Image processing apparatus that identifies character pixel in target image using first and second candidate character pixels

Patent metadata

Field	Value
Publication number	US-10423854-B2
Application number	US-201816136422-A
Country	US
Kind code	B2
Filing date	Sep 20, 2018
Priority date	Sep 20, 2017
Publication date	Sep 24, 2019
Grant date	Sep 24, 2019

Abstract

In an image processing apparatus, a controller is configured to perform: acquiring target image data representing a target image including a plurality of pixels; determining a plurality of first candidate character pixels from among the plurality of pixels, determination of the plurality of first candidate character pixels being made for each of the plurality of pixels; setting a plurality of object regions in the target image; determining a plurality of second candidate character pixels from among the plurality of pixels, determination of the plurality of second candidate character pixels being made for each of the plurality of object regions according to a first determination condition; and identifying a character pixel from among the plurality of pixels, the character pixel being included in both the plurality of first candidate character pixels and the plurality of second candidate character pixels.

First claim

What is claimed is:

1. An image processing apparatus comprising a controller configured to perform:
(a) acquiring target image data representing a target image, the target image including a plurality of pixels;
(b) determining a plurality of first candidate character pixels from among the plurality of pixels, each of the plurality of first candidate character pixels being a candidate to be a character pixel, determination of the plurality of first candidate character pixels being made for each of the plurality of pixels;
(c) setting a plurality of object regions in the target image, each of the plurality of object regions including a plurality of object pixels;
(d) determining a plurality of second candidate character pixels from among the plurality of pixels, each of the plurality of second candidate character pixels being a candidate to be the character pixel, determination of the plurality of second candidate character pixels being made for each of the plurality of object regions according to a first determination condition; and
(e) identifying the character pixel from among the plurality of pixels, the character pixel being included in both the plurality of first candidate character pixels and the plurality of second candidate character pixels.

2. The image processing apparatus according to claim 1 , wherein the (d) determining comprises:
(d1) specifying a non-character region from among the plurality of object regions, the non-character region satisfying the first determination condition and including a plurality of specific object pixels; and
(d2) determining the plurality of second candidate character pixels other than the plurality of specific pixels from among the plurality of pixels.

3. The image processing apparatus according to claim 1 , wherein the controller is configured to further perform (f) executing a pre-process on the target image data to generate pre-processed image data representing a pre-processed image, the pre-process including an expansion process, the expansion process expanding an edge in the target image, and
wherein the (c) setting sets the plurality of object regions in the pre-processed image.

4. The image processing apparatus according to claim 3 , wherein the pre-process further includes a contraction process, the contraction process being performed after the expansion process and contracting the expanded edge.

5. The image processing apparatus according to claim 4 , wherein in the pre-process, degree of contraction in the contraction process is greater than degree of expansion in the expansion process.

6. The image processing apparatus according to claim 5 , wherein in the pre-process, the expansion process includes a first number of unit expansion processes, and the contraction process includes a second number of unit expansion processes, the second number being greater than the first number.

7. The image processing apparatus according to claim 3 , wherein each of the plurality of object regions is configured of a plurality of specific object pixels, the plurality of specific object pixels being contiguously arranged in the pre-processed image, each of the plurality of specific object pixels satisfying a second determination condition.

8. The image processing apparatus according to claim 2 , wherein the (d1) specifying comprises:
(d11) setting a determination region for each of the plurality of object regions; and
(d12) calculating an occupancy ratio of a pixel number in the each of the plurality of object regions to a pixel number in the determination region, and wherein the first determination condition includes a condition that the occupancy ratio be greater than or equal to a reference ratio.

9. The image processing apparatus according to claim 2 , wherein the (d1) specifying comprises (d13) calculating a pixel number in the each of the plurality of object regions, and
wherein the first determination condition includes a condition that the pixel number be greater than or equal to a reference number.

10. The image processing apparatus according to claim 3 , wherein the target image data includes a plurality of color values corresponding to respective ones of the plurality of pixels, each of the plurality of color values having a plurality of component values, and
wherein the (f) executing comprises:
(f1) generating at least one of first component data and second component data, the first component data including a plurality of first pixel values corresponding to respective ones of the plurality of pixels, each of the plurality of first pixel values being related to a maximum value among the plurality of component values of corresponding one of the plurality of pixels, the second component data including a plurality of second pixel values corresponding to respective ones of the plurality of pixels, each of the plurality of second pixel values being related to a minimum value among the plurality of component values of corresponding one of the plurality of pixels;
(f2) generating intermediate image data using the at least one of the first component data and the second component data; and
(f3) executing the pre-process on the intermediate image data to generate the pre-processed image data.

11. The image processing apparatus according to claim 1 , wherein the plurality of pixels includes the character pixel and a non-character pixel different from the character pixel, the character pixel having a character pixel value in the target image data, the non-character pixel having a non-character pixel value in the target image data, and
wherein the controller is configured to further perform (g) executing a first image process on the character pixel value and a second image process on the non-character pixel value to generate processed target image data, the first process being different from the second process.

12. The image processing apparatus according to claim 11 , wherein the controller is configured to further perform (h) generating print data using the processed target image data.

13. The image processing apparatus according to claim 1 , wherein the plurality of object pixels has respective ones of a plurality of object pixel values and is positioned at respective ones of a plurality of object pixel positions, and
wherein in the (d) determining, the determination for the each of the plurality of object regions is made using the plurality of object pixel values and the plurality of object pixel positions.

14. The image processing apparatus according to claim 13 , wherein the (d) determining comprises:
(d3) calculating a character probability for the each of the plurality of object regions using the plurality of object pixel values and the plurality of object pixel positions;
(d4) specifying a character region from among the plurality of object regions, the character region having the character probability greater than or equal to a probability threshold and including a plurality of specific object pixels; and
(d5) determining the plurality of specific object pixels as the plurality of second candidate character pixels.

15. The image processing apparatus according to claim 13 , wherein the (d) determining comprises:
(d6) specifying a character region from among the plurality of object regions, the character region satisfying the first determination condition and including a plurality of specific object pixels; and
(d7) determining the plurality of specific object pixels as the plurality of second candidate character pixels.

16. The image processing apparatus according to claim 15 , wherein the (d 6 ) specifying comprises:
(d8) determin

Assignees

• Brother Ind Ltd

Inventors

• Yamada Ryuji

Classifications

• G06V30/18076

  by analysing connectivity, e.g. edge linking, connected component analysis or slices · CPC title

• G06V30/162 Primary

  Quantising the image signal · CPC title

• G06V30/10

  Character recognition · CPC title

• H04N1/40062

  Discrimination between different image types, e.g. two-tone, continuous tone · CPC title

• H04N1/4092

  Edge or detail enhancement · CPC title