Image processing device, control method, and non-transitory recording medium
An image processing device includes an image reader that reads an image, a first determiner that determines whether character crushing occurs when the image is binarized, a second determiner that determines a rate of a photographic region in the image, and a controller that performs conversion into monochrome N-gradation image data based on determination results of the first and second determiners.
1. An image processing device comprising:
an image reader that reads an image;
a first determiner that determines whether character crushing occurs when the image is binarized;
a second determiner that determines a rate of a photographic region in the image; and
a controller that performs conversion into monochrome N-gradation image data based on determination results of the first and second determiners.
2. The image processing device according to claim 1 , wherein the controller converts the image data into monochrome two-gradation image data when the first determiner determines that character crushing does not occur.
3. The image processing device according to claim 1 , wherein the controller
converts the image into monochrome N-gradation image data when the rate of the photographic region in the image is equal to or greater than a threshold value, and
converts the image into monochrome M-gradation image data when the rate of the photographic region in the image is less than the threshold value, M being larger than 2 and smaller than N.
4. The image processing device according to claim 3 , wherein the controller changes the threshold value by a user operation.
5. The image processing device according to claim 3 , wherein the controller converts the image into monochrome N-gradation image data or monochrome M-gradation image data only when the first determiner determines that character crushing occurs.
6. The image processing device according to claim 3 , wherein
the N gradations represents each pixel with 8 bits when the image is quantized, and
the M gradations represents each pixel with 2 to 7 bits when the image is quantized.
7. The image processing device according to claim 1 , further comprising:
a third determiner that determines whether a pseudo contour is to be generated when predetermined image processing is executed on the image, wherein
as a result of the predetermined image processing performed on the image, the controller
converts the image into monochrome N-gradation image data when the pseudo contour is generated, and
converts the image into monochrome M-gradation image data when the pseudo contour is not generated, M being larger than 2 and smaller than N.
8. The image processing device according to claim 7 , wherein the controller converts the image into monochrome N-gradation image data or monochrome M-gradation image data only when the first determiner determines that character crushing occurs.
9. The image processing device according to claim 7 , wherein
the N gradations represents each pixel with 8 bits when the image is quantized, and
the M gradations represents each pixel with 2 to 7 bits when the image is quantized.
10. A control method comprising:
reading an image;
determining whether character crushing occurs when the image is binarized;
determining a rate of a photographic region in the image; and
performing conversion into monochrome N-gradation image data based on determination results of the determinations.
11. A non-transitory computer readable recording medium recording a program that causes a computer to execute:
reading an image;
determining whether character crushing occurs when the image is binarized;
determining a rate of a photographic region in the image; and
performing conversion into monochrome N-gradation image data based on determination results of the determinations.