Image transforming method and apparatus

An image transforming apparatus, in which a first picture element value of each of picture elements constituting a color image is replaced by a second picture element value that is set to have correspondence to the first picture element value by a predetermined transformation formula, the apparatus comprising:

• a transformation means for obtaining information representing coordinates of vertexes of a plurality of blocks, into which a multi-dimensional color space has been divided in units of a block having a predetermined size, carrying out an operation with the transformation formula with respect to the coordinates of each of the vertexes of each block, and thereby calculating transformed values of the coordinates of vertexes of each block,
• a storage means for storing information representing the transformed values having been calculated by the transformation means, and
• an interpolating operation means for carrying out an interpolating operation with respect to the first picture element value and in accordance with weight factors of the vertexes, which weight factors are determined in accordance with a position of the first picture element value in a block, and the transformed values of the coordinates of the vertexes of the block, which contains the first picture element value, and thereby calculating the second picture element value,
• wherein the apparatus further comprises a generation means operating such that, in cases where a block having a size different from the predetermined size is contained in the plurality of the blocks, said generation means may replace said block having the different size by a virtual block, which has a size identical with the predetermined size, and said generation means may then generate transformed values of coordinates of vertexes of said virtual block from the transformed values of the coordinates of the vertexes of said block having the different size,
• the storage means stores information, which represents a transformed value table, and information, which represents a factor table, said transformed value table recording the transformed values of the coordinates of the vertexes with respect to each of the blocks, including said virtual block, said factor table recording vertexes, which have weight factors other than 0, and the weight factors of the vertexes, which have weight factors other than 0, with respect to each of positions in a block, and
• the interpolating operation means carries out the interpolating operation by utilizing only the vertexes, which have weight factors other than 0, and in accordance with the transformed values, which have been recorded in said transformed value table stored in the storage means, and the vertexes and their weight factors, which have been recorded in said factor table stored in the storage means.

A recording medium, on which a program for causing a computer to execute image transformation processing has been recorded, the image transformation processing being carried out for replacing a first picture element value of each of picture elements, which constitute a color image, by a second picture element value that is set to have correspondence to the first picture element value by a predetermined transformation formula, the image transformation processing comprising:

• a first step for dividing a multi-dimensional color space into a plurality of blocks in units of a block having a predetermined size, carrying out an operation with the transformation formula with respect to coordinates of each of vertexes of each block, and thereby calculating transformed values of the coordinates of vertexes of each block, and
• a second step for carrying out an interpolating operation with respect to the first picture element value and in accordance with weight factors of the vertexes, which weight factors are determined in accordance with a position of the first picture element value in a block, and the transformed values of the coordinates of the vertexes of the block, which contains the first picture element value, and thereby calculating the second picture element value,
• the first picture element value being replaced by the second picture element value, image transformation being thereby carried out,
• wherein the improvement comprises:
• i) in the first step, in cases where a block having a size different from the predetermined size is contained in the plurality of the blocks, replacing said block having the different size by a virtual block, which has a size identical with the predetermined size, transformed values of coordinates of vertexes of said virtual block being then calculated from the transformed values of the coordinates of the vertexes of said block having the different size,
• ii) previously storing information, which represents a transformed value table, and information, which represents a factor table, in a memory, said transformed value table recording the transformed values of the coordinates of the vertexes with respect to each of the blocks, including said virtual block, said factor table recording vertexes, which have weight factors other than 0, and the weight factors of the vertexes, which have weight factors other than 0, with respect to each of positions in a block, and
• iii) in the second step, carrying out the interpolating operation by utilizing only the vertexes, which have weight factors other than 0, and in accordance with the transformed values, which have been recorded in said transformed value table, and the vertexes and their weight factors, which have been recorded in said factor table.