of at least a selected region of a body; a data memory means (30) for storing image data from the data generating apparatus (A); a transform means (32, 34, 36) for converting the data from the data memory means (30) into an electronic image representation which includes an array of pixel values; an average pixel value determining means (38, 70, 72) for determining an average pixel value of pixel values neighboring each pixel value; and combining means (82, 84, 86, 88) for adjusting each pixel value, in accordance with the corresponding said average pixel value; characterised in that the apparatus further includes a data noise statistic determining means (40, 76) for determining a noise statistic from the data stored in said data memory means (30); and in that said combining means (82, 84, 86, 88) combines each pixel value with the corresponding average pixel value and the data noise statistic.
Claim 19
Dependent Claim
93 words
An apparatus according to Claim 14 further including: a variance determining means (74) for determining a variance between each pixel value and its neighboring pixel values; a weighting function determining means (78) for determining a weighting function for each pixel value in accordance with (i) a data noise level from the noise statistic determining means (40, 76) and (ii) the variance corresponding to the same pixel value; and wherein the combining means (82, 84, 86, 88) weights a combination of each pixel value and the corresponding average pixel value with the weighting function.
Claim 20
Dependent Claim
69 words
An apparatus according to Claim 14 or Claim 15 wherein the combining means (82, 84, 86, 88) includes: a subtraction means (82) for subtractively combining each pixel value with its corresponding average of neighboring pixel values; means for weighting (84) the difference from the subtractive combining means with the weighting factor; and an adding means (86) for combining the corresponding average of neighboring pixel values with the weighted difference.
Claim 21
Independent Claim
38 words
An apparatus according to any one of Claims 14 to 16 further including: an analog-to-digital converter (22) for digitizing the image data; and wherein the data memory means (30) stores the digitized data in a rectangular matrix array.
Claim 22
Dependent Claim
136 words
An apparatus according to Claim 17 wherein the image data generating apparatus (A) is a magnetic resonance imager (A); wherein the digital data values around a periphery of the rectangular matrix array tend to have a smaller signal contribution; and further including: a data memory addressing means (42) for addressing the data values around the periphery of the matrix; a data variance determining means (44) for determining a data value variance between each addressed matrix value and its neighboring matrix values; and a comparing means (46, 48) for comparing each determined data value variance of previously addressed data points, the smallest of the determined data value variances being the data noise statistic, the comparing means (46, 48) being operatively connected with the combining means (82, 84, 86, 88) for supplying the smallest data value variance thereto.
Claim 23
Independent Claim
66 words
An apparatus according to any one of Claims 14 to 18 further including: a mean image noise determining means (80) for determining a mean image noise value from the output of the data noise statistic means (40, 76); and wherein the combining means (82, 84, 86, 88) subtracts the mean image noise value from the combination of each pixel value and the corresponding average pixel value.
Claim 24
Independent Claim
34 words
An apparatus according to any one of Claims 14 to 19 further including an image memory (90) connected with the combining means (82, 84, 86, 88) for storing the adjusted pixel values produced thereby.
Claim 25
Dependent Claim
230 words
An imaging apparatus comprising: an apparatus (A) for generating data indicative of at least a selected region of a body under examination; a data memory means (30) for storing data from the data generating apparatus (A); a transform means (32, 34, 36) for converting the collected data from the data memory means (30) into an electronic image representation which includes an array of pixel values: a variance determining means (74) for determining a variance between each pixel value and its neighboring pixel values; an average pixel value determining means (38, 70. 72) for determining an average pixel value of pixel values neighboring each pixel value; and combining means (82, 84, 86. 88) for adjusting each pixel value in accordance with the corresponding said average pixel value characterised in that the apparatus further includes: a data noise statistic determining means (40. 76) for determining a noise statistic value of the collected data stored in said data memory means (30); a weighting function determining means (78) for determining a weighting function for each pixel value in accordance with (i) the data noise statistic value from the data noise statistic determining means (40, 76) and (ii) the said variance corresponding to the same pixel value; and in that said combining means (82, 84, 86, 88) combines each pixel value with the corresponding pixel value average and weights the combination with the weighting factor.
Claim 26
Dependent Claim
230 words
An imaging apparatus comprising: an apparatus (A) for generating data indicative of at least a selected region of a body under examination; a data memory means (30) for storing data from the data generating apparatus (A); a transform means (32, 34, 36) for converting the collected data from the data memory means (30) into an electronic image representation which includes an array of pixel values: a variance determining means (74) for determining a variance between each pixel value and its neighboring pixel values; an average pixel value determining means (38, 70. 72) for determining an average pixel value of pixel values neighboring each pixel value; and combining means (82, 84, 86. 88) for adjusting each pixel value in accordance with the corresponding said average pixel value characterised in that the apparatus further includes: a data noise statistic determining means (40. 76) for determining a noise statistic value of the collected data stored in said data memory means (30); a weighting function determining means (78) for determining a weighting function for each pixel value in accordance with (i) the data noise statistic value from the data noise statistic determining means (40, 76) and (ii) the said variance corresponding to the same pixel value; and in that said combining means (82, 84, 86, 88) combines each pixel value with the corresponding pixel value average and weights the combination with the weighting factor.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.