Method and system for correcting a distorted input image
View Patent ↗A method for correcting a distorted input image includes determining a local region of an image to be displayed and dividing the region into an array of rectangular tiles, each tile corresponding to a distorted tile with a non-rectangular boundary within the input image. For each tile of the local region, maximum and minimum memory address locations of successive rows of the input image sufficient to span the boundary of the distorted tile are determined. Successive rows of the distorted input from between the maximum and minimum addresses are read. Distortion of the non-rectangular portion of the distorted input image is corrected to provide a tile of a corrected output image which is stored.
1. A method for correcting distorted images, the method comprising:
dividing an input image that contains distortions into a plurality of input tiles, each input tile having a plurality of input tile coordinates;
for each input tile, of the plurality of input tiles, generating a corresponding output tile by:
determining a mapping between the plurality of input tile coordinates and a plurality of output tile coordinates;
based, at least in part, on the mapping, determining corrected tile information for the input tile;
based, at least in part, on the corrected tile information, determining a minimum memory address location and a maximum memory address location of a memory space in which pixel information for the input tile is stored;
based on the minimum memory address location and the maximum memory address location, retrieving the pixel information for the input tile from the memory space;
based, at least in part, on the mapping and the pixel information of the input tile, generating corrected pixel information which does not contain one or more distortions of the distortions; and
storing the corrected pixel information in the corresponding output tile.
2. The method of claim 1 , wherein the mapping is determined based on characteristics of a lens system having a wide field of view lens used to capture the input image.
3. The method of claim 1 , further comprising:
modifying the minimum memory address location and the maximum memory address location of the memory space to include one or more pixels located immediately outside a boundary of the input tile in generating the corrected pixel information.
4. The method of claim 1 , further comprising:
modifying the minimum memory address location and the maximum memory address location of the memory space to enable interpolation of pixels located along a boundary of the input tile in generating the corrected pixel information.
5. The method of claim 1 , further comprising:
for each input tile of the plurality of input tiles:
determining an affine transformation applicable to the plurality of input tile coordinates; and
transforming the plurality of input tile coordinates onto the plurality of output tile coordinates of the corresponding output tile according to the affine transformation.
6. The method of claim 5 , wherein the affine transformation comprises multiplying coordinate values u, v of each of the plurality of input tile coordinates using the following matrix transformation:
[
u
′
v
′
]
=
[
a
1
a
2
a
3
a
4
]
[
u
v
]
+
[
a
5
a
6
]
to produce transformed coordinate values u′, v′ of each of the plurality of coordinates of the corresponding output tile.
7. The method of claim 1 , further comprising:
determining an image acquisition focal length of a lens system with which the input image was captured; and
based, at least in part, on the image acquisition focal length, determining a global transformation to be applied to the plurality of input tile coordinates to compensate for one or more non-uniformities present in the lens system.
8. An image acquisition device comprising:
a lens and an image sensor for capturing an input image containing distortions;
a processor;
a memory for storing images;
a system bus connected to the memory; and
a distortion correction module connected to the system bus and configured to perform:
dividing the input image into a plurality of input tiles, each input tile having a plurality of coordinates;
for each input tile, of the plurality of input tiles, generating an corresponding output tile by:
determining a mapping between the plurality of input tile coordinates and a plurality of output tile coordinates;
based, at least in part, on the mapping, determining corrected tile information for the input tile;
based, at least in part, on the corrected tile information, determining a minimum memory address location and a maximum memory address location of a memory space in which pixel information for the input tile is stored;
based on the minimum memory address location and the maximum memory address location, retrieving the pixel information for the input tile from the memory space;
based, at least in part, on the mapping and the pixel information of the input tile, generating corrected pixel information which does not contain one or more distortions of the distortions; and
storing the corrected pixel information in the corresponding output tile.
9. The image acquisition device of claim 8 , wherein the mapping is determined based on characteristics of a lens system having a wide field of view lens used to capture the input image.
10. The image acquisition device of claim 8 , wherein the distortion correction module is further configured to perform:
modifying the minimum memory address location and the maximum memory address location of the memory space to include one or more pixels located immediately outside a boundary of the input tile in generating the corrected pixel information.
11. The image acquisition device of claim 8 , wherein the distortion correction module is further configured to perform:
modifying the minimum memory address location and the maximum memory address location of the memory space to enable interpolation of pixels located along a boundary of the input tile in generating the corrected pixel information.
12. The image acquisition device of claim 8 , wherein the distortion correction module is further configured to perform:
for each input tile of the plurality of input tiles:
determining an affine transformation applicable to the plurality of input tile coordinates; and
transforming the plurality of input tile coordinates onto the plurality of coordinates of the corresponding output tile according to the affine transformation.
13. The image acquisition device of claim 12 , wherein the affine transformation comprises multiplying coordinate values u, v of each of the plurality of input tile coordinates using the following matrix transformation:
[
u
′
v
′
]
=
[
a
1
a
2
a
3
a
4
]
[
u
v
]
+
[
a
5
a
6
]
to produce transformed coordinate values u′, v′ of each of the plurality of coordinates of the corresponding output tile.
14. The image acquisition device of claim 8 , wherein the distortion correction module is further configured to perform:
determining an image acquisition focal length of a lens system with which the input image was captured; and
based, at least in part, on the image acquisition focal length, determining a global transformation to be applied to the plurality of input tile coordinates to compensate for one or more non-uniformities present in the lens system.
15. A non-transitory computer-readable storage medium storing one or more instructions which, when executed by one or more processors, cause the processors to perform:
capturing an input image containing distortions;
dividing the input image into a plurality of input tiles, each input tile having a plurality of coordinates;
for each input tile, of the plurality of input tiles, generating an corresponding output tile by:
determining a mapping between the plurality of input tile coordinates and a plurality of output tile coordinates;
based, at least in part, on the mapping, determining corrected tile information for the input tile;
based, at least in part, on the corrected tile information, determining a minimum memory address location and a maximum memory address location of a memory space in which pixel information for the input tile is stored;
retrieving the pixel information for the input tile from the memory space;
based, at least in part, on the mapping and the pixel information of the input tile, generating corrected pixel information which does not contain one or more distortions of the distortions; and
storing the corrected pixel information in the corresponding output tile.
16. The non-transitory computer-readable storage medium of claim 15 , wherein the mapping is determined based on characteristics of a lens system having a wide field of view lens used to capture the input image.
17. The non-transitory computer-readable storage medium of claim 15 , further comprising additional instructions which, when executed by the one or more processors, cause the processors to perform:
modifying the minimum memory address location and the maximum memory address location of the memory space to include one or more pixels located immediately outside a boundary of the input tile in generating the corrected pixel information.
18. The non-transitory computer-readable storage medium of claim 15 , further comprising additional instructions which, when executed by the one or more processors, cause the processors to perform:
modifying the minimum memory address location and the maximum memory address location of the memory space to enable interpolation of pixels located along a boundary of the input tile in generating the corrected pixel information.
19. The non-transitory computer-readable storage medium of claim 15 , further comprising additional instructions which, when executed by the one or more processors, cause the processors to perform:
for each input tile of the plurality of input tiles:
determining an affine transformation applicable to the plurality of input tile coordinates; and
transforming the plurality of input tile coordinates onto the plurality of coordinates of the corresponding output tile according to the affine transformation.
20. The non-transitory computer-readable storage medium of claim 19 , wherein the affine transformation comprises multiplying coordinate values u, v of each of the plurality of input tile coordinates using the following matrix transformation:
[
u
′
v
′
]
=
[
a
1
a
2
a
3
a
4
]
[
u
v
]
+
[
a
5
a
6
]
to produce transformed coordinate values u′, v′ of each of the plurality of coordinates of the corresponding output tile.
21. The non-transitory computer-readable storage medium of claim 15 , further comprising additional instructions which, when executed by the one or more processors, cause the processors to perform:
determining an image acquisition focal length of a lens system with which the input image was captured; and
based, at least in part, on the image acquisition focal length, determining a global transformation to be applied to the plurality of input tile coordinates to compensate for one or more non-uniformities present in the lens system.