Method for determining the orientation in which an object was placed when the image of the object was recorded

• US 5,533,143 A
• Filed: 04/28/1994
• Issued: 07/02/1996
• Est. Priority Date: 04/27/1993
• Status: Expired due to Term

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Takeo, Hideya
• Primary Examiner(s): Boudreau, Leo
• Assistant Examiner(s): Johns, Andrew W.
• Application Number:
  US08/233,980
• Time in Patent Office: 796 Days
• Field of Search: 382/1, 382/6, 382/48, 382/128, 382/132, 382/286, 382/288, 364/413.13, 348/94, 348/95
• US Class Current: 382/132
• CPC Class Codes: G06T 7/68 of symmetry
• CPC Class Codes: G06T 7/70 Determining position or orientation of objects or cameras camera calibration G06T7/80

Abstract

An image signal, which represents an image capable of taking either a symmetric orientation or an asymmetric orientation with respect to a center line of the image serving as the axis of symmetry, is obtained. The image signal is made up of a series of image signal components representing picture elements in the image. A predetermined operation is then carried out to find the difference between values of image signal components representing at least a single pair of picture elements, which correspond symmetrically to each other with respect to the center line of the image, and to calculate a characteristic value, which represents symmetry or asymmetry of the image, from the value of the difference. A judgment is then made from the level of the characteristic value as to whether the image is a symmetric image or is an asymmetric image.

Claims

1. A method for determining an orientation from a recorded image of a physical object, wherein the orientation, in which the physical object was placed when the image of the physical object was recorded, is determined, the method comprising the steps of:

i) retrieving an image signal of the physical object which is stored on an image storing means, the image represented by said image signal being capable of taking either a symmetric orientation or an asymmetric orientation with respect to a center line of the image serving as the axis of symmetry, said image signal being made up of a series of image signal components representing picture elements in the image,

ii) sending the retrieved image signal to an image processing means,

iii) calculating, using said image processing means, the difference between values of image signal components representing at least a single pair of picture elements, which correspond symmetrically to each other with respect to the center line of the image, and calculating a characteristic value, which represents symmetry or asymmetry of the image, from the value of said difference by carrying out a predetermined operation, and

iv) using said image processing means for making a judgment from the level of said characteristic value as to determine whether the image of the object represents a symmetric orientation or an asymmetric orientation.

2. A method as defined in claim 1 wherein the predetermined operation comprises the steps of:

calculating the absolute value of the difference between the values of the image signal components representing each pair of the picture elements, which correspond symmetrically to each other,

thereafter calculating the total sum of the absolute values of the differences, which have been calculated for the respective pairs of the picture elements corresponding symmetrically to each other, and

taking said total sum as said characteristic value.

3. A method as defined in claim 1 wherein the predetermined operation comprises the steps of:

calculating the difference between the values of the image signal components representing each pair of the picture elements, which correspond symmetrically to each other,

thereafter calculating the total sum of square values of the differences, which have been calculated for the respective pairs of the picture elements corresponding symmetrically to each other, and

taking said total sum as said characteristic value.

4. A method as defined in any one of claims 1, 2, or 3 wherein the values of the image signal components representing the picture elements in the image are binarized with a predetermined threshold value, and thereafter the predetermined operation is carried out on the binary values which have thus been obtained.

5. A method as defined in claim 1 wherein the image is a radiation image.

6. A method as defined in claim 5, wherein said image storing means is a stimulable phosphor sheet.

7. A method as defined in claim 6 wherein an image signal, which represents the radiation image and serves as said image signal, is detected by exposing the stimulable phosphor sheet to stimulating rays, which cause the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation, and photoelectrically detecting the emitted light.

8. A method as defined in claim 7 wherein said stimulating rays are a laser beam.

9. A method as defined in claim 1, wherein said image storing means is a photographic film.

10. A method as defined in claim 1, wherein the image processing means is a digital computer.

11. An apparatus for determining an object orientation from a recorded image, wherein the orientation, in which the object was placed when the image of the object was recorded, is determined, the apparatus comprising:

i) means for obtaining an image signal, which represents the image capable of taking either a symmetric orientation or an asymmetric orientation with respect to a center line of the image serving as the axis of symmetry, said image signal being made up of a series of image signal components representing picture elements in the image,

ii) means for calculating the difference between values of image signal components representing at least a single pair of picture elements, which correspond symmetrically to each other with respect to the center line of the image, and for calculating a characteristic value, which represents symmetry or asymmetry of the image, from the value of said difference by carrying out a predetermined operation, and

iii) means for making a judgment from the level of said characteristic value as to whether the image is a symmetric image or is an asymmetric image.

12. An apparatus as defined in claim 11, wherein the image is a radiation image.

13. An apparatus as defined in claim 12, wherein the radiation has been stored on a stimulable phosphor sheet.

14. An apparatus as defined in claim 13, wherein an image signal, which represents the radiation image and serves as an image signal, is detected by exposing the stimulable phosphor sheet to stimulating rays, which cause the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation, and photoelectrically detecting the emitted light.

15. An apparatus as defined in claim 14, wherein said stimulating rays are a laser beam.

16. An apparatus as defined in claim 11, wherein the image has been recorded on photographic film.

17. An apparatus as defined in claim 11, wherein the image processing means is a digital computer.

18. A method for determining an orientation from a recorded image of a physical object, wherein the orientation, in which the physical object was placed when the image of the physical object was recorded, is determined, the method comprising the steps of:

i) obtaining an image signal of the physical object using an image readout means, said image signal representing the image capable of taking either a symmetric orientation or an asymmetric orientation with respect to a center line of the image serving as the axis of symmetry, said image signal being made up of a series of image signal components representing picture elements in the image,

ii) sending the obtained image signal to an image processing means,

iii) calculating, using said image processing means, the difference between values of image signal components representing at least a single pair of picture elements, which correspond symmetrically to each other with respect to the center line of the image, and calculating a characteristic value, which represents symmetry or asymmetry of the image, from the value of said difference by carrying out a predetermined operation, and

iv) using said image processing means for making a judgment from the level of said characteristic value as to determine whether the image of the object represents a symmetric orientation or an asymmetric orientation.

19. A method as defined in claim 18, wherein the image processing means is a digital computer.