In an image processing method, a square submatrix formed from adjacent original
pixels is equally divided into small square regions along the X- and Y-coordinate
axes. Approximate points are set at the vertexes of the regions. Interpolation
coefficients are derived based on a predetermined interpolation function. Interpolation
coefficients normalized so as to adjust the sum of the coefficient values of interpolation
coefficients used for one interpolation operation to 2k (k is a positive
integer) are calculated, and stored in a coefficient buffer in advance. A new pixel
position of each pixel constituting a new image is calculated in accordance with
magnifications representing enlargement/reduction ratios along the X- and Y-coordinate
axes for an original image. An approximate point closest to the new pixel position
is selected as the approximate point of the new pixel position. Interpolation coefficients
corresponding to the interpolation original pixels are read out from the coefficient
buffer. Interpolation operation is performed by product-sum operation, thereby
calculating a pixel value at the approximate point. The calculated pixel value
is divided by 2k to output a pixel value at the new pixel position.
An image processing apparatus is also disclosed.
