Patent ID: 7630574
Filing Date: 2009-12-08
Classification: H04N

Abstract:
1. An image encoding apparatus, comprising: a processor, said processor encoding image data of an original image by performing steps comprising: transforming a color component to a spatial frequency area; a color transformation processing for changing at least one of color representing values of colors belonging to two clusters corresponding to two areas represented in a color space to a color representing value in a direction of separating the two clusters; and compressing an amount of information of image data by an entropy compression method, wherein, in the color transformation processing, a color representing value of each pixel is judged as being corresponding to white when the color representing value of each pixel is equal to or more than a previously set density, and a color representing value of a pixel corresponding to white is changed to an inverse direction for the direction of black, on the basis of a value obtained by multiplying a constant coefficient by a difference between a minimum density value and a maximum density value of an image on the color transformation processing, wherein when the original image is compared with an image reproduced by performing inverse transformation of the encoded image and a color difference between both images is equal to or more than a predetermined color difference, the constant coefficient is changed until the color difference between both images fits in an extent of the predetermined color difference, and wherein a warning is given to a user when the color difference between the reproduced image and the original image does not fall in the extent of the predetermined color difference in spite of changing the constant coefficient a predetermined number of times.