Image processing apparatus, crease forming device, and folding device specifying the position of a folding line based on acquiring first image information and second image information

1. An image processing apparatus comprising:

a processor configured to:

acquire image information obtained by an image reading apparatus including a light source emitting to a sheet an uneven balance in an amount of light in a sub-scanning direction, wherein the light source of the image reading apparatus is disposed underneath the sheet, wherein the light source emits to the sheet a different amount of light on a second side in the sub-scanning direction than that on a first side in the sub-scanning direction; and

specify a position of a folding line in the sheet from the acquired image information, wherein

the acquiring by the processor comprises acquiring

first image information obtained by reading a surface of the sheet in a first state, using the light source, in which the folding line in the sheet is positioned in a direction intersecting the sub-scanning direction of the image reading apparatus, and an outer edge of the sheet faces toward a first main scanning direction perpendicular to the sub-scanning direction, and

second image information obtained by rotating the sheet to a second state and reading the same surface of the sheet in the second state, in which the outer edge of the sheet faces toward a second main scanning direction that is opposite to the first main scanning direction, and the same surface of the sheet is read in the second state using the same light source as used in the first state, and

the specifying by the processor comprises specifying the position of the folding line in the sheet based on the first image information and the second image information.

2. The image processing apparatus according to claim 1 , wherein

the first image information and the second image information are image information obtained by the image reading apparatus by moving the light source in the sub-scanning direction and receiving reflected light from the sheet.

3. The image processing apparatus according to claim 1 , wherein

the first state is a state in which a upper side of the sheet intersecting the folding line in the sheet is directed to one side, and

the second state is a state in which the upper side of the sheet is directed to an opposite side to the one side.

4. The image processing apparatus according to claim 2 , wherein

the first state is a state in which a upper side of the sheet intersecting the folding line in the sheet is directed to one side, and

the second state is a state in which the upper side of the sheet is directed to an opposite side to the one side.

5. The image processing apparatus according to claim 1 , wherein

the processor specifies the position of the folding line in the sheet based on a magnitude relation between brightness of the first image information and brightness of the second image information.

6. The image processing apparatus according to claim 2 , wherein

the processor specifies the position of the folding line in the sheet based on a magnitude relation between brightness of the first image information and brightness of the second image information.

7. The image processing apparatus according to claim 3 , wherein

the processor specifies the position of the folding line in the sheet based on a magnitude relation between brightness of the first image information and brightness of the second image information.

8. The image processing apparatus according to claim 4 , wherein

the processor specifies the position of the folding line in the sheet based on a magnitude relation between brightness of the first image information and brightness of the second image information.

9. The image processing apparatus according to claim 1 , wherein

the processor specifies, as the position of the folding line in the sheet, one of two positions adjacent to a first range or a second range in the sub-scanning direction based on a magnitude relation between brightness of the first image information and brightness of the second image information,

the first range is a range in the first image information where brightness is equal to or greater than a predetermined value, and

the second range is a range in the second image information where brightness is equal to or greater than the predetermined value.

10. The image processing apparatus according to claim 9 , wherein

the light source has a smaller amount of light on a second side in the sub-scanning direction than that on a first side in the sub-scanning direction, and

when the brightness of the first image information is larger than the brightness of the second image information, the processor specifies, as the position of the folding line in the sheet, a position adjacent to the second side of the first range in the sub-scanning direction or a position adjacent to the first side of the second range in the sub-scanning direction.

11. The image processing apparatus according to claim 9 , wherein

the light source has a smaller amount of light on a second side in the sub-scanning direction than that on a first side in the sub-scanning direction, and

when the brightness of the first image information is smaller than the brightness of the second image information, the processor specifies, as the position of the folding line in the sheet, a position adjacent to the first side of the first range in the sub-scanning direction or a position adjacent to the second side of the second range in the sub-scanning direction.

12. The image processing apparatus according to claim 9 , wherein

the light source has a larger amount of light on a second side in the sub-scanning direction than that on a first side in the sub-scanning direction, and

when the brightness of the first image information is larger than the brightness of the second image information, the processor specifies, as the position of the folding line in the sheet, a position adjacent to the first side of the first range in the sub-scanning direction or a position adjacent to the second side of the second range in the sub-scanning direction.

13. The image processing apparatus according to claim 9 , wherein

the light source has a larger amount of light on a second side in the sub-scanning direction than that on a first side in the sub-scanning direction, and

when the brightness of the first image information is smaller than the brightness of the second image information, the processor specifies, as the position of the folding line in the sheet, a position adjacent to the second side of the first range in the sub-scanning direction or a position adjacent to the first side of the second range in the sub-scanning direction.

14. The image processing apparatus according to claim 1 , wherein the folding line is a crease having one steeply inclined surface and one gently inclined surface, wherein a recess of the crease faces down to the light source.

15. The image processing apparatus according to claim 1 , wherein the folding line is a fold.

16. A crease forming device that changes a position where a crease is formed in a sheet based on the position of the crease in the sheet, which is specified by the image processing apparatus according to claim 14 .

17. A folding device that changes a folding position in a sheet based on the position of the fold of the sheet, which is specified by the image processing apparatus according to claim 15 .

18. An image processing method comprising:

acquiring image information obtained by an image reading apparatus including a light source emitting to a sheet an uneven balance in an amount of light in a sub-scanning direction, wherein the light source of the image reading apparatus is disposed underneath the sheet, wherein the light source emits to the sheet a different amount of light on a second side in the sub-scanning direction than that on a first side in the sub-scanning direction; and

specifying a position of a folding line in the sheet from the acquired image information, wherein

the acquiring comprises acquiring

first image information obtained by reading a surface of the sheet in a first state, using the light source, in which the folding line in the sheet is positioned in a direction intersecting the sub-scanning direction of the image reading apparatus, and an outer edge of the sheet faces toward a first main scanning direction perpendicular to the sub-scanning direction, and

second image information obtained by rotating the sheet to a second state and reading the same surface of the sheet in the second state, in which the outer edge of the sheet faces toward a second main scanning direction that is opposite to the first main scanning direction, and the same surface of the sheet is read in the second state using the same light source as used in the first state, and

the specifying comprises specifying the position of the folding line in the sheet based on the first image info nation and the second image information.