Method for removing the effect of light scattering in a digitized image of a light-scattering film

1. A method for removing the effect of light scattering in a digitized image of a light-scattering film comprising:

a) providing a light-scattering correction film that has a uniform optical density;

b) providing a light scattering target film that has a pattern of optical densities;

c) scanning said correction film with a film scanner to create a digital correction film image;

d) scanning said target film with said film scanner to create a digital target film image;

e) measuring the two-dimensional pattern of responses present in said digital correction film image;

f) determining a correction function from said two-dimensional pattern of responses to correct for the effect of light scattering in said digital correction film image; and

g) applying said correction function to said target film image to provide a corrected target film image.

2. The method of claim 1 wherein said light scattering film is a radiochromic film.

3. The method of claim 1 wherein said light-scattering film is a radiochromic film and said light scattering target film has a pattern of optical densities created by exposing said target film to doses of actinic radiation.

4. The method of claim 2 wherein said radiochromic film contains a polyacetylene.

5. The method of claim 1 wherein said film scanner is a CCD film scanner.

6. The method of claim 1 wherein said film scanner is a laser scanner.

7. The method of claim 1 further comprising:

a) obtaining data in at least one response channel of said film scanner to create a 2 n bit digitized image where n is an integer and wherein the digitized value of 2 n represents the highest light intensity and the value 0 represents the lowest light intensity;

b) inverting said 2 n bit digitized image by subtracting each pixel value within the image from 2 n to create an inverted image;

c) plotting a profile of the inverted pixel values across the film and normalizing the profile;

d) fitting said profile to a mathematical function that defines the normalized inverted pixel value IPV N (x) as a function of x, where x is the location of the pixel relative to the light source;

e) scanning said target film to create a 2 n bit digitized image where n is an integer and wherein the digitized value of 2 n represents the highest light intensity and the value 0 represents the lowest light intensity;

f) inverting the 2 n bit digitized image by subtracting each pixel value within the image from 2 n to create an inverted target film image;

g) determining the position x of each pixel in said inverted target film image in relation to the light source; and

h) correcting said inverted target film image by dividing the pixel value of each pixel at position x in said inverted target film image by said normalized inverted pixel value IPV N (x) to create a corrected inverted target film image.

8. The method of claim 7 wherein a plurality of light-scattering correction films with different uniform optical densities are:

a) scanned with a film scanner to create a plurality of digitized images;

b) inverted to provide a plurality of inverted digitized images;

c) plotted and normalized to provide a plurality of normalized profiles; and

d) said plurality of normalized profiles are then combined to form an averaged normalized profile that is fitted to said mathematical function which is used to correct the inverted target film image.

9. The method of claim 8 wherein said mathematical function is a polynomial function.

10. The method of claim 9 wherein said polynomial function is a quadratic function.

11. The method of claim 10 wherein said quadratic function is a parabolic function.

12. The method of claim 1 further comprising:

a) creating a 2 n bit digitized image in at least one response channel of said film scanner where n is an integer and wherein the digitized value of 2 n represents the highest light intensity and the value 0 represents the lowest light intensity;

b) inverting said 2 n bit digitized image by subtracting each pixel value within said image from 2 n to create an inverted image;

c) measuring the mean pixel value within said inverted image and dividing each pixel in the inverted image by the mean pixel value to create a normalized inverted image;

d) scanning said target film to create a 2 n bit digitized image where n is an integer and wherein the digitized value of 2 n represents the highest light intensity and the value 0 represents the lowest light intensity;

e) inverting said 2 n bit digitized image by subtracting each pixel value within said image from 2 n to create an inverted target image; and

f) correcting said inverted target image by dividing each pixel in the inverted target image by the corresponding pixel in said normalized inverted image to create a corrected target image.

13. The method of claim 1 wherein said light-scattering correction film has a pattern of optical densities parallel in one direction and variable in the orthogonal direction.