U.S. patent application number 12/805850 was filed with the patent office on 2011-03-03 for method in relation to acquiring digital images.
This patent application is currently assigned to Scalado AB. Invention is credited to Sami Niemi, Johan Windmark, Zhengrong Yao.
Application Number | 20110050960 12/805850 |
Document ID | / |
Family ID | 38957023 |
Filed Date | 2011-03-03 |
United States Patent
Application |
20110050960 |
Kind Code |
A1 |
Niemi; Sami ; et
al. |
March 3, 2011 |
Method in relation to acquiring digital images
Abstract
A method for acquiring at least two digital images by means of a
digital camera, wherein the digital images are to be stitched into
a panoramic image, comprises capturing a first digital image,
wherein a first scenery is imaged, determining a relation between
the first scenery and a second scenery being viewed by the digital
camera, while said second scenery being viewed by the digital
camera is changed, analysing the relation between the first scenery
and the second scenery being viewed by the digital camera in order
to identify an appropriate view to be captured by the digital
camera in a second digital image, and indicating to a user that the
camera is directed towards an appropriate view for capturing a
second digital image.
Inventors: |
Niemi; Sami; (Skanor,
SE) ; Windmark; Johan; (Lund, SE) ; Yao;
Zhengrong; (Lund, SE) |
Assignee: |
Scalado AB
|
Family ID: |
38957023 |
Appl. No.: |
12/805850 |
Filed: |
August 20, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11634264 |
Dec 6, 2006 |
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12805850 |
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Current U.S.
Class: |
348/239 ;
348/E5.051 |
Current CPC
Class: |
G06T 7/20 20130101; H04N
5/23248 20130101; G06T 2207/10016 20130101; H04N 5/232 20130101;
H04N 5/23238 20130101; H04N 5/23258 20130101; G03B 37/02 20130101;
H04N 5/23222 20130101; H04N 5/23293 20130101; G03B 17/18
20130101 |
Class at
Publication: |
348/239 ;
348/E05.051 |
International
Class: |
H04N 5/262 20060101
H04N005/262 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 19, 2006 |
SE |
0601577-0 |
Claims
1-17. (canceled)
18. A method for forming a combined image from a plurality of
digital images, comprising: capturing a first digital image using a
digital camera, the first digital image comprising a first scenery;
determining a relation between the first scenery and a second
scenery being viewed by the digital camera, while a view of the
second scenery being viewed by the digital camera is being changed;
analyzing the relation between the first scenery and the second
scenery to identify an appropriate view to be captured by the
digital camera, where the appropriate view represents a second
digital image for facilitating formation of the combined image;
communicating information to the user regarding the change of the
second scenery, wherein the communicating information comprises
emitting a signal from the digital camera that is tactile to the
user; generating an indication when the digital camera is directed
towards the appropriate view; and forming the combined image from
the first and second digital images.
19. The method according to claim 18, wherein in the tactile signal
is increasing in amplitude as an appropriate view is
approached.
20. The method according to claim 18, wherein in the tactile signal
is decreasing in amplitude as an appropriate view is
approached.
21. The method according to claim 18, wherein determining a
relation comprises monitoring a position of the first scenery in
relation to the second scenery while the digital camera is
moved.
22. The method according to claim 21, wherein monitoring comprises
comparing images.
23. The method according to claim 21, wherein monitoring comprises
sensing a change in direction of the digital camera.
24. The method according to claim 23, further comprising:
displaying an animation indicating a desired movement of the
digital camera, the animation being synchronized to movement of the
digital camera.
25. The method according to claim 18, wherein communicating
information further comprises emitting a sound signal to indicate
that the digital camera is directed towards the appropriate
view.
26. The method according to claims 18-25, further comprising:
automatically capturing the second digital image when the digital
camera is directed towards the appropriate view.
27. The method according to claim 26, wherein: the indication is a
first indication, and the method comprises generating a second
indication to the user that an image will be automatically
captured, wherein generating the second indication is performed in
advance of the actual capture of the image.
28. The method according to claim 18, wherein analyzing comprises
using a predetermined desired overlap between adjacent images, for
identifying an appropriate view.
29. The method according to claim 27, wherein analyzing comprises
using a predetermined desired overlap between adjacent images, for
identifying an appropriate view.
30. A method for forming a combined image from a plurality of
digital images, comprising: capturing a first digital image using a
digital camera, the first digital image comprising a first scenery;
detecting user movement of the digital camera towards a second
scenery partly overlapping the first scenery; generating a tactile
indication that a second digital image will be automatically
captured; automatically capturing the second digital image; and
forming a combined image from the first and second digital
images.
31. The method according to claim 30, wherein automatically
capturing is performed at a predetermined period of time after
generating an indication to the user.
32. The method according to claim 30, wherein automatically
capturing is performed in response to detection of a stopped
movement of the digital camera.
33. The method according to claim 30, wherein the automatic
capturing is triggered when: user movement of the digital camera
towards a second scenery in a direction is detected, and the
movement of the digital camera in the direction exceeds a
predetermined threshold value of camera movement.
34. The method according to claim 33, wherein: the digital camera
further comprises a gyroscope; and the detecting of the movement of
the camera is performed by the gyroscope.
35. The method according to claim 33, wherein: the digital camera
further comprises a compass; and the detecting of the movement of
the camera is performed by the compass.
36. A method for forming a combined image from a plurality of
digital images, comprising: capturing a first digital image using a
digital camera, the first digital image comprising a first scenery;
determining a relation between the first scenery and a second
scenery being viewed by the digital camera, while a view of the
second scenery being viewed by the digital camera is being changed;
analyzing the relation between the first scenery and the second
scenery in order to identify an appropriate view to be captured by
the digital camera, where the appropriate view represents a second
digital image for facilitating formation of the combined image;
communicating information regarding the change of the second
scenery, wherein: the communicating information comprises emitting
a signal from the digital camera that is tactile to the user, and
the tactile signal is activated during tracking when the digital
camera is moved; generating an indication that the digital camera
is directed towards the appropriate view by deactivating the
tactile signal; and forming the combined image from the first and
second digital images.
37. The method according to claim 36, wherein the tactile signal
decreases in amplitude as an appropriate view is approached.
38. The method according to claim 36, wherein the tactile signal
increases in amplitude as an appropriate view is approached.
39. The method according to claim 36, wherein analyzing comprises
identifying an appropriate view by detecting a predetermined
desired overlap between adjacent images.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for acquiring at
least two digital images by means of a digital camera, wherein the
digital images are to be stitched into a combined image.
BACKGROUND OF THE INVENTION
[0002] When using a digital camera to capture images of a
landscape, an image with a wide field of view may often be desired.
This may be artificially created by capturing a plurality of images
which are then stitched together to create a large image of the
landscape.
[0003] A most effective result of the stitched image may be
obtained by capturing images that are suitable for being stitched
together. In this regard, the images should be captured with an
appropriate overlap and a good alignment. An overlap is needed to
enable the images to be seamlessly stitched together. Further, the
final panoramic image is limited in the vertical direction by the
top of the lowest image of the plurality of images forming the
panorama, and the bottom of the highest image. Thus, a good
alignment will enable the final panoramic image to be created with
a maximum or near maximum vertical size.
[0004] It is difficult to capture images optimally suited for
creating a panoramic image even for an experienced photographer. In
order to achieve adequate results, it may be required to use a
tripod.
[0005] Therefore, there is a need for aiding a user in taking
images that are suited for forming a panoramic image. In US
2005/0118594, a method for guiding a user through the image-taking
procedure for creating a panoramic photograph is disclosed.
According to the method, an algorithm displays indicia that are
overlaid and moved over a live image during the image-taking
process to help align the subsequent image to be taken with the
previously recorded image.
[0006] Thus, the display simultaneously shows to the user a part of
the image that was previously recorded and apart of the image that
will be recorded. This helps the user to correctly align and
correlate the images to each other.
[0007] Another method of helping users to acquire panoramic images
is described in P. Baudisch, D. Tan, D. Steedly, E. Rudolph, M.
Uyttendaele, C. Pal, and R. Szeliski, "Panoramic Viewfinder:
Providing a Real-Time Preview to Help Users Avoid Flaws in
Panoramic Pictures", Proceedings of OZCHI 2005. According to this
method, a panoramic viewfinder is used, which simultaneously shows
three different types of information to the user; (1) a preview
shows the panorama in its current state of completion, (2) the
viewfinder shows what the camera sees at the moment, and (3) the
real-time cropping frame shows the extent the panorama will have
after cropping if the user stopped shooting at this instant.
[0008] However, panoramic images are often captured in a bright
environment, which makes it hard to view an overlap of images and
therefore the display is ineffective in helping the user in the
image-taking process. Further, if a self-portrait is desired, the
user is not able to see the viewfinder and is not helped at
all.
[0009] Therefore, an improved user interface for aiding a user in
taking several images to be stitched together is desired.
SUMMARY OF THE INVENTION
[0010] It is an object of the invention to provide a method that
aids a user in taking images to be stitched into a combined image.
It is a specific object of the invention to provide such a method
that is effective in bright environments and when a self-portrait
is taken.
[0011] These and other objects of the invention, which may become
apparent from the following description, are at least partly
achieved by means of a method according to any of the independent
claims. Specific embodiments are set out in the dependent
claims.
[0012] Thus, according to a first aspect of the invention, a method
for acquiring at least two digital images by means of a digital
camera, wherein the digital images are to be stitched into a
combined image, comprises capturing a first digital image, wherein
a first scenery is imaged; determining a relation between the first
scenery and a second scenery being viewed by the digital camera,
while said second scenery being viewed by the digital camera is
changed; analysing the relation between the first scenery and the
second scenery being viewed by the digital camera in order to
identify an appropriate view to be captured by the digital camera
in a second digital image for facilitating stitching of the first
and second digital images; and indicating to the user that the
camera is directed towards an appropriate view for capturing a
second digital image.
[0013] By means of the method, the digital camera determines the
relationship between the previously captured image and the image to
be captured. Thus, the camera itself determines the view to be
imaged in the image to be captured. The user is then guided by an
indication from the digital camera that the camera is properly
directed for capturing an image. Thus, guidance of a user for
aiding in acquiring combined images may be accomplished in bright
environments and even when a user is not able to see the viewfinder
(such as when taking a self-portrait).
[0014] The method deprives the user of the control of the capturing
of the images since the second scenery to be imaged is determined
by the camera. However, this enables the camera to guide the user
in a more effective manner.
[0015] The indication to the user that the camera is directed
towards an appropriate view need not necessarily guide the user to
an optimal view for capturing a second digital image. The
indication may provide information to the user of how far away the
present view is from an optimal view. The user may thus use this
information to control capturing of a second digital image when the
user finds it appropriate. Further, the indication may inform the
user of a situation when the camera is being moved in a direction
away from a suitable view of a second image. In this situation, an
indication may be given that a second image is to be captured
before the camera is moved so far away from the suitable view that
the captured images are no longer suited to be stitched at all.
Thus, the indication may force a second image to be captured,
wherein the second image is not depicting a particularly suitable
view for stitching, but the second image is depicting a view that
is able to be stitched to the first image.
[0016] In the context of this application, the term "combined
image" should be construed as an image that is formed from a
combination of at least two captured images. The captured images
may be formed into a panoramic image that is oblong and shows a
wide angle of a scenery. However, the captured images may be
related to each other in any way. For example, they may form a
matrix of n times m images, where n and m are arbitrary numbers.
Further, the combined image need not be rectangular. On the
contrary, the captured images may be stitched together to form a
combined image of an arbitrary shape.
[0017] The second scenery may change in different ways. The scenery
may change by movements taking place in front of the camera. In
such case, the camera may be held still, while the scenery in front
of the camera is changing. Then, several images may be taken by a
stationary camera. Movements in relation to a background may then
be illustrated in the combined image. The combined image may thus
be a combination of several images that are placed on top of each
other.
[0018] Alternatively, the second scenery may change by the camera
being moved. The determining may comprise keeping track of a
position of the first scenery in relation to the second scenery
being viewed by the digital camera, while the digital camera is
moved to change said second scenery being viewed by the digital
camera. In this case, the camera is being moved and, thus, the
scenery being viewed by the camera is changed. The relation between
the first scenery and the changing second scenery is monitored in
order to enable a second image to be captured that is suitable for
stitching to the first image.
[0019] According to one embodiment, keeping track of a position of
the first scenery in relation to the second scenery comprises
comparing images. This implies that movement of the camera is
monitored by comparing views towards which the camera is being
directed. This may be realized, for instance, by continuously
comparing temporary small images being captured by the viewfinder.
A comparison may be made to any of the previously captured
temporary images in order to constantly update the relation between
the second scenery and the first scenery.
[0020] According to another embodiment, keeping track of a position
of the first scenery in relation to the second scenery comprises
sensing a change in direction of the digital camera. The sensing
may be achieved e.g. by means of a gyroscope, that detects any
rotation of the digital camera. Alternatively, the sensing may be
achieved by means of a compass, whereby rotations in relation to
the earth's magnetic field may be detected. With knowledge of a
viewing angle of the digital camera, an allowed rotation of the
digital camera may be set.
[0021] The method may further comprise communicating information to
the user related to the change of the second scenery. This implies
that the camera may give the user information of the status of a
movement of the camera and thereby guide the movement such that the
camera may be directed towards an appropriate part of the
scenery.
[0022] According to one embodiment, the communicating may comprise
emitting a signal that is tactile for a user. The human body
responds very quickly to the tactile sense. Therefore, by emitting
any kind of message or signal that may be sensed by the user, the
user may very quickly react to the signal.
[0023] The tactile signal may be accomplished in different ways. It
may be in form of a small electric impulse, a change in temperature
or a sensed vibration.
[0024] For example, the emitting may comprise activating a vibrator
to inform a user of the relation between the first scenery and the
second scenery. The vibrator may be activated during tracking when
the digital camera is moved and be deactivated to indicate that the
camera is directed towards an appropriate view for capturing an
image. This implies that the user is continuously guided in the
movement of the camera. The guidance is not affected by a bright or
noisy environment, since the user may sense the deactivation of the
vibrator by means of his hand holding the camera. The user will
then know that the camera has been properly directed.
[0025] Of course, the vibrator may be used in other ways to
communicate with the user. The vibrator may be used in the reverse
manner, i.e. the vibrator being activated for a short period of
time when the camera has been properly directed. The intensity of
the vibrator may alternatively be varied in order to communicate to
the user how far away the camera is from being directed towards an
appropriate or an optimal view.
[0026] According to an alternative embodiment, the communicating
may comprise emitting a sound signal from the digital camera in
order to indicate that the camera is directed towards an
appropriate view for capturing an image.
[0027] According to another alternative embodiment, the
communicating may comprise displaying a schematic representation of
the relation between the first scenery and the second scenery being
viewed by the digital camera.
[0028] These alternative embodiments also enable a user to be
guided in a bright environment when the details of the viewfinder
are difficult to discern.
[0029] The method may further comprise capturing a second digital
image when the camera is directed towards an appropriate view, said
capturing being automatically performed by the digital camera.
[0030] In this way, an automated method of acquiring a combined
image is achieved. Thus, the user will not need to push the capture
button during the acquiring of the second and subsequent images.
This implies that the camera will not be moved out of position due
to the capture button being pressed. Instead, the user may focus
entirely on aiming the camera in a correct direction.
[0031] Moreover, the communication of information related to the
movement of the camera to the user may allow the user to
temporarily stop moving the camera at various positions when it is
indicated that an image is to be acquired. Thus, motion blur is
prevented and high quality sharp images may be acquired.
[0032] This method allows several images that are to form a
combined image to be captured very quickly. The user simply pushes
the capture button to start acquiring the images and then Sweeps
the camera over the scenery to be imaged. The user is continuously
guided when to temporarily stop sweeping the camera to allow
another image to be captured.
[0033] This is a highly automated method that will help the user to
acquire images for creation of a combined image. The user will not
need to take any decisions regarding when to capture images. In
fact, wide the user has started the procedure to acquire a combined
image, the user may merely follow instructions communicated by the
camera. In particular, the user will not need to see the viewfinder
of the camera and may thus acquire a self-portrait or a combined
image in bright or dark environment.
[0034] The indicating may comprise communicating information to the
user that an image will be automatically captured in advance of the
actual capture of the image. This implies that the user will be
able to stop movement of the digital camera before the second
digital image is captured. Thus, motion blur may effectively be
eliminated.
[0035] The automatic capture may be performed a predefined period
of time after information is communicated to the user that a second
image is about to be captured. Alternatively, the automatic capture
may be performed in response to detection that the movement of the
camera has been stopped.
[0036] The analysing may use a predefined desired overlap between
adjacent images for identifying an appropriate view. This overlap
may be set to fit the optical set-up of the camera and, thus,
optimal combined images may be obtained by using a programmed
algorithm for acquiring images.
[0037] According to an alternative, the analysing may comprise
determining whether conditions prevail that are appropriate for
capturing a second digital image. For example, the analysis may
detect that the camera is hardly being moved. In such case, the
conditions are such that a second image may appropriately be
captured. Since the camera is only slightly moved, if moved at all,
motion blur may be avoided. Thus, if the camera is aimed at a view
that may be appropriate for stitching and these non-movement
conditions of the camera prevail, a decision may be taken to
capture a second digital image. As an alternative, the analysis may
detect that the camera is directed towards a view being
particularly suited for stitching to previously captured images.
This may be detected as appropriate conditions for capturing a
second digital image, even if the camera is being moved at the
time. An indication may then be communicated to the user that an
image will soon be captured allowing the user to stop the movement
of the camera at the appropriate position. Thereafter, a second
digital image is captured.
[0038] The method may further comprise displaying an animation of
desired movement of the digital camera, wherein the animation is
synchronised with the actual movement of the digital camera. This
animation gives the user an easy understanding of how to move the
camera. For example, the animation may show to the user that the
camera is merely to be rotated and that neither any linear movement
of the camera nor any tilting movement of the camera is to be made
if a panoramic image is to be captured.
[0039] According to a second aspect of the invention, a method for
acquiring at least two digital images by means of a digital camera,
wherein the digital images are to be stitched into a combined
image, comprises: capturing a first digital image, wherein a first
scenery is imaged; allowing a user to move the digital camera to
direct the camera towards a second scenery partly overlapping the
first scenery; communicating to a user that a second digital image
is about to be automatically captured; and automatically capturing
a second digital image.
[0040] The method aids the user in acquiring images for forming a
combined image, wherein motion blur in the images is prevented.
Since the user is informed that a digital image is to be captured
before the image is actually captured, the user will be able to
stop movement of the camera. The automatic capture of the second
image implies that no motion blur may be formed due to the user
pressing a capture button.
[0041] Further, when several subsequent images are to be captured,
the communication to the user may occur at regular intervals. This
implies that the user may be aided in sweeping a scenery and
capturing images appropriate for stitching. Since the user need not
make any decisions regarding appropriate directions of the camera,
the user may move the camera in a steady, uniform manner. This
implies that the difference in viewing angle between adjacent
images may be constant throughout sweeping of the scenery. Thereby,
the user is aided by the camera to obtain images suitable for
stitching into a combined image, even though no analysis is made
regarding the relation between the imaged sceneries during capture
of images.
[0042] The communication to the user may be achieved in many
different ways, as described above with reference to the first
aspect of the invention.
[0043] The automatic capture of the second digital image may be
performed at a predetermined period of time after said
communicating. The predetermined period of time may be any suitable
time period allowing the user to stop movement of the camera before
the second digital image is captured. This predetermined period of
time may typically be less than a second.
[0044] Alternatively, the method further comprises detecting a
stopped movement of the digital camera, wherein the automatic
capturing of the second digital image is performed in response to
detection of a stopped movement. This implies that it is positively
ensured that the second digital image does not contain any motion
blur.
[0045] According to a third aspect of the invention, a method for
acquiring at least two digital images by means of a digital camera,
wherein the digital images are to be stitched into a combined
image, comprises: capturing a first digital image, wherein a first
scenery is imaged; allowing a user to move the digital camera to
direct the camera towards a second scenery; detecting a stopped
movement of the digital camera; and automatically capturing a
second digital image in response to detection of a stopped
movement.
[0046] According to this aspect of the invention, the user controls
the positioning of the camera when an image is captured. By
stopping movement of the camera, the user will initiate capturing
of an image. This implies that the images are captured without any
motion blur. Further, since images are automatically captured in
response to a detected stopped movement of the digital camera, the
images may be very quickly captured. This allows the user to move
the camera in a rapid manner and thereby the user may be able to
move the camera in a steady, uniform manner. Also, the automatic
capture of the second image implies that no motion blur may be
formed due to the user pressing a capture button.
BRIEF DESCRIPTION OF DRAWINGS
[0047] The invention will now be described in further detail by way
of example under reference to the accompanying drawings.
[0048] FIG. 1 is a flow chart of a method according to an
embodiment of the invention.
[0049] FIG. 2 is a schematic view of a digital camera to be used in
the method.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0050] Referring now to FIG. 1, a method of guiding a user in
acquiring digital images to be stitched into a combined image will
be described.
[0051] A user initiates the acquiring of the digital images by
pressing a capture button in a combined image Capturing mode of the
digital camera, step 10. The camera is thus activated to capture a
first image of a first scenery viewed by the digital camera, step
12. Further, the camera is activated to guide the user in directing
the camera towards appropriate views of further sceneries for
forming the combined image.
[0052] The camera records temporary images of the scenery being
viewed by the camera as the camera is moved, step 14. These
temporary images are displayed on the viewfinder. Further, the
previously recorded image is compared to the temporary images and a
position of the scenery being imaged in the previously recorded
image is tracked, step 16. The camera analyses the relation between
the scenery that has been imaged in the previously recorded digital
image and the scenery being viewed, step 18. Based on this
analysis, the camera decides whether the camera is directed towards
an appropriate view for capturing a subsequent image. When the
camera is directed towards an appropriate view, the camera
automatically captures a digital image, step 20.
[0053] The temporary images being continuously captured may be
compared to each other for continuously updating how the camera has
been moved. This implies that only small images are being compared
to each other keeping computation complexity of the tracking
relatively low. The position of the scenery being imaged in the
previously recorded image may be modelled by a first temporary
image that is registered in the viewfinder immediately after
capturing an image.
[0054] A predefined overlap may be programmed in the camera. Thus,
the camera analyses the overlap of the scenery that has been imaged
with the scenery being viewed in order to determine the overlap.
During movement of the camera, the overlap continuously decreases.
When the overlap reaches the predefined level, the analysis decides
that the camera is directed towards an appropriate view.
[0055] The predefined overlap allows the camera to be appropriately
programmed to suit the optical set-up of the camera. However, the
user may be allowed to change the predefined overlap before
capturing a combined image.
[0056] The tracking may be performed in real time, since the
tracking uses the image of the viewfinder, which is very small.
Tracking may be performed in any suitable way to compare and match
the previously recorded image to the temporary image in the
viewfinder, as will be appreciated by those skilled in the art. For
example, an optical flow algorithm or a two-dimensional correlation
algorithm may be used for comparing the images to each other in
order to determine whether the images correlate in such a way that
it is appropriate to capture another image.
[0057] As an alternative to using a predefined overlap, the
analysis may comprise determining whether conditions prevail that
are appropriate for capturing a second digital image. For example,
the analysis may detect that the camera is hardly being moved. In
such case, the conditions are such that a second image may
appropriately be captured. Since the camera is only slightly moved,
if moved at all, motion blur may be avoided. Thus, if the camera is
aimed at a view that may be appropriate for stitching and these
non-movement conditions of the camera prevail, a decision may be
taken to capture a second digital image.
[0058] As a further alternative, the analysis may detect that the
camera is directed towards a view being particularly suited for
stitching to previously captured images. This may be detected as
appropriate conditions for capturing a second digital image, even
if the camera is being moved at the time. An indication may then be
communicated to the user that an image will soon be captured
allowing the user to stop the movement of the camera at the
appropriate position. Thereafter, a second digital image is
captured.
[0059] The camera is arranged to capture the subsequent image
automatically when the analysis decides that the camera is directed
towards an appropriate view. This implies that the user will not
need to give any further input to the camera, such as pressing a
capture button. Thus, the user may focus on directing the camera
correctly and, in particular, no movement of the camera out of
position will occur due to the user shaking when the button is
pressed.
[0060] However, according to an alternative embodiment, the user
may initiate the capturing of each image by pressing a button when
the user has been guided by the camera to direct the camera towards
the appropriate view.
[0061] During the movement of the camera for capturing images of
different parts of the scenery, the camera continuously guides the
user in the movement. Thus, simultaneously with steps 14-20, the
camera informs the user of how to move the camera. The camera
displays an animation of how the user should move the camera, step
22. Further, the camera indicates when the movement should be
temporarily stopped for acquiring an image, step 24.
[0062] The camera may indicate when the movement should be
temporarily stopped in many different ways. According to a first
alternative, the camera activates a vibrator while the camera is
moved. When the camera is properly directed for capturing an image,
the vibrator is deactivated. Thus, user will sense the vibrator
being activated with his hand holding the camera. This implies that
no visual or audible communication with the user is needed, which
may be advantageous when capturing a combined image in a bright or
dark environment or in a noisy environment. Further, the physical
response to a tactile impulse is very quick and, therefore, the
user may quickly react on the sensed communication. The vibrator
may be used in many different ways to communicate with the user.
For example, the intensity of the vibration may be increased as an
appropriate view is approached. Thus, the user may get feedback on
how far away the camera is from being directed towards an
appropriate view.
[0063] According to a second alternative, the camera emits a sound
signal when an image is to be captured. The first two alternatives
are especially advantageous in conditions when the user has trouble
seeing visual indications. For example, this facilitates capturing
a panoramic self-portrait or other combined images when the
viewfinder may not be watched.
[0064] According to a third alternative, the camera displays a
schematic view of the relation of the scenery imaged in the
previously recorded image to the scenery being viewed. The
previously recorded image may be represented by a first rectangle
and the scenery being viewed may be represented by a second
rectangle being moved relative the first rectangle. A third
rectangle indicating the desired position of the subsequent image
to be captured may also be displayed. Thus, the user may
continuously see how the part of the scenery being viewed
approaches the appropriate view for capturing the subsequent image.
This gives the user continuous feedback of how close the camera
view is to the subsequent desired view and may thus improve the
ability of the user to aim the camera correctly.
[0065] Two or more of the above alternatives may be used in
conjunction with each other. In such manner, the guidance of the
user may be further improved.
[0066] When the entire scenery to be imaged in the combined image
has been swept, the image-capturing process is stopped, step 26.
The user may stop the process by pushing a button or stopping the
movement of the camera. Alternatively, the process may be stopped
when a predetermined number of images to be stitched together have
been captured.
[0067] When all needed images have been captured, the images are
stitched together to form one large combined image, step 28. The
captured images may be processed in order to facilitate matching.
For instance, a cylindrical projection and lens correction of the
images may be performed. Then the captured and processed images are
analysed in order to match them together appropriately. This may be
performed using any suitable matching algorithm as will be
appreciated by those skilled in the art.
[0068] According to an alternative embodiment, indications May be
given to the user at regular time intervals that an image is to be
captured. This implies that no tracking of the position of the
scenery being imaged in the previously recorded image is performed.
Further, no analysis whether the camera is directed towards an
appropriate view is performed. The user is merely aided to stop
movement of the camera at regular time intervals for allowing the
camera to capture images without motion blur. Thereafter, the
captured images may be stitched together into a combined image. The
stitching of these images may require more computations, since no
control that an acceptable overlap of the images was present
occurred during capturing of the images. However, the regular
timing of the capturing of the images makes it likely that a good
result of stitching maybe achieved.
[0069] According to another alternative embodiment, the user will
further control when images are to be captured. A processor is
arranged to detect when a movement of the camera has been stopped.
In response to this non-movement, an image mill be captured. Thus,
there will be no motion blur in the captured image. By stopping
movement of the camera at appropriate positions, the user may force
the camera to capture images at these positions. The capturing of
images is performed automatically as detection of non-movement is
made.
[0070] The non-movement may be detected by means of comparing
temporary images captured by the viewfinder to each other. When
there is no or insignificant difference between two subsequent
temporary images, this maybe interpreted as the camera not being
moved. In order to make the detection of non-movement more
reliable, it may be required that no or merely insignificant
difference should exist between three or more subsequent temporary
images.
[0071] According to yet another alternative embodiment, the images
to be combined may be captured without any movement of the camera
occurring. Instead, the camera may be directed towards a scenery in
which objects are moving. The camera may thus capture several
images of a view having a common background, wherein movements are
occurring. These images may be combined on top of each other such
that the movements of objects may be illustrated in relation to the
common background. In this case, a difference between the
previously recorded image and the scenery being viewed may be
tracked in a similar way as described above with reference to steps
16-18. When the difference is determined to be larger than a
predetermined threshold, a new image may be captured.
[0072] Referring now to FIG. 2, a camera will be described that may
be used in capturing a combined image according to the method
described above. The camera 40 is specifically suited to be
incorporated in a mobile phone, since a mobile phone camera is
particularly used for acquiring images in a quick and simple
manner. However, the method may be implemented in any kind of
digital camera. The camera 40 comprises a viewfinder 42 in which
the view of the camera is imaged. The viewfinder 42 forms a part of
a display 44 and shows a live image of the view of the camera. The
display 44 is further arranged to guide the user in capturing
combined images. The display 44 may show an animation of how the
camera should be moved and the display 44 may also present a
schematic representation of the previously recorded image to the
present view of the camera.
[0073] The camera 40 further comprises a vibrator 46, which may be
activated and deactivated for guiding the user in movement of the
camera. The camera 40 may also comprise a speaker 48 such that a
sound signal may be emitted for guiding the user.
[0074] The camera 40 also comprises a processor unit 50. The
processor unit 50 compares the previously recorded image to the
present view of the camera and decides whether the camera is
directed towards an appropriate view for capturing a subsequent
image. The processor unit 50 also processes all captured images in
order to stitch the images to a large combined image. The captured
images may temporarily be stored in a RAM memory 52 during the
image-capturing process and while the images are stitched together.
When the combined image has been created it may be stored in a
permanent memory 54.
[0075] It should be emphasized that the preferred embodiment
described herein is in no way limiting and that many alternative
embodiments are possible within the scope of protection defined by
the appended claims.
[0076] For example, a decision whether the camera is directed
towards an appropriate view for capturing a subsequent image may be
performed using a sensor for detecting the direction of the camera.
This sensor may e.g. be a gyroscope or a compass. The sensor may
thus store information of a direction of the camera at time of
capturing the previous image. When a change in direction exceeds a
threshold, an indication may be given that it is time to capture a
subsequent image.
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