Pre-processing method and apparatus for wide dynamic range image processing

A method of wide dynamic range (WDR) image processing, the method comprising:

• (a) receiving luminance and chrominance signals having different exposure times and normalizing a luminance signal having a first exposure time so as to correspond to a luminance signal having a second exposure time that is longer than the first exposure time;
• (b) adding up, utilizing a processor, the luminance signal having the second exposure time and the normalized luminance signal having the first exposure time using a first weight;
• (c) adding up a chrominance signal having the first exposure time and a chrominance signal having the second exposure time using a second weight to which the result of the adding in (b) is reflected;
• and
• (d) converting the added luminance signal and the added chrominance signal into a RGB signal to be output as a WDR resultant image signal.

A non-transitory computer readable storage medium having embodied thereon a computer program for executing a method of pre-processing in wide dynamic range (WDR) image processing, the method comprising:

• (a) receiving luminance and chrominance signals having different exposure times, analyzing the correlation between a luminance signal having a first exposure time and a luminance signal having a second exposure time that is longer than the first exposure time;
• (b) based on the result of the analysis, dividing each of the luminance signal having the first exposure time and the luminance signal having the second exposure time into at least one of a bright region, a transition region, and a dark region;
• and
• (c) normalizing the regions of the luminance signal having the first exposure time to respectively correspond to the regions of the luminance signal having the second exposure time.

A wide dynamic range (WDR) image processing apparatus, comprising:

• a luminance/chrominance converting unit for converting image signals obtained at different exposure times into luminance and chrominance signals;
• a pre-processing unit for normalizing a luminance signal having a first exposure time among the different exposure times to correspond to a luminance signal having a second exposure time that is longer than the first exposure time;
• a luminance fusing unit for adding up the luminance signal having the second exposure time and the normalized luminance signal having the first exposure time using a first weight;
• a chrominance fusing unit for adding up a chrominance signal having the first exposure time and a chrominance signal having the second exposure time using a second weight to which the result of the addition of the luminance fusing unit is reflected;
• and
• an RGB converting unit for converting the fused luminance signal output from the luminance fusing unit and the fused chrominance signal output from the chrominance fusing unit into an RGB signal to be output as a WDR resultant image signal.