Image scaling processor and image scaling processing method

An image scaling processor that performs an image scaling process of interpolating pixels of input image data and converting the input image data to U/D times (U and D are natural numbers) as output image data, the processor comprising:

• a coefficient computing circuit that calculates interpolation coefficients to be used in said image scaling process;
• a multiplier that multiplies said input image data by said interpolation coefficients provided from said coefficient computing circuit such that said interpolation coefficients respectively correspond to input pixels constituting said input image data;
• an adder that iteratively adds pieces of multiplied data output from said multiplier and obtains a total sum of said pieces of multiplied data for a predetermined number of said input pixels;
• a selector that outputs a total sum of said pieces of multiplied data at a timing at which the total sum of said pieces of multiplied data is obtained for the predetermined number of said input pixels;
• and
• a shift circuit that shifts an output of said selector to adjust a bit count of said output image data to a bit count of said input image data, wherein
• said coefficient computing circuit includes:
• a coordinate computing circuit that calculates a coordinate of an interpolation point of a pixel to be interpolated for said input image data;
• and
• a plurality of coefficient computing circuits that respectively output interpolation coefficients corresponding to said predetermined number of said input pixels,
• one of said plurality of coefficient computing circuits subtracts a sum of said interpolation coefficients calculated by the other coefficient computing circuits from a value of 2 raised by a predetermined number to calculate the other interpolation coefficient, and
• said interpolation coefficients calculated by said coefficient computing circuit are converted into integers such that a total sum thereof is equal to 2 raised by said predetermined number.