|Budget Amount *help
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2002: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2001: ¥1,800,000 (Direct Cost: ¥1,800,000)
1. Digital watermarking in hard copy images using image generation function
A digital image printed as a binary halftone image can have an optical watermark, which becomes visible only if the associated halftone image is superimposed on it. Such pair of images can be generated using different halftone cells on each image for a watermark dot. To make the watermark invisible on either image, a halftone cell should be randomly selected from those available for representing each level. This randomness, however, results in noisy appearance of the generated halftone images. In this research, to reduce the degradation of halftone quality those cells used for each level are limited to two, one of which is selected randomly. A set of two cells for each level which yields less noisy halftone quality has been obtained through computer simulation.
2. Fundamental study on information distribution using iteration function system
An image can be generated using fractal transformation based on local iteration function system. In this research, property of information distribution in the image, location and amount, in the iteration of the transformation has been analyzed theoretically. Computer simulation showed the validity of the theoretical analysis.
3. Fast image block matching for fractal image transform
An image block matching algorithm that uses a sum of square errors between blocks as an evaluation function can be accelerated by the indirect judgment scheme. In this research, this scheme is applied on the sequential similarity detection algorithm (SSDA), which is known as a fast block matching algorithm, to perform the faster block matching. By computer simulation the acceleration effect of indirect judgment has been evaluated in detail. Then, the conditions for achieving time reduction from the original SSDA scheme are derived. Also, the amount of operations for the preprocessing required in the proposed scheme was estimated theoretically.