X-ray imaging apparatus and image processing method thereof
An X-ray imaging apparatus includes: an X-ray source configured to irradiate X-rays to an object; an X-ray detector configured to obtain a first X-ray image of the object; a noise-reduced image creator configured to generate a noise-reduced image in which a noise is reduced from the first X-ray image; a noise image creator configured to generate a noise image based on differences between the first X-ray image and the noise-reduced image; an edge image creator configured to generate, from the noise image, an edge image in which edges are enhanced; an output image creator configured to combine the noise-reduced image with the edge image to generate a second X-ray image; and a display configured to display the second X-ray image. By enhancing edges while reducing noise, an image with high definition and high quality may be output and a user can obtain accurate information from the image.
1. An X-ray imaging apparatus comprising:
an X-ray source configured to irradiate X-rays to an object;
an X-ray detector configured to obtain a first X-ray image of the object by detecting the X-rays having passed through the object;
an image processor configured to perform image processing on the first X-ray image, and to create a second X-ray image; and
a display configured to display the second X-ray image,
wherein the image processor is configured to generate a noise-reduced image in which a noise is reduced from the first X-ray image, generate a noise image based on differences between the first X-ray image and the noise-reduced image, generate from the noise image, an edge image in which edges are enhanced, combine the noise-reduced image with the edge image to generate the second X-ray image,
wherein the image processor is further configured to generate the edge image by multiplying a differential image based on a differentiation for the noise image by a standard deviation image based on a standard deviation for the noise image to generate a first edge filter, and rescaling the first edge filter to generate a second edge filter.
2. The X-ray imaging apparatus according to claim 1 ,
wherein the image processor is further configured to separate frequencies of the first X-ray image into low-frequency components and high-frequency components, and to generate a low-frequency image of the first X-ray image corresponding to the low-frequency components and a high-frequency image of the first X-ray image corresponding to the high-frequency components.
3. The X-ray imaging apparatus according to claim 2 , wherein the image processor is further configured to create the noise-reduced image in which noise is reduced from the high-frequency image of the first X-ray image.
4. The X-ray imaging apparatus according to claim 3 , wherein the image processor is further configured to combine the low-frequency image of the first X-ray image, the noise-reduced image, and the edge image to generate the second X-ray image.
5. The X-ray imaging apparatus according to claim 1 , wherein the image processor is further configured to perform the differentiation for the noise image to generate the differential image.
6. The X-ray imaging apparatus according to claim 5 , wherein the image processor is further configured to calculate the standard deviation for the noise image to generate the standard deviation image.
7. The X-ray imaging apparatus according to claim 1 , wherein the image processor further configured to multiply the noise image by the second edge filter to generate the edge image.
8. The X-ray imaging apparatus according to claim 1 , wherein the image processor is further configured to rescale the first edge filter by multiplying each pixel of the first edge filter by a weight value.
9. The X-ray imaging apparatus according to claim 8 , wherein the weight value increases as a linear or non-linear function with respect to an increase of a pixel value of the pixel.
10. The X-ray imaging apparatus according to claim 8 , wherein the weight value ranges from a predetermined value to 1, and
the predetermined value ranges from 0 to 1.
11. An image processing method of an X-ray imaging apparatus, the method comprising:
generating a noise-reduced image in which noise is reduced from a first X-ray image obtained an X-ray detector,
generating a noise image based on differences between the first X-ray image and the noise-reduced image;
generating an edge image in which edges are enhanced from the noise image;
combining the noise-reduced image with the edge image to generate a second X-ray image; and
outputting the second X-ray image on a display
wherein the generating the edge image comprises:
multiplying a differential image based on a differentiation for the noise image by a standard deviation image based on a standard deviation for the noise image to generate a first edge filter; and
rescaling the first edge filter to generate a second edge filter.
12. The image processing method according to claim 11 , further comprising:
separating frequencies of the first X-ray image into low-frequency components and high-frequency components, and
generating a low-frequency image of the first X-ray image corresponding to the low-frequency components and a high-frequency image of the first X-ray image corresponding to the high-frequency components.
13. The image processing method according to claim 12 , wherein the generating the noise-reduced image further comprises:
generating the noise-reduced image in which the noise is reduced from the high-frequency image of the first X-ray image.
14. The image processing method according to claim 13 , wherein the generating the second X-ray image further comprises:
combining the low-frequency image of the first X-ray image, the noise-reduced image, and the edge image.
15. The image processing method according to claim 11 , wherein the generating the edge image further comprises:
performing the differentiation on the noise image; and
generating the differential image based on the performing.
16. The image processing method according to claim 15 , wherein the generating the edge image further comprises:
calculating the standard deviation for the noise image; and
generating the standard deviation image based on the calculating.
17. The image processing method according to claim 11 , wherein the generating the edge image further comprises:
multiplying the noise image by the second edge filter to generate the edge image.
18. The image processing method according to claim 11 , wherein the rescaling further comprises:
multiplying each pixel of the first edge filter by a weight value.
19. The image processing method according to claim 18 , wherein the weight value increases as a linear or non-linear function with respect to an increase in a pixel value of the pixel.
20. The image processing method according to claim 18 , wherein the weight value ranges from a predetermined value to 1, and the predetermined value ranges from 0 to 1.