JPS6423679A - Image input device - Google Patents

Abstract

PURPOSE:To prevent the change of a density from an original image and a rough image by changing the sub-scanning directional matrix of a dither pattern to an enlargement, a magnification, a reduction, etc., for each one line of a main-scanning direction effective to the sub-scanning direction to the rotation of a roller. CONSTITUTION:When an image is converted to an electric signal by a CCD 25, a roller to rotate relatively to the image, an encoder to detect the quantity of this roller rotation, a sub-scan detecting circuit 112 to judge the effectiveness of main-scanning directional image data through the output signal from this encoder and a decoder circuit 103 to output the matrix of the dithered pattern to express the intermediate color tone of the image are equipped. When the effectiveness of sub-scanning directional image data and the change of the dithered pattern are obtained, the dithered pattern is changed one by one toward the line effective to the sub-scanning direction regardless of the enlargement or the reduction. When an outputted image is referred to, it means that even a half time reduction or an equal magnification is only the change of the size but is similarly faithful to the inputting image. Thus, the density of the outputted image remains unchanged and an unusual roughness does not occur.