A computer readable medium comprising a program for forming a composite image obtained by combining a two-dimensional code image and an arbitrary image, wherein the program comprises:
- a program code for generating an image storage which stores a two-dimensional code image and arbitrary n (n≧5)-gradation image therein;
- a program code for generating a first converted image forming unit that forms a n-gradation two-dimensional code image obtained by converting the two-dimensional code image stored in the image storage to the same image format as that of the arbitrary image;
- a program code for generating a display unit which displays the n-gradation two-dimensional code image produced in the first converted image forming unit and the arbitrary image stored in the image storage on a display in an overlapping manner;
- a program code for generating a moving unit which moves at least one of the n-gradation two-dimensional code image and the arbitrary image displayed on the display in the overlapping manner relative to the other thereof based upon input information from an input unit;
- a program code for generating a position information acquiring unit which acquires position information regarding the n-gradation two-dimensional code image and the arbitrary image after the movement has been performed by the moving unit;
- a program code for generating a second converted image forming unit which forms a converted two-dimensional code image and converted arbitrary image obtained by converting gradations of respective pixels of an overlapping portion of the n-gradation two-dimensional code image and the arbitrary image with each other to predetermined gradations based upon the position information acquired by the position information acquiring unit, and color and gradation information for respective pixels of the n-gradation two-dimensional code image and the arbitrary image;
- and
- a program code for generating a composition image forming unit which forms a composite image obtained by combining the converted two-dimensional code image and the converted arbitrary image obtained in the second converted image forming unit by overlay based upon the position information obtained in the position information acquiring unit, wherein
- the second converted image forming unit,
- regarding at least five divided regions of a first region, a second region, a third region including a central value of the n gradations, a fourth region, and a fifth region obtained by preliminarily dividing the n gradations of a shadow side to a highlight side, converts gradations of the respective pixels of an overlapping portion of the arbitrary image with the n-gradation two-dimensional code image to gradations within the shadow side except for the first and third regions when corresponding pixels of the n-gradation two-dimensional code image in the overlapping portion thereof are positioned on the shadow side, and converts the gradations of the respective pixels to gradations within the highlight side except for the third and fifth regions when the corresponding pixels of the n-gradation two-dimensional code image in the overlapping portion thereof are positioned on the highlight side;
- and
- converts gradations of respective pixels of a overlapping portion of the n-gradation two-dimensional code image with the arbitrary image to gradations within the shadow side except for the first and third regions of the at least five divided regions when the pixels are positioned in the shadow side, and converts the gradations of the respective pixels to gradations within the highlight side except for the third and fifth regions when the pixels are positioned on the highlight side.