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Digital Camera Patent Abstract
The invention relates to a digital camera device for identifying
an object, and to a method and a computer program for producing
the same. According to prior art, digital camera devices comprising
an objective, a light sensor and an image producing device are known.
It is also known that the recorded images have a distortion effect
that depends on the focal length of the objective, said distortion
effect until now being corrected by calculation in the image producing
device during processing of the image. The claim of the invention
is to render one such calculated correction superfluous. Towards
this end, the density of pixel elements is determined according
to the focal length of the objective for the flat arrangement of
said pixel elements in the light sensor device.
Digital Camera Patent Claims
8. A digital camera device for detecting an object, in particular
in the environment of a vehicle, the device comprising: a lens member
for the acceptance and further passage of light representing the
object; a light sensor member having a plurality of pixel elements
disposed in flat arrangement, wherein each pixel element produces
a pixel signal which represents an intensity of light transported
from said lens member onto that pixel element, wherein a density
of said pixel elements within said light sensor member is distributed
in dependence on a geometric shape or an index of refraction of
said lens member; and an imaging member for production of an image
signal from a plurality of pixel signals representing a recorded
object.
9. The digital camera device of claim 8, wherein said density of
pixel elements is defined in dependence on a focal length of said
lens member.
10. The digital camera device of claim 8, wherein said camera device
is at least partially configured as a CMOS or CD imaging chip.
11. A method for production of a digital camera device having a
lens member and a light sensor member disposed downstream of the
lens member and having a plurality of pixel elements in flat arrangement,
the method comprising the following steps: a) determining a density
distribution of the pixel elements in dependence on a geometric
shape or an index of refraction of the lens member; b) initially
manufacturing pixels in a region of high pixel density; and c) subsequently
producing regions having lower pixel density.
12. The method of claim 11, wherein the density distribution of
the pixel elements is defined by a focal length of the lens member.
13. A computer program having a program code configured to calculate
the distribution of the density of pixel elements for the light
sensor member according to the method of 11.
Digital Camera Patent Description
[0001] The invention concerns a digital camera device as well as
a method and a computer program for its production.
[0002] Digital camera devices are known in the art for recording
an object which may be located in the environment of a vehicle.
These types of camera devices usually include a lens device for
the acceptance and further passage of light representing the object.
These devices also have a light sensor device comprising a plurality
of pixel elements distributed in flat orientation, with the pixel
elements being evenly distributed within the flat area, e.g. their
density is constant throughout the area of the light sensor device.
Each pixel element produces a signal which represents the intensity
of the light passed from the lens device onto the corresponding
pixel element. The camera device also includes an imaging device
for the production of an image signal from the plurality of pixel
signals, which represents the recorded object.
[0003] When a camera device of this type is utilized for the examination
of the environment of the vehicle it is usually configured in such
a way as to image as wide a field of view as possible. This wide
field of view is usually realized by configuring the lens device
with a very short focal length. The short focal length, however,
has the disadvantage of associated distortion effects (so-called
fish-eye effect). The distortions in the image of a recorded object
caused by these effect increase with decreasing focal length.
[0004] These distortion effects are conventionally corrected by
software in the imaging device of the digital camera device.
[0005] Departing from this prior art, it is the purpose of the
present invention to further improve a conventional camera device
and a method as well as a computer program for its production in
such a fashion that correction of the distortion effects is at least
substantially avoided.
[0006] This purpose is achieved with the camera device in accordance
with claim 1. The object the invention is achieved for the above
described camera device in that the density of the pixel elements
in the flat arrangement of the light sensor device is determined
in dependence on the focal length of the lens device.
[0007] "Density of pixel elements" within the sense of
the current invention refers to the number of pixel elements per
unit area.
ADVANTAGES OF THE INVENTION
[0008] The proposed determination of the density of the pixel elements
in the flat disposition of the sensor device advantageously permits
correction of the distortion of imaging information caused by the
lens device. This hardware correction obviates the need for software
corrections (calculated corrections) in the imaging device during
image processing.
[0009] Advantageously, not only the density but also its distribution
in the flat configuration is optimized to correct for the distortions.
Towards this end not only the focal length but also the geometric
shape and index of refraction of the lens device are advantageously
taken into consideration.
[0010] The claimed digital camera device is advantageously at least
partially configured as a complementary symmetry metal oxide semi-conductor
CMOS or as a charged couple device CCD imaging chip.
[0011] The above mentioned purpose of the invention is also achieved
by a method and by a computer program for the production of a digital
camera device and, in particular, a light sensor device.
[0012] In carrying out that method, regions of the flat light sensor
device having highest pixel density are advantageously initially
calculated and produced and regions having lower pixel density are
subsequently calculated and produced. This simplifies production
of the chips.
[0013] The method and the computer program also share the advantages
mentioned above with respect to the digital camera device.
DRAWINGS
[0014] FIG. 1 shows the structure of a digital camera device;
[0015] FIG. 2 is a first embodiment of a configuration of the light
sensor device in accordance with the invention; and
[0016] FIG. 3 is a second embodiment of a configuration of the
light sensor device in accordance with the invention.
[0017] The invention as described in detail below using two embodiments
with reference to the accompanying drawings.
[0018] FIG. 1 shows the basic construction of a digital camera
device 100. The camera device 100 serves to recognize an object
200, in particular in the environment of the vehicle. Towards this
end, the device comprises a lens device 110 for the acceptance and
further passage of light representing the object 200. The lens device
110 is, in the simplest case, a single lens. Light passed through
the lens device 110 is incident on a light sensor device 120 comprising
a plurality of pixel elements 122-1 . . . -N, disposed in flat arrangement.
When activated, each of these pixel elements, produces a pixel signal
which represents the intensity of the light incident on the corresponding
pixel element. The pixel signals are received by an imaging device
130 disposed downstream of the light sensor 120 and processed to
produce an image signal from a plurality of pixel signals which
represents the recorded object 200. The imaging signal is preferentially
stored in a storage device 140 associated with the camera device
100.
[0019] In accordance with the invention, the light sensor device
120 is configured in such a fashion that the density of its pixel
elements is determined in dependence on the focal length of the
lens device 110. In particular, the density of the pixel elements
is lower for smaller focal lengths than for larger focal lengths,
and vice versa.
[0020] In addition to the focal length, the geometrical shape of
the lens device or its index of refraction should also be taken
into consideration when optimizing the distribution of the density
of pixel elements throughout the flat surface.
[0021] FIG. 2 shows a first embodiment for configuration of the
light sensor device 120 in accordance with the invention and, in
particular, its pixel distribution. The device has a convex lens
device 110 by means of which the light rays passed on to the pixel
elements 120-1 . . . -N diverge. In a lens device of this type 110,
distortion effects occur as the image is expanded. In accordance
with the invention, the separation between neighboring pixel elements
120-1 . . . -N is increased in correspondence with the expansion,
e.g. the density of pixel elements is accordingly reduced.
[0022] FIG. 3 shows a second embodiment for the light sensor device
120 in accordance with the invention. In the event that the lens
device 110 is concave the light ray incident on the pixel elements
122-1 . . . -N converges. Distortion effects are thereby produced
as the image of the object 200 on the pixel elements is compressed.
In this case, the separation between the pixel elements 122-1- .
. . -N is reduced in correspondence with the compression, e.g. the
density of the pixel elements is increased accordingly.
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