Image processing apparatus and method

Abstract

An image processing apparatus determines a correction gain factor at a high rate of speed to synthesize an image. The apparatus includes a long second middle luminance image detecting unit for detecting a pixel having a pixel value in a first middle luminance pixel value region derived from a long second exposure image; a short second middle luminance image detecting unit for detecting a pixel having a pixel value in second middle luminance pixel value region derived from a shorter second exposure image; a correction gain factor calculating unit for designating, as a common pixel, the pixel detected by the long second middle luminance image detecting unit and the pixel detected by the short second middle luminance image detecting unit, each of the pixels at a common position, and for calculating a correction gain factor based on the pixel values of the common pixels.

1 - 6 . (canceled) 
     
     
         7 . An image processing apparatus for synthesizing a first image and a second image, the first image being derived by a longer exposure time than the second image, the apparatus comprising:
 a first selecting unit configured to select a pixel outputting, as a part of the first image, a pixel value within a first range from a plurality of pixels;   a second selecting unit configured to select a pixel outputting, as a part of the second image, a pixel value within a second range from the plurality of pixels;   a calculating unit configured to calculate a gain factor based on the pixel value of the first image and the pixel value of the second image, wherein the pixel values are output from a pixel selected by both of the first selecting unit and the second selecting unit; and   a synthesizing unit configured to synthesize the first image and the second image based on the gain factor calculated by the calculating unit.   
     
     
         8 . The image processing apparatus according to  claim 7 , wherein the first range is between a first lower threshold value and a first higher threshold value. 
     
     
         9 . The image processing apparatus according to  claim 8 , wherein the first selecting unit selects the pixel based on comparing the pixel value with the first lower threshold value and with the first higher threshold value. 
     
     
         10 . The image processing apparatus according to  claim 7 , wherein the second range is between a second lower threshold value and a second higher threshold value. 
     
     
         11 . The image processing apparatus according to  claim 10 , wherein the second selecting unit selects the pixel based on comparing the pixel value with the second lower threshold value and with the second higher threshold value. 
     
     
         12 . The image processing apparatus according to  claim 7 , wherein, at the pixel outputting the pixel value within the first range, a saturation into white and a black sinking do not occur. 
     
     
         13 . The image processing apparatus according to  claim 7 , wherein, at the pixel outputting the pixel value within the second range, a saturation into white and a black sinking do not occur. 
     
     
         14 . The image processing apparatus according to  claim 7 , wherein the first selecting unit assigns a first symbol to the pixel outputting the pixel value within the first range and a second symbol to a pixel outputting, as a part of the first image, a pixel value outside the first range, and
 wherein the second selecting unit assigns the first symbol to the pixel outputting the pixel value within the second range and the second symbol to a pixel outputting, as a part of the second image, a pixel value outside the second range.   
     
     
         15 . The image processing apparatus according to  claim 14 , wherein the calculating unit performs an AND operation to pixels at a same coordinate position in the first image and in the second image. 
     
     
         16 . The image processing apparatus according to  claim 14 , wherein the calculating unit excludes the pixel value output from the pixel assigned with the second symbol from calculation of the gain factor. 
     
     
         17 . The image processing apparatus according to  claim 7 , wherein the first selecting unit and the second selecting unit select the pixel by parallel processing. 
     
     
         18 . The image processing apparatus according to  claim 7 , wherein a number of the pixels selected by the first or second selecting unit is converted by the apparatus operating in a first mode and a second mode. 
     
     
         19 . An image processing method for synthesizing a first image and a second image, the first image being derived by a longer exposure time than the second image, the method comprising:
 a first selecting step for selecting a pixel outputting, as a part of the first image, a pixel value within a first range from a plurality of pixels;   a second selecting step for selecting a pixel outputting, as a part of the second image, a pixel value within a second range from the plurality of pixels;   a calculating step for calculating a gain factor based on the pixel value of the first image and the pixel value of the second image, wherein the pixel values are output from a pixel selected by both of the first selecting step and the second selecting step; and   a synthesizing step for synthesizing the first image and the second image based on the gain factor calculated by the calculating step.   
     
     
         20 . The image processing method according to  claim 19 , wherein the first range is between a first lower threshold value and a first higher threshold value. 
     
     
         21 . The image processing method according to  claim 19 , wherein the second range is between a second lower threshold value and a second higher threshold value. 
     
     
         22 . The image processing method according to  claim 19 , wherein the first selecting step includes a step of assigning a first symbol to the pixel outputting the pixel value within the first range and a second symbol to a pixel outputting, as a part of the first image, a pixel value outside the first range, and
 wherein the second selecting step includes a step of assigning the first symbol to the pixel outputting the pixel value within the second range and the second symbol to a pixel outputting, as a part of the second image, a pixel value outside the second range.   
     
     
         23 . The image processing method according to  claim 19 , wherein the first selecting step and the second selecting step are executed by parallel processing.