Note: Descriptions are shown in the official language in which they were submitted.
CA 02306755 2000-04-12
WO 99/13431 PCT/I89801516
Method for Receiving and Storing Optically
Detectable Data
The present invention relates to a method for recording and
storing optically detectable data of an object on a storage
medium, as defined generically in Patent Claim 1.
Methods of this kind are used in various wavelength ranges, for
example, in the domain of infrared or ultraviolet radiation, of
visible light, or of thermal radiation. Appropriate cameras and
the associated optics are used, depending on the wavelength
range. The object of interest is either recorded as a whole or
in separate sections. Each of the individual recordings is of a
specific size. Because of the settings of the optical components
7.'=~ of the camera, and of the spatial distance between the object and
the camera, the recording will incorporate areas that are sharply
focused or not so sharply focused. A recording that is sharp in
all of its areas cannot be achieved, for only those parts of the
object that lie within the focus of the optical system that is
used will be clearly focused. The focus is spatially limited and
is, in most instances, smaller than the object. Furthermore, if
the object is three-dimensional, not all areas of the surface or
of the layers that lie immediately beneath the surface can be
sharply imaged with the a:id of one recording. In addition, it is
2.5 a further disadvantage that the diaphragm of the camera cannot be
opened wide, so that brilliance of the recording is less, since a
CA 02306755 2000-04-12
WO 99/13431 PCT/IB9801516
widely opened diaphragm reduces the depth of focus, with the
result that only a correspondingly small part of the object can
be sharply imaged.
The prior art (DE 39 31 934 C2, DE 39 05 G19 A1) describes an
image input and output device that incorporates a focusing
system. Using this focusing system, the optical components of the
image~input device are adjusted sharply to a plurality of
different object planes. In order to record image information, a
1U plurality of images of one object are recorded using various
settings of the optical components, and the information obtained
by doing this is combined. Digital methods are used in order to
do this. Using this known device, it is a disadvantage that the
variable adjustment of the optical components requires a
mechanism that moves the optical components with a very high
degree of precision. Such a mechanism is costly to manufacture,
and is vulnerable to damage, wear, and other impairments when it
is used. In addition, because of the various optical settings
that are used, the information can be assembled only at great
cost, since the scale of the images changes for, each recording
because of the changes to the optical components.
In contrast to the foregoing, the method according to the present
invention, which is use for recording and storing optically
-2-
CA 02306755 2000-04-12
WO 99/13431 PCT/IB9801516
detectable data of an object entails the advantage that, using
one camera, a sequence of a plurality of individual recordings of
the object is made using different spatial settings with respect
to the position between the object and the camera. The setting
used for the optical components, and the resulting focus, remain
unchanged when this is done. Because of this, the method is
simpler to use than the methods already known from the prior art.
A mechanism for effecting precise changes to the optical
components is rendered unnecessary. Because of this, application
I~_~ of this method is more cost-effective than previously known
methods and it is less vulnerable to impairments, disruptions, or
wear when it is used.
The sharply imaged areas of the individual recordings are
determined and are assembled, and a plurality of resulting images
are formed therefrom. Since the optical components remain
unchanged during the different individual recordings, the scale
does not change. This leads to the fact that when the individual
recordings are being assembled, there is no need to match these
with respect to scale. Thus, assembly of the information is less
costly than in the case of the known methods.
This method can be used both to record individual images of
objects as well as to record films. The method can be used
-3-
CA 02306755 2000-04-12
WO 99/13431 PCT/IB9801516
manually by cutting out and pasting the sharply focused areas or
this can be done by means of screening. However, this method can
also be used with the aid of a computer. In the case of two
dimensional objects, or in the case of objects of which a two-
s dimensional resulting image will suffice, it can be sufficient to
assemble the sharp areas to form one single resulting image. In
the case of three-dimensional objects, the sharp areas of
different planes of the object can be assembled to form one or a
plurality of resulting images. The latter case entails the
1o advantage that various features will be shown in different
resulting images. Because of this, it becomes simpler to process
the images, in particular with respect to recognizing the
features. It is also possible to assemble different resulting
images for the different depths of penetration into the object
15 that are achieved with the radiation that is used. More
advantageously, the individual recordings can be made with the
camera lens at larger diaphragm apertures. When this is done,
sharp resulting images will be obtained, despite the large
diaphragm apertures. This increases the light sensitivity of the
2o recordings. The camera does not have to be sharply focused for
each individual recording, since the sharp images are selected
electronically, and stored, and images that are not sharp are not
stored. Even if the object moves during the recording process,
-4-
CA 02306755 2000-04-12
WO 99/13431 PCT/IB9801516
the resulting image will be sharp. The number of individual
recordings that are made for each object will depend on the
particular application. As a rule, about twenty individual
recordings is sufficient. However, in certain cases it may be
many more, for example, more than 100 individual recordings, or
it may be fewer, for example, five individual recordings.
Exposure times will be selected depending on the object and the
camera that is used. It depends on the number of individual
recordings that a desired per second or per minute. Many types of
to cameras, for example, CCD cameras, make it possible to reduce the
exposure time electronically.
The objects that are recorded can be machines, structural
elements, works of art, jewellry, or other valuable items, or
they can be individuals or animals. Biometric or anatomical
features are used in order to recognise or identify persons or
animals, in particular breeding animals, and these are recorded
in the individual images. Both intentional as well as
unintentional movements of the object can be used in order to
obtain information. Parallel shifts or rotations that are
perpendicular to the optical axis are used in order to achieve
greater resolution from the camera. Higher resolution can also be
achieved by computation. Parallel shifts of the object
-5-
CA 02306755 2000-04-12
WO 99/13431 PCT/IB9801516
only one camera is used to record a sequence of individual
recordings. When this is done, one exploits the fact that
specific areas of the object that has been recorded can be imaged
in sequences of individual recordings as their sharpness changes
continuously. In this way, it is also possible to obtain
information regarding the topography and the surface
configuration of an object.
Using a sequence of a plurality of recordings made at pre-set
intervals of time, it is a:Lso possible to identify dynamic
processes of the object. Thus, this method permits the
examination of the object over time. This means that movement of
an object can be followed and recorded. This recorded movement
can be used, for example, to disclose or identify the object or
to control specific processes. For example, faulty elements in a
production process can be revealed, or an individual can be
identified. Intentional movements made by an individual can also
supply additional information.
The restricted depth of focus can be used in order to identify,
image, and evaluate features beneath the surface of the object.
-G-
CA 02306755 2000-04-12
WO 99/13431 PCT/IB9801516
The method according to the present invention permits the use of
a large diaphragm aperture. 'this makes it possible to obtain an
image with the specific degree of sharpness.
According to one preferred embodiment of the present invention,
the individual recordings are stored in a computer and the
sharply imaged areas of the individual recordings are determined
by the computer, using digital methods. The resulting images are
assembled with the aid of the computer. Specific and suitable
software is used for this purpose. This software also determines
the limits of the sharply imaged areas. When the resulting image
is being assembled, it is also possible to use knowledge of the
Trelly method that is known from information theory and signal
processing methods. As an example, the individual recordings are
stored in RAM or or on the hard disk of the computer. The
sequence of individual recordings will only be required until
such time as the resulting images is generated. Once this has
been done, the sequence of individual recordings is erased.
It is possible to use different methods in order to generate a
resulting image. Using a first method, n individual images are
filtered with a high pass filter and a sharp areas are copied.
When this is done, the transition frequency of the filter is
matched to the ranges of sharp focus. This filter can also be
CA 02306755 2000-04-12
WO 99/13431 PCT/IB9801516
made up of a number of different filters. In order to do this, it
is possible to use digital methods such as Fourier
transformations, wavelet transformations, digital filters,
differential or difference formation, as well as Bessel,
Butterworth, or Gauss filters. It is also possible to evaluate
other information in addition to the sharply imaged areas of the
individual images; examples of this are the enlargement or
reduction of the imaging relative to the plane of focus in the
areas on both sides of the play the focus. Assembly of the
sharply imaged areas of the individual images is effected, for
example, with the aid of known digital processes. One or more
resulting images will be assembled, depending on the shape of the
object and its surface configuration, as well as the'number of
strata depths or the types of features that are of interest.
In a second method, as compared to the first method, the topology
or morphology of the characteristic features of the object are
also taken into consideration. As an example, if the object to
be recorded is a finger then, using this method, different
?0 principle layers and glands as well as, for example, the
papillary layer and sweat and sebaceous glands can be evaluated.
When this is done, it is possible to take into account the fact
that the papillary lines are largely joined and are on the
surface.
_g_
CA 02306755 2000-04-12
WO 99/13431 PCT/IB9801516
In a third method, three-dimensional resulting images are
generated from the sequence of individual recordings with the aid
of digital functions. Subsequently, such an image can be rotated,
tilted, inclined, or moved in any other way, so that the user can
see various views of the object on the display screen. This
method is particularly suitable in those instances when the data
recorded using the method according to the present invention is
to be~recognized in a data set that is recorded~subsequently. Any
rotation or shifting of the object in the first data set relative
to the second data set can be corrected and compensated for, so
that recognition is nonetheless possible.
According to another advantageous version of the present
invention, the sharply imaged areas are determined by way of
numerical images of the derivative. The derivative is to be
formed in both dimensions of the two-dimensional individual
recordings. The derivative is maximal or minimal at the sharply
imaged locations. The sharply imaged areas can also be obtained
when suitable filters are used, by comparing them with images
recorded using different filters.
In another advantageous version of the present invention, the
parameters for recording the sequence of individual recordings is
-9-
CA 02306755 2000-04-12
WO 99/13431 PCT/IB9801516
predetermined by a computer and the recording sequence is
controlled by this same computer.
According to another advantageous version of the present
invention, recording the sequence of individual recordings is
started automatically. Thus, for example, recording can be
started at a specific time or when the object is in a specific
position. Recording can also be started when the computer that is
processing the individual recordings identifies sharply imaged
1 ~J areas.
In another advantageous version of the present invention,
recording the sequence of individual recordings is started by a
photoelectric barrier. This method is particularly suitable if
the object moves towards and away from the camera during the
recording process. The recording is then started automatically if
the object approaches to within a specific distance from the
camera.
According to another advantageous version of the present
invention, the individual recordings are made at precisely fixed
intervals of time. Thus, the camera can take twenty-five
individual recordings as images or fifty individual recordings as
half images each second, and these are then transferred to the
-1o-
CA 02306755 2000-04-12
WO 99/13431 PCT/IB9801516
computer memory. These values apply in the case of a CCIR
standard. Other values will apply in the case of other
standards. Not all of the individual recordings have to be stored
in memory. The time for beginning a recording and the time at
which storage begins in the computer memory can be different. The
underlying principle in this case is that recording the sequence
of individual recordings and their storage in the computer memory
are processes that are not linked to each other.
According to another advantageous version of the present
invention, the individual recordings are made at fixed relative
distances between the camera and the object. This can be done,
for example, by appropriately arranged photoelectric'barriers.
l~ In another advantageous version of the present invention, a CCD
camera is used to record the sequence of individual recordings.
A line camera or a scanner can also be used in place of the CCD
camera.
2U According to another advantageous version of the present
invention, initially al.l the individual recordings of the
sequence are stored in the computer. Once the sequence has been
recorded, the sharply imaged areas of the individual recordings
are identified and assembled to form a resulting image.
-11-
CA 02306755 2000-04-12
WO 99/13431 PCT/IB9801516
In a further advantageous configuration of the present invention,
the sharp areas of each individual recording of the sequence are
identified immediately after they have been recorded, and then
incorporated into the resulting image. The individual recordings
S are not stored. Providing the CPU of the computer is operating
fast enough, identification of the sharp areas and their
incorporation into the resulting image can take place in real
time.'If this is not the case, then the data relevant to the
individual recordings must be placed in intermediate storage. If
a plurality of resulting images are generated from the individual
recordings, the assembly of the individual resulting images can
be effected using different methods. In order to further speed up
the recording of the data and storage in the computer, a
plurality of processors can be used for assembling one or more
resulting images. The interaction of the processors can be
organised from different standpoints. On the one hand, the
digital computations involved in Methods 1 to 3 described above
can be divided into as many sections as can run concurrently.
Each section will be processed by a different processing. The
~'0 processors are synchronised by input, output, or by the end of
the process for each section. The data are passed on, or a RAM
with more than one access is used (multiported RAM). The
assembly of a plurality of resulting images can be effected in
part in parallel. Thus, all the resulting images can be formed,
-12-
CA 02306755 2000-04-12
WO 99/13431 PCT/IB9801516
even as an object is approaching the camera. To the extent that
this is not possible, the missing resulting images will be
computed subsequently. This will result in grid patterns with all
the information that has been read out or computed.
According to another advantageous version of the present
invention, a plurality of resulting images will be assembled from
the sequence of individual recordings, with a different area of
the object being shown in the resulting images in each instance.
1 ~~
According to another advantageous configuration of the present
invention, the plane of the image is divided into a plurality of
areas, and these areas are then processed in parallel. This
method is particularly suitable if a plurality 'of processors is
1'r available for processing. The areas involved can be squares,
rectangles, circles, ovals, or other shapes. These can be
adjacent to each other or can overlap each other.
According to another advantageous version of the present
2.C) invention, the method is used up to identify the features of a
finger, in particular, of a fingertip. In order to record the
data, the finger it is brought clo~~e to a camera. The process for
recording the sequence of individual recordings is started during
this approach. Still more individual recordings can be made as
-13-
CA 02306755 2000-04-12
WO 99/13431 PCT/IB9801516
the finger is moving away from a camera. F'or purposes of
recognition, particularly characteristic features at the
fingertips are identified from the resulting image and are looked
for during a repeated recording of the finger. The sweat and
S sebaceous glands as well as the papillary layer, as well as the
openings of the glands on the surface of the skin, which form the
dermis and the epidermis, are particularly characteristic
features of a finger tip. The papilla are also the basis for the
behaviour of the skin. The papillary layer, the sweat and
7.« sebaceous glands, as well as the openings of the glands on the
surface of the skin can be recorded in different resulting
images. This simplifies recognition. Using the method according
to the present invention, it can also be determined as to whether
or not blood is flowing through the finger. If the finger is
15 illuminated with a source of infra-red light, a sequence of
individual recordings can be made to show variations of
brightness as a function of the individual's heartbeat.
Furthermore, as blood flows through the fingers, this causes a
periodic shift of the cells in the blood vessels within the
20 finger, and this can also be identified with the aid of the
method according to the present invention.
According to another advantageous version of the present
invention, the object is illuminated with a light source.
-14-
CA 02306755 2000-04-12
WO 99/13431 PCT/IB9801516
According to another advantageous version of the present
invention, a pulsed light source is used, and this is
synchronised with the camera. The object is only illuminated when
an individual recording is to be made.
According to another advantageous configuration of the present
invention, the object is illuminated by a plurality of light
sources of different wavelength ranges and i.n different
arrangements. Different types of illumination can be used.
Because of the different spatial arrangements, the light will
arrive at different angles of incidence. In this way, different
spatial, geometric or perspective individual recordings can be
made. As an example, flash tubes with different optical filters
can be used as the light sources.
1J
Because of the filters, electromagnetic radiation in various
wavelength ranges is obtained with the aid of one light source.
According to another advantageous version of the present
2U invention, the objective is illuminated only whilst it is moving
toward and away from the camera. The individual recordings are
made during this interval of time. In this way, one obtains
individual recordings made at different distances from the
camera, which are thus of various depths of focus.
-15-
CA 02306755 2000-04-12
WO 99/13431 PCT/IB9801516
According to another advantageous version of the present
invention, only those areas of the object that are within focus
of the camera are illuminated. This is made possible in that the
focus of the camera is not changed between the recording of the
individual images. The evaluation and assembly of the individual
recordings is simplified in that there is no information from the
unsharp areas in the individual recordings.
It is advantageous that a system that incorporates a computer, a
camera, and a control device is used it to carry out the method
according to the present invention.
Additional advantages and advantageous configurations of the
present invention are set out in the Patent Claims.
According to the present invention, all of the features that are
set out in the description and in the claims can be used either
singly or in any combination with each other, as essential to the
present invention.
'U
-16-
