Data managing device in image variable magnification processing apparatus

The data managing device in an image variable magnification processing apparatus, comprising:

• variable magnification processing means for enlarging or reducing an image composed of a plurality of pixels by overlapping or thinning the pixels;
• first processing means provided in a preceding stage of said variable magnification processing means for taking the pixels composing the image before variable magnification processing as object pixels in order and subjecting each of the object pixels to first processing on the basis of first processing data related to a predetermined pixel in the vicinity of the object pixel;
• second processing means provided in a succeeding stage of said variable magnification processing means for taking the pixels composing the image after the variable magnification processing as object pixels in order and subjecting each of the object pixels to second processing on the basis of second processing data related to a predetermined pixel in the vicinity of the object pixel;
• temporary storing means for temporarily storing the first processing data and said second processing data;
• and
• data managing means for writing or reading out the first processing data required to process the object pixel in said first processing means and the second processing data required to process the object pixel in said second processing means to and from the same address in said temporary storing means at access timing which is synchronized with the overlapping or thinning of the pixels by said variable magnification processing means, wherein
• said first processing means is area separating means for taking pixels composing an image, in which a character image and a halftone image are present as a mixture, as object pixels in order and judging which of the character area and the halftone area is an area to which the object pixel belongs in consideration of BF data indicating which of the character area and the halftone area is an area to which a predetermined pixel in the vicinity of the object pixel belongs,
• the first processing data is the BF data,
• said second processing means is an error diffusing means for adding, if pixels represented by multi-valued density data are identified as black or white pixels in order, produced error data distributed from a plurality of predetermined pixels in the vicinity of each of the object pixels to be identified as black or white pixels to density data representing the object pixel and comparing the result of the addition with a predetermined binary-coding threshold value, thereby to binary-code the object pixel, and
• the second processing data is the produced error data, and wherein
• said BF data have a first number of bits,
• said produced error data have a second number of bits, different from said first number, and
• said data managing means includes data generating means which receives said BF data and said produced error data and mixes said BF data and said produced error data to generate output data having a third number of bits, different from either said first number or said second number.