FR2915816A1 - Image e.g. photograph, acquiring method, involves introducing control for selecting visual characteristic, acquiring image by adjusting lens with new focal distance, and storing data of image by associating to photograph capturing control - Google Patents

Abstract

The method involves acquiring an image with a focal distance calculated from an object at center of the image. A control is introduced for selecting a visual characteristic from a set of visual characteristics, and the image is detected from a zone possessing the selected visual characteristic. A photograph capturing control is introduced to trigger the calculation of new focal distance based on the detected zone. Another image is acquired by adjusting the lens with new focal distance, and the data of the latter image is stored by associating to the photograph capturing control. An independent claim is also included for an image acquiring apparatus, comprising a control introduction unit.

Description

The present invention relates to the field of image acquisition

  using a camera with a photographic lens.

  Many models of digital cameras are currently on the market. The image is projected into the camera on a CCD or CMOS sensor, converted to digital data and stored in a memory. Thanks to digital technology, the user takes a photograph and can see it immediately afterwards on a small screen usually located on the back of the camera. The user checks the quality of the displayed image and decides whether to keep the photograph by storing it in a removable medium, or to erase it. Most cameras now have digital zoom and analog zoom. Digital zooming involves taking only a portion of the digital data converted by the CCD or CMOS sensor. Generally, it is the central part, the peripheral part of the acquired digital image is not preserved in the data of the photograph. The analog zoom acts on the optical part of the camera, it makes it possible to enlarge and reduce the width of the image field that reaches the CCD or CMOS sensor. In the case of a digital zoom, magnification causes precision to be lost because only part of the data from the sensor is kept. The digital data corresponding to the photograph taken are incorporated into a file that can be transferred to a computer. The computer can store them in an album, and display them on demand. Generally the focus of the image is made at the moment the user presses the shutter button. The focus is set on the object in the middle of the image perceived by the sensors. Some devices are able to automatically detect a silhouette within the image and determine how far away from the camera. The camera then adjusts the focal length so that the detected silhouette is sharp. But, this option is fixed in the operation of the device, so there is a real need to make more flexible the ability to develop a photograph by focusing on areas of interest.

  The subject of the invention is a method for acquiring an image by an apparatus capable of acquiring an image comprising a lens whose focal length is adjustable, comprising a step of acquiring a first image with a first focal length calculated from the object in the center of the image and a step of introducing a command to take a photograph; characterized in that it comprises the steps of: -introducing a command to select a visual characteristic from among several visual characteristics, io-detecting within the first image at least one area having the selected visual characteristic, the step of introducing a shot control of a photograph triggering the calculation of a new focal distance based on a detected area, acquisition of a second frame by setting the lens with this new focal length and storing the data of this second image by associating them with the photographing control. Thus, the focal length of the photograph associated with the shooting control is automatically calculated using a visual characteristic selected by the user. In this way, the user can select the type of object of most interest and which should not be blurred in the final photograph. According to a first refinement, if multiple areas having the selected characteristic are detected in the first image, then the user can input a command to select the area used to adjust the focal length. In this way, the user chooses precisely the object with the most interest and which must not be blurred in the final photograph. According to another improvement, the camera displays several second images, each of these second images being focused on a different zone. The user selects a second image by introducing a single command when that second image is displayed. In this way, just a simple touch to select the object with the most interest.

  According to another improvement, the camera records part of the second image delimited by the area, the recorded data then represent the acquired image. In this way, the amount of data for photograph storage is optimized.

  According to another improvement, an optical zoom enlarges the second image, the enlarged image portion having the zone having the characteristic selected by the user. In this way, the image thus stored has a better definition. According to another improvement, the camera stores the image portion delimited by the zone 10 with the maximum accuracy of encoding. In this way, this part of the image can be reproduced with a better definition. According to another improvement, the camera also stores the entire first image, the first and the second recorded image representing the acquired image. In this way, the user can optionally view the image whose focal length is calculated from the object in the center, or the image whose focal length is calculated on an object having a specific visual characteristic. According to another improvement, the apparatus comprises a computer connection means making it possible to download a program for the detection of a visual characteristic. Once downloaded, this program can be selected to calculate the focal length on an object having this visual characteristic. In this way, the camera can increase its detection capabilities.

  The invention also relates to an image acquisition apparatus comprising means for introducing a command, a lens whose focal length is adjustable, and means for acquiring a first image with a first image. focal length calculated from the object in the center of the image; characterized in that the input means makes it possible to select a visual characteristic from among several visual characteristics, and in that it comprises a detection means within the first image of at least one area having the selected characteristic, a control of taking a photograph introduced on the introduction means triggering the adjustment of the focal length of the lens on a detected area, acquiring a second image with the new focal distance, and storing the data of this second image by associating them with the control of photography.

  Other features and advantages of the invention will now become apparent in greater detail in the context of the following description of exemplary embodiments given by way of illustration with reference to the appended figures which represent: FIGS. 1.b show a front view and a rear view of a camera for implementing an exemplary embodiment of the invention; - FIG. 2 an example of a flow chart of the main steps performed for the implementation. 3.a, 3.b and 3.c show screen appearances displayed by the camera with focal lengths calculated on various objects.

  First, the operation of a digital camera 1 will be described, as shown in FIGS. 1.a and 1.b. The camera is an example of image acquisition means, it goes without saying that any other image acquisition means such as a video recorder, a camera, a videoconferencing tool, ... between in the field of the present invention. Figures 1.a and 1.b show a front view and a rear view of a camera. We will first list the main elements for carrying out the present invention. Externally, the digital camera 1 has a lens 2, a screen 3 of LCD or OLED technology, an optionally removable memory module 4, and buttons 5 command introduction, navigation (typically four direction keys: 4, T, 4 and F) and adjustment. The 30 buttons make it possible, among other things, to place the device 1 either in the shooting mode where the screen 3 displays the image detected by the CCD sensors, or in the reproduction mode of stored contents where the images recorded in the memory module 4 are 3. Camera 1 also has a CPU (not shown) directly connected to program memory for command management and image scanning. According to some models, the commands are accessible by icons displayed on the screen 3. An icon is highlighted and the associated function is executed by pressing the OK key. The camera 1 has many shooting modes, including one for recording a photograph with its sound environment, called Taking pictures with sound. It is also possible to record a sound sequence using a microphone 6 arranged on the front panel and to play it back by a small speaker 7 during the reproduction of the audiovisual sequences recorded in the camera 1. Optionally, the camera has a connector 8 for establishing a computer connection with another device, for example a laptop and thus to transmit visual and sound content. Typically, the communication is via a USB link. Photos are saved in files that are transferred to the computer. The user can see his photos on a large screen and listen to the sound content through speakers connected to a computer. Having detailed the main components of an exemplary apparatus 20 for putting the invention, we will explain how they cooperate.

  The flowchart of FIG. 2 describes the progress of the main steps of the method according to an exemplary embodiment of the invention. In step 2.1, the user turns on his camera 1, the lens 2 is removed from its slot and if the camera is in the shooting mode, the screen 3 displays the image captured by Objective 2. The user presses a configuration key and displays the menu for initializing the configuration parameters. In the Choice of a visual characteristic menu, it selects a visual characteristic possibly present in the image captured by the objective (step 2.2). This menu presents the visual characteristics detectable in image zones, each characteristic corresponding to a specific detection algorithm: - face detection (the targeted zone corresponds to a face), - silhouette detection (the targeted zone corresponds to a silhouette ), - detection of a tree (the target area corresponds to an entire tree), - detection of a rocky peak (the target zone corresponds to a peak), - detection of a building (the targeted zone corresponds to a façade of a building, or an entire building in aerial view), text detection (the target area corresponds to a document containing text). The selection consists of graphically highlighting the visual characteristic and pressing the OK key. The user wishes to take a photograph and configures his camera by selecting with a button the mode of operation focusing on determined characteristic. The camera acquires the image in front of the lens and displays the image data on the screen 3 (step 2.4). According to a preferred embodiment, the automatic detection of the selected visual characteristic is constantly performed on the image in front of the lens, without the user entering a command. The focal length is then, either fixed by default to infinity, or set on the object in the center of the image. An alternative is that the detection is performed when the user slightly presses the shooting button (step 2.3). In this way, the processor running the detection software is only active at the time of shooting, thereby saving the power source of the apparatus. The software module detecting the visual characteristic takes into account the fact that image parts can be blurred. The software module continuously analyzes the image to determine if there is at least one area in the image having the initially programmed visual characteristic (step 2.5). Typically, the analysis step lasts 40 milliseconds maximum, in this way it is possible to refresh the screen 25 times per second by displaying the detected areas in real time. If no area of the image has the visual characteristic then the focus will be on the central portion 30 of the screen (step 2.6). Otherwise, the focal length is calculated on the detected area (step 2.7) and the mechanical part of the lens is requested to take into account this setting. In step 2.8, the user presses the shooting button which triggers the acquisition of the image in front of the lens followed in step 2.9, of storing the photograph. Figures 3.a, 3.b, and 3.0 illustrate how focus is achieved based on several types of displayed images.

  Figure 3.a illustrates an image detected by the CCD sensor with a focus window in the center of the image. The focus cell is set to calculate the focal length on the object in the middle of the image. This setting defaults when no object is detected in the detection window. Figure 3.b illustrates the same image detected by the CCD as before, but the focusing window is fixed on an object that is not in the center of the image. The camera detected the presence of a face in the right part of the image, and placed the focus window on the object. The focal length is thus calculated with respect to the distance between the camera and the detected face. Figure 3.c illustrates another image detected by the CCD sensor having two focusing windows on two different objects. In this case, the apparatus proposes to the user to make the choice of the object on which the focusing is carried out. Figure 3.c shows a graphic selection frame 20 on the object proposed in priority by the device. If the user wishes to change objects, he or she moves the selection graphic box with the selection keys. Pressing the shutter button focuses on the selected object. According to an improvement, the central unit analyzes the image acquired by the sensors, determines if there are one or more zones having the initially programmed visual characteristic and displays on the screen 3 the acquired image with visual references delimiting the images. detected areas. This display is particularly didactic since the user can easily see the detected areas and find that the image (outside a zone) is blurred. If more than one area is detected, then the screen displays visual identifiers allowing the user to select the area on which focus is being made. According to a preferred embodiment, the user selects an area with the direction keys moving a graphic distinction from one area to another. The Select key validating the choice of the zone is thus highlighted. Another way is that each zone is identified by a number, the user pronounces the correct number. The sound is received by the microphone, a speech recognition engine embedded in the program memory analyzes the sound and recognizes the number spoken. Then, the visual cue of the area identified by this number changes appearance, typically the frame changes color, and the focus setting is based on the area selected by the user. If the objects move in the image received by the apparatus, the zones identifying said objects move in the same way on the screen 3. The highlighting of the objects allows the user to frame the photo so that the detected areas are present at interesting places, most frequently: in the center of the screen. Other methods of selecting zones are possible, in particular by equipping the apparatus 1 with a touch screen and by pressing in the zone delimited by the visual cue. Another method consists in that the central unit successively selects the objects of the captured image having the selected visual characteristic and positions on each object a visual distinction, typically a frame. At the same time, the image displayed on the screen is focused on the object thus highlighted. Then, after a determined duration, typically one second, another object is highlighted. The set of objects thus scrolls in a carousel that stops when an object is selected by the user. The selection can be made by pressing the OK button, or simply by pressing the shutter button fully, which triggers the taking of the photograph. Advantageously, during the carousel, a sound signal is emitted at each change of object. Advantageously, the screen 3 displays the first image whose focal length is calculated from the object in the center of the image, even if this object has no visual characteristic. Then, after the transmission of an audible signal, the screen 3 displays a second image acquired with the focal length 30 set on an object having the visual characteristic selected by the user. In this way, the priority is given to the manual focusing then, it is the visual characteristic detection algorithm that takes the hand and selects the objects for the calculation of the focal length.

  According to one variant, the visual characteristic selected by the user determines the zone of the image taken for the photograph. Suppose for example, an image with many objects including several people, if the visual characteristic is a silhouette, the photograph taken is framed on a particular individual, and only this silhouette is stored in the device. In this way, the user does (practically) no longer need to frame the photographs on a part of the image having a specific characteristic. The apparatus performs this operation automatically using a detection algorithm. An improvement of this variant consists in using the optical zoom to improve the definition of the image finally extracted from the captured image. This enhancement can only be used if the object selected by the camera is in the central area of the captured image. Optical zoom makes it possible to improve the definition of an object taken from a distance. For example if the dimensions of the area of the object are one-fourth in height and width of the image at the start, the area actually stored corresponds to one sixteenth of the captured image. Take an optical zoom to enlarge the image 3 times, if the area of the object can be enlarged in these proportions, the loss of quality 20 is only 9 / 16. A variant allows to maintain a good quality of the final image extracted from an area containing an object, is to use the maximum precision. Indeed, generally the user sets his camera so that in normal, the definition is average, which minimizes the memory size of the acquired photo and limit the encoding time. According to the variant, the encoding process only takes the pixels of the area of the image containing the object and this encoding is carried out with maximum precision. An improvement consists in memorizing two photographs during each shooting, the so-called main photograph is taken by setting the focal length on the object in the middle of the captured image. The second photograph is that of a zone containing the visual characteristic previously selected by the user. Advantageously, this second photograph is done with the maximum resolution since this zone contains a visual characteristic that is selected by the user. The two photographs are memorized under the same reference, pressing a key during the reproduction makes it possible to switch from one to the other. In this way, when reproducing photographs by a reproduction device, the user sees the image as it was framed, and another image benefiting from the framing made by the device. The transition from one to the other taking place by pressing a key. The user can choose to keep one or the other (or both) photographs. An improvement is that the camera uses the connector 8, which typically allows a USB connection, to download new visual character detection software from a computer. Once loaded into the device, these programs are identified by a name, for example face, tree, building, text, etc. A menu displays the different identifiers and the arrow keys allow navigation. Pressing the Select key validates the user's choice.

  Although the present invention has been described with reference to the particular embodiments illustrated, it is not limited by these embodiments, but only by the appended claims.

The invention also applies to Reflex cameras where the image in front of the lens is divided by a prism to be visible on the camera's eyepiece. In this case, the camera does not need an external screen 3 but is capable of embedding graphic characters in the visible image in the eyepiece. It should be noted that any means of navigation equivalent to the direction keys 25 is likely to apply for the implementation of the invention.

Claims (9)

claims   A method of acquiring an image by an apparatus capable of acquiring an image (1) comprising an objective (2) whose focal length is adjustable, comprising a step of acquiring (2.4) a first image with a first focal length calculated from the object in the center of the image and a step of introducing a control of taking a photograph; characterized in that it comprises the steps of: - introducing a command (2.2) to select a visual characteristic from among several visual characteristics, - detecting (2.5) within the first image of at least one area having the selected visual characteristic, the step of introducing a shot control of a photograph triggering the calculation (2.7) of a new focal distance based on a detected area, the acquisition (2.8) of a second image by setting the objective with this new focal length and, the memorization (2,9) of the data of this second image by associating them with the control of photography.   2. Method of acquiring an image according to claim 1; Characterized in that if multiple areas having the selected characteristic are detected in the first image, then it includes a step of inputting a command to select the area used to adjust the focal length.   3. Method of acquiring an image according to claim 2; Characterized in that it comprises a plurality of second image display steps, each of the second images being focused on a different area, the selecting step of inputting a command at the time of displaying a second image. 30   4. A method of acquiring an image according to any one of the preceding claims; characterized in that it comprises a step of recording (2.9) the portion of the second image delimited by the area, the recorded data representing the acquired image.   5. Method of acquiring an image according to claim 4; characterized in that it comprises a step of enlarging the second image with an optical zoom, the enlarged image portion having the area having the selected feature.   6. A method of acquiring an image according to any one of claims 4 or 5; characterized in that the step of recording the image portion delimited by the area is performed with the maximum accuracy of encoding   7. A method of acquiring an image according to any one of claims 4 to 6; characterized in that it comprises another recording step which stores the whole of the first image, the two recorded images representing the acquired image.   8. A method of acquiring an image according to any one of claims 1 to 7; characterized in that it comprises a step of downloading into the apparatus (1) a software element for detecting a visual characteristic in the first image, this program being activated by the selection command.   An image acquisition apparatus (1) comprising means for introducing (5) a control, a lens (2) whose focal length is adjustable, and a means for acquiring a first image with a first focal length calculated from the object in the center of the image; characterized in that the insertion means (5) makes it possible to select a visual characteristic from among several visual characteristics, and in that it comprises a detection means within the first image of at least one zone having the selected characteristic. a shot control of a photograph input to the input means (5) triggering adjustment of the focal length of the lens to a detected area, acquisition of a second picture with the new focal distance, and memorizing the data of this second image by associating them with the photographing control.