An image processing apparatus comprising: a controller to generate image data, wherein the controller is configured to perform rasterizing processing and generate for each pixel (aij) a pixel value and an attribute data (Tag(aij)) indicating the attribute of each pixel, wherein the attribute indicated by the attribute data (Tag(aij)) includes text, graphics or photographic image; and an image compression conversion unit to quantize an image having attribute data for each pixel, wherein the image compression conversion unit is configured to extract a region of 8x8 pixels from the image and to extract a region of 2x2 pixels among the 8x8 pixels, and to determine an attribute data (Tag(bij)) of the 2x2 region based on the attribute data (Tag(aij)) of each pixel therein; when the region of 2x2 pixels has an attribute data (Tag(bij)) indicating photographic image, the image compression conversion unit quantizes the 2x2 region by a first block truncation coding method; when the 2x2 region is not a photographic image and when one of the following conditions - is satisfied for the 2x2 region, when there is at least 1 pixel which satisfies THa1 <aij ≤THa3 among 4 pixels aij when all 4 pixels aij satisfy aij≤THa1 when all 4 pixels aij satisfy aij>THa3 when (Max-min)<T (0≤T≤255) is satisfied, wherein Max and min correspond to the maximum and minimum value of the 8x8 region to which the 2x2 region belongs, where THa1 and THa3 are thresholds based on Max and min, and THa1<THa3 and wherein T is a threshold value set to judge whether the density difference in the region is small or not, the region of 2x2 pixels is regarded as a halftone region, the image compression conversion unit quantizes the 2x2 halftone region by a second block truncation coding method having a higher compression rate than the first block truncation coding method; when the 2x2 region is not a photographic image and when there is a pixel which satisfies aij≤THa1 and there is a pixel which satisfies aij>THa3 in the 2x2 region, the region of 2x2 pixels is regarded as a high resolution region, a binarization is performed and the value of 0, 1 is set to the position of each pixel (aij) of the 2x2 region, so that when aij>THa3 is satisfied, aij=1, when aij≤ THa1 is satisfied, aij=0 thereby a density pattern of the 2x2 region is generated, then the image compression conversion unit quantizes the 2x2 region according to the generated density pattern, as density patterns are previously sorted out into several groups and quantized data is previously allotted for each group. a controller to generate image data, wherein the controller is configured to perform rasterizing processing and generate for each pixel (aij) a pixel value and an attribute data (Tag(aij)) indicating the attribute of each pixel, wherein the attribute indicated by the attribute data (Tag(aij)) includes text, graphics or photographic image; and an image compression conversion unit to quantize an image having attribute data for each pixel, wherein the image compression conversion unit is configured to extract a region of 8x8 pixels from the image and to extract a region of 2x2 pixels among the 8x8 pixels, and to determine an attribute data (Tag(bij)) of the 2x2 region based on the attribute data (Tag(aij)) of each pixel therein; when the region of 2x2 pixels has an attribute data (Tag(bij)) indicating photographic image, the image compression conversion unit quantizes the 2x2 region by a first block truncation coding method; when the 2x2 region is not a photographic image and when one of the following conditions - is satisfied for the 2x2 region, when there is at least 1 pixel which satisfies THa1 <aij ≤THa3 among 4 pixels aij when all 4 pixels aij satisfy aij≤THa1 when all 4 pixels aij satisfy aij>THa3 when (Max-min)<T (0≤T≤255) is satisfied, when there is at least 1 pixel which satisfies THa1 <aij ≤THa3 among 4 pixels aij when all 4 pixels aij satisfy aij≤THa1 when all 4 pixels aij satisfy aij>THa3 when (Max-min)<T (0≤T≤255) is satisfied, wherein Max and min correspond to the maximum and minimum value of the 8x8 region to which the 2x2 region belongs, where THa1 and THa3 are thresholds based on Max and min, and THa1<THa3 and wherein T is a threshold value set to judge whether the density difference in the region is small or not, the region of 2x2 pixels is regarded as a halftone region, the image compression conversion unit quantizes the 2x2 halftone region by a second block truncation coding method having a higher compression rate than the first block truncation coding method; when the 2x2 region is not a photographic image and when there is a pixel which satisfies aij≤THa1 and there is a pixel which satisfies aij>THa3 in the 2x2 region, the region of 2x2 pixels is regarded as a high resolution region, a binarization is performed and the value of 0, 1 is set to the position of each pixel (aij) of the 2x2 region, so that when aij>THa3 is satisfied, aij=1, when aij≤ THa1 is satisfied, aij=0 thereby a density pattern of the 2x2 region is generated, then the image compression conversion unit quantizes the 2x2 region according to the generated density pattern, as density patterns are previously sorted out into several groups and quantized data is previously allotted for each group.