Image processing apparatus and image processing method

An image processing method for converting inputted image data having low resolution to image data having high resolution and performing a process for increasing the number of pixels of the inputted image data, comprising the steps of:

• detecting a maximum pixel value and a minimum pixel value of the image data having a low resolution in a block of interest;
• determining an interpolation value of an interpolation point by using a function depending upon spatial distances between the interpolation point and positions of a pixels of the image data having the low resolution in the neighborhood of the interpolation pixel;
• calculating a difference value between the interpolation value and a reference value obtained from the maximum pixel value and the minimum pixel value;
• calculating a contrast value on the basis of the maximum pixel value and the minimum pixel value;
• and
• determining an output value at the interpolation point on the basis of a relationship between the difference value and the contrast value.

An image processing apparatus for converting inputted image data having low resolution and increasing the number of pixels of the inputted image data, comprising:

• interpolation means for determining an interpolation value C(k) of an interpolation point k by using a function depending upon spatial distances between the interpolation point and positions of pixels of the image data having low resolution in the neighborhood of the interpolation point k;
• detection means for detecting m (m.gtoreq.1) pixels (note that a pixel value of a pixel at an observation point n included in the m pixels is P(n)) from pixels neighboring the interpolation point k;
• and
• calculation means for calculating an output value h(k) at the interpolation point k, by calculating ##EQU9## where .alpha.(n) and .beta. are arbitrary coefficients, and ##EQU10## and .beta..noteq.0.

An image processing method for converting inputted image data having low resolution and increasing the number of pixels of the inputted image data, comprising the steps of:

• determining an interpolation value C(k) of an interpolation point k by using a function depending upon spatial distances between the interpolation point k and positions of pixels of the image data having low resolution in the neighborhood of the interpolation point k;
• detecting m (m.gtoreq.1) pixels (note that a pixel value of a pixel at an observation point n included in the m pixels is P(n)) from pixels neighboring the interpolation point k;
• and
• calculating an output pixel value h(k) at the interpolation point k, by calculating ##EQU12## where .alpha.(n) and .beta. are arbitrary coefficients, and ##EQU13## and .beta..noteq.0.