Image processing apparatus and image processing method
View Patent ↗An image processing apparatus for scaling an image including: an operation position determining section for determining a pixel operation position, which is either a pixel inserting or deleting position, based on a scaling ratio; an inserting/deleting section for inserting/deleting a pixel to/from the pixel operation position determined by the operation position determining section; an error calculating section for calculating a density difference as an error between densities in a vicinity of the inserted/deleted pixel via the inserting/deleting section, before and after the insertion or deletion; and an error allocating section for allocating the error, calculated by the error calculating section, to the inserted pixel and pixels in a vicinity of the inserted or deleted pixel, so that a pixel value, after allocation, of a pixel of an allocation destination, falls within an allowable range estimated from a pixel value of a pixel near the pixel of allocation destination.
1. An image processing apparatus for scaling an image comprising:
a memory to store data representing the image; and
a processor, which:
determines a pixel operation position which is either a position for inserting or deleting a first pixel in accordance with a scaling ratio;
inserts the first pixel or deletes the first pixel from the pixel operation position;
calculates an error between a value of the first pixel and a first density representing densities of a first set of pixels located in a vicinity of the first pixel; and
allocates the error to a second pixel selected from the first set of pixels, in such a manner that a value of the second pixel falls within an allowable range estimated from values of a second set of pixels near the second pixel.
2. The image processing apparatus of claim 1 , wherein the processor restricts the vicinity to an area adjacent to the first pixel in a direction of scaling.
3. The image processing apparatus of claim 1 , wherein the processor allocates the error to pixels within a predetermined area with respect to the first pixel.
4. The image processing apparatus of claim 1 , wherein the processor:
allocates a first portion of the error to the second pixel;
selects a third pixel from the first set of pixels; and
allocates a second portion of the error to the third pixel.
5. The image processing apparatus of claim 4 , wherein
the second pixel is located at a first distance from the first pixel,
the third pixel is located at a second distance from the first pixel, and
the second distance is greater than the first distance.
6. The image processing apparatus of claim 5 , wherein the first portion of the error is greater than the second portion of the error.
7. The image processing apparatus of claim 1 , wherein the processor estimates the allowable range using an interpolation algorithm.
8. The image processing apparatus of claim 1 , wherein the processor determines a maximum value and a minimum value of the allowable range, based on values of pixels adjacent to the second pixel.
9. A computer-implemented image processing method for scaling an image comprising steps of:
determining a pixel operation position;
inserting or deleting a first pixel at the pixel operation position;
calculating an error between a value of the first pixel and a first density representing densities of a first set of pixels located in a vicinity of the first pixel; and
allocating error to a second pixel selected from the first set of pixels in such a manner that a value, of the second pixel falls within an allowable range estimated from values of a second set of pixels near the second pixel.
10. The computer-implemented image processing method of claim 9 , further including restricting the vicinity to an area adjacent to the first pixel in a direction of scaling.
11. The computer-implemented image processing method of claim 10 , wherein the area is a one-dimensional area.
12. The computer-implemented image processing method of claim 9 , wherein the vicinity comprises a two-dimensional area adjacent to the first pixel.
13. The computer-implemented image processing method of claim 9 , further including allocating the error to pixels within a predetermined area with respect to the first pixel.
14. The computer-implemented image processing method of claim 9 , further including:
allocating a first portion of the error to the second pixel;
selecting a third pixel from the first set of pixels; and
allocating a second portion of the error to the third pixel.
15. The computer-implemented image processing method of claim 14 , wherein
the second pixel is located at a first distance from the first pixel,
the third pixel is located at a second distance from the first pixel, and
the second distance is greater than the first distance.
16. The computer-implemented image processing method of claim 15 , wherein the first portion of the error is greater than the second portion of the error.
17. The computer-implemented image processing method of claim 9 , further including estimating the allowable range using an interpolation algorithm.
18. The computer-implemented image processing method of claim 17 , wherein the interpolation algorithm is a spline interpolation algorithm.
19. The computer-implemented image processing method of claim 9 , further including determining a maximum value and a minimum value of the allowable range based on values of pixels adjacent the second pixel.