Automatic tone scale adjustment using image activity measures
AssigneeEastman Kodak Company
InventorsHsien-Che Lee, Lori L. Barski, Robert A. Senn
Life of this patent
Estimating the term…
Abstract
A method of automatically adjusting the tone scale adjustment for digital radiographic images. The method includes the steps of providing an input digital radiographic image; estimating the image noise as a function of code value of the image; determining the range of code values in the input image; determining which way the input image should be processed; determining a bounding box which contains the region of interest of the input image; computing the image activity histogram of the input image; determining four points from the image activity histogram; constructing the tone-scale curve for the input image; and mapping the input image through the tone-scale curve to produce an output image with good tone scale.
Claims22
A method of automatic tone scale adjustment for digital radiographic images comprising the steps of:
- providing an input digital radiographic image;
- estimating the image noise as a function of code value of said image;
- determining the range of code values in said input image;
- determining which way said input image should be processed;
- determining a bounding box which contains the region of interest of said input image;
- computing the image activity histogram of said input image;
- determining four points from said image activity histogram;
- constructing the tone-scale curve for said input image;
- and
- mapping said input image through said tone-scale curve to produce an output image with good tone scale.
A method of extracting the important range of code values from an input digital image by computing image activity as a function of code value, comprising the steps of:
- (a) processing the digital image on a line by line basis;
- (b) calculating image activity at each pixel for each image line;
- (c) accumulating the image activity for each code value from each image line to form a cumulative activity histogram as a function of code value;
- and
- (d) locating the highest peak(s) of the activity histogram and one point on each side (the left and the right) of the peak(s) wherein the histogram height falls below certain thresholds;
- and
- (e) extracting the range of code values between the left point and the right point, as identified in the previous step.
A method of extracting the important range of code values from an input digital image by counting the number of level-crossings for each code value, comprising the steps of:
- (a) processing the digital image on a line by line basis;
- (b) for each image line, updating an array that keeps track of the number of sign changes for each code value;
- (c) accumulating the number of sign changes for each code value from each image line to form a cumulative histogram of level-crossings as a function of code value;
- and
- (d) locating the highest peak of the level-crossing histogram and one point on each side (the left and the right) of the peak where the histogram height falls below certain criteria;
- and
- (e) extracting the range of code values between the left point and the right point, as identified in the previous step.
Dependencies are inferred from the claim text.