Transparency and/or color processing

1. A method of automated image processing that automatically determines a color and transparency for a pixel with an observed color when given the pixel and a background reference color, the method comprising:

automatically finding a found point in a color space by extrapolating in the color space based on two points in the color space that respectively correspond to or that respectively approximate the observed color and the given background reference color;

automatically determining a color for the given pixel that corresponds to or approximates the found point in the color space; and

based on the found point and the two points in the color space that respectively correspond to the observed color and the given reference color, automatically determining a transparency for the pixel by dividing a distance between the background reference color and the observed color by a distance between the background reference color and the found point in color space.

2. A method according to claim 1 , wherein the extrapolating comprises determining a point in the color space according to an extrapolated color vector in the color space, where the color vector has an origin based on the point in the color space corresponding to the given background reference color and where the color vector has a non-origin point based on the point in the color space that corresponds to the observed pixel color.

3. A method according to claim 2 , wherein the found point is on the color vector, the origin is the point in the color space corresponding to the given background reference color, and the non-origin point is the point in the color space that corresponds to the observed pixel color.

4. A method according to claim 2 , wherein the found point is found according to the color vector and a boundary of the color space.

5. A method according to claim 1 , wherein the found point is on the boundary of the color space.

6. A method according to claim 1 , wherein the color space comprises a red, green, and blue (RGB) color cube.

7. A method according to claim 1 , wherein the observed color corresponds to a color of a coloring substance as applied to a physical medium, wherein the background reference color corresponds to a color of the physical medium without the physical coloring substance, and wherein the determined color for the pixel corresponds to a color of the pigment.

8. A method according to claim 7 , wherein the observed pixel is a pixel of a captured image of the physical medium with the coloring substance applied thereto.

9. A method according to claim 1 , further comprising automatically checking a first criteria to determine whether the extrapolating is to be used to find the point in the color space and using a different technique than the extrapolating to find the point in the color space.

10. A method according to claim 9 , wherein the criteria is based on the observed color and the background color or their points in the color space.

11. A method according to claim 9 , wherein the criteria comprises a color distance between the background reference color and the observed color.

12. A computing apparatus configured to perform a method according to claim 1 .

13. A volatile or non-volatile computer-readable storage storing information to enable a computer to perform a method according to claim 1 .

14. A method of automated image processing that automatically determines a color and transparency for a pixel with an observed color when given the pixel and a background reference color, the method comprising:

automatically finding a found point in a color space by extrapolating in the color space based on two points in the color space that respectively correspond to or that respectively approximate the observed color and the given background reference color;

automatically determining a color for the given pixel that corresponds to or approximates the found point in the color space; and

based on the found point and the two points in the color space that respectively correspond to the observed color and the given reference color, automatically determining a transparency for the pixel, and

wherein the automatically determining the transparency for the pixel is based on: a color distance in the color space between the point corresponding to or approximating the given background reference and the point corresponding to or approximating the observed color; and a color distance in the color space between the point of the given background reference color and the found point.

15. A method according to claim 14 , wherein the transparency is based on a ratio of the color distances excluding divide by zero ratios.

16. A method of automated image processing that automatically determines a color and transparency for a pixel with an observed color when given the pixel and a background reference color, the method comprising:

automatically finding a found point in a color space by extrapolating in the color space based on two points in the color space that respectively correspond to or that respectively approximate the observed color and the given background reference color;

automatically determining a color for the given pixel that corresponds to or approximates the found point in the color space; and

based on the found point and the two points in the color space that respectively correspond to the observed color and the given reference color, automatically determining a transparency for the pixel,

wherein the extrapolating comprises determining a point in the color space according to an extrapolated color vector in the color space, where the color vector has an origin based on the point in the color space corresponding to the given background reference color and where the color vector has a non-origin point based on the point in the color space that corresponds to the observed pixel color,

wherein the found point is on the color vector, the origin is the point in the color space corresponding to the given background reference color, and the non-origin point is the point in the color space that corresponds to the observed pixel color,

wherein the found point is found according to the color vector and a boundary of the color space, and

wherein a user is allowed to control a general transparency of an image by controlling where the found point will be on the color vector.

17. A method of automated image processing that automatically determines a color and transparency for a pixel with an observed color when given the pixel and a background reference color, the method comprising:

automatically finding a found point in a color space by extrapolating in the color space based on two points in the color space that respectively correspond to or that respectively approximate the observed color and the given background reference color;

automatically determining a color for the given pixel that corresponds to or approximates the found point in the color space;

based on the found point and the two points in the color space that respectively correspond to the observed color and the given reference color, automatically determining a transparency for the pixel; and

automatically checking a first criteria to determine whether the extrapolating is to be used to find the point in the color space and using a different technique than the extrapolating to find the point in the color space,

wherein the criteria is based on the observed color and the background color or their points in the color space,

wherein the criteria comprises a color distance between the background reference color and the observed color, and

wherein the different technique comprises using the observed color as the found point.

18. A method of image processing, comprising:

given a reference digital color and an original color image comprising original pixels each having an original color, automatically generating a new image with pixels corresponding to respective pixels in the original color image, by automatically calculating respective colors and transparencies according to the reference color and respective digital colors of the original color pixels, where the new image has a characteristic that it can be blended over the reference digital color to approximate the original image and pixels of the original image that are close in color to the reference digital color are substantially transparent and the transparencies are determined by dividing a distance between the reference digital color and the original color by a distance between the reference digital color and the respective color.

19. A computing apparatus configured to perform a method according to claim 18 .

20. A volatile or non-volatile computer-readable storage storing information to enable a computer to perform a method according to claim 18 .

21. A method of processing a captured digital image of a physical subject, the subject comprising a coloring substance applied to a physical medium of a substantially uniform color, where, given a digital color representing the substantially uniform color of the physical medium, the processing comprises:

for each pixel in a set of pixels of the digital image, using the given digital color representing the substantially uniform color of the medium and the pixels digital color as a basis to automatically calculate a transparency value and an associated digital color approximating, for a portion of the subject represented by the pixel, the color of the coloring substance without the physical medium and the transparency value is determined by dividing a distance between the given digital color and the pixel' digital color by a distance between the given digital color and associated digital color.

22. A computing apparatus configured to perform a method according to claim 21 .

23. A volatile or non-volatile computer-readable storage storing information to enable a computer to perform a method according to claim 21 .

24. A method of automated image processing that automatically determines a color and transparency for a pixel with an observed color when given the pixel and a background reference color, the method comprising:

automatically finding a point in a color space by extrapolating in the color space based on two points in the color space that respectively correspond to or that respectively approximate the observed color and the given background reference color;

automatically determining a color for the given pixel that corresponds to or approximates the found point in the color space; and based on the found point and the two points in the color space that respectively correspond to the observed color and the given reference color;

automatically determining a new transparency for the given pixel by dividing a distance between the background reference color and the observed color by a distance between the background reference color and the found point in color space;

automatically replacing the observed color of the pixel with the found color; and

automatically replacing the transparency of the pixel with the new transparency.