Automatic focusing method and digital photographing apparatus using the same
View Patent ↗Provided are an automatic focusing method in which a photograph region is brought into focus through automatic movement of a focal lens to a focal position, in response to a photographing-command signal, and a digital photographing apparatus using the method. The method includes dividing the photograph region into a plurality of sub-regions, focusing on the sub-regions and obtaining focal position values DS FOC , calculating an average focal position value ADS FOC of the focal position values DS FOC , selecting focal position values DS FOC whose differences from the average focal position value ADS FOC are equal to or less than a threshold value D TH , and moving the focal lens to a focal position corresponding to the focal position value DS FOC having the shortest focal distance among the selected focal position values DS FOC .
1. An automatic focusing method in which a photograph region is brought into focus through automatic movement of a focal lens to a focal position in response to a photographing-command signal, the method comprising:
dividing the photograph region into a plurality of sub-regions;
obtaining focal position values DS FOC and maximum focus values FV MAX for the sub-regions;
calculating an average focal position value ADS FOC for the focal position values DS FOC of the sub-regions;
calculating an average maximum focus value AFV MAX for the maximum focus values FV MAX of the sub-regions;
selecting a first set of sub-regions having focal position values DS FOC that differ from the average focal position value ADS FOC by a value that is equal to or less than a threshold value D TH ;
selecting a second set of sub-regions from the first set of sub-regions, sub-regions of the second set having maximum focus values FV MAX that are greater than or equal to an average maximum focus value AFV MAX ;
selecting from the second set of sub-regions, a particular sub-region having the shortest focal distance; and
moving the focal lens to a focal position corresponding to the focal position value DS FOC of the particular sub-region.
2. The method of claim 1 , wherein the photographing command signal is generated when a shutter release button is depressed.
3. The method of claim 1 wherein the focal position value DS FOC is the number of driving steps of a focus motor that moves the focal lens.
4. An automatic focusing method in which a photograph region is brought into focus through automatic movement of a focal lens to a focal position, in response to a photographing-command signal, the method comprising:
dividing the photograph region into a plurality of sub-regions;
obtaining maximum focus values FV MAX for the sub-regions;
obtaining focal position values DS FOC for the sub-regions which correspond to the maximum focus values FV MAX ;
calculating an average focal position value ADS FOC for the focal position values DS FOC of the sub-regions;
calculating an average maximum focus value AFV MAX for the maximum focus values FV MAX of the sub-regions;
selecting a first set of sub-regions having focal position values DS FOC that differ from the average focal position value ADS FOC by a value that is equal to or less than a threshold value D TH ;
selecting from the first set of selected sub-regions, a second set of sub-regions having maximum focus values FV MAX that are equal to or greater than the average maximum focus value AFV MAX ;
selecting from the second set of sub-regions, a particular sub-region having the shortest focal distance; and
moving the focal lens to a focal position corresponding to the focal position value DS FOC of the particular sub-region.
5. A digital photographing apparatus using an automatic focusing method in which a photograph region is brought into focus through automatic movement of a focal lens to a focal position, in response to a photographing-command signal, the method comprising:
dividing the photograph region into a plurality of sub-regions;
obtaining focal position values DS FOC and maximum focus values FV MAX for the sub-regions;
calculating an average focal position value ADS FOC for the focal position values DS FOC of the sub-regions;
calculating an average maximum focus value AFV MAX for the maximum focus values FV MAX of the sub-regions;
selecting a first set of sub-regions having focal position values DS FOC that differ from the average focal position value ADS FOC by a value that is equal to or less than a threshold value D TH ;
selecting a second set of sub-regions from the first set of sub-regions, sub-regions of the second set having maximum focus values FV MAx that are greater than or equal to an average maximum focus value AFV MAX ;
selecting from the second set of sub-regions, a particular sub-region having the shortest focal distance; and
moving the focal lens to a focal position corresponding to the focal position value DS FOC of the particular sub-region.
6. A digital photographing apparatus using an automatic focusing method in which a photograph region is brought into focus through automatic movement of a focal lens to a focal position, in response to a photographing-command signal, the method comprising:
dividing the photograph region into a plurality of sub-regions;
obtaining maximum focus values FV MAX for the sub-regions;
obtaining focal position values DS FOC for the sub-regions which correspond to the maximum focus values FV MAX ;
calculating an average focal position value ADS FOC for the focal position values DS FOC of the sub-regions;
calculating an average maximum focus value AFV MAX for the maximum focus values FV MAX of the sub-regions;
selecting a first set of sub-regions having focal position values DS FOC that differ from the average focal position value ADS FOC by a value that is equal to or less than a threshold value D TH ;
selecting from the first set of selected sub-regions, a second set of sub-regions having maximum focus values FV MAX that are equal to or greater than the average maximum focus value AFV MAX ;
selecting from the second set of sub-regions, a particular sub-region having the shortest focal distance; and
moving the focal lens to a focal position corresponding to the focal position value DS FOC of the particular sub-region.