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Digital Camera Patent Abstract
A digital camera is connected to a computer through a serial terminal.
The computer is connected to a server through an internet. To the
server, the digital camera transmits uncompensated image data to
which no defect pixel compensation is applied, and defect pixel
information preliminarily read from a nonvolatile memory. The server
analyses this image data to compare with the defect pixel information,
and then creates new defect pixel information. The new defect pixel
information is transmitted to the digital camera, and additionally
written to the nonvolatile memory. The digital camera compensates
image data obtained by image capturing, based on the defect pixel
information.
Digital Camera Patent Claims
1. A digital camera, which includes a solid state imaging device
having a plurality of pixels for photoelectrically converting a
subject image to obtain image data of said subject image, comprising:
a rewritable nonvolatile memory for storing defect pixel information
about defect pixels; a compensation processing section which applies
defect pixel compensating process to said image data based on said
defect pixel information stored in said nonvolatile memory; a communicating
section for transmitting uncompensated image data to a server through
an internet and for receiving new defect pixel information from
said server, said uncompensated image data being image data to which
said defect pixel compensating process is not applied, and said
new defect pixel information being obtained by analysis of said
uncompensated image data performed by said server; and a defect
pixel information recording section which updates said nonvolatile
memory with said new defect pixel information.
2. A digital camera claimed in claim 1, wherein said communicating
section transmits said defect pixel information with said uncompensated
image data to said server.
3. A digital camera claimed in claim 1, wherein said communicating
section transmits unique identification information of said solid
state imaging device with said uncompensated image data to said
server.
4. A digital camera claimed in claim 1, wherein said communicating
section has a serial terminal for serial communication with an external
computer, said external computer accessing said internet for internet
communication with said server.
5. A defect pixel compensation system comprising: A. an imaging
apparatus including: a solid state imaging device having a plurality
of pixels for photoelectrically converting a subject image; a rewritable
nonvolatile memory for storing defect pixel information about defect
pixels; and a compensation processing section which applies defect
pixel compensating process to said image data based on said defect
pixel information stored in said nonvolatile memory, and B. a server
for analyzing uncompensated image data received from said imaging
apparatus to create new defect pixel information and transmitting
said new defect pixel information to said imaging apparatus, said
uncompensated image data being image data to which said defect pixel
compensating process is not applied.
6. A defect pixel compensation system claimed in claim 5, wherein
said imaging apparatus comprises: a communicating section for transmitting
said uncompensated image data to said server through an internet
and for receiving said new defect pixel information from said server;
and a defect pixel information recording section which updates said
nonvolatile memory with said new defect pixel information.
7. A defect pixel compensation system claimed in claim 6, wherein
said server analyzes said uncompensated image data to compare with
said defect pixel information, said server creating said new defect
pixel information by adding positions of said new defect pixels
to said defect pixel information when detecting new defect pixels
generated by aging degradation.
8. A defect pixel compensation system claimed in claim 6, wherein
said server has a defect pixel information memory for preliminarily
storing said defect pixel information and analyzes said uncompensated
image data to compare with said defect pixel information in said
defect pixel information memory, said server creating said new defect
pixel information by adding positions of said new defect pixels
to said defect pixel information memory when detecting new defect
pixels generated by aging degradation.
9. A defect pixel compensation system claimed in claim 8, wherein
said defect pixel information memory has plural recording regions
each of which contains said defect pixel information and unique
identification information of a solid state imaging device incorporated
in each of imaging apparatuses, said imaging apparatus transmitting
said identification information with said uncompensated image data
to said server, said server creating said new defect pixel information
by adding positions of said new defect pixels to said recording
region designated by said identification information.
10. A defect pixel compensation system claimed in claim 6, wherein
said communicating section has a serial terminal for performing
serial communication with an external computer, said external computer
accessing said internet for performing internet communication with
said server.
11. A defect pixel compensation system claimed in claim 6, wherein
said communicating section has a wireless communication function
and wirelessly accesses said internet for performing internet communication
with said server.
Digital Camera Patent Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a digital camera which
compensates defect pixels of a solid state imaging device, and a
system for compensating defect pixels of a solid state imaging device.
[0003] 2. Description Related to the Prior Art
[0004] In recent years, a digital camera having a solid state imaging
device such as a CCD sensor or a CMOS sensor is used. Since such
solid state imaging device has at least millions of pixels, it is
practically difficult to produce the solid state imaging device
with no defect pixel. Accordingly, there is a need to use the solid
state imaging device in view of the presence of certain defect pixels.
[0005] The defect pixel is a pixel which does not output the signal
correctly corresponding to subject brightness. For example, there
are a white defect pixel which generates signal (charge) even when
the light is not entered and a black defect pixel which does not
generate signal (charge) even when the light is entered. The white
defect makes a picture pixel brighter, and the black defect makes
a picture pixel darker. To prevent a deterioration of image quality
caused by the defect pixel, it is already developed a digital camera
which compensates the signals of defect pixels by software process.
[0006] In digital cameras disclosed in Japanese Patent Laid-Open
Publications No. 2000-059690 and No. 05-068209, defect pixels of
a solid state imaging device are detected in a production process
by a defect inspection machine. Then information of position, kind
and degree of the defect of each defect pixel is stored for example
in a memory incorporated in the digital camera. Accordingly, output
signal of the defect pixel can be compensated by interpolating the
output signal of the defect pixels with the output signal of surrounding
normal pixels. The solid state imaging devices are expected to have
more and more pixels, and therefore the accurate compensation of
the defect pixels is essential to increase quality of product.
[0007] However, in the digital cameras disclosed in the Japanese
Patent Laid-Open Publications No. 2000-059690 and No. 05-068209,
although the defect pixels detected at a factory can be compensated,
defect pixels newly generated by aging degradation of the solid
state device after shipment cannot be compensated.
SUMMARY OF THE INVENTION
[0008] An object of the present invention is to provide a digital
camera and a defect pixel compensation system which enable to compensate
defect pixels generated by aging degradation of a solid state imaging
device.
[0009] In order to achieve the above object and other objects,
a digital camera of the present invention comprises a rewritable
nonvolatile memory for storing defect pixel information, a compensation
processing section which applies defect pixel compensating process
to image data based on the defect pixel information in the nonvolatile
memory, a communicating section for transmitting uncompensated image
data to a server through an internet and for receiving new defect
pixel information from the server, and a defect pixel information
recording section which updates the nonvolatile memory with the
new defect pixel information. The uncompensated image data is image
data to which said defect pixel compensating process is not applied,
and the new defect pixel information is obtained on analysis of
the uncompensated image data performed by the server.
[0010] A defect pixel compensation system of the present invention
comprises an imaging apparatus and a server. The imaging apparatus
compensates image data of defect pixels with use of defect pixel
information. The server analyzes uncompensated image data received
from the imaging apparatus to create new defect pixel information
and transmitting the new defect pixel information to the imaging
apparatus.
[0011] According to the present invention, the defect pixel information
can be updated at any timing only by the access of the imaging apparatus
to the server through the internet. Accordingly, it is possible
to compensate the image captured by the solid state imaging device,
which includes the defect pixels generated by the aging degradation,
without using a tool such as a flash memory writer. Therefore, even
if the defect pixels are generated during the lifetime of the solid
state imaging device, the image with high quality can be obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The above objects and advantages of the present invention
will become easily understood by one of ordinary skill in the art
when the following detailed description would be read in connection
with the accompanying drawings.
[0013] FIG. 1 is a block diagram showing a construction of a digital
camera of the present invention;
[0014] FIG. 2 is a block diagram showing a construction of a DSPLSI
in the digital camera;
[0015] FIG. 3 is a schematic view of a defect pixel compensation
system comprised of a server and a digital camera or a camera phone.
[0016] FIG. 4 is a flowchart showing updating processes for defect
pixel information based on the defect pixel information memorized
in the digital camera or the camera phone; and
[0017] FIG. 5 is a flowchart showing updating processes for defect
pixel information based on the defect pixel information memorized
in the server.
PREFERRED EMBODIMENTS OF THE INVENTION
[0018] As shown in FIG. 1, a CCD imaging device 3 is provided behind
a taking lens 1 and a mechanical shutter 2. The taking lens 1 is
moved toward a focal point by a lens driver 5, which is controlled
by a central control circuit 4, and focuses a subject light on the
CCD imaging device 3. The mechanical shutter 2 is normally in an
open state. It is set in a closed state when exposure time passed
after the start of image taking action by release operation of a
user. Then it is set in the open state again after the image taking
action.
[0019] The CCD imaging device 3 has a plurality of pixels and converts
an optical image of the subject focused on the pixels into electrical
signals. A CCD driver 6 generates transfer pulses and feeds them
to the CCD imaging device 3. The CCD imaging device 3 outputs image
signals based on the transfer pulses.
[0020] To the CCD imaging device 3, a CDS (correlated double sampling)
circuit 7 is connected. The CDS 7 is for reducing noises, and is
driven by drive pulses outputted from the CCD driver 6. To an output
terminal of the CDS 7, an A/D converter 8 is connected. The A/D
converter 8 converts the image signal of analog into digital signal
(image data) and outputs the image data. The image data of each
pixel obtained through the A/D converter 8 is temporarily stored
in an image memory 9.
[0021] The image data stored in the image memory 9 is subject to
various image processes performed by the central control circuit
4 and is finally recorded in a recording medium 10 such as a memory
card or a magnetic optical disc. One of the image processes is a
process for compensating the image data from the defect pixels of
the CCD imaging device 3 (defect pixel compensation process).
[0022] In the central control circuit 4, a DSPLSI 18 is provided
for performing the defect pixel compensation process. To the central
control circuit 4, a serial terminal 11 for accessing a FLASH ROM
34 incorporated in the DSPLSI 18 is connected. In addition, to the
central control circuit 4, an LCD driver 17 for driving an LCD 16
is connected.
[0023] Next, the DSPLSI 18 will be described in detail with reference
to FIG. 2. The DSPLSI 18 comprises a DSP 30 for performing the image
processes, a CPU 33 which controls each process and reads/writes
data from/to each device (a shared memory 31, a work SRAM 36, the
FLASH ROM 34, the LCD driver 17 and the recording medium 10) through
a CPU bus 32, the shared memory 31 from/to which both the DSP 30
and the CPU 33 can read/write data, and the work SRAM 36 storing
data to be processed by the CPU 33. In addition, the DSPLSI 18 comprises
the FLASH ROM 34 which is a nonvolatile memory storing data including
a serial number of the CCD imaging device 3 and the defect pixel
information showing positions of the defect pixels, and a FLASH
ROM interface 35 which is a circuit for communicating with a computer
through serial communication to read out data stored in the FLASH
ROM 34 and to write data into the FLASH ROM 34.
[0024] The defect pixel information and the serial number is written
in the FLASH ROM 34 in a production process of a digital camera
40. The defect pixel information is used to determine the positions
of the defect pixels, and the serial number is used to authenticate
the CCD imaging device 3 when updating of the defect pixel information
through the communication with the server 45.
[0025] Since new defect pixels are generated in the CCD imaging
sensor 3 by time deterioration after shipment, the update of the
defect pixel information is required. As shown in FIG. 3, the user
connects the digital camera 40 to the computer 43 at an appropriate
timing to update the defect pixel information from the server 45
through an internet 44.
[0026] The FLASH ROM interface 35 outputs the serial number of
the CCD imaging device 3, the defect pixel information and image
data for a defect pixel analysis to the server 45 through the serial
terminal 11 according to control signal from the CPU 33. The image
data for the analysis is image data which is read from the recording
medium 10 and written in the FLASH ROM 34 by the CPU 33. In addition,
the FLASH ROM interface 35 receives an authentication completion
notice of the serial number of the CCD imaging device 3 and renewed
defect pixel information, from the server 45 through the serial
terminal 11. This reception is informed to the CPU 33 by control
signal from the CPU 33. When receiving the renewed defect pixel
information, the FLASH ROM interface 35 updates the defect pixel
information stored in the FLASH ROM 34.
[0027] The CPU 33 reads out the defect pixel information, which
is used by the DSP 30 for the image compensation, from the FLASH
ROM 34 and writes it to the shared memory 31. The DSP 30 performs
the defect pixel compensation process to the image data stored in
the image memory 9 using the defect pixel information written in
the shared memory 31, and writes the compensated image data into
the shared memory 31. The defect pixel compensation process may
be the interpolation of the output signal from the defect pixels
with the output signal from surrounding normal pixels. Then the
image data in the shared memory 31 is written in the recording medium
10 by the CPU 33. To reproduce the image, the CPU 33 reads out the
image data from the recording medium 10, and outputs the image data
to the LCD 16 through the LCD driver 17. Note that in the work SRAM
36, data used by the CPU 33 to perform each process is stored.
[0028] For the connection between the digital camera 40 and the
computer 43, one end terminal of a serial cable 42 is connected
to the serial terminal 41 of the digital camera 40, and the other
end terminal of the serial cable 42 is connected to a serial terminal
of the computer 43. The computer 43 accesses the internet 44 for
communicating with the server 45. The computer 43 stores a software
for mutually converting the serial communication between the computer
43 and the digital camera 40 and the internet communication between
the computer 43 and the server 45.
[0029] With reference to FIG. 4, the operation of the server 45
and the digital camera 40 for updating the defect pixel information
will be described. In the updating, at first the CCD serial number
stored in the FLASH ROM 34 is transmitted to the server 45. The
server 45 performs authentication of the CCD serial number, to determine
whether the CCD imaging device 3 is the authenticated product or
not. When the CCD serial number is not authenticated, the updating
is stopped. When the CCD serial number is authenticated, the server
45 transmits the authentication completion notice to the digital
camera 40. The digital camera 40 transmits the defect pixel information
and the image data for the defect pixel analysis stored in the FLASH
ROM 34 to the server 45 after receiving the authentication completion
notice. The image data for defect pixels is image data previously
captured by the user, to which the defect pixel compensation process
is not applied.
[0030] The server 45 analyzes this image data to compare with the
defect pixel information, and determines positions of defect pixels
newly generated by the aging degradation. When there is no new defect
pixel, the server 45 stops the updating. When there are new defect
pixels, the server 45 creates the new defect pixel information by
adding the positions of the new defect pixels to the received defect
pixel information, and transmits the new defect pixel information
to the digital camera 40. The digital camera 40 receives the new
defect pixel information, and updates the defect pixel information
stored in the FLASH ROM 34.
[0031] In the above embodiment, the defect pixel information is
stored in the digital camera and transmitted to the server from
the digital camera. However, the defect pixel information may be
stored in a memory of the server preliminarily. In this case, as
shown in a flowchart of FIG. 5, the defect pixel information is
obtained from a defect pixel information memory provided in the
server. The defect pixel information memory has plural storing regions
respectively assigned to each of the CCD serial numbers, and the
defect pixel information determined in the production process is
stored in the corresponding storing region. After completing the
receive of the CCD serial number from the digital camera and the
authentication of the CCD serial number, the server searches the
storing regions of the defect pixel information memory to obtain
the defect pixel information corresponding to the CCD serial number.
Then the server analyzes image data received from the digital camera
to compare with the defect pixel information, and determines positions
of defect pixels newly generated. When there is no new defect pixel,
the server stops the updating. When there are new defect pixels,
the server creates the new defect pixel information by adding the
positions of the new defect pixels to the defect pixel information
memory, and transmits the new defect pixel information to the digital
camera.
[0032] In the above embodiment, the digital camera 40 is used in
the defect pixel compensation system. However, a camera phone 46
also may be used in this system. In this case, the camera phone
46 communicates with the server 45 through a wireless communication
function incorporated in the camera phone, to perform the processes
shown in FIG. 4 and FIG. 5. Accordingly, the updating of the defect
pixel information can be performed as same as the system with the
digital camera 40. In addition, although the CCD imaging device
is used in the above embodiment, a CMOS imaging device also may
be used.
[0033] Although the present invention has been fully described
by way of the preferred embodiments thereof with reference to the
accompanying drawings, various changes and modifications will be
apparent to those having skill in this field. Therefore, unless
otherwise these changes and modifications depart from the scope
of the present invention, they should be construed as included therein.
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