Method and apparatus for dithering a pixel value in image

An apparatus for dithering input image data and outputting the dithered image data, the apparatus comprising:

• a flat/non-flat area check unit for checking a difference in chrominance signals between a particular pixel and a pixel adjacent to the particular pixel included in a predetermined unit block, in an input image, and designating the unit block as a flat or non-flat area;
• a bit removal unit for removing a number of lower bits of the chrominance signal of the particular pixel of the unit block in response to a desired output bit count;
• a random number generation unit for generating a random number in a range of the value determined by said number of lower bits removed by the bit removal unit;
• a comparison unit for comparing a value of the number of lower bits removed by the bit removal unit with the random number generated by the random number generation unit, and outputting a result of the comparison;
• and
• a dithering arithmetic unit for receiving as an input a signal indicating whether the particular pixel corresponds to the flat or non-flat area from the flat/non-flat area check unit, and, in response to the input signal, outputting the chrominance signal with the lower bits removed by the bit removal unit, or dithering the chrominance signal with the removed lower bits based on the result of the comparison from the comparison unit.

A device for altering the pixel values within an image, comprising:

• a processor in communication with a memory, the memory including code which when accessed by the processor causes the processor to execute:
• receiving an image including a plurality of unit block comprising a plurality of pixel elements;
• determining an absolute value of a difference in chrominance signals between a specified pixel and each of a plurality of pixel adjacent to the specified pixels included in a unit block,
• determining whether said unit block is a flat area or a non-flat area based on said absolute values of the differences, wherein said unit block is a flat area when an accumulation of the number of said absolute value of the differences over a first threshold is less than a second threshold and a non-flat area when said accumulation of the number of said absolute value of the differences over a first threshold is greater than a second threshold, wherein said second threshold is determined based on a number of pixels included in the unit block;
• and
• dithering pixels of the unit block designated as the non-flat area comprising:
• removing a number of lower bits of bits representing a chrominance signal in consideration of a magnitude of an image to be reduced;
• generating a random number in a range corresponding to a value associated with the removed number of lower bits;
• comparing a value represented by the removed lower bits with the generated random number;
• and
• adding a value of “1” to a Least Significant Bit (LSB) of the remaining bits if it is determined that the value represented by the removed lower bits is larger than the generated random number.