1. A wavelet transformation-based image encoder comprising: an image tiling unit for dividing the original image into a predetermined number images; a wavelet transformation unit for: determining the number of the wavelet transformation for each of the divided images, performing an wavelet transformation for each of the divided images according to a known number; and outputting the wavelet transformed data; an extractor for receiving the wavelet transformed data for each of the divided images and extracting only specific wavelet transformed data for each of the divided images; a range mapping unit for performing range mapping of color values of each pixel included in each of the specific extracted wavelet transformed data; and an assembling unit for: receiving the range-mapped, wavelet transformed data; and reconstructing the data to generate a thumbnail image corresponding to the original image.