Image processing and formation with line thininng by reducing intensity of target pixel based on extracted contour pixel and area connectedness information

An image processing method, comprising:

• extracting a contour pixel component from a bit plane, the bit plane being a set of bits, the number of the bits being equal to the number of pixels, and each of the bits being 1 bit of a plurality of bits representing an intensity of each of pixels;
• detecting equivalent bits adjacent to each other in a window including a bit corresponding to a target pixel on the bit plane;
• and
• reducing an intensity of the target pixel by a reduction amount determined in accordance with the extracted contour pixel component and the detected equivalent bits adjacent to each other.

An image forming apparatus comprising:

• a contour pixel extraction unit configured to extract a contour pixel component from a bit plane, the bit plane being a set of bits, the number of the bits being equal to the number of pixels, and each of the bits being 1 bit of a plurality of bits representing an intensity of each of pixels;
• a connectedness detection unit configured to detect equivalent bits adjacent to each other in a window including a bit corresponding to a target pixel on the bit plane;
• a filter unit configured to reduce an intensity of the target pixel by a reduction amount determined in accordance with the contour pixel component extracted by the contour pixel extraction unit and the equivalent bits adjacent to each other detected by the connectedness detection unit;
• and
• a selection output unit configured to output a selected signal by determining whether to select an input image signal of a plurality of bits of the target pixel or an output signal obtained by the filter unit, in accordance with a value of the input image signal of the plurality of bits thereof.