Pixel density converting apparatus

A pixel density converting apparatus for a binary image which employs the linear interpolation method, comprising:

• a pixel taking out means for taking out 4 original pixels surrounding a converted pixel on a projection surface formed by projecting a converted image onto an original image;
• a position operation means for operating a position of said converted pixel relative to said four original pixels;
• an area determination means for determining a predetermined area from said relative position obtained;
• and
• a converted pixel determination means for determining a value of said converted pixel from a logical expression determined by said determined area.

A pixel density converting apparatus for converting a pixel density of binary image, comprising:

• an operation means for operating a tone or luminance of a pixel to be converted and converting a pixel density;
• a threshold level setting means for setting a threshold level used for binarization of the tone or luminance of a pixel in accordance with a conversion factor;
• and
• a binarization means for binarizing the tone or luminance of the converted pixel by the comparison results of the threshold level and the tone or luminance of the converted pixel.

A pixel density converting apparatus for converting a pixel density of binary image by a desired conversion factor, comprising:

• an operation means for operating an average tone or luminance of a pixel to be converted by the projection method;
• an edge emphasis means for emphasizing an edge of the image data converted by said operation means as multi-level image data;
• and
• a binarization means for binarizing the image data emphasized by said edge emphasis means.