Patent ID: 6101273
Filing Date: 2000-08-08
Classification: H04N

Abstract:
An image reproducing method, wherein a visible image is reproduced from an image signal representing a color image, the method comprising the steps of:i) forming a histogram of the image signal,ii) calculating a dynamic range of the image signal in accordance with the histogram,iii) setting a rate of dynamic range compression corresponding to a region of the image signal, in which a signal value is comparatively large, a region of the image signal, in which a signal value is comparatively small, and/or an entire region of the image signal, the rate of dynamic range compression being set in accordance with the dynamic range and by taking a predetermined reference level of the image signal as a reference,iv) carrying out a dynamic range compressing process on the image signal with the rate of dynamic range compression set in said step (iii),v) carrying out gradation processing on an image signal, which has been obtained from the dynamic range compressing process, a processed image signal being obtained from the gradation processing, andvi) reproducing a visible image from the processed image signal without an image artifact,wherein the image signal is converted into a luminance signal, an unsharp image signal, which represents an unsharp image of the image represented by the luminance signal is formed, and the calculation of the dynamic range, the setting of the rate of dynamic range compression, and said dynamic range compressing process are carried out in accordance with the unsharp image signal,wherein said dynamic range compressing process is carried out only when the dynamic range is larger than a predetermined threshold value.