Electronic camera with quick view and quick erase features

An electronic camera includes a sensor for capturing an image, an electronic image display for displaying the captured image, and a user interface for selectively enabling a quick view feature in which the image display is automatically turned on for a set period of time after an image is captured, and then automatically turned off, in order to quickly review the captured image. The camera further includes a processor for performing processing on the captured image and generating a processed image file therefrom, and a memory for storing the processed image file. When an erase command is provided to the processor, the processing of the image file is terminated and the partially completed image file is deleted from the second memory.

FIELD OF THE INVENTION

The invention relates generally to the field of electronic photography, and in particular to digital cameras having an image display and review capability.

BACKGROUND OF THE INVENTION

Some electronic cameras in the prior art use an electronic image display, such as a liquid crystal display (LCD), for image review both before and after capture. In these cameras, the LCD display is powered on prior to image capture, since the LCD is used to review the image prior to capture. For example, in the electronic camera described in U.S. Pat. No. 4,456,931, initial depression of the shutter release causes a motion image to be displayed on a monitor on the camera. Further depression of the shutter release causes a still image to be captured from the motion sequence, stored in a buffer memory, and displayed on the monitor. Complete depression of the shutter release causes the transfer of the still image in the buffer memory to a separate output memory system. In prior art cameras of this type, considerable power is dissipated in sustained operation of the image display for image review prior to capture.

Some digital cameras rely on an optical viewfinder for composing images and an image display, such as an LCD display, for viewing captured still images. For instance, in Ser. No. 08/803,342, entitled “Electronic Camera with Quick Review of Last Captured Image”, filed Feb. 20, 1997 in the name of the same assignee as the present application, an electronic camera has a working memory for storing a working image corresponding to the last captured image and a non-volatile memory, such as internal flash memory or a removable memory card. When an image is captured, the image data is stored in the working memory, and the image data is also immediately processed for storage in the non-volatile memory. The working image is displayed on a display screen in a quick review mode of operation in response to user actuation of a quick review switch. The display screen is thus kept in an inactive state until the quick review is requested, and returns to an inactive state after a predetermined time period or when the quick review switch is again activated. In this manner, energy to drive the display screen may be conserved.

In the Kodak DC25 camera, which includes an optical viewfinder and a color LCD display, a still image is read from its sensor and temporarily stored in a buffer memory. The image is then read from the buffer, processed, and stored on a removable memory card, which altogether typically takes 5 to 10 seconds. Since the color LCD requires a backlight in order to provide a bright image, it draws a substantial amount of power when it is turned on. To allow reduced battery drain, the DC25 camera includes a display switch so the user can manually turn the display on and off. In order to immediately view images captured by the DC25 camera, the user must first push the display switch to turn on the display before capturing an image. Therefore, the LCD display is powered even during the time the user is looking through the optical viewfinder to compose an image. Once the user presses a shutter button and takes an image, a low resolution version of the image from the buffer memory is immediately displayed on the LCD display. At the same time a high resolution version is being processed and stored in the removable memory card.

In order to reduce memory space, the DC25 camera includes an erase button that can be used to delete one or more images from the removable memory. If the displayed image is unacceptable, the user typically wants to immediately erase the unacceptable image and take a new picture of the same scene. With the DC25 camera, however, the user must wait until the high resolution processing is completed, which takes 5 to 10 seconds. Therefore, the user is not able to immediately take a new image, but must instead wait until the processing of the undesired image is completed. As a result, the camera wastes battery power by creating and storing an image file that will be immediately deleted. Moreover, the picture opportunity may be lost due to the interim wait.

In the type of camera that relies on an optical viewfinder for image composition, what is needed is an LCD based camera design that enables users to quickly view and (when desired) immediately erase newly taken images, while minimizing the camera battery drain by powering the LCD only when necessary to review an image.

SUMMARY OF THE INVENTION

The present invention is directed to overcoming one or more of the problems set forth above. Briefly summarized, according to one aspect of the present invention, an electronic camera includes a sensor for capturing an image, an electronic image display for displaying the captured image, and a quick view feature in which the image display is automatically turned on for a period of time after an image is captured, and then automatically turned off. The quick view feature is embodied in a control section responsive to the quick view feature for powering up the image display after the image is captured by the sensor in order to display the captured image, and then automatically turning off the image display after the period has elapsed.

In a further embodiment, the camera includes a first buffer memory for storing the captured image, a processor for performing image processing on the captured image over a period of time and generating a processed image file therefrom, and a second memory for storing the processed image file. The user interface further provides an erase command to the processor, which responds to the erase command by terminating the processing of the image file and deleting the partially completed image file from the second memory.

Typically, the image is read from the buffer, processed, and stored on a removable memory card, which typically takes 5 to 10 seconds. The advantage of the invention lies in the “quick view” feature, which reduces battery drain. When this feature is enabled, the LCD display is turned on immediately after each picture is taken, typically for about 3 seconds, and then turned off. This allows the user to verify that an acceptable image was taken. If so, the user waits until the processing is completed, and can then take the next image. The LCD display remains “off” most of the time to reduce battery drain, without requiring the user to manually turn it on and off. When displaying a newly taken image, the LCD display includes an “erase” icon. If a user does not want to keep a new image, a delete key is pressed. This immediately stops the current image from being processed. Therefore, a new image can be taken immediately, rather than waiting for the processing to be completed.

DETAILED DESCRIPTION OF THE INVENTION

Because digital cameras employing electronic sensors and electronic processing and storage are well known, the present description will be directed in particular to elements forming part of, or cooperating more directly with, apparatus in accordance with the present invention. Elements not specifically shown or described herein may be selected from those known in the art. Certain aspects of the embodiments to be described may be provided in software. Given the system as described in the following materials, all such software implementation needed to practice the invention is conventional and within the ordinary skill in such arts.

Referring first toFIG. 1, a digital camera10includes a zoom lens section12for directing image light toward an image sensor14, a processing section16, and a removable output memory18, such as a flash memory card. The image sensor14is typically a color sensor, and includes a color filter array, such as the well-known Bayer pattern (see U.S. Pat. No. 3,971,065). The processing section16includes an analog signal processing A/D converter20, a DRAM buffer memory22, an image processing block24(which may be a programmable DSP capable processor, such as a Hitachi SH-DSP processor), and an output interface26to the removable memory18. The output interface26is a memory card interface adapted to a conventional card interface standard, such as the PCMCIA card interface standard, such as described in thePC Card Standard, published by The Personal Computer Memory Card International Association, Sunnyvale, Calif., March 1997. The removable memory18accordingly is a non-volatile PCMCIA memory card containing either solid state memory, such as Flash EPROM memory, or a small hard drive (categorized as a PCMCIA-ATA Type III Hard Drive under the PCMCIA card interface standard). Another card interface standard is the CompactFlash ATA with DOS file format. Alternatively, other non-volatile storage devices may be used, such as a floppy disk magnetic medium or optical storage (in such cases, a suitable interface and a conventional read/write apparatus would be provided in the camera10, e.g., a magnetic or optical read/write head).

The DRAM buffer memory22has sufficient memory space for at least one full resolution image captured by the image sensor14. The camera10also includes a zooming optical viewfinder28, an image liquid crystal display (LCD)30, a control section31including a control processor and timing generator32, a flash unit34, a status LCD36, and a user interface comprising a group of user controls38. Nearby, or within, the optical viewfinder is a ready light40that is connected to the control processor and timing circuit32. A set of autofocus and autoexposure detectors42provide data to the control processor and timing circuit32for driving zoom and focus motors44connected to the zoom lens12, and for enabling clock drivers46in order to activate the image sensor14.

The control section31further includes a power management controller48, which is connected to the control processor and timing generator32for conserving power demands by the various components of the camera10. Power supplied by batteries50is applied on demand to the clock drivers46, the processing section16, and the image LCD30. More specifically, a capture power enable line52supplies power to the clock drivers46and the analog signal processing and A/D converter20and a separate process power enable line54supplies power to the DRAM buffer memory22, the image processing block24, and the memory card interface26. The power management controller48also enables LCD drivers56to input data from the DRAM buffer memory22to the image LCD30, and further enables an LCD backlight58to provide a variable amount of backlight to the image on the image LCD30. In the preferred embodiment, the image LCD30is a color LCD for displaying color images.

FIG. 2Ashows a view of the camera10from the front, showing the aforementioned zoom lens section12, the optical viewfinder28, the flash unit34, and certain of the user controls38—including a shutter button60, and telephoto and wide angle buttons62,64for controlling the zoom lens section12. The camera also includes a viewfinder cover63which is slid open (as shown inFIG. 2A) to power up the camera.FIG. 2Aalso shows a pair of autofocus sensors65. The image LCD30is part of a flip up section66on the back of the camera10.FIG. 2Bshows the camera back with the flip up section “down”, andFIG. 2Cshows the camera back with the flip up section “up”. The camera back includes the aforementioned image LCD30, the status LCD36, the back of the optical viewfinder28, the ready light40, and a further set of user controls38—including a TAB button68, a select button70, and an enter button72for the status display36; and a quick view switch74, an erase button76, and display button78for the image LCD30. The status LCD36displays camera status information, such as the number of images that can still be stored, the flash setting (auto, off, fill), the battery level, and the compression level setting. The tab, select, and enter buttons68,70,72enable the user to modify these settings. When the flip-up screen66is “up”, as shown inFIG. 2C, a cover80for the batteries50is revealed, as well as a card slot82for the removable memory18, a card eject button84, and an LCD brightness wheel86for controlling the LCD backlight58. A handle88is further included on the side of the camera10for hand holding the camera.

A flow diagram of the steps involved in a typical picture-taking situation is shown inFIG. 3, and will be referenced in connection with the following operational description of the camera. The user turns the camera on by sliding open the viewfinder lens cover63(step100ofFIG. 3), which enables a hidden power switch (not shown). When the camera is powered up, the image LCD30initially remains off, to save power, and the ready light40in the viewfinder28is turned on (step102), indicating to the user that the camera is ready to take a picture. If the auto exposure detector42reads a low ambient light condition, the flash34is turned on, and the ready light40does not light until the flash is sufficiently charged. When the quick view switch74is set to its “on” position (step104), the camera LCD operates in the quick view mode as images are captured.

The user looks through the optical viewfinder28to compose the image (step106), pressing the telephoto or wide angle buttons62,64to set the zoom lens to the desired focal length. Once the picture is composed, the user presses the shutter button60(step108). The camera control processor and timing generator32then generates the signals that expose the sensor14, and clock out the sensor signal. The analog signal from the sensor is processed in the analog signal processor20, which performs correlated double sampling and A/D conversion, and then stored in the DRAM buffer memory22(step110).

If the quick view mode is enabled (step112), the image processing block24subsamples the high resolution Bayer color filter array image stored in the buffer memory22in order to create an image with the proper number of pixels needed for the display on the image LCD30(step114). The subsampled image is then stored back into the buffer memory22. This processing can be done quickly, typically in less than 1 second. The image LCD30is then turned on, and the image is retrieved from the buffer22and displayed on the screen of the image LCD30for a predetermined period of time. This predetermined period of time may be a set period of time, for example 3 seconds (step116), a period of time adjustable by the user, or a period of time that corresponds to the processing time in the image processing block24. In the latter case, the predetermined period of time may vary somewhat depending on the extent of processing that occurs. This allows the user to review the image, to see if it is acceptable. After the preset time, the image LCD30is turned off, in order to minimize the battery drain (step118). (Alternatively, if battery drain is not of major concern, the image LCD30may stay on until the quick view switch74is again pressed—perhaps with backup auto turnoff after, say, 10 seconds.)

Once the LCD size image is stored in the buffer memory22(step114), the image processing block24begins processing the full resolution Bayer image (step120). This processing includes, for example, color filter array interpolation, white balance, color correction, edge enhancement, image compression, and file formatting. The resulting image file is stored on the removable memory card18in a standard image file format, such as the JPEG interchange format (JIF) described in ISO/IEC 10918-1:1994. A typical JPEG compression algorithm is the Discrete Cosine Transform (DCT). Depending on the size of the sensor14and the amount of detail in the scene, this processing may take 5 to 10 seconds to complete. Based on the image displayed on the image LCD30, the user may decide that the picture just taken is unacceptable, for example if the framing was not good, or if the subject of the picture was not smiling. Rather than wait for the image to be completely processed and stored, the user can press the erase button76(step122). This immediately halts the image processing (step124), and causes the partially completed JIF file to be deleted from the memory card18(step126). The ready light is then illuminated, indicating that the camera is immediately ready to take the next picture (step128). If the erase button is not pressed, the image processing is completed as normal (step130).

As mentioned above, the camera provides the image LCD30with three controls: the quick view switch74, the erase button76, and the display button78. When the display button78is pushed, the screen of the image LCD30displays the last image stored on the removable memory card18. The image LCD30can be turned off by pressing the display button78a second time. In the image review mode, the zoom buttons62,64are additionally used to cycle through the images stored on the card in forwards or backward order. An image may be erased from the card by using the erase button76. The erase button76is positioned at a level below the camera case, to reduce the chance of accidental erasures.

The invention has been described with reference to a preferred embodiment. However, it will be appreciated that variations and modifications can be effected by a person of ordinary skill in the art without departing from the scope of the invention. For example, while the preferred embodiment shows a switch for enabling the quick view feature, the camera may be designed such that the feature is always enabled and therefore always provides a timed replay of the just-captured image. Moreover, the invention can also be applied to a motion sequence capture device, e.g., the burst capture mode of a still camera, where the quick view feature would entail replay of one or more images in the burst sequence.

PARTS LIST