Image processing apparatus, image processing method, and image processing program

Abstract

An image processing apparatus includes the following elements. An image data obtaining unit obtains image data. A sampling unit samples the image data. A statistic value determining unit determines a statistic value based on statistic information in a histogram with respect to a grayscale value of image data that is obtained by performing rough quantization and linear interpolation on the sampled image data. A correction-amount determining unit determines a correction amount to be used for image processing based on the statistic value. An image processing unit performs the image processing according to the correction amount.

1 . An image processing apparatus comprising: 
 an image data obtaining unit that obtains image data;    a sampling unit that samples the image data;    a statistic value determining unit that determines a statistic value based on statistic information in a histogram with respect to a grayscale value of image data that is obtained by performing rough quantization and linear interpolation on the sampled image data;    a correction-amount determining unit that determines a correction amount to be used for image processing based on the statistic value; and    an image processing unit that performs the image processing according to the correction amount.    
   
   
       2 . The image processing apparatus according to  claim 1 , wherein the correction-amount determining unit includes a correction-amount adjusting unit that determines a ratio of pixels having a specific color in all pixels based on the sampled image data and that adjusts the correction amount according to the ratio of the pixels having the specific color.  
   
   
       3 . The image processing apparatus according to claim  1 , wherein an image defined by the image data is divided into a central area and a surrounding area surrounding the central area, and 
 the sampling unit includes a divisional area sampling unit that samples the image data in the central area and the surrounding area at a low resolution.    
   
   
       4 . The image processing apparatus according to  claim 3 , wherein the correction-amount determining unit includes a backlit-image determining unit that determines whether or not the image data is backlit image data using the histogram and a statistic value that is determined based on sampled image data in the central area and the surrounding area.  
   
   
       5 . An image processing method comprising: 
 obtaining image data;    sampling the image data;    determining a statistic value based on statistic information in a histogram with respect to a grayscale value of image data that is obtained by performing rough quantization and linear interpolation on the sampled image data;    determining a correction amount to be used for image processing based on the statistic value; and    performing the image processing according to the correction amount.    
   
   
       6 . An image processing program executed by an image processing apparatus including a control circuit to cause the image processing apparatus to function as: 
 an image data obtaining unit that obtains image data;    a sampling unit that samples the image data;    a statistic value determining unit that determines a statistic value based on statistic information in a histogram with respect to a grayscale value of image data that is obtained by performing rough quantization and linear interpolation on the sampled image data;    a correction-amount determining unit that determines a correction amount to be used for image processing based on the statistic value; and    an image processing unit that performs the image processing according to the correction amount.