Lateral adjustment of print substrate based on a camera image

1. A printing device comprising:

a camera to capture an image of at least a portion of a print substrate;

a controller to determine, from the image, a location of a portion of a side edge of the print substrate, and determine a distance of the print substrate from a predetermined location; and

an adjustment apparatus to adjust, based on the determined distance, the print substrate laterally relative to a direction of transport of the print substrate,

wherein:

the adjustment apparatus comprises nip rollers and a gripper,

the controller is to control the gripper and/or the nip rollers to hold the print substrate still while the camera captures the image, and control the nip rollers to release the print substrate to allow the gripper to adjust the print substrate laterally based on the determined distance, and

the predetermined location is a location on the gripper.

2. The printing device of claim 1 , wherein the controller is to determine a location of a corner of the print substrate from the image, and the adjustment apparatus is to adjust the print substrate based on the determined location of the corner.

3. The printing device of claim 2 , wherein the controller is to determine a location of a portion of a leading edge of the substrate, and determine the location of the corner based on the location of the portion of the side edge and the location of the portion of the leading edge.

4. The printing device of claim 3 , wherein the print substrate comprises a first sheet, and the controller is to:

control the adjustment apparatus to adjust the first sheet such that a corner of the first sheet is relocated to a predetermined location, and

control the adjustment apparatus to subsequently adjust a second sheet such that a corresponding corner of the second sheet is relocated to the predetermined location.

5. The printing device of claim 3 , wherein the controller further is to detect a reference in the image and to determine the location of the portion of the side edge and/or the location of the portion of the leading edge relative to the reference, the reference corresponding to a known location in the printing device.

6. The printing device of claim 1 , further comprising feed apparatus and print apparatus, wherein the camera and the adjustment apparatus are located between the feed apparatus and the print apparatus.

7. The printing device of claim 1 , further comprising a memory to store information defining a plurality of search windows within the image for detecting edges located within the plurality of search windows, each search window of the plurality of search windows being associated with a respective substrate size,

wherein the controller is coupled to the memory to select a search window from the plurality of search windows based on a size of the print substrate, to detect the portion of the side edge.

8. The printing device of claim 1 , wherein the controller is to control the nip rollers to rotate the print substrate to correct for a skew of the print substrate.

9. The printing device of claim 8 , wherein the controller is to, after correcting for the skew of the print substrate, control the gripper to move laterally relative to the direction of transport of the print substrate, to adjust the print substrate laterally.

10. The printing device of claim 8 , wherein the controller is to control the nip rollers to rotate the print substrate by continuing to move a first subset of the nip rollers while holding still a second subset of the nip rollers.

11. A method comprising:

capturing, using a camera during registration of a print substrate in a printing device, an image of a portion of the print substrate;

determining, from the image, a location of a portion of a boundary of the print substrate;

determining a distance of the location of the portion of the boundary from a reference location on a gripper of the printing device, the gripper to grip the print substrate; and

adjusting, by controlling the gripper based on the determined distance, the print substrate laterally relative to a direction of transport of the print substrate, to register the print substrate relative to the reference location, wherein the portion of the boundary is a portion of a side edge or a corner of the print substrate.

12. The method of claim 11 , wherein the determining of the location of the boundary of the print substrate comprises:

determining a location and an orientation of the portion of the side edge;

determining a location and an orientation of a portion of a leading edge of the print substrate; and

extrapolating from the location and the orientation of the portion of the side edge and the location and the orientation of the leading edge to determine a location of the corner of the print substrate.

13. The method of claim 12 , further comprising

determining a size of the print substrate; and

selecting, based on the determined size, a first search window and a second search window for detecting the portion of the side edge and the portion of the leading edge, respectively.

14. The method of claim 11 , wherein the capturing of the image and the adjusting are performed before printing on the print substrate.

15. The method of claim 11 , further comprising detecting the reference location within the image.

16. The method of claim 11 , further comprising:

controlling, by a controller, the gripper and/or nip rollers to hold the print substrate still while the camera captures the image; and

controlling, by the controller, the nip rollers to release the print substrate, while controlling the gripper to adjust the print substrate laterally relative to the direction of transport.

17. The method of claim 11 , further comprising:

detecting a skew of the print substrate; and

rotating the print substrate to correct for the skew of the print substrate, wherein the adjusting of the print substrate laterally is performed after the correcting for the skew.

18. A non-transitory machine-readable storage medium comprising instructions that upon execution cause a system to:

receive an image captured by a camera of at least a portion of a print substrate in a printing device;

determine a location of a portion of a side edge of the print substrate from the image;

detect, in the image, a reference location on a gripper in the printing device, the gripper to rig substrate; and

determine a lateral adjustment, relative to a direction of transport of the print substrate, based on the determined location and the reference location, the lateral adjustment to relocate the print substrate to a target location using the gripper.

19. The non-transitory machine-readable storage medium of claim 18 , wherein the instructions upon execution cause the system to:

determine an orientation of the portion of the side edge;

determine a location and an orientation of a portion of a leading edge of the print substrate; and

extrapolate from the location and the orientation of the portion of the side edge and the location and the orientation of the portion of the leading edge a location of a corner of the print substrate, and wherein the instructions to determine the lateral adjustment comprise instructions to determine a lateral adjustment, from the determined location of the corner, to relocate the print substrate such that the corner is in a target location.

20. The non-transitory machine-readable storage medium of claim 18 , wherein the instructions upon execution cause the system to;

control the gripper and/or nip rollers to hold the print substrate still while the camera captures the image; and

control the nip rollers to release the print substrate, while controlling the gripper to adjust the print substrate laterally relative to the direction of transport.