Image processing method and apparatus, and image display method and apparatus, with variable interpolation spacing

A method of processing an input image to obtain an output image, the input image being formed from input pixels having brightness levels, the method comprising the steps of:

• detecting pixel-to-pixel variations in the brightness levels in at least one direction in the input image, thereby generating high spatial frequency information;
• setting interpolation points with spacing varying according to the high spatial frequency information;
• generating output pixels from the input pixels by interpolation at the interpolation points;
• wherein said detecting includes calculating a first derivative of the brightness levels in said one direction;
• performing two low-pass spatial filtering operations, with different cut-off frequencies, to obtain two low spatial frequency components of the image;
• and
• taking a difference between said two low spatial frequency components.