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Sony’s CMOS Sensors:
Exceptional Imaging Quality and Speed
High-Speed CMOS Sensor and Camera Systems Creating a New Imaging World |
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Record moving picture
and still shots seamlessly |
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Camera shake correction
for still images using
multiplane addition
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High-speed imaging
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Figure 1 The Future High-Speed Imaging World
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Starting with their adoption in cellular
phones in 2002, Sony’s CMOS sensors for
megapixel class camera cellular phones,
digital high-definition video cameras, and
Digital Single Lens Reflexs (DSLRs) have
become widely used in commercial
products. The greatest strength of CMOS
sensors is that by including both digital
and analog circuits on the same chip, their
readout speed can be made dramatically
faster than that of CCD. Sony is now pushing forward with the development of high-speed CMOS sensors for digital cameras
that can provide continuous imaging from
all pixels at the high frame rate of 60
frame/s. Sony is also developing in parallel a camera digital signal processor (DSP)
that can take full advantage of this performance. Sony is now proposing a new
way of enjoying photography in which one
photographs and records images without
concern for the difference between moving images and still images by using this
frame readout of 60 frame/s high-speed
CMOS sensor and new camera DSP.
This reality is close at hand. A new digital camera that makes it fun to photograph,
fun to look at your photographs and moving images, and fun to show them to
people. |
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Life You Wanted to Capture.
Moments You Missed. |
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Recently, the trend towards higher pixel
counts in consumer digital cameras has
continued, and it is now possible to take
high-resolution still images conveniently.
Sony has, until now, focused its efforts in
the image sensor area on increasing the
pixel count (shrinking the size of the unit
pixel)and improving the pixel’s characteristics to achieve high-resolution still
imaging and has contributed to increasing the popularity of digital cameras. We
feel, though, that we can say that we have
now achieved a level higher than just capturing “pretty” images. We think that from
here on, what will become important for
the further development of digital
cameras is evolving from recording still
images to the digital camera being a tool
for communication and self expression
using moving images.
One theme for that evolution that we can
present is high frame rate imaging at high
pixel counts. In particular, if it will become possible to shoot continuously at 60
frame/s at a high pixel count, while the individual images that make up the moving image will have the quality of still
images and the dividing line between still
and moving images will blur. Since the
user can take moving and/or still images
without concern for the difference, a previously unavailable expressive power will
become available. Although the message
delivered by a single still image is not
large, by interweaving that still images
with moving images, the amount of information that can be transmitted increases dramatically, and a strong impact
can be delivered to the viewers. Furthermore, choosing the one “that’s it!” image
from the 60 frame/s of high-resolution
images captured in a second allows one
to find the perfect shutter moment after
the fact.
Sony, in aiming for an image sensor that
can capture and express surprise and
emotion, is now putting its efforts into the
development of both a CMOS sensor that
can express, in particular, motion and the
beauty of a moment and a camera DSP
that can get the full performance from that
sensor. Sony’s theme for this effort is capturing “Life you wanted to capture. Moments you missed.” Sony is committed
to contributing to this new imaging world. |
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Capturing the “Perfect
Shot” from a Moving Picture |
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Up to now image sensors have been able
to read out the entire frame at only a few
frames per second. Additionally, when
switching to moving picture mode, a few
frames at the beginning and the end will
not be output correctly. Therefore, a user
trying to take that “perfect shot” while
capturing moving picture would lose that
shot and the moving picture would be
stopped for a few frames. Even if the user
succeeded in getting that “perfect shot”,
the critical scene would be missing from
the moving picture. So users have to give
up on capturing moving picture for the
scene if they want to capture a still shot.
If, however, still images are captured
seamlessly at 60 frame/s during moving
picture, it would be possible to dramatically increase the flexibility of imaging.
The user could, without concern for any
limitations on imaging, freely record moving picture that is no interrupted for stills,
and capture the scenes before and after a
still image without interrupting the moving picture. For example, if your child hits
a winning home run in the bottom of the
ninth, you would not be limited to a single
still photograph, but could see that image
woven into the continuous moving picture. Were this possible, the feeling of live
performance, dynamism, and import of
that single image would be amplified. We
hope this ability dramatically increases the
impact that photographs have on people.
(See figure 2.)
This functionality would be effective at
a variety of events, such as parties and
wedding receptions. Furthermore, raw
footage of mixed still and moving images
acquired together can be processed with
software to create TV commercials or
promotion video class productions and
expressions, even from ordinarily photographed scenes.
Figure 2 Record Moving Picture and Still Shots Seamlessly
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High Picture Quality that
Captures the Moment |
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Although image quality improves as you
increase the amount of information
captured, until now, still image picture
quality has been improved by increasing
the spatial resolution. However, the
amount of information can be increased
not only by increasing the spatial resolution, but by increasing the amount of
information in the time direction as well.
Picture quality can be greatly increased
by increasing this time direction information.
• Multiplane Addition
Recently, the number of users who want
to shoot indoors or evening/night scenes
cleanly and preferably without flash has
been increasing. Thus cameras that boast
camera shake correction or high ISO sensitivity have appeared in the market.
These products adopt either camera shake
correction functions in the lens or high-sensitivity image sensors.
However, there is another way to achieve
camera shake correction and higher
sensitivity (higher signal-to-noise ratio).
This method consists of continuous
imaging of the entire frame at 60 frame/s,
and using this increased amount of information in the time direction to create a
single high-quality image. This can be
implemented in a total camera system that
includes a camera DSP. For example, if
someone applies multiplane addition to
several images that were captured at 60
frame/s, an image with a signal-to-noise
ratio several times better can be acquired.
(See figure 3.) Also, a high-speed camera
shake correction function can be implemented if images are stacked while applying camera shake correction to each
image. (See figure 4.) This function can
make it possible to capture bright, camera-shake-free images even without an inlens camera shake correction function
even in slightly darker environments
where camera shake can easily occur,
such as school festivals, children’s plays
or presentations, or indoor events. |
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The More Clearly You See
Life, the Better It Gets |
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People are often surprised and moved by
images and moments that normally cannot be seen. Moving picture at high frame
rates, that is frame rates far in excess of
60 frame/s, can arouse our sleeping
curiosity and lead to new, previously unknown, surprises and discoveries. The
high-speed imaging achieved by high-speed CMOS sensors also have the possibility for creating new cameras. The
world of high-speed imaging, which was
previously only used for special applications by organizations such as TV stations, can now be implemented easily for
consumer products is truly revolutionary.
There are many situations where it can
be fascinating to play back high-speed
video in slow motion. These include
checking a golf or baseball swing, reviewing your children’s sports or a goal they
made at a school sporting event with the family. Or, by academics in various fields
to find out how birds take off from the
water, how a water balloon breaks, or how
other natural phenomena occur. (See
figure 5.) If you add appropriate background music, these slow-motion videos
can be truly moving. If we modify the
CMOS sensor readout method slightly, it
will be comparatively easy to create high-speed imaging at over 60 frame/s. Sony
is working to create high-speed CMOS
sensors that can easily capture events that
exceed the capabilities of the human eye. |
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Future Developments |
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Sony has developed image sensors that
take the utmost advantage of the high-speed characteristics of Sony’s CMOS
technology for applications such as hard
disk video recording and seamless
capture of moving and still images. Sony
is also aiming at achieving high-speed
imaging in the several hundred frame/s
range and is searching for possibilities for
new types of digital cameras. Sony is
aiming to increase the number of pixels
that can be read out at 60 frame/s and to
achieve even higher speed imaging to
contribute to a new axis of high-quality
multifunctional digital camera products.
By combining the pixel design technologies fostered in Sony’s CCD work with
Sony’s CMOS analog and digital circuit
technologies, Sony delivers products that
lead to even further productivity in the
imaging world. Keep your eye on Sony
for even more exciting developments in
our CMOS sensor area. |
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See
all articles with figures and tables.  |
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Vol.43 |
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