Image compression device and image compression method for compressing images by smoothing them, reversibly compressing the residual images and compressing the smoothed images based on fractal theory

An image compression device comprising:

• image smoothing means for producing a smooth image by performing a smoothing process on an original image;
• edge detection means for producing an edge image by subtracting said smoothed image from said original image;
• corrected edge image generating means for detecting minute edge images comprising pixels having density values smaller than a predetermined threshold value relative to the density value of each pixel of the edge image, and generating a corrected edge image by erasing said minute edge images from the edge image;
• corrected smooth image generating means for generating a corrected smooth image by adding said minute edge images to the smoothed image;
• fractal encoding means for encoding said corrected smoothed image by fractal image compression;
• reversible encoding means for encoding said corrected edge image by reversible image compression;
• and
• output means for combining the output of said fractal encoding means and the output of said reversible encoding means, and outputting said data as compressed data of the original image.

An image compression method comprising the steps of:

• producing a smoothed image by performing a smoothing process on an original image;
• producing an edge image by subtracting said smoothed image from the original image;
• encoding said smoothed image by fractal image compression;
• encoding said edge image by reversible image compression;
• combining the output of said fractal encoding step and the output of said reversible encoding step;
• and
• outputting said data as compressed data of said original image.

An image compression method comprising the steps of:

• producing a smoothed image by performing a smoothing process on an original image;
• producing an edge image by subtracting said smoothed image from the original image;
• detecting minute edge images comprising pixels having density values smaller than a predetermined threshold value relative to the density value of each pixel of the edge image;
• generating a corrected edge image by erasing said minute edge images from the edge image;
• generating a corrected smooth image by adding said minute edge images to the smoothed image;
• encoding said corrected smooth image by fractal image compression;
• encoding said corrected edge image by reversible image compression;
• combining the output of said fractal encoding step and the output of said reversible encoding step;
• and
• outputting said data as compressed data of said original image.