Method of image enhancement by raster scanning
AssigneeMinnesota Mining and Manufacturing Company
InventorsA. B. Mahmoodi, Owen L. Nelson
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Abstract
A method of enhancing images comprises making a point-by-point record of an image with successive pixels in a logical array, determining the standard deviation of the pixels, determining an effective central pixel value, and then displaying or recording the image using the determined central pixel values.
Claims21
A method of displaying or recording an image showing enhanced detail relative to an original image or record comprising:
- (a) making a point by point record of the original image by scanning it in a manner to select successive pixels in a logical array,
- (b) storing the pixel values in such a way and for such a period that a window comprising a sub-array of adjacent pixels can be selected and analysed statistically said window comprising between 5 and 225 pixels,
- (c) analyse the pixel values of the window surrounding each pixel in turn to give the average value D and the standard deviation .sigma.,
- (d) processing the central fixed value D.sub.c to give an improved value D'.sub.c such that
- D.sub.c '=kD.sub.c +(1-k)D
- wherein k is a variable having a value between 0 and 0.99 which varies from pixel to pixel based on the value of .sigma., said value of k being related monotonically to .sigma. in such a way as to have an upper and lower bound within the said range 0 to 0.99,
- (e) displaying or recording the enhanced image based on the derived values D.sub.c '.
A method of displaying or recording an enhanced radiation image comprising:
- (a) exposing stimulable phosphor to radiation which will cause an imagewise storage of energy by the phosphors,
- (b) scanning said stimulable phosphor with radiation that will cause said imagewise storage of energy to be released in a different form of energy or at a different wavelength than the exposing energy,
- (c) reading out said released energy and converting it into an original electric signal,
- (d) processing said original signal to produce an output signal in accordance with
- D.sub.c '[D.sub.c ']=kD.sub.c +D.(1-k)
- wherein
- D.sub.c ' is the strength of the enhanced image of a pixel,
- D.sub.c is the strength of image at the center pixel of a scanning window,
- D is the mean level of the strength of the image of the pixels in the window,
- k is a variable present during the process and having a value between 0 and 0.99 and which is related monotonically to the standard deviation of the fixed values within the scanning window and,
- (e) displaying a visual image in response to said output signal.
An apparatus for displaying or recording an image showing enhanced detail relative to an original image or record comprising:
- (a) means for making a point by point record of the original image by scanning it in a manner to select successive pixels in a logical array,
- (b) a means for storing the pixel values in such a way and for such a period that a window comprising a sub-array of adjacent pixels can be selected and analysed statistically said window comprising between 5 and 225 pixels,
- (c) a means for analysing the pixel values of the window surrounding each pixel in turn to give the average value D and the standard deviation .sigma.,
- (d) a means for processing the central fixed value D.sub.c to give an improved value D.sub.c ' such that
- D.sub.c '=kD.sub.c +(1-k)D
- wherein k is a variable having a value between 0 and 0.99 which varies from pixel to pixel based on the value of .sigma., said value of k being related monotonically to .sigma. in such a way as to have an upper and lower bound within the said range 0 to 0.99, and
- (e) a means for displaying or recording the enhanced image based on the derived values D.sub.c '.
Dependencies are inferred from the claim text.