1. An image composing apparatus for connecting a reference image and an image to compose which are digital images each of which is a different portion of a composite image, with end portions of the digital images having an overlap region in which the image to compose overlaps the reference image for a predetermined width, comprising: reference block setting means for (i) setting a search area in the reference image within the overlap region, (ii) for setting in the search area a first reference block at a portion having an appropriate dispersion value of pixel values existing in said first reference block, said dispersion value being independent of the image to compose and based only on the reference image, and (iii) for setting a second reference block at a portion of the reference image different from said first reference block in said overlap region and having an appropriate dispersion value which is independent of the image to compose and is based only on the reference image; means for identifying corresponding pixels in the image to compose which correspond, respectively, to respective predetermined pixels in the first and second reference blocks; displacement amount detection means for detecting a displacement amount from said each predetermined pixel in each of the first and second reference blocks set by said reference block setting means, to a position of its said respective corresponding pixel in the image to compose when the reference image and image to compose are composed with each other; interpolation means for interpolating pixels in said image to compose on the basis of the displacement amount detected by said displacement amount detection means to obtain an interpolated image to compose such that an object in the reference image within said overlap region coincides with the same object in the image to compose within said overlap region; and image composing means to derive the composite image by connecting said reference image with said interpolated image to compose.