Generating an image of a seal impression

1. A method for generating an image of a seal impression, said method comprising:

causing, by a processor of an information processing apparatus, irradiation of a face of a seal with N beams of light striking the face in succession from N respective different directions respectively corresponding to N different angles of incidence of the light on the face, said face having a character engraved thereon, said N at least 2;

said processor acquiring N still images of the face corresponding respectively to the N beams of light striking the face in succession, each still image structured as a set of pixels such that each pixel comprises a red-green-blue (RGB) color combination; and

said processor combining the N still images to generate a composite image of pixels, said combining comprising generating in the composite image a common area of pixels that commonly appears on the face of the seal in all still images of the N still images, said common area having a luminance value exceeding a specified luminance threshold, said common area including a character area pertaining to where the engraved character is located on the face of the seal.

2. The method of claim 1 , wherein the face of the seal is circular and characterized by a radius, and wherein each beam forms on the face a shadow whose length is at least the radius of the face.

3. The method of claim 1 , wherein said combining comprises:

adding the R, G, and B luminance values of corresponding pixels in the N still images to form the pixels of the composite image;

normalizing the pixels in the composite image such that the largest luminance value of each of R, G and B in the composite image becomes equal to the largest luminance value of each of R, G and B in the N still images; and

rendering the pixels in the composite image having a luminance value exceeding and not exceeding the specified luminance threshold as having a luminance value of 1 and 0, respectively.

4. The method of claim 1 , wherein said combining comprises:

prior to said combining, rendering the pixels in each still image having a luminance value exceeding and not exceeding the specified luminance threshold as having a luminance value of 1 and 0, respectively; and

logically ANDing the corresponding pixels in the N still images to form the composite image.

5. The method of claim 1 , said method further comprising;

after said combining, said processor reversing light and dark portions in the composite image by (i) replacing the luminance values of 1 with luminance values of 0 and (ii) replacing the luminance values of 0 with luminance values of 1; and

said processor converting all pixels having a luminance value of 1 to a color of red.

6. The method of claim 1 , wherein the common area further includes an outer rim of the face.

7. The method of claim 1 , wherein N is at least 3.

8. An information processing apparatus, comprising a processor, a memory coupled to the processor, and a computer readable storage device coupled to the processor, said storage device containing program code configured to be executed by the processor via the memory to implement a method for generating an image of a seal impression, said method comprising:

said processor causing irradiation of a face of a seal with N beams of light striking the face in succession from N respective different directions respectively corresponding to N different angles of incidence of the light on the face, said face having a character engraved thereon, said N at least 2;

said processor acquiring N still images of the face corresponding respectively to the N beams of light striking the face in succession, each still image structured as a set of pixels such that each pixel comprises a red-green-blue (RGB) color combination; and

said processor combining the N still images to generate a composite image of pixels, said combining comprising generating in the composite image a common area of pixels that commonly appears on the face of the seal in all still images of the N still images, said common area having a luminance value exceeding a specified luminance threshold, said common area including a character area pertaining to where the engraved character is located on the face of the seal.

9. The apparatus of claim 8 , wherein the face of the seal is circular and characterized by a radius, and wherein each beam forms on the face a shadow whose length is at least the radius of the face.

10. The apparatus of claim 8 , wherein said combining comprises:

adding the R, G, and B luminance values of corresponding pixels in the N still images to form the pixels of the composite image;

normalizing the pixels in the composite image such that the largest luminance value of each of R, G and B in the composite image becomes equal to the largest luminance value of each of R, G and B in the N still images; and

rendering the pixels in the composite image having a luminance value exceeding and not exceeding the specified luminance threshold as having a luminance value of 1 and 0, respectively.

11. The apparatus of claim 8 , wherein said combining comprises:

prior to said combining, rendering the pixels in each still image having a luminance value exceeding and not exceeding the specified luminance threshold as having a luminance value of 1 and 0, respectively; and

logically ANDing the corresponding pixels in the N still images to form the composite image.

12. The apparatus of claim 8 , said method further comprising;

after said combining, said processor reversing light and dark portions in the composite image by (i) replacing the luminance values of 1 with luminance values of 0 and (ii) replacing the luminance values of 0 with luminance values of 1; and

said processor converting all pixels having a luminance value of 1 to a color of red.

13. The apparatus of claim 8 , wherein the common area further includes an outer rim of the face.

14. The apparatus of claim 8 , wherein N is at least 3.

15. A computer program product, comprising a computer readable storage device having a computer readable program code stored therein, said program code configured to be executed by a processor of an information processing apparatus to implement a method for generating an image of a seal impression, said method comprising:

causing, by the processor of the information processing apparatus, irradiation of a face of a seal with N beams of light striking the face in succession from N respective different directions respectively corresponding to N different angles of incidence of the light on the face, said face having a character engraved thereon, said N at least 2;

said processor acquiring N still images of the face corresponding respectively to the N beams of light striking the face in succession, each still image structured as a set of pixels such that each pixel comprises a red-green-blue (RGB) color combination; and

said processor combining the N still images to generate a composite image of pixels, said combining comprising generating in the composite image a common area of pixels that commonly appears on the face of the seal in all still images of the N still images, said common area having a luminance value exceeding a specified luminance threshold, said common area including a character area pertaining to where the engraved character is located on the face of the seal.

16. The computer product of claim 15 , wherein the face of the seal is circular and characterized by a radius, and wherein each beam forms on the face a shadow whose length is at least the radius of the face.

17. The computer product of claim 15 , wherein said combining comprises:

adding the R, G, and B luminance values of corresponding pixels in the N still images to form the pixels of the composite image;

normalizing the pixels in the composite image such that the largest luminance value of each of R, G and B in the composite image becomes equal to the largest luminance value of each of R, G and B in the N still images; and

rendering the pixels in the composite image having a luminance value exceeding and not exceeding the specified luminance threshold as having a luminance value of 1 and 0, respectively.

18. The computer product of claim 15 , wherein said combining comprises:

prior to said combining, rendering the pixels in each still image having a luminance value exceeding and not exceeding the specified luminance threshold as having a luminance value of 1 and 0, respectively; and

logically ANDing the corresponding pixels in the N still images to form the composite image.

19. The computer product of claim 15 , said method further comprising;

after said combining, said processor reversing light and dark portions in the composite image by (i) replacing the luminance values of 1 with luminance values of 0 and (ii) replacing the luminance values of 0 with luminance values of 1; and

said processor converting all pixels having a luminance value of 1 to a color of red.

20. The computer product of claim 15 , wherein the common area further includes an outer rim of the face.