Abstract: In the present invention statistical methods are used to estimate the reflectance of the paper and align the tone gamut to the dynamic range of a digital input device such as a scanner during a single scan. The estimate is refined during the scan. This refinement increases the robustness with respect to unfavorable originals (e.g., originals with a dark border) and at the same time also can take into account such phenomena as the change of the response of the sensor due to thermal effect during slow scans. In the present invention no spatial information on the image is collected. Instead a histogram of the occurrence of each tone level is accumulated during the scan. The background color of the image, i.e., the tone value of the paper is estimated by analyzing the histogram. When this value is known, the parameters for a tone reproduction curve (TRC) can be calculated. The shape of the TRC is not altered by these parameters, i.e., the exposure can be controlled independently of the tone reproduction.

Abstract: A quantizer for quantizing scanned DCT coefficients in a video encoder is disclosed.

Abstract: An image compression device comprises an image smoothing device which produces a smooth image by performing a smoothing process on an original image, an edge detection device which produces an edge image by subtracting said smoothed image from said original image, a fractal encoding device which encodes said smoothed image by fractal image compression, a reversible encoding device which encodes said edge image by reversible image compression, and an output device which combines the output of said fractal encoding means and the output of said reversible encoding means, and outputs said data as compressed data of the original image.

Abstract: A method and apparatus using the discrete cosine transform (DCT) to resize an image. To reduce an image, the method and apparatus exploits the convolution-multiplication property of the DCT to implement the anti-aliasing filter in the DCT domain, then the filtered coefficients are operated on to produce DCT coefficients of the reduced-size image. To increase an image, the DCT coefficients of the original image are operated on to produce coefficients of the larger image, then the convolution-multiplication property of the DCT is used to implement an anti-imaging filter. These DCT operations can be applied to the image as a whole or can be applied to non-overlapping blocks of the image.