Patent ID: 7995105

Claim:
A brightness adjusting method used in an image-retrieving apparatus for producing a suitable brightness adjusting value, said image-retrieving apparatus having a filter and defining a first threshold value, a second threshold value set, a third threshold value, and a fourth threshold value, said second threshold value set including a high value and a low value, comprising the steps as follow: a. disable the filter and retrieve a first picture of a scene, the first picture having a plurality of pixels and a brightness value of each pixel is obtained; b. enable the filter and retrieve a second picture of the same scene, the second picture having a plurality of pixels and a brightness value of each pixel is obtained; c. compare the brightness value of each pixel in the second picture with the first threshold value so as to obtain a fine detail area and a blurred area in the first picture; d. for each pixel in the blurred areas, by respectively using the high value and the low value of the second threshold value set to determine an over-exposure area and an under-exposure area in the blurred areas according to the brightness value of each pixel in the first picture, and calculate the area sum of the over-exposure areas, A 1 , and the area sum of the under-exposure areas, A 2 ; e. based on a result after comparing the third threshold value with A 1 and/or A 2 , determine whether to adjust the brightness value of the pixels in the over-exposure areas and/or under-exposure areas; and f. determine the brightness adjusting value for the pixels in the first picture based on the fourth threshold value, a desired brightness value BV target , an average brightness value of all pixels in the over-exposure areas, BV a1 , and an average brightness value of all pixels in the under-exposure areas, BV a2 .