# Patent

## Title
Apparatus and method for image recognition of facial areas in photographic images from a digital camera

## Abstract

Disclosed is an apparatus for photographing an image using a digital camera capable of providing a preview image, including: an image sensor for capturing an image of a subject; a first image signal processor for processing at least one captured image as a sequent image in order to display the captured image as a preview image on a display window and detecting a face area from the captured image; a buffer for storing the image including at least one detected face area; a capture button for capturing a still image during outputting the sequent image as the preview image on the display window; a second image signal processor for processing the captured still image using the capture button; a controller for controlling to store the captured still image and information related on the face area detected from the first image signal processor prior to the input of the capture button; and a memory for storing the processed still image together with the information related on the detected face area.

## Background
CLAIM OF PRIORITY
The present application is a Continuation of U.S. patent application Ser. No. 12/197,566 filed on Aug. 25, 2008 which claims the benefit of an earlier patent application entitled “Apparatus and Method for Photographing Image Using Digital Camera Capable of Providing A Preview Image,” filed in the Korean Intellectual Property Office on Aug. 23, 2007 and assigned Serial No. 2007-0085125, the content of which are hereby incorporated by reference.


BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system and a method of photographing an image and automatically classifying the image, and more particularly to a system and a method of automatically classifying a facial image for each person, which includes a scheme for photographing images for classification and a scheme for classifying images.
2. Description of the Related Art
Due to a recent wide usages of a digital camera and a personal blog, a scheme is used in which an image photographed directly by a user is semi-automatically classified. In general, the scheme classifies the image for each person, or in reference to a scene or a background, such as the mountain and the sea. Here, the scheme for recognizing a face in the image and classifying the image requires registering many facial images for recognition in advance. Otherwise, there would be many errors, especially, in a case where the facial image is not a frontal image, or the facial image includes various facial expressions. That is, the photographed facial images with a natural pose include a face shape with various angles, but a rate of face recognition is lowered in the case of a non-front facial image, so that it is difficult to secure the accuracy of classification.
SUMMARY OF THE INVENTION
Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art and provides additional advantages, by providing an apparatus and a method for photographing and classifying a facial image while removing errors on recognizing and classifying the photographed image so as to accurately classify the image.
In accordance with an aspect of the present invention, an apparatus for photographing an image using a digital camera capable of providing a preview image includes: an image sensor for capturing an image of a subject; a first image signal processor for processing at least one captured image as a sequent image in order to display the captured image as a preview image on a display and detecting a face area from the captured image; a buffer for storing the image including at least one detected face area; a capture button for capturing a still image using outputting the sequent image as the preview image on the display window; a second image signal processor for processing the captured still image using the capture button; a controller for controlling to store the captured still image and information related on the face area detected from the first image signal processor prior to the input of the capture button; and a memory for storing the processed still image together with the information related on the detected face area.
In accordance with another aspect of the present invention, a method for photographing an image using a digital camera capable of providing a preview image includes: capturing at least one image of a subject; processing at least one captured image as a sequent image in order to display the captured image as a preview image on a display window; detecting a face area from the captured image, and storing the detected face area; capturing a photographed still image using a predetermined capture button; and storing the processed still image together with information related on the detected face area.



BRIEF DESCRIPTION OF THE DRAWINGS
The above and other aspects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a diagram illustrating an apparatus of photographing an image according to an exemplary embodiment of the present invention;
FIG. 2 is a diagram illustrating an image information unit and an image classifying unit according to an exemplary embodiment of the present invention; and
FIG. 3 is a flowchart illustrating a method for photographing and classifying a facial image according to an exemplary embodiment of the present invention.



DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same elements will be designated by the same reference numerals although they are shown in different drawings. For the purposes of clarity and simplicity, detailed explanation of known related functions and constitutions may be omitted to avoid unnecessarily obscuring the subject manner of the present invention.
FIG. 1 is a diagram illustrating an apparatus of photographing an image according to an exemplary embodiment of the present invention. As shown in FIG. 1, the inventive apparatus of photographing the image includes a lens 101, an image sensor 103, a first image signal processor 105, a controller 107, a memory 111, a buffer 113, and a second image signal processor 109.
The lens 101 optically receives an image of a subject. If the lens were included in a camera photographing the still image, the lens optically receives a still image as it is. If the lens were included in a camcorder photographing a moving image, the lens classifies the moving image into a plurality of still image and optically receives the still images in sequence. The image sensor 103 converts the image optically inputted by the lens 101 into an electrical signal. The second image signal processor 109 processes the electric signal converted-image based on a frame unit.
The memory 111 stores a photographed picture. The controller 107 shifts the lens 101 for adjusting focus on the subject.
The first image signal processor 105 selects the image including a face among the images processed based on the frame unit, determines the image, classifies, and stores the image. The classified facial image is stored in the buffer 113. The description of the first image signal processor 105 will be described in details.
Even though not shown in the figures, the apparatus for photographing the image can further include a display unit capable of outputting the photographed image and have a function of providing a preview image. That is, the inventive apparatus for photographing the image is also equipped with the ability to provide preview images during a predetermined time period before and after a point of time of capturing in an image.
FIG. 2 is a diagram illustrating an image information unit and an image classifying unit according to an exemplary embodiment of the present invention. As shown, the first image signal processor 105 includes an image information unit 210 and an image classifying unit 230. Note that FIG. 2 illustrates a state where the facial image is received from the camera and the connection state of each element. More particularly, the inventive apparatus for photographing image includes the image information unit 210, an image storing unit 220, and an image classifying unit 230, and further includes a registered image DB 240, and a person image or facial image DB 150. Hereinafter, the configuration and operation thereof will be described, respectively.
The image information unit 210 photographs the image, extracts a specific area from the image, and collects information for classifying the extracted specific area according to a predetermined reference. In the present exemplary embodiment, the image information unit 210 photographs a facial image and extracts a face area. In order to classify the extracted face area for each person, the image information unit 210 collects facial image classification basis information from the extracted face area. To this end, the image information unit 210 includes an image selecting unit 222, an image detecting unit 223, an image tracking unit 224, and a facial image classification basis information collecting unit 215. The description of each configuration is as follows.
The image selecting unit 222 selects the facial image received from the image signal processor of a camera module. The image selecting unit 222 selects not only the image selected by the activation of the shutter of the camera, but also a predetermined number of preview images provided by the camera during before and after. The predetermined number of preview images can be determined by the user in advance. Note that the image can be passively selected by the user, or controlled to be automatically selected. For example, the user predetermines the number of preview images to be “5”, presses the shutter of the camera, and photographs the image. Here, the preview images are provided continuously before and after the photographing time point. The image selecting unit 212 selects not only the photographed image, but also the predetermined number of preview images photographed before and after the photographing time point. Since the predetermined number of preview images is set to be “5” in the present exemplary embodiment for illustrative purposes, the image selecting unit 212 selects and extracts the photographed image, two preview images right before the photographing time point, and two preview images right after the photographing time point. Therefore, a total of five images are selected and extracted, which are the facial images used for collecting the facial image classification basis information in the facial image classification basis information collecting unit 215 described later.
The image detecting unit 223 detects a facial area from the facial images selected in the image selecting unit 222. Here, the face area can be detected by using the distribution of facial colors in the image, or by an active contour of the face, such as eyes, the nose, the mouth, or the like. Note that various methods known in the artisians can be applied to detect the face area.
The image tracking unit 22 tracks the movement of the face area detected in the image detecting unit 22. That is, as shown in the above, the selected 5 facial images are the serial images, so that the face area moves when the person in the image moves. Therefore, the moving face area is tracked through the image tracking unit 224 It is reliable that the face areas detected according to the above tracking scheme are the face areas of the same person. In order to track the image, a tracking apparatus, such as a Kalman filter, or the like, can be employed by using the position similarity or the characteristic similarity between a present face and a previous face. The collected facial images for the same person are provided to the facial image classification basis information collecting unit 215.
The facial image classification basis information collecting unit 215 collects information for classifying the facial images from the facial images of the same people collected in the image tracking unit 214 for each corresponding person according to a predetermined reference. The facial image classification basis information can include all information available for classifying the facial image for each person, e.g. information obtained through recognizing the image of the face area for comparing the pre-registered image, or Principle Component Analysis (PCA) feature vector. When a plurality of face areas are detected from a specific facial image, the facial image classification basis information collecting unit 215 can collect facial image classification basis information for each face area. That is, when three face areas are detected and tracked in the facial image, the facial image classification basis information is collected for every detected and tracked face area. In this case, the image classifying module 230 described later classifies the same image as each facial image of three people. The image storing module 220 stores the facial image and the preview images selected in the image selecting unit 222 together with the facial image classification basis information collected from them. The facial image and the preview images and the facial image classification basis information are provided to the image classifying module 230.
The image classifying module 230 recognizes the facial images selected among the images photographed in the image information unit 210, and classifies the recognized facial images according to the predetermined reference. The classification of tracked face area according to predetermine reference can be classified into a person individually or a group. The image classifying unit 230 is related to a classifying scheme through the image recognition. The image classifying module 230 includes an image recognizing unit 231 and an image classifying unit 232, whose descriptions are as follows.
The image recognizing unit 231 recognizes the facial image and the preview image provided from the image storing unit 220 by using the facial image classification basis information. A lot of schemes for recognizing the facial image have existed conventionally, and in the present invention, the face shape can be recognized using the Support Vector Machine (SVM) or the artificial neural network.
In the meantime, the image classifying unit 232 classifies the facial image recognized in the image recognizing unit 231 for the corresponding person so as to store them in the person image or facial image DB 150. More particularly, the image classifying unit 232 compares the facial image classification basis information with the information extracted from the facial image previously registered in the registered image DB 240, retrieves the person corresponding to the facial image, and classifies the facial image for the corresponding person If the registered facial image corresponding to the recognized facial image does not exist in the registered image DB 240, the image classifying unit 132 classifies the recognized facial image as be a non-classified facial image so as to store it to the registered image DB 240.
The afore-described each module and DB can be unified into a unit. However, the module, i.e. the image information unit 210, the image storing unit 220, and the image classifying unit 230 can be separated, respectively. For example, the image information unit 210 may be achieved by a camcorder, the image storing unit 220 may be achieved by a separate storing unit, and each of the image classifying module 230, the registered image DB 240, and the person image DB 150 may be achieved by either a separate unit or software installed in the computer.
In the meantime, the inventive apparatus can be designed to classify the image based on the reference of the mountain, the sea, the river, or the like, other than the facial image. The classification reference can be varied depending on the design.
FIG. 3 is a flowchart illustrating a method for photographing and classifying the facial image according to an exemplary embodiment of the present invention. Referring to FIG. 3, the facial image is photographed by using the camera in step S210. Then, the image selecting unit 222 selects and extracts the photographed facial image and the predetermined number of preview images photographed before and after the photographing time point in step S220. The image detecting unit 223 detects the face area from the facial image, and the image tracking unit 224 tracks the movement of the face area in the detected face area in step S230. In this step, when the facial images include a plurality of people, a plurality of face areas can be separately detected and tracked. Alternatively, the plurality of face can be classified into a group.
In the meantime, the facial image classification basis information collecting Unit 215 collects the respective facial image classification basis information in the detected and tracked face areas in step S240. The facial image classification basis information is basis information for classifying the facial images for each corresponding person. Next, the facial image and the preview images selected by the image selecting unit 222, and the facial image classification basis information collected by the facial image classification basis information collecting unit 215, are stored in the image storing module 220 in step S250. Then, the facial image classification basis information is compared with the information extracted from the registered facial image previously registered in the DB 240, so that the selected facial image is recognized in step S260. Consequently, it is determined that the facial image recognized in the image recognizing unit 231 belongs to which registered facial image among the facial images previously registered in the registered image DB 240 in step S270. If the selected facial image has been previously registered, the image classifying unit 232 classifies the selected facial image as the facial image of the registered facial image, then stores the classified facial image to person image or the facial image DB 150 in step S280. However, if the selected facial image has not been previously registered, the image classifying unit 232 classifies the selected facial image as the non-classified facial image, so as to store the non-classified facial image to the person image or facial image DB 150 in step S285 as a new entry.
As seen above, the present invention is effective in removing errors in recognition and classification of the photographed image, and in accurately classifying the photographed image according to a predetermined reference scheme. Especially, even though the non-front facial image with various angles due to the natural movement is photographed, the person can be accurately recognized and classified by the facial image classification basis information extracted from the facial image of the photographing time point and the preview images photographed before and after the photographing time point. Further, even if the user has registered a small number of facial images for recognizing the face, simulation can be performed based on the facial image classification basis information extracted from the photographed image and the predetermined number of preview images photographed before and after the photographing time point and stored together with the photographed image. Therefore, the system and method for photographing an image and classifying the image according to the present invention can increase the recognition rate of the face shape and the accuracy of the classification, as if the recognition were performed with a lot of registered facial images.
As described above, the input method, the configuration of the apparatus, and its action in the mobile communication terminal having the touch screen can be implemented according to the exemplary embodiment of the present invention. While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

## Claims

1. An apparatus comprising:
a person image DB;
a registered image database (DB) for storing at least one registered facial image;
an image sensor for capturing an image of a subject;
a display for displaying the captured image of the subject, the captured image including at least a portion of a facial image; and
a processor operable to:
process the captured image to be displayed on the display as a preview image, detect face information from series of preview images including the at least a portion of the facial image respectively,
apply face recognition to the detected face information by comparing the face information to at least one registered facial image in the registered image DB,
store the recognized facial image from the face recognition in the person image DB; and
group the captured images into at least one classification based on the applied face recognition, wherein the processor comprises:
an image selecting unit for selecting a predetermined number of the series of preview images for a predetermined time period;
an image detecting unit for detecting every face area from each of series of preview images;
an image tracking unit for tracking a motion of every face in order to search for an identical face; and
a face collecting unit for collecting face information from the face area corresponding to an identical person collected in the image tracking unit according to a predetermined reference.

2. The apparatus as claimed in claim 1, wherein the image detecting unit detects the face area using a spread of a skin color or an active contour of the face area.

3. The apparatus as claimed in claim 2, wherein the collected face information includes an image of the tracked face area or Principle Component Analysis (PCA) feature vectors.

4. The apparatus as claimed in claim 3, wherein the processor further comprises:
an image recognizing unit for recognizing the face area; and
an image classifying unit for classifying the recognized facial image for a corresponding person so as to provide the classified facial image.

5. The apparatus as claimed in claim 4, wherein the image recognizing unit recognizes the facial image using a Support Vector Machine (SVM) or an artificial neural network.

6. The apparatus as claimed in claim 4, further comprising:
an image storing unit for registering the at least one stored registered images in the registered image DB.

7. The apparatus as claimed in claim 4, wherein the person image DB stores the recognized facial image classified for each corresponding person.

8. A method for photographing an image using a digital camera capable of providing a preview image, the method comprising:
capturing images of a subject;
processing the captured images to be displayed on a display of the digital camera as preview images before photographing a still image of the subject when a shutter of the digital camera is pressed;
when a user presses the shutter, photographing the still image of the subject;
selecting a predetermined number of series of preview images which are captured around a point of time of pressing the shutter;
detecting every face area from each of the series of preview images;
tracking a motion of every face in order to search for an identical face; and
collecting the-face information from the face area corresponding to an identical person according to a predetermined reference.

9. The method as claimed in claim 8, further comprising:
grouping the captured images into at least one classification based on the applied face recognition; and
grouping the face information into at least one classification.

10. The method as claimed in claim 8, wherein detecting every face area includes detecting the face area using a spread of a skin color or an active contour of the face area.

11. The method as claimed in claim 8, wherein the collected face information includes an image of the tracked face area or Principle Component Analysis (PCA) feature vectors.

12. The method as claimed in claim 8, further comprising:
recognizing the face area; and
classifying the recognized facial image for a corresponding person so as to provide the classified facial image.

13. The method as claimed in claim 12 further comprising recognizing the facial image using a Support Vector Machine (SVM) or an artificial neural network.

14. The method as claimed in claim 12, further comprising registering the at least one stored registered facial image.

15. The method as claimed in claim 12, wherein storing the recognized facial image includes storing the recognized facial image classified for each corresponding person.

16. An apparatus comprising:
a person image database;
a registered image database to store at least one registered facial image;
an image sensor to capture an image of a subject;
a display to display the captured image of the subject; and
a processor configured to:
process the captured image to be displayed on the display as a preview image,
in response to a shutter press operation to photograph the subject, extract facial information from each of a predetermined plurality of sequential preview images captured around the time of the shutter press operation;
recognize a person on the basis of the extracted facial information from all of the sequential preview images, through comparison of the extracted facial information to at least one registered facial image in the registered image database, and
classify and store the captured image in association with the recognized person in the person image database.

17. The apparatus of claim 16, wherein the predetermined plurality of sequential preview images comprises sequential images photographed before and after a time point of the shutter press operation.

18. The apparatus of claim 16, wherein the processor comprises a face image classification basis information collecting unit, and the extracted facial information is facial image classification basis information collected by the face image classification basis information collecting unit.

19. The apparatus of claim 18, wherein the processor is further configured to perform simulation based on the facial image classification basis information of all of the sequential preview images.