JP2018151681A5 - - Google Patents

Claims (19)

An area setting unit configured to set a plurality of determination areas including the pixel of interest and pixels adjacent to the pixel of interest for the pixel of interest in the input image;
Color determination means for determining whether each of the determination areas set by the area setting means is a uniform uniform color area;
A correction unit that reduces noise of the input image by performing correction processing according to the determination result of the color determination unit on the pixel of interest;
An image processing apparatus comprising:   The correction means may execute the correction process according to the number of pixels included in a union of areas determined to be the same color area by the color determination means among the areas included in the plurality of determination areas. The image processing apparatus according to claim 1, characterized in that   The image processing apparatus according to claim 1, wherein the plurality of determination areas include determination areas having different numbers of pixels.   The image processing apparatus according to any one of claims 1 to 3, wherein the plurality of determination areas include determination areas having different shapes.   The plurality of determination areas include a set area including a plurality of sub areas, the shape of each sub area is directional, and it is isotropic when all the sub areas included in the set area are combined. The image processing apparatus according to any one of claims 1 to 4, wherein Each subregion included in the set region has the same number of pixels,
The plurality of determination areas include a plurality of set areas having different numbers of pixels,
The image processing apparatus according to claim 5, wherein The correction unit executes a correction process according to the determination result of the color determination unit when the pixel of interest is a chromatic color pixel and is not a pixel forming a flat area.
When the target pixel is at least an achromatic pixel or a pixel constituting a flat area, the correction processing is performed without referring to the determination result of the color determination unit.
The image processing apparatus according to any one of claims 1 to 6, characterized in that: The image processing apparatus further comprises reference area setting means for setting a reference area for determining a pixel to be used for the correction process for the pixel of interest,
The correction means executes the correction process with reference to pixels included in the reference area.
The image processing apparatus according to claim 2, characterized in that:   The reference area setting unit may set the target area according to the number of pixels included in the union in the case where the target pixel is a pixel whose chromatic target is the target pixel and does not constitute a flat area. The image processing apparatus according to claim 8, wherein a reference area is set.   The reference area setting means determines a preset isotropic area as the reference area when the number of pixels included in the union is less than a predetermined threshold, and is included in the union. 10. The image processing apparatus according to claim 9, wherein the union is determined as the reference area when the number of pixels is equal to or greater than a predetermined threshold.   The image according to any one of claims 1 to 10, wherein the correction process is a process of averaging the pixel values of the target pixel and the pixel values of pixels around the target pixel. Processing unit.   The said correction means determines whether it is used for the said correction process about each pixel contained in the said reference area based on a substitute pixel value, It is described in any one of the Claims 8 thru | or 10 characterized by the above-mentioned. Image processing device.   The correction means is a weighted average value of the pixel value of the pixel of interest and the pixel values of peripheral pixels surrounding the pixel of interest when the pixel of interest constitutes a flat part or the color of the pixel of interest is achromatic The image processing apparatus according to claim 12, wherein the substitute pixel value is set as the substitute pixel value. The apparatus further comprises edge direction determination means for determining the edge direction of the target pixel,
The correction means is adjacent to the pixel direction of the pixel of interest and the edge direction determined by the edge direction determination means when the pixel of interest is not a pixel constituting a flat part and the color of the pixel of interest is not achromatic. Setting a weighted average value with the pixel value of the target pixel as the alternative pixel value
The image processing apparatus according to claim 13, characterized in that:   The image processing apparatus according to claim 10, wherein the reference area setting unit uses a threshold set according to the noise amount of the input image as the predetermined threshold.   The color determination unit performs the determination using an evaluation value indicating uniformity of color, which is calculated based on a difference between the target pixel and each pixel forming the determination region. The image processing apparatus according to any one of claims 1 to 15. The evaluation value is represented by the following formula (1) or (2):

In the equations (1) and (2), N represents the number of pixels forming the determination area, xi represents the pixel value of each pixel forming the determination area, u represents the pixel value of the target pixel,
The image processing apparatus according to claim 16, characterized in that: An area setting step of setting a plurality of judgment areas including the target pixel and pixels adjacent to the target pixel for the target pixel in the input image;
A color determination step of determining whether each of the determination regions set in the region setting step is a uniform uniform color region;
A correction step of reducing noise of the input image by executing a correction process according to the determination result in the color determination step on the target pixel;
An image processing method comprising:   A program for causing a computer to function as the image processing apparatus according to any one of claims 1 to 17.