PHOTOGRAPHING APPARATUS, METHOD OF CONTROLLING THE SAME, AND COMPUTER-READABLE RECORDING MEDIUM

A method of controlling a photographing apparatus is provided that includes: setting a first exposure time according to a user's input; determining a number of times photographing is performed according to an illuminance and the first exposure time; continuously capturing a plurality of still images the number of times photographing is performed; and generating a resultant image corresponding to the first exposure time by combining the captured plurality of still images.

DETAILED DESCRIPTION

The following description and the attached drawings are provided for better understanding of the invention, and descriptions of techniques or structures related to the invention which would be obvious to one of ordinary skill in the art will be omitted.

Various embodiments of the invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those of ordinary skill in the art.

FIG. 1is a block diagram illustrating a photographing apparatus100according to an embodiment of the invention.

The photographing apparatus100may include a photographing unit110, an analog signal processing unit120, a memory130, a storage/read control unit140, a data storage unit142, a program storage unit150, a display driving unit162, a display unit164, a central processing unit/digital signal processor (CPU/DSP)170, and a manipulation unit180.

An overall operation of the photographing apparatus100is controlled by the CPU/DSP170. The CPU/DSP170applies control signals to the lens driving unit112, the iris driving unit115, and the imaging device control unit119.

The photographing unit110which is an element for generating an image of an electrical signal from incident light includes a lens111, the lens driving unit112, an iris113, the iris driving unit115, an imaging device118, and the imaging device control unit119.

The lens111may include a plurality of groups of lenses or a plurality of lenses. A position of the lens111is adjusted by the lens driving unit112. The lens driving unit112adjusts a position of the lens111according to a control signal applied by the CPU/DSP170.

An extent to which the iris113is opened/closed is adjusted by the iris driving unit115, and the iris113adjusts the amount of light incident on the imaging device118.

An optical signal passing through the lens111and the iris113reaches a light-receiving surface of the imaging device118to form an image of a subject. The imaging device118may be a charge-coupled device (CCD) image sensor a complementary metal-oxide semiconductor image sensor (CIS) which converts the optical signal into an electrical signal, or any other similar imaging device. A sensitivity of the imaging device118may be adjusted by the imaging device control unit119. The imaging device control unit119may control the imaging device118according to a control signal automatically generated by an image signal input in real time or a control signal manually input by a user's manipulation.

An exposure time of the imaging device118is adjusted by a shutter (not shown). The shutter may be a mechanical shutter that adjusts incidence of light by moving the iris113or an electronic shutter that adjusts exposure by applying an electrical signal to the imaging device118.

The analog signal processing unit120performs noise reduction, gain adjustment, waveform shaping, analog-to-digital conversion, etc., on an analog signal applied from the imaging device118.

The analog signal processed by the analog signal processing unit120may be input to the CPU/DSP170through the memory130, or may be directly input to the CPU/DSP170without passing through the memory130. The memory130functions as a main memory of the photographing apparatus100and temporarily stores necessary information during an operation of the CPU/DSP170. The program storage unit150stores programs including an operation system, an application system, and so on for driving the digital photographing apparatus100.

In addition, the photographing apparatus100includes the display unit164that displays information about an image obtained by the photographing apparatus100or an operating state of the photographing apparatus100. The display unit164may provide visual information and/or acoustic information to the user. In order to provide the visual information, the display unit164may include, for example, a liquid crystal display (LCD) panel or an organic light-emitting display panel. Alternatively, the display unit164may be a touchscreen that may recognize a touch input.

The display driving unit162applies a driving signal to the display unit164.

The CPU/DSP170processes an image signal input thereto, and controls each element according to the image signal or an external input signal. The CPU/DSP170may perform image signal processing such as noise reduction, gamma correction, color filter array interpolation, color matrix, color correction, or color enhancement on input image data to improve image quality. Also, the CPU/DSP170may generate an image file by compressing image data generated by performing the image signal processing for improving image quality, or may restore image data from the image file. An image compression format may be reversible or irreversible. In the case of a still image, examples of the image compression format may include a joint photographic experts group (JPEG) format and a JPEG 2000 format. Also, in the case where a moving picture is recorded, a moving picture file may be generated by compressing a plurality of frames according to the moving picture experts group (MPEG) standard. The image file may be generated according to, for example, the exchangeable image file format (Exif) standard.

The image data output from the CPU/DSP170is input to the storage/read control unit140directly or through the memory130, and the storage/read control unit140stores the image data in the data storage unit142automatically or according to a signal from the user. Also, the storage/read control unit140may read data about an image from an image file stored in the data storage unit142, and may input the data to the display driving unit162through the memory130or another path to display the image on the display unit164. The data storage unit142may be detachably attached to the photographing apparatus100or may be permanently attached to the photographing apparatus100.

Also, the CPU/DSP170may perform color processing, blur processing, edge emphasis, image analysis, image recognition, image effect processing, and so on. Examples of the image recognition may include face recognition and scene recognition. In addition, the CPU/DSP170may perform display image signal processing for displaying the image on the display unit164. For example, the CPU/DSP170may perform brightness level adjustment, color correction, contrast adjustment, contour emphasis, screen splitting, character image generation, and image synthesis. The CPU/DSP170may be connected to an external monitor, may perform predetermined image signal processing to display the image on the external monitor, and may transmit processed image data to display a corresponding image on the external monitor.

Also, the CPU/DSP170may generate a control signal for controlling auto-focusing, zoom change, focus change, auto-exposure correction, and so on by executing a program stored in the program storage unit130or by including a separate module and may provide the control signal to the iris driving unit115, the lens driving unit112, and the imaging device control unit119to control operations of elements included in the photographing apparatus100such as a shutter and a strobe.

The manipulation unit180is an element through which the user may input a control signal. The manipulation unit180may include various functional buttons such as a shutter-release button for inputting a shutter-release signal by exposing the imaging device118to light for a predetermined period of time to take a photograph, a power button for inputting a control signal to control power on/off, a zoom button for widening or narrowing a viewing angle according to an input, a mode selection button, and a photographing setting value adjustment button. The manipulation unit180may be embodied as any of various forms that allow the user to input a control signal such as buttons, a keyboard, a touch pad, a touchscreen, and a remote controller.

FIG. 2is a block diagram illustrating a CPU/DSP170aand the photographing unit110according to an embodiment of the invention.

Referring toFIG. 2, the CPU/DSP170aincludes an exposure time setting unit210, a photographing control unit220, and an image combining unit230.

The exposure time setting unit210sets a first exposure time that is a total exposure time of a resultant image according to the user's input. In the present embodiment, the user may set the first exposure time that is greater than a maximum exposure time allowed by the photographing apparatus100. In the present embodiment, the user may photograph a subject, for example, a waterfall, a fountain, bubbles, a firework, a night scene, or stars, for an exposure time greater than an exposure time allowed by the photographing apparatus100to show all tracks of the subject. For example, even when a maximum exposure time allowed by the photographing apparatus100is 1 second, the user may set the first exposure time to 5 seconds. The user may set the first exposure time in various ways. For example, the user may directly set the first exposure time or indirectly set the first exposure time to be long, medium, and short. Also, the user may give an input through the manipulation unit180.

In the present embodiment, long exposure photographing may be performed in a specific mode that may be set by the photographing apparatus100. When the photographing apparatus100is set to a specific mode, the exposure time setting unit210may provide a user interface through which the user may set the first exposure time.

The photographing control unit220determines a number of times photographing is performed according to an illuminance and the first exposure time. Also, the photographing control unit220controls the photographing unit110to continuously capture a plurality of still images, and the determined number of times photographing is performed.

FIG. 3is a diagram for explaining a process of capturing a plurality of still images, according to an embodiment of the invention.

The first exposure time is set by the exposure time setting unit210according to the user's input as described above. The photographing control unit220controls the photographing unit110to continuously capture a plurality of still images in order to generate a resultant image corresponding to the first exposure time. To this end, the photographing control unit220determines a number of times photographing is performed for the first exposure time. For example, the photographing control unit220may determine a range of an exposure time needed to capture each still image according to the illuminance and may determine a number of times photographing is performed according to the determined range of the exposure time. A second exposure time for which each still image is exposed may be determined by dividing the first exposure time by the number of times photographing is performed.

In the present embodiment, the number of times photographing is performed is determined according to the illuminance and the first exposure time. A range of an exposure time needed to capture each image according to the illuminance may be determined and the number of times photographing is performed may be determined. Also, the number of times photographing is performed may be determined in consideration of both the illuminance and an iris value.

Once the number of times photographing is performed and the second exposure time are determined, the photographing control unit220controls the photographing unit110to continuously capture the plurality of still images, and the number of times photographing is performed. The plurality of still images may be captured in various ways. For example, the plurality of still images may be captured in response to a shutter-release signal, may be captured when there is no movement of the photographing apparatus100, or may be captured with a timer.

Also, the photographing control unit220may control an operation of capturing the plurality of still images according to a type of a shutter included in the photographing unit110. For example, when the shutter is a mechanical shutter that blocks incident light by moving a blade, the photographing control unit220controls the photographing unit110to capture the plurality of still images at time intervals according to a movement of the shutter and reads out the captured images. Alternatively, when the shutter is an electronic shutter such as a rolling shutter which controls an exposure time by using an electronic film, the photographing control unit220may control the electronic film to continuously capture the plurality of still images.

The photographing unit110continuously captures the plurality of still images, and the number of times photographing is performed for the second exposure time under the control of the photographing control unit220. Also, the photographing unit110applies the captured plurality of still images to the image combining unit230.

The image combining unit230generates a resultant image corresponding to the first exposure time by combining the plurality of still images. Referring toFIG. 3, when a still image is continuously captured4times in order to capture a resultant image Ioutcorresponding to the first exposure time, a plurality of still images I1, I2, I3, and I4are generated by the photographing unit110. The image combining unit230generates the resultant image Ioutby combining the plurality of still images I1, I2, I3, and I4. In the present embodiment, the resultant image Ioutmay be an image generated by summing brightness values of pixels of the plurality of still images I1, I2, I3, and I4through linear combination. When the brightness values of the pixels of the plurality of still images I1, I2, I3, and I4are summed up, saturation may occur due to high brightness values of pixels of the resultant image lout thereby not displaying the subject or reducing contrast. In the present embodiment, however, when the brightness values of the pixels of the plurality of still images I1, I2, I3, and I4are summed through linear combination, in order not to saturate the brightness values of the pixels of the resultant image Iout, linear combination may be performed by adjusting weights applied to the brightness values of the pixels of the plurality of still images I1, I2, I3, and I4. For example, when the number of times photographing is performed is 4, the resultant image Ioutmay be generated by multiplying the brightness values of the pixels of the still images I1, I2, I3, and I4by ¼ to obtain reduced brightness values and summing the reduced brightness values.

In the present embodiment, when a mechanical shutter is used, the image combining unit230may combine the plurality of still images by correcting a global motion generated due to the mechanical shutter.

In the present embodiment, the user may obtain a resultant image having an exposure time greater than a maximum exposure time which the user may set. Also, even when long exposure photographing is performed by mounting a filter or the like on a lens barrel, the maximum exposure time which the user may set has a limitation and an additional accessory is needed. In the present embodiment, however, long exposure photographing may be performed without mounting an additional accessory. Also, in the present embodiment, even when the user is inexperienced in manipulating the photographing apparatus100, the user may easily perform long exposure photographing.

FIG. 4is a view illustrating the resultant image Ioutand the plurality of still images I1, I2, and I3, according to an embodiment of the invention. In the present embodiment, the resultant image Ioutwhich is a long exposure image may be generated by continuously photographing a firework to obtain the plurality of still images I1, I2, and I3.

FIG. 5is a view illustrating resultant images Iout1and Iout2according to an embodiment of the invention. The user may adjust effects of the resultant images Iout1and Iout2by adjusting the first exposure time. For example, the resultant image Iout2ofFIG. 5is obtained by setting the first exposure time to be greater than that of the resultant image Iout1. As shown inFIG. 5, effects of tracks along which objects move vary according to the first exposure time.

FIG. 6is a flowchart illustrating a method of controlling the photographing apparatus100, according to an embodiment of the invention.

Referring toFIG. 6, in operation S602, a first exposure time is set according to the user's input. InFIG. 6, the first exposure time may be set only when the photographing apparatus is set to a specific mode.

In operation S604, a number of times photographing is performed to obtain a plurality of still images is determined according to an illuminance. InFIG. 6, the number of times photographing is performed may be set in consideration of the illuminance and an iris value. Also, a second exposure time applied to each of the plurality of still images is determined according to the number of times photographing is performed.

Next, in operation S606, the plurality of still images are continuously captured, and the number of times photographing is performed. Each of the plurality of still images is captured for the second exposure time.

In operation S608, a resultant image corresponding to the first exposure time is generated by combining the plurality of still images. The resultant image may be generated by summing brightness values of pixels of the plurality of still images through linear combination. In this case, the brightness values of the pixels of the plurality of still images may be linearly combined so as not to saturate brightness values of pixels of the resultant image.

Alternatively, whenever a still image is input from the photographing unit110, the image combining unit230may combine a current stored combined image with the input still image. In the present embodiment, since only one combined image and one still image are temporarily stored in the memory130without temporarily storing all of the plurality of still images, a space of the memory130may be saved. Also, even the photographing apparatus100having a limited space of the memory130may capture a long exposure image.

FIG. 7is a flowchart illustrating a method of controlling the photographing apparatus100, according to another embodiment of the invention.

In operation S702, a first exposure time is determined according to the user's input. In operation S704, a number of times N photographing is performed to obtain continuously captured still images is determined according to an illuminance and the first exposure time. Next, in operation S706, a variable n indicating a current number of times photographing is performed is set to 1. In operation S708, a first still image I1is captured. In operation S710, the variable n is increased by 1. In operation S712, a second still image I2is captured. In operation S714, a combined image Ynis generated according to Equation 1.

where Yn(x, y) indicates a brightness value of each pixel of the combined image Yn, Yn-1(X, y) indicates a brightness value of each pixel of a currently stored combined image obtained by combining still images from the first still image i1to an n-1thstill image In, and In(x, y) indicates a brightness value of each pixel of a still image input from the photographing unit110.

In operation S716, it is determined whether the variable n is equal to the number of times N photographing is performed. Operations S710, S712, and S714are repeatedly performed until an Nthinput image INis input and a combined image YNis generated. In operation S718, when the Nthinput image INis input and the combined image YNis generated, a resultant image Ioutmay be obtained.

For example, when a total number of times N photographing is performed is 4, a resultant image Ioutis generated as shown by Equation 2.

In the present embodiment, a combined image may be generated whenever a still image is input, and contributions of a plurality of still images in a resultant image may be the same. The earlier an image is captured and input, the more image combination processes the image undergoes. In the present embodiment, contributions of a plurality of still images in a resultant image may be the same by making a weight applied to an existing combined image greater than or equal to a weight applied to an input still image.

FIG. 8is a block diagram illustrating a CPU/DSP170band the photographing unit110according to another embodiment of the invention. Referring toFIG. 8, the CPU/DSP170bmay include the exposure time setting unit210, the photographing control unit220, the image combining unit230, and a movement detecting unit810.

In the present embodiment, only when there is no movement of the photographing apparatus100, may long exposure photographing be performed. Long exposure photographing may be effectively performed when there is no movement of the photographing apparatus100and only a specific subject moves. Accordingly, when there is a movement of the photographing apparatus100, it is difficult to obtain a long exposure image having a desired effect. In the present embodiment, since a plurality of still images are captured only when there is no movement of the photographing apparatus100or a movement is less than a reference value, a resultant image desired by the user may be obtained.

In the present embodiment, the movement detecting unit810detects whether there is a movement of the photographing apparatus100.

For example, the movement detecting unit810may be embodied as a sensor (e.g., a gyro sensor) that directly detects a movement of the photographing apparatus100. In this case, the movement detecting unit810may be disposed outside the CPU/DSP170b, unlike inFIG. 8.

Alternatively, the movement detecting unit810may detect a movement of the photographing apparatus100from an image input from the photographing unit110. The image input from the photographing unit110may be, for example, a live-view image.

In the present embodiment, the photographing control unit220may continuously capture a plurality of still images only when the movement detecting unit810determines that there is no movement of the photographing apparatus100or a movement is less than a reference value.

For example, when it is determined that there is no movement or a movement is less than a reference value, the photographing apparatus100may enter a specific mode in which long exposure photographing is performed.

Alternatively, the photographing control unit220may continuously capture a plurality of still images only when it is determined that there is no movement or a movement is less than a reference value. In this case, even when a shutter-release signal is input, if a movement is equal to or greater than a predetermined value, the photographing control unit220may not capture a plurality of still images. For example, the photographing control unit220may automatically capture a plurality of still images when a movement is equal to or less than a predetermined value.

In the present embodiment, the image combining unit230may combine a plurality of still images by correcting a global motion due to a movement generated in the plurality of still images according to movement information obtained by the movement detecting unit810.

FIG. 9is a flowchart illustrating a method of controlling the photographing apparatus100, according to another embodiment of the invention.

Referring toFIG. 9, in operation S902, a first exposure time is determined. In operation S904, a number of times photographing is performed is determined according to an illuminance and the first exposure time.

In operation S906, a movement of the photographing apparatus100is detected. In operation S908, it is determined whether the movement is equal to or greater than a reference value. In the present embodiment, determination may be performed in various ways. For example, it may be determined whether there is a movement or a movement is equal to or less than a reference value.

When it is determined in operation S908that the movement is equal to or greater than the reference value, the plurality of still images are not captured. When it is determined in operation S908that the movement is less than the reference value, the method proceeds to operation S910. In operation S910, the plurality of still images are captured for a second exposure time the determined number of times photographing is performed. Next, in operation S912, a resultant image corresponding to the first exposure time is generated by combining the plurality of still images.

FIG. 10is a view illustrating a user interface screen according to an embodiment of the invention.

Referring toFIG. 10, when a movement is equal to or greater than a predetermined value, the movement detecting unit810or the photographing control unit220may output to the user an alarm message through the display unit164, a warning light, or a sound. For example, the movement detecting unit810or the photographing control unit220may display an alarm message on the user interface screen as shown inFIG. 10.

According to the one or more embodiments, a user may easily capture a long exposure image.

Also, according to the one or more embodiments, even a low specification photographing apparatus may capture a long exposure image.

The apparatus described herein may include a processor, a memory for storing program data and executing it, a permanent storage unit such as a disk drive, a communication port for handling communications with external devices, and user interface devices, etc. Any processes may be implemented as software modules or algorithms, and may be stored as program instructions or computer readable codes executable by a processor on computer-readable media such as read-only memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes, floppy disks, and optical data storage devices. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. This media can be read by the computer, stored in the memory, and executed by the processor.

While the invention has been particularly shown and described with reference to exemplary embodiments thereof by using specific terms, the embodiments and terms have merely been used to explain the invention and should not be construed as limiting the scope of the invention as defined by the claims. The exemplary embodiments should be considered in a descriptive sense only and not for purposes of limitation. Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope will be construed as being included in the invention.