Rotation processing method of image and system therefor

A system for rotating image data by an arbitrary angle on orthogonal coordinates of image elements having image processing means, storage means connected to the image processing means for storing data and output means, the image processing means comprising:

• means for dividing the image data into a plurality of data blocks;
• means for oblique-axis transforming each image data of said divided data blocks in each axis direction of the orthogonal coordinates, positions of each image data on the orthogonal coordinates being shifted by amounts corresponding to the arbitrary angle;
• and
• means for storing error data between said amounts shifted by said transforming means and oblique axis to be transformed by said transforming means.

A system for rotating an image data region by an angle .theta. on orthogonal coordinates (x,y), said system having image processing means, image storing means for storing image data in a matrix corresponding to the orthogonal coordinates (x,y), input means, and raster-type display means, the image processing means comprising:

• means for dividing the image data region into a plurality of rectangular data regions;
• means for oblique-axis transforming each image data position of said rectangular data regions in two axis directions of the orthogonal coordinates (x,y), one of said two axis directions corresponding to a raster direction of the raster-type display means;
• and
• means for storing error data between a shift amount to each image data position shifted by said transforming means and an oblique axis to be transformed by said transforming means at a dividing point of said rectangular data regions.