Patent ID: 8121441

Claim:
An image processing apparatus arranged to acquire a rotated image by performing a process of rotating a raster image, which corresponds to an original image, comprising: an integer parameter input unit to which a first integer parameter and a second integer parameter having a ratio value that is equal to a tangent value of a rotation angle are input; an original image corresponding position calculating unit arranged to perform: a process of adding the first integer parameter to a y-direction weighting factor each time an x-coordinate of a target pixel of the rotated image is changed by prescribed pixels; processes of subtracting the second integer parameter from the y-direction weighting factor and changing by prescribed pixels a y-coordinate of a corresponding target pixel, which corresponds to the target pixel in the original image, when the y-direction weighting factor becomes more than or equal to the second integer parameter; a process of adding the first integer parameter to an x-direction weighting factor each time a y-coordinate of the target pixel of the rotated image is changed by prescribed pixels; and processes of subtracting the second integer parameter from the x-direction weighting factor and changing by prescribed pixels an x-coordinate of the corresponding target pixel of the original image when the x-direction weighting factor becomes more than or equal to the second integer parameter; and a two-dimensional interpolation unit arranged to use the corresponding target pixel of the original image and three pixels each having at least one of the x-coordinate and the y-coordinate that are different by prescribed pixels from the corresponding target pixel, so as to acquire a pixel value of the target pixel of the rotated image by performing two-dimensional interpolation by a ratio acquired by dividing the x-direction weighting factor by the second integer parameter and a ratio acquired by dividing the y-direction weighting factor by the second integer parameter.