Image processing apparatus, image forming apparatus, and non-transitory computer readable medium

1. An image processing apparatus comprising:

at least one processor configured to implement:

a receiver configured to receive:

a first read value indicating a result of reading a first color by a reader from a recording medium in which the first color is applied to a first area in which in-plane density unevenness is confirmable within the recording medium,

wherein the reader comprises at least one sensor; and

a second read value indicating a result of reading a second color by the reader, the second color being different from the first color and being applied to a second area that is substantially the same as the first area in a superimposed manner; and

a correcting unit configured to correct in-plane density unevenness of the second color applied to the first color in the superimposed manner using the first read value received by the receiver and the second read value received by the receiver.

2. The image processing apparatus according to claim 1 , wherein the correcting unit is configured to derive a corrected read value obtained by removing influence of the first color from the second read value using the first read value and the second read value, and

wherein the correcting unit is configured to correct the in-plane density unevenness of the second color applied to the first color in the superimposed manner using the derived corrected read value.

3. The image processing apparatus according to claim 2 , wherein the correcting unit is configured to derive the corrected read value corresponding to a receiving result from the receiver using a correspondence relationship among the first read value, the second read value, and the corrected read value.

4. The image processing apparatus according to claim 3 , wherein the reader is configured to read, along a sub scanning direction, the second color of each of multiple divided areas obtained by dividing the second area along a main scanning direction, and

wherein the correcting unit is configured to derive the corrected read value corresponding to the receiving result for each of the multiple divided areas.

5. The image processing apparatus according to claim 1 , wherein the first color is black, and

wherein the second color is white.

6. An image forming apparatus comprising:

an image forming unit comprising:

a light source;

a charger;

a developing roller;

a photoconductor drum;

a transfer belt;

a secondary transfer roller; and

a backup roller;

wherein the image forming unit is configured to form an image by operations comprising:

applying a first color to a first area in which in-plane density unevenness is confirmable within a recording medium; and

applying a second color different from the first color to a second area that is substantially the same as the first area in a superimposed manner;

a reader comprising at least one sensor:

wherein the reader is configured to read the first color from the first area resulting in a first read value,

wherein the reader is configured to read the second color from the second area resulting in a second read value; and

at least one processor configured to implement a correcting unit configured to correct in-plane density unevenness of the second color applied to the first color in the superimposed manner using the first read value and the second read value.

7. The image forming apparatus according to claim 6 , wherein the correcting unit is configured to derive a corrected read value obtained by removing influence of the first color from the second read value using the first read value and the second read value, and

wherein the correcting unit is configured to correct the in-plane density unevenness of the second color applied to the first color in the superimposed manner using the derived corrected read value.

8. The image forming apparatus according to claim 7 , wherein the correcting unit is configured to derive the corrected read value corresponding to a read result of the reader using a correspondence relationship among the first read value, the second read value, and the corrected read value.

9. The image forming apparatus according to claim 8 , wherein the reader is configured to read, along a sub scanning direction, the second color of each of multiple divided areas obtained by dividing the second area along a main scanning direction, and

wherein the correcting unit is configured to derive the corrected read value corresponding to the read result for each of the multiple divided areas.

10. The image forming apparatus according to claim 9 , wherein the correcting unit is configured to correct the in-plane density unevenness of the second color using a correction value using the corrected read value derived for each of the multiple divided areas.

11. The image forming apparatus according to claim 10 , wherein the image forming unit comprises a transfer member configured to transfer the first color and the second color to the recording medium by circulating in the sub scanning direction,

wherein the at least one sensor comprises a first sensor and a second sensor,

wherein the second sensor is configured to read the second color from a reference image of the second color formed on the transfer member along the sub scanning direction,

wherein the correcting unit is configured to develop a correction value using a third read value indicating a result of reading the second color of the reference image along the sub scanning direction by the second sensor in a plane defined by a position in the main scanning direction and a position in the sub scanning direction of each of the multiple divided areas according to a deviation characteristic between the corrected read values for the multiple divided areas, and

wherein the correcting unit is configured to correct the in-plane density unevenness of the second color using the developed correction value.

12. The image forming apparatus according to claim 11 , wherein the third read value is a read value indicating the result of reading the second color along the sub scanning direction by the second sensor from an image area for one cycle in the sub scanning direction of the reference image by the transfer member.

13. The image forming apparatus according to claim 11 , wherein the third read value is a value obtained by adding the results of reading the second color along the sub scanning direction by the second sensor from the image area for plural cycles in the sub scanning direction of the reference image by the transfer member and averaging the results for one cycle.

14. The image forming apparatus according to claim 11 , wherein the transfer member comprises a belt-shaped member configured to circulate in the sub scanning direction.

15. The image forming apparatus according to claim 11 , wherein the correcting unit is configured to develop the correction value for each of the multiple divided areas according to the characteristic, and

wherein the correcting unit is configured to develop the correction value developed for each of the multiple divided areas in the main scanning direction by an interpolation method.

16. A non-transitory computer readable medium storing a program that, if executed, causes a computer to execute image processing, the image processing comprising:

receiving, by a receiver, values comprising:

a first read value indicating a result of reading a first color by a reader from a recording medium in which the first color is applied to a first area in which in-plane density unevenness is confirmable within the recording medium,

wherein the reader comprises at least one sensor; and

a second read value indicating a result of reading a second color by the reader, the second color being different from the first color and being applied to a second area that is substantially the same as the first area in a superimposed manner; and

correcting in-plane density unevenness of the second color applied to the first color in the superimposed manner using the first read value received by the receiver and the second read value received by the receiver.