Image processing apparatus and image processing method

1. An image processing apparatus, comprising:

a processor coupled to a memory, configured to:

detect corresponding relationships between first lines included in one of a pair of images each having different local deformation and second lines included in the other of the pair of images,

correct the local deformation of each of the pair of images by associating each of the first lines with one of the second lines based on the corresponding relationships between the pair of images,

concatenate the pair of images in which the local deformation is corrected using the first lines and the second lines into a single image, and

correct the local deformation in lines of one of the pair of images when there are a plurality of lines corresponding to a same line in the other of the images by deleting, excluding one line, the plurality of lines corresponding to the same line of the other of the images based on the corresponding relationships between the lines.

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

the processor is configured to detect the corresponding relationships by calculating feature quantities of the pair of images at image ends where the pair of images are connected.

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

the processor is configured to correct the local deformation by performing processing to change, in an area defined by a first pair of adjacent lines on one of the pair of images, an interval between the first pair of lines so that the interval matches an interval between a second pair of lines in an area defined by the second pair of lines corresponding to the first pair of lines in the other of the images, based on the corresponding relationships between the lines.

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

the processor is configured to detect the corresponding relationships by comparing the calculated feature quantities in the image ends of the pair of images so as to detect corresponding relationships between the lines in the pair of images.

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

the processor is configured to detect the corresponding relationships by applying dynamic programming when comparing the calculated feature quantities at the image ends of the pair of images so as to detect corresponding relationships between the lines in the pair of images.

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

the pair of images each having different local deformation are images each obtained by reading a document line by line at different timing while transporting the document, and

the processor is configured to detect the corresponding relationships based on an amount of transport of the document detected for each line in a period of reading the document line by line while the document is being transported.

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

the processor is configured to detect the corresponding relationships by comparing the amount of transport of the document detected at the time of reading individual lines of one of the pair of images with the amount of transport of the document detected at the time of reading individual lines of the other of the images, and by associating a line of the one of the images with a corresponding line having a nearest amount of transport of the document in the individual lines of the other of the images so as to detect the corresponding relationships of the individual lines.

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

the processor is configured to detect the corresponding relationships by comparing the amount of transport of the document detected at the time of reading individual lines of each of the pair of images with an ideal amount of transport of the document at the time of reading individual lines of the image, calculated from a resolution of reading the document, and by associating a line of the image with a line having a nearest ideal amount of transport of the document in the individual lines so as to detect the corresponding relationships of the individual lines.

9. An image processing method, comprising:

detecting, with a processor, corresponding relationships between first lines included in one of a pair of images each having different local deformation and second lines included in the other of the pair of images;

correcting the local deformation of each of the pair of images by associating each of the first lines with one of the second lines based on the corresponding relationships between the pair of images detected by the detecting; and

combining the pair of images subjected to the correcting using the first lines and the second lines into a single image; wherein,

in lines of one of the pair of images, when there are a plurality of lines corresponding to a same line in the other of the images, the correcting includes deleting, excluding one line, the plurality of lines corresponding to the same line of the other of the images, based on the corresponding relationships between the lines.

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

the detecting of the corresponding relationships is performed by calculating feature quantities of the pair of images at image ends where the pair of images are connected.

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

the correcting includes changing, in an area defined by a first pair of adjacent lines on one of the pair of images, an interval between the first pair of lines so that the interval matches an interval between a second pair of lines in an area defined by the second pair of lines corresponding to the first pair of lines in the other of the images, based on the corresponding relationships between the lines.

12. The image processing method according to claim 10 ,

wherein the detecting corresponding relationships comparing the calculated feature quantities in the image ends of the pair of images.

13. The image processing method according to claim 12 , wherein

the detecting includes applying dynamic programming when comparing the calculated feature quantities in the image ends of the pair of images.

14. The image processing method according to claim 9 , wherein

the pair of images each having different local deformation are images each obtained by reading a document line by line at different timing while transporting the document, and

the detecting includes detecting, based on an amount of transport of the document detected for each line in a period of reading the document line by line while the document is being transported.

15. The image processing method according to claim 14 , wherein

the detecting includes comparing the amount of transport of the document detected at the time of reading individual lines of one of the pair of images with the amount of transport of the document detected at the time of reading individual lines of the other of the images, and associating a line of the one of the images with a corresponding line having a nearest amount of transport of the document in the individual lines of the other of the images.

16. The image processing method according to claim 14 , wherein

the detecting includes comparing the amount of transport of the document detected at the time of reading individual lines of each of the pair of the images with an ideal amount of transport of the document at the time of reading individual lines of the image, calculated from a resolution of reading the document, and associating a line of the image with a line having a nearest ideal amount of transport of the document in the individual lines.

17. An image processing method, comprising:

detecting corresponding relationships between first lines included in one of a pair of images each having different local deformation and second lines included in the other of the pair of images;

correcting the local deformation of each of the pair of images by associating each of the first lines with one of the second lines based on the corresponding relationships between the pair of images detected by the detecting; and

combining the pair of images subjected to the correcting using the first lines and the second lines into a single image, wherein

the pair of images each having different local deformation are images each obtained by reading a document line by line at different timing while transporting the document, and

the detecting includes detecting, based on an amount of transport of the document detected, by an amount-of-transport detection sensor, for each line in a period of reading the document line by line while the document is being transported.

18. The image processing method according to claim 17 , wherein

the amount-of-transport detection sensor irradiates the document with light, reads reflected light by an image sensor, and detects an amount of movement of the document as the amount of transport of the document.

19. The image processing method according to claim 13 , wherein

the corresponding relationships are detected based on recurrence relations of the dynamic programming using a difference between the calculated feature quantities.

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

the processor is configured to detect the corresponding relationships based on recurrence relations of the dynamic programming using a difference between the calculated feature quantities.