Digital Camera Patent AbstractA digital camera has a plurality of shooting modes such as a day
scenic shooting mode, a night scenic shooting mode and a person
shooting mode and displays a composition assist frame selected from
a plurality of composition assist frames on a liquid crystal monitor
to assist composition. If a user sets the person shooting mode by
a mode dial, one or more composition assist frames that are suitable
for a person shooting are extracted from the plurality of the composition
assist frames, and the user selects one of the extracted composition
assist frames by a left key and a right key of a cross key. Therefore,
the appropriate composition assist frame can be automatically or
easily selected.
Digital Camera Patent ClaimsWhat is claimed is:
1. A digital camera comprising: a shooting mode selecting device
that enables selection of a shooting mode from a plurality of shooting
modes; an imaging device that images a subject in the shooting mode
selected by the shooting mode selecting device and outputs image
signals; an image displaying device that displays the image according
to the image signals outputted from the imaging device; a storing
device that stores data of a plurality of composition assist frames,
wherein the storing device stores more than one composition assist
frame associated with each of the plurality of shooting modes; an
extracting device that extracts more than one composition assist
frame that can be selected from the plurality of composition assist
frames according to the shooting mode selected by the shooting mode
selecting device; a composition assist frame selecting device that
enables selection of a composition assist frame from the more than
one composition assist frames extracted by the extracting device;
and a composition assist frame displaying device that displays the
composition assist frame selected by the composition assist frame
selecting device on the image displaying device displaying the image.
2. The digital camera as defined in claim 1, wherein the plurality
of shooting modes include at least two of an automatic shooting
mode, a day scenic shooting mode, a person shooting mode and a night
scenic shooting mode.
3. The digital camera as defined in claim 1, further comprising
a luminance determining device that determines subject luminance
by weighting areas of the image according to the shooting mode selected
by the shooting mode selecting device, the imaging device controlling
exposure according to the subject luminance determined by the luminance
determining device.
4. The digital camera as defined in claim 3, wherein the luminance
determining device corrects the subject luminance according to the
shooting mode selected by the shooting mode selecting device.
5. The digital camera as defined in claim 1, further comprising
a storage device that stores the image signals outputted from the
imaging device in a storage medium.
6. A digital camera comprising: an imaging device that images a
subject and outputs image signals; an image displaying device that
displays the image according to the image signals outputted from
the imaging device; a storing device that stores data of a plurality
of composition assist frames wherein the storing device stores more
than one composition assist frame associated with each of a widthwise
direction and a lengthwise direction of the camera; a direction
determining device that determines whether the digital camera is
held in the widthwise direction or the lengthwise direction; an
extracting device that extracts more than one composition assist
frame that can be selected from the plurality of composition assist
frames according to the widthwise or lengthwise direction of the
camera determined by the direction determining device; a composition
assist frame selecting device that enables selection of a composition
assist frame from the more than one composition assist frames extracted
by the extracting device; and a composition assist frame displaying
device that displays the composition assist frame selected by the
composition assist frame selecting device on the image displaying
device displaying the image.
7. The digital camera as defined in claim 6, further comprising
a storage device that stores the image signals outputted from the
imaging device in a storage medium.
8. A digital camera comprising: a shooting mode selecting device
that enables selection of a shooting mode from a plurality of shooting
modes; an imaging device that images a subject in the shooting mode
selected by the shooting mode selecting device and outputs image
signals; an image displaying device that displays the image according
to the image signals outputted from the imaging device; a storing
device that stores data of a plurality of composition assist frames
wherein the storing device stores more than one composition assist
frame associated with each of a widthwise direction and a lengthwise
direction of the camera; a direction determining device that determines
whether the digital camera is held in the widthwise direction or
the lengthwise direction; an extracting device that extracts more
than one composition assist frame that can be selected from the
plurality of composition assist frames according to the shooting
mode selected by the shooting mode selecting device and the widthwise
or lengthwise direction of the camera determined by the direction
determining device; a composition assist frame selecting device
that enables selection of a composition assist frame from the more
than one composition assist frames extracted by the extracting device;
and a composition assist frame displaying device that displays the
composition assist frame selected by the composition assist frame
selecting device on the image displaying device displaying the image.
9. The digital camera as defined in claim 8, wherein the plurality
of shooting modes include at least two of an automatic shooting
mode, a day scenic shooting mode, a person shooting mode and a night
scenic shooting mode.
10. The digital camera as defined in claim 8, further comprising
a luminance determining device that determines subject luminance
by weighting areas of the image according to the shooting mode selected
by the shooting mode selecting device, the imaging device controlling
exposure according to the subject luminance determined by the luminance
determining device.
11. The digital camera as defined in claim 10, wherein the luminance
determining device corrects the subject luminance according to the
shooting mode selected by the shooting mode selecting device.
12. The digital camera as defined in claim 8, further comprising
a storage device that stores the image signals outputted from the
imaging device in a storage medium.
13. A composition assist frame selecting method for a digital camera,
the method comprising: enabling selection of a shooting mode from
a plurality of shooting modes; imaging a subject in the selected
shooting mode and outputting image signals; displaying the outputted
image signals on a display; storing data of a plurality of composition
assist frames, wherein more than one composition assist frame is
associated with each of the plurality of shooting modes; extracting
more than one composition assist frame that can be selected from
the plurality of composition assist frames according to the selected
shooting mode; enabling selection of a composition assist frame
from the extracted more than one composition assist frame; and displaying
the selected composition assist frame on the display device to assist
composition.
14. The composition assist frame selecting method for the digital
camera as defined in claim 13, wherein the plurality of shooting
modes include at least two of an automatic shooting mode, a day
scenic shooting mode, a person shooting mode and a night scenic
shooting mode.
15. The method of claim 13, wherein each of the plurality of composition
assist frames circumscribes an area within the display.
16. A composition assist frame selecting method for a digital camera,
the method comprising: imaging a subject and outputting image signals;
displaying the image on a display according to the outputted image
signals; storing a plurality of composition assist frames wherein
more than one composition assist frame is associated with each of
a widthwise direction and a lengthwise direction of the camera;
determining whether the digital camera is held in the widthwise
direction or the lengthwise direction; extracting more than one
composition assist frame that can be selected from the plurality
of composition assist frames according to the determining whether
the digital camera is held the widthwise direction or the lengthwise
direction; enabling selection of a composition assist frame from
the more than one extracted composition assist frames; and displaying
the selected composition assist frame on the display displaying
the image to assist composition.
17. A composition assist frame selecting method for a digital camera,
the method comprising: enabling selection of a shooting mode from
a plurality of shooting modes; imaging a subject in the selected
shooting mode and outputting image signals; displaying the image
according to the outputted image signals; storing data of a plurality
of composition assist frames wherein more than one composition assist
frame is associated with each of a widthwise direction and a lengthwise
direction of the camera; determining whether the digital camera
is held in the widthwise direction or the lengthwise direction;
extracting more than one composition assist frame that can be selected
from the plurality of composition assist frames according to the
selected shooting mode and the determination of whether the digital
camera is held widthwise or lengthwise; enabling selection of a
composition assist frame from the extracted more than one composition
assist frames; and displaying the selected composition assist frame
on the display displaying the image to assist composition.
18. The composition assist frame selecting method for the digital
camera as defined in claim 17, wherein the plurality of shooting
modes include at least two of an automatic shooting mode, a day
scenic shooting mode, a person shooting mode and a night scenic
shooting mode. Digital Camera Patent DescriptionBACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a digital camera and
a composition assist frame selecting method for the digital camera.
The present invention relates more particularly to a digital camera
that has multiple shooting modes and a composition assist frame
selecting method for the digital camera.
2. Description of Related Art
In recent years, a digital camera with the best framing function
has been proposed. In the best framing function, one of composition
assist frames is displayed on a liquid crystal monitor with an image
so that even a novice can compose an excellent image.
The composition assist frames are a lattice frame, a frame for
shooting two persons, a frame for shooting one person, and so on.
One of the composition assist frames is displayed on the liquid
crystal monitor when the user presses a display button, and the
composition assist frames are sequentially displayed when the user
repeatedly presses a multifunction cross key.
However, it is troublesome to select the desired composition assist
frame from the composition assist frames. Especially, if the number
of the composition assist frames are large, it takes a long time
to select the desired composition assist frame, and the user can
miss an opportunity for a photograph.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention
to provide a digital camera and a composition assist frame selecting
method for the digital camera in which a desired composition assist
frame can be automatically or easily selected from a plurality of
composition assist frames.
To achieve the above-mentioned object, the present invention is
directed to a composition assist frame selecting method for a digital
camera that images a subject in a shooting mode selected from a
plurality of shooting modes and displays a composition assist frame
selected from a plurality of composition assist frames on an image
displaying device that displays the image of the subject to assist
composition, wherein: the digital camera extracts at least one composition
assist frame that can be selected from the plurality of composition
assist frames according to the shooting mode.
The present invention is also directed to a composition assist
frame selecting method for a digital camera that displays a composition
assist frame selected from a plurality of composition assist frames
on an image displaying device that displays an image of a subject
to assist composition, wherein: the digital camera has a direction
determining device that determines whether the digital camera is
held widthwise or lengthwise; and the digital camera extracts at
least one composition assist frame that can be selected from the
plurality of composition assist frames according to the direction
of the camera determined by the direction determining device.
The present invention is also directed to a composition assist
frame selecting method for a digital camera that images a subject
in a shooting mode selected from a plurality of shooting modes and
displays a composition assist frame selected from a plurality of
composition assist frames on an image displaying device that displays
the image of the subject to assist composition, wherein: the digital
camera has a direction determining device that determines whether
the digital camera is held widthwise or lengthwise; and the digital
camera extracts at least one composition assist frame that can be
selected from the plurality of composition assist frames according
to the shooting mode and the direction of the camera determined
by the direction determining device.
The plurality of shooting modes include at least two of an automatic
shooting mode, a day scenic shooting mode, a person shooting mode
and a night scenic shooting mode.
If the day scenic shooting mode or the night scenic shooting mode
is set, frames that are suitable for shooting a day scene or a night
scene are extracted. If the person shooting mode is set, frames
that are suitable for shooting one or more persons are extracted.
If the user holds the camera widthwise, frames that are suitable
for a shooting in that direction are extracted. If the user holds
the camera lengthwise, frames that are suitable for a shooting in
that direction are extracted.
The composition assist frames are extracted from the plurality
of composition assist frames according to the shooting mode and
the direction of the camera. Therefore, the appropriate composition
frame can be automatically or easily selected.
The present invention is also directed to a digital camera comprising:
a shooting mode selecting device that selects a shooting mode from
a plurality of shooting modes; an imaging device that images a subject
in the shooting mode selected by the shooting mode selecting device
and outputs image signals; an image displaying device that displays
the image according to the image signals outputted from the imaging
device; a storing device that stores data of a plurality of composition
assist frames; an extracting device that extracts one or more composition
assist frames that can be selected from the plurality of composition
assist frames according to the shooting mode selected by the shooting
mode selecting device; a composition assist frame selecting device
that selects a composition assist frame from the composition assist
frames extracted by the extracting device; and a composition assist
frame displaying device that displays the composition assist frame
selected by the composition assist frame selecting device on the
image displaying device displaying the image.
The present invention is also directed to a digital camera comprising:
an imaging device that images a subject and outputs image signals;
an image displaying device that displays the image according to
the image signals outputted from the imaging device; a storing device
that stores data of a plurality of composition assist frames; a
direction determining device that determines whether the digital
camera is held widthwise or lengthwise; an extracting device that
extracts one or more composition assist frames that can be selected
from the plurality of composition assist frames according to the
direction of the camera determined by the direction determining
device; a composition assist frame selecting device that selects
a composition assist frame from the composition assist frames extracted
by the extracting device; and a composition assist frame displaying
device that displays the composition assist frame selected by the
composition assist frame selecting device on the image displaying
device displaying the image.
The present invention is also directed to a digital camera comprising:
a shooting mode selecting device that selects a shooting mode from
a plurality of shooting modes; an imaging device that images a subject
in the shooting mode selected by the shooting mode selecting device
and outputs image signals; an image displaying device that displays
the image according to the image signals outputted from the imaging
device; a storing device that stores data of a plurality of composition
assist frames; a direction determining device that determines whether
the digital camera is held widthwise or lengthwise; an extracting
device that extracts one or more composition assist frames that
can be selected from the plurality of composition assist frames
according to the shooting mode selected by the shooting mode selecting
device and the direction of the camera determined by the direction
determining device; a composition assist frame selecting device
that selects a composition assist frame from the composition assist
frames extracted by the extracting device; and a composition assist
frame displaying device that displays the composition assist frame
selected by the composition assist frame selecting device on the
image displaying device displaying the image.
The plurality of shooting modes include at least two of an automatic
shooting mode, a day scenic shooting mode, a person shooting mode
and a night scenic shooting mode.
The digital camera further comprises a luminance determining device
that determines subject luminance by weighting areas of the image
according to the shooting mode selected by the shooting mode selecting
device, and the imaging device controls exposure according to the
subject luminance determined by the luminance determining device.
The luminance determining device corrects the subject luminance
according to the shooting mode selected by the shooting mode selecting
device.
The digital camera further comprises a storage device that stores
the image signals outputted from the imaging device in a storage
medium.
BRIEF DESCRIPTION OF THE DRAWINGS
The nature of this invention, as well as other objects and advantages
thereof, will be explained in the following with reference to the
accompanying drawings, in which like reference characters designate
the same or similar parts throughout the figures and wherein:
FIG. 1 is a back view of a digital camera according to the present
invention;
FIG. 2 is a plan view of a mode dial provided on the top of the
digital camera in FIG. 1;
FIG. 3 is a block diagram showing the inner structure of the digital
camera in FIG. 1;
FIG. 4 is an explanatory drawing showing the method of calculating
exposure values;
FIGS. 5(A), 5(B) and 5(C) are tables showing weight coefficients
of areas for shooting modes;
FIG. 6 is a flowchart showing a method of automatically controlling
white balance;
FIG. 7 is a flowchart showing a method of automatically controlling
white balance;
FIG. 8 is a graph diagram showing ranges of determination frames
for light sources;
FIG. 9 is a graph diagram of a membership function indicating possibility
of outdoors;
FIG. 10 is a graph diagram of a membership function indicating
possibility of shade-cloudiness;
FIG. 11 is a graph diagram of a membership function indicating
possibility of blue sky;
FIG. 12 is a graph diagram of a membership function indicating
possibility of indoors;
FIG. 13 is a graph diagram of a membership function indicating
possibility of a tungsten lamp and fluorescent lamps;
FIG. 14 is a graph diagram of a membership function indicating
possibility of skin;
FIGS. 15(A), 15(B), 15(C), 15(D), 15(E) and 15(F) are diagrams
showing composition assist frames;
FIG. 16 is a back view of the digital camera displaying a composition
assist frame on a liquid crystal monitor in the day scenic shooting
mode;
FIG. 17 is a back view of the digital camera displaying the composition
assist frame on the liquid crystal monitor in the night scenic shooting
mode;
FIG. 18 is a back view of the digital camera displaying a composition
assist frame on the liquid crystal monitor in the automatic shooting
mode; and
FIG. 19 is a back view of the digital camera displaying a composition
assist frame on the liquid crystal monitor in the person shooting
mode.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
This invention will be described in further detail by way of example
with reference to the accompanying drawings.
FIG. 1 is a back view of a digital camera according to the present
invention, and FIG. 2 is a plan view of a mode dial 1 provided on
the top of the camera.
As shown in FIG. 2, the mode dial 1 has icons 1A, 1B, 1C, 1D, 1E
and 1F for shooting modes that are a sequential shooting/bracketing
mode, a manual shooting mode, an automatic shooting mode, a person
shooting mode, a day scenic shooting mode and a night scenic shooting
mode, respectively. A user rotates the mode dial 1 to set one of
the icons 1A-1F at a mark M in order to set the corresponding shooting
mode (the day scenic shooting mode in FIG. 2). A shutter release
button 2 is provided in the center of the mode dial 1, and the shutter
release button 2 can be pressed half and fully.
As shown in FIG. 1, an eyepiece 3, a shift key 4, a display key
5, a shooting/reproducing switch 6, a cancel key 7, an execution
key 8, a multifunction cross key 9 and a liquid crystal monitor
52 are provided on the back of the digital camera.
FIG. 3 is a block diagram showing the inner structure of the digital
camera in FIG. 1.
A subject image formed on a light-receiving surface of a charge
coupled device (CCD) 14 through a taking lens 10 and a diaphragm
12 is converted into signal electric charges corresponding to the
amount of an incident light by each sensor. The stored signal electric
charges are read out to shift registers with read gate pulses applied
from a CCD driving circuit 16, and sequentially read out as voltage
signals corresponding to the signal electric charges with register
transfer pulses. The CCD 14 has an electric shutter function for
controlling the exposure time (shutter speed) by outputting the
stored signal electric charges with shutter gate pulses.
The voltage signals are outputted from the CCD 14 to a correlative
double sampling circuit (CDS circuit) 18, which samples and holds
R, G and B signals of each pixel. The CDS circuit 18 outputs the
R, G and B signals to an A/D converter 20, which converts the R,
G and B signals into 10-bit digital R, G and B signals (0-1023)
and outputs the digital R, G and B signals. The CCD driving circuit
16, the CDS circuit 18 and the A/D converter 20 are synchronized
by timing signals outputted from a timing generator 22.
The digital R, G and B signals outputted from the A/D converter
20 are temporarily stored in a memory 24, and then outputted to
a digital signal processing circuit 26. The digital signal processing
circuit 26 comprises a synchronizing circuit 28, a white balance
adjusting circuit 30, a gamma correcting circuit 32, a YC signal
producing circuit 34 and a memory 36.
The synchronizing circuit 28 converts the dot-sequential R, G and
B signals read from the memory 24 into synchronous R, G and B signals,
which are outputted to the white balance adjusting circuit 30. The
white balance adjusting circuit 30 has multipliers 30R, 30G and
30B that increases or decreases digital values of the R, G and B
signals, and the R, G and B signals are inputted to the multipliers
30R, 30G and 30B, respectively. White balance correction values
(gains) Rg, Gg and Bg for adjusting the white balance are outputted
from a central processing unit (CPU) 38 to the multipliers 30R,
30G and 30B, respectively. Each of the multipliers 30R, 30G and
30B multiplies the corresponding digital value and gain together,
and the multipliers 30R, 30G and 30B get R', G' and B' signals.
The white balance adjusting circuit 30 outputs the R', G' and B'
signals to the gamma correcting circuit 32. The gains Rg, Gg and
Bg will be later explained in detail.
The gamma correcting circuit 32 corrects the 10-bit R', G' and
B' signals to 8-bit R, G and B signals with desired gamma characteristic
and outputs the R, G and B signals to the YC signal producing circuit
34. The YC signal producing circuit 34 produces luminance signals
Y and chroma signals Cr and Cb (YC signals) from the R, G and B
signals. The YC signals are stored in the memory 36.
The YC signals are read from the memory 36 and outputted from the
liquid crystal monitor 52 through a mixer 51 so that a moving image
or a still image is displayed on the liquid crystal monitor 52.
After the shooting, the YC signals are compressed with a predetermined
format by the compressing/decompressing circuit 54, and the compressed
image data is stored in a storage medium such as a memory card by
a storage part 56. In the reproducing mode, the image data stored
in the memory card or the like is decompressed, and the decompressed
image data is outputted to the liquid crystal monitor 52 through
the mixer 51 so that the image is displayed on the liquid crystal
monitor 52.
The CPU 38 controls the circuits according to inputs from a camera
control part 40 including the mode dial 1 and the shutter release
button 2 and a direction sensor 41 that determines whether the user
holds the camera sideways or upright. The CPU 38 also controls automatic
focusing, automatic exposure, automatic white balance and selection
of a composition assist frame that assists the composition. For
example, the automatic focusing is contrast automatic focusing that
moves the taking lens 10 through a driving part 42 so that the high-frequency
component of the G signal is the maximum when the shutter release
button 2 is half pressed.
In the automatic exposure, the R, G and B signals are read up to
four times as shown in FIG. 4, and the subject brightness (exposure
values) is determined according to integrated values of the R, G
and B signals.
The method of determining the exposure value will now be explained
in detail.
The image is divided into multiple areas (8 by 8), and luminance
signals found from the R, G and B signals of each area are integrated,
and the exposure value (EVi) of each area is found from the integrated
value. Then, as shown in FIGS. 5(A), 5(B) and 5(C), weight coefficients
of the areas are determined for each shooting mode, and an exposure
value EV' of the whole image is calculated by the following equation
1, EV'=log.sub.2{.SIGMA.(W.sub.i.times.2.sup.EVi)/.SIGMA.W.sub.i}
equation 1,
wherein i is an area number from 0 to 63 and W.sub.i is the weight
coefficient of the area i for each shooting mode.
As shown in FIG. 5(A), in the automatic mode or the person shooting
mode, the closer an area is to the center of the image, the larger
the weight coefficient is. As shown in FIG. 5(B), in the day scenic
shooting mode, the weight coefficients of the peripheral areas are
smaller than that of the other areas. As shown in FIG. 5(C), in
the night scenic shooting mode, the weight coefficients of all the
areas are the same.
Then, the exposure value EV is calculated by the following equation
2, EV=EV'-.DELTA.EV equation 2,
wherein .DELTA.EV is a correction value for each shooting mode.
For example, the correction value .DELTA.EV is 0 in the person shooting
mode, and it is 0.3 in the day scenic mode and the night scenic
shooting mode.
The F-number and the shutter speed are determined from the exposure
value EV.
When the shutter release button 2 is fully pressed, the CPU 38
drives the diaphragm 12 through a diaphragm driving part 44 for
the determined F-number, and controls the exposure time for the
determined shutter speed.
The methods of automatically controlling the white balance will
now be explained with reference to flowcharts of FIGS. 6 and 7.
If an electronic flash 46 emits a light, the gains Rg, Gg and Bg
for the light are outputted to the white balance adjusting circuit
30. The case in which the electronic flash 46 does not emit the
light will now be explained.
FIG. 6 shows the method of automatically controlling the white
balance in the automatic mode or the person shooting mode.
First, the exposure value determined when the shutter release button
2 was half pressed is obtained (step 10).
Then, the image is divided into the multiple areas (8 by 8), and
the average values of the R, G and B signals in each area stored
in the memory 24 when the shutter release button 2 was fully pressed
are calculated, and the ratio (R/G) of the average value of the
R signals to that of the G signals and the ratio (B/G) of the average
value of the B signals to that of the G signals of each area are
calculated (step 12).
The ratios R/G and B/G of each area are used to determine which
one of determination frames in FIG. 8 includes the area. The determination
frames such as a shade-cloudiness frame and a daylight color frame
define ranges of the ratios for various types of light sources.
The integrating circuit 48 in FIG. 3 calculates the average values
of the R, G and B signals in each area and outputs them to the CPU
38. Multipliers 50R, 50G and 50B are provided between the integrating
circuit 48 and the CPU 38, and gains are inputted to the multipliers
50R, 50G and 50B.
Then, an evaluation for shade-cloudiness, evaluations for fluorescent
lamps (daylight color, day white-white and warm white) and an evaluation
for a tungsten lamp are calculated by the following equations 3,
4, 5, 6 and 7 (step 14),
Evaluation for shade-cloudiness =F(outdoors).times.F(shade-cloudiness).times.F(blue
sky), equation 3
Evaluation for daylight fluorescent lamp F.sub.1(indoors).times.F(daylight
fluorescent lamp), equation 4
Evaluation for day white-white fluorescent lamp =F.sub.1(indoors).times.F(day
white-white fluorescent lamp), equation 5
Evaluation for warm white fluorescent lamp =F.sub.1(indoors).times.F(warm
white fluorescent lamp).times.F(skin), equation 6 and
Evaluation for tungsten lamp =F.sub.2(indoors).times.F(tungsten
lamp).times.F(skin). equation 7
F(outdoor) in the equation 3 is a membership function of the exposure
value obtained at step 10 as shown in FIG. 9, and it indicates the
possibility of the outdoors.
F.sub.1(indoors) in the equations 4, 5 and 6 is a membership function
of the exposure value as shown in FIG. 12, and it indicates the
possibility of the indoors (the fluorescent lamps). F.sub.2(indoors)
in the equation 7 is a membership function of the exposure value
(values in brackets) as shown in FIG. 12, and it indicates the possibility
of the indoors (the tungsten lamp). The exposure values in FIGS.
9 and 12 are values determined with the weight coefficients for
the automatic mode and the person shooting mode regardless of the
selected shooting mode.
F(shade-cloudiness) in the equation 3 is a membership function
of the number of areas whose exposure values are 12 or less and
that are in the shade-cloudiness frame as shown in FIG. 10, and
it indicates the possibility of the shade-cloudiness. F(blue sky)
in the equation 3 is a membership function of the number of areas
whose exposure values are larger than 12.5 and that are in an outdoors-clear
weather frame as shown in FIG. 11, and it indicates the possibility
of blue sky.
The larger the number of the areas for F(blue sky) is, the lower
the evaluation for the shade-cloudiness is. The luminance (exposure
value Evi) of each area is calculated by the following equation
8, Evi=Ev+log.sub.2(Gi/45), equation 8 wherein Ev is the exposure
value and Gi is the average value of the G signals of each area.
45 is the appropriate value of the signal after the A/D conversion.
Likewise, F(daylight fluorescent lamp), F(day white-white fluorescent
lamp), F(warm white fluorescent lamp) and F(tungsten lamp) in the
equations 4, 5, 6 and 7 are membership functions in FIG. 13 of the
numbers of areas in the daylight color frame, a day white-white
frame, a warm white frame and a tungsten lamp frame in FIG. 8, respectively,
and they indicate the possibilities of the fluorescent lamps and
the tungsten lamp.
F(skin) in the equations 6 and 7 is a membership function in FIG.
14 of the number of areas in a skin pigmentation frame in FIG. 8.
The larger the number of the areas for F(skin) is, the lower the
evaluation for the tungsten lamp is. The reason is that redness
of skin pigmentation is washed out and people look pale if the white
balance is controlled too much for the tungsten lamp.
After the evaluation for the shade-cloudiness, the evaluation for
the daylight fluorescent lamp, the evaluation for the day white-white
fluorescent lamp, the evaluation for the warm white fluorescent
lamp and the evaluation for the tungsten lamp are calculated, whether
or not the maximum of the evaluations is 0.4 or higher is determined
(step 16 in FIG. 6). If the maximum is 0.4 or higher, the white
balance is controlled according to a white balance correction value
for the light source with the maximum evaluation (step 18).
If the maximum is lower than 0.4, the white balance is controlled
according to a white balance correction value for the daylight (step
20).
The white balance correction value is calculated by the following
equation 9,
White balance correction value =(automatic setting value-1.0).times.evaluation+1.0
equation 9.
The automatic setting value is previously set for each light source.
The automatic setting values for the shade-cloudiness, the daylight
fluorescent lamp, the day white-white fluorescent lamp, the warm
white fluorescent lamp and the tungsten lamp are selected in the
following ways.
(1) In case of the shade-cloudiness, the number of areas in a cloudiness
area in FIG. 8 is compared with the number of areas in the shade
area, and the automatic setting value of the frame including more
areas is adopted. Alternatively, the automatic setting value of
the frame including more areas is weighted to calculate the automatic
setting value.
(2) In case of the day white-white fluorescent lamp, the numbers
of areas in six frames of the day white-white frame in FIG. 8 are
compared, and the automatic setting value of the frame with the
largest number of areas is adopted. Alternatively, automatic setting
values of the six frames are weighted according to the numbers of
the areas to calculate the automatic setting value.
(3) In case of the tungsten lamp, the numbers of areas in two frames
of the tungsten lamp frame in FIG. 8 are compared, and the automatic
setting value of the frame with more areas is adopted. Alternatively,
automatic setting values of the two frames are weighted according
to the numbers of the areas to calculate the automatic setting value.
The R, G and B signals are corrected to the R', G' and B' signals
calculated by the following equations 10, R'=Rg.times.R, G'=Gg.times.G,
and B'=Bg.times.B, equations 10
wherein Rg, Gg and Bg are the white balance correction values found
by the equation 9.
FIG. 7 shows the method of automatically controlling the white
balance in the day scenic shooting mode. Steps 30 and 32 in FIG.
7 are the same as steps 10 and 12 in FIG. 6, respectively, and they
will not be explained.
The evaluation for the shade-cloudiness of the equation 3 is calculated
according to the exposure value acquired at step 30 and the ratios
R/G and B/G calculated at step 32 (step 34). The evaluations for
the fluorescent lamps (daylight color, day white-white and warm
white) and the tungsten lamp in step 14 of FIG. 6 are not calculated.
This is because the fluorescent lamps and the tungsten lamp are
not used when the shooting is performed outdoors in the day scenic
shooting mode.
Then, whether or not the evaluation for the shade-cloudiness is
0.4 or higher is determined (step 36). If the evaluation is 0.4
or higher, the white balance correction value is calculated according
to the automatic setting value for the shade-cloudiness (see the
equation 9), and the white balance is controlled according to the
white balance correction value (step 38).
If the evaluation is lower than 0.4, the white balance is controlled
according to the white balance correction value for the daylight
(step 40).
In case of the night scenic shooting mode, the white balance is
not automatically controlled and the white balance correction value
for the daylight is adopted. Thus, the white balance control is
not affected by artificial light sources.
The method of selecting the composition assist frame for the digital
camera according to the present invention will now be explained.
A read only memory (ROM) 55 stores frame data of various composition
assist frames for displaying the composition assist frames on the
liquid crystal monitor 52.
FIGS. 15(A), 15(B), 15(C), 15(D), 15(E) and 15(F) are diagrams
showing the composition assist frames 1, 2, 3, 4, 5 and 6, respectively.
The composition assist frames 1 and 2 in FIGS. 15(A) and 15(B) are
mainly used to shoot a day scene so that the horizon and a horizontal
line of a construction are horizontal and a vertical line of a construction
is vertical in the pictures.
The composition assist frames 3-6 in FIGS. 15(C)-15(F) are mainly
used to shoot persons. The composition assist frames 3 and 5 are
used when the user holds the camera upright (the image is wider
than it is long), and the composition assist frame 3 is used to
shoot one or two persons, and the composition assist frame 5 is
used to shoot a group of people. The composition assist frames 4
and 6 are used when the user holds the camera sideways (the image
is longer than it is wide).
If one of the composition assist frames 3-6 is used, one or more
persons are in the center of a picture. Generally, a lens has a
distortion and the periphery of a picture is distorted. However,
the persons are not distorted even if the quality of the lens is
low. Also, the periphery of the picture may not be printed. For
these reasons, the persons should be in the center of the picture.
To display one of the composition assist frames on the liquid crystal
monitor 52, the user pushes the display button 5 (see FIG. 1) twice.
When the user first pushes the display button 1, a moving image
of a subject is displayed on the liquid crystal monitor 52. When
the user next pushes the display button 1, the best framing mode
is set to display the composition assist frame with the moving image.
When the user pushes the display button 1 once more, the liquid
crystal monitor 52 is turned off.
When the best framing mode is set, the CPU 38 reads the frame data
of the appropriate composition assist frame from the ROM 55 and
outputs the frame data to the mixer 51.
The mixer 51 receives the YC signals of the moving image from the
memory 36, and mixes the high-luminance frame data with the luminance
signals Y of the YC signals to output the mixed signals to the liquid
crystal monitor 52, which displays the moving image of the subject
and the composition assist frame (white lines).
The method in which the CPU 38 selects the composition assist frame
when the best framing mode is set will now be explained.
As shown in FIG. 3, the CPU 38 receives operation signals from
the camera control part 40 including the mode dial 1 and the cross
key 9 and receives a direction signal from the direction sensor
41 that determines whether the user holds the camera sideways or
upright. The CPU 38 determines which one of the day scenic shooting
mode, the night scenic shooting mode, the automatic shooting mode
and the person shooting mode has been set according to a signal
from the mode dial 1, and determines whether the user holds the
camera sideways or upright according to the direction signal from
the direction sensor 41.
Then, the CPU 38 extracts composition assist frames that can be
selected according to the shooting mode and the direction of the
camera as shown in the following table 1.
TABLE-US-00001 Upright Sideways Day scenic shooting mode or frames
1, 2 and 3 frames 1, 2 and 4 night scenic shooting mode Automatic
shooting mode frames 3, 5, 1 and 2 frames 4, 6, 1 and 2 Person shooting
mode frames 5, 3 and 1 frames 6, 4 and 1
As shown in the table 1, when the shooting mode is the day scenic
shooting mode or the night scenic shooting mode and the user holds
the camera upright, the composition assist frames 1, 2 and 3 can
be selected, and the user selects one of them with the left key
and the right key of the cross key 9. The composition assist frame
1 is displayed first, and the composition assist frames 2, 3 and
1 are displayed in that order when the user repeatedly presses the
right key. The composition assist frames 3, 2 and 1 are displayed
in that order when the user repeatedly presses the left key.
When the shooting mode is the day scenic shooting mode or the night
scenic shooting mode and the user holds the camera sideways, the
composition assist frames 1, 2 and 4 can be selected, and the user
selects one of them with the left key and the right key of the cross
key 9.
As stated above, when the shooting mode is the day scenic shooting
mode or the night scenic shooting mode, the composition assist frames
1 and 2 can be selected regardless of the direction of the camera.
The composition assist frame 3 can be also selected when the user
holds the camera upright, and the composition assist frame 4 can
be also selected when the user holds the camera sideways. FIGS.
16 and 17 are back views of the digital camera displaying the composition
assist frame 1 on the liquid crystal monitor 52 in the day scenic
shooting mode and the night scenic shooting mode, respectively.
When the shooting mode is the automatic shooting mode and the user
holds the camera upright, the composition assist frames 3, 5, 1
and 2 can be selected. When the shooting mode is the automatic shooting
mode and the user holds the camera sideways, the composition assist
frames 4, 6, 1 and 2 can be selected. The composition assist frames
1 and 2 can be selected regardless of the direction of the camera.
The composition assist frames 3 and 5 can be also selected when
the user holds the camera upright, and the composition assist frames
4 and 6 can be also selected when the user holds the camera sideways.
FIG. 18 is a back view of the digital camera displaying the composition
assist frame 3 on the liquid crystal monitor 52 in the automatic
shooting mode.
When the shooting mode is the automatic shooting mode and the user
holds the camera upright, the composition assist frames 5, 3 and
1 can be selected. When the shooting mode is the automatic shooting
mode and the user holds the camera sideways, the composition assist
frames 6, 4 and 1 can be selected. The composition assist frame
1 can be selected regardless of the direction of the camera. The
composition assist frames 5 and 3 can be also selected when the
user holds the camera upright, and the composition assist frames
6 and 4 can be also selected when the user holds the camera sideways.
FIG. 19 is a back view of the digital camera displaying the composition
assist frame 5 on the liquid crystal monitor 52 in the person shooting
mode.
The composition assist frames that can be selected according to
the shooting modes and the directions of the camera are not limited
to those in the table 1. For example, the composition assist frames
1 and 2 can be selected in case of the day scenic shooting mode
or the night scenic shooting mode, and the composition assist frames
5 and 3 can be selected when the shooting mode is the person shooting
mode and the user holds the camera upright, and the composition
assist frames 6 and 4 can be selected when the shooting mode is
the person shooting mode and the user holds the camera sideways.
In another example, the composition assist frame 1 can be selected
in case of the day scenic shooting mode or the night scenic shooting
mode, and the composition assist frame 5 can be selected when the
shooting mode is the person shooting mode and the user holds the
camera upright, and the composition assist frame 6 can be selected
when the shooting mode is the person shooting mode and the user
holds the camera sideways. In this case, one composition assist
frame is automatically selected according to the shooting mode and
the direction of the camera.
The composition assist frames are not limited to those in FIGS.
15(A)-15(F).
The composition assist frames that can be selected are extracted
according to the shooting mode and the direction of the camera in
the embodiment. However, the composition assist frames may be extracted
according to only the shooting mode, and they may be extracted according
to only the direction of the camera.
According to the present invention, one or more composition assist
frames that can be selected are extracted according to the shooting
mode such as the day scenic shooting mode, the night scenic shooting
mode and the person shooting mode and the direction of the camera.
Therefore, the appropriate composition assist frame can be automatically
or easily selected.
It should be understood, however, that there is no intention to
limit the invention to the specific forms disclosed, but on the
contrary, the invention is to cover all modifications, alternate
constructions and equivalents falling within the spirit and scope
of the invention as expressed in the appended claims.
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