JP2609138B2 - Digital electronic still camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a digital signal processing device that performs digital signal processing on a video signal obtained by imaging with an image sensor and electronically records and reproduces a still image. More specifically, the present invention relates to a memory for storing image data of the still image.

[Conventional technology]

In a conventional electronic still camera, a video signal obtained by an image sensor is subjected to analog signal processing. That is, CC
After adjusting the gamma correction and white balance of the video signal read from the image sensor such as D, and generating a luminance signal and a color difference signal by a matrix circuit, the luminance signal and the color difference signal are applied to a low-pass filter of a predetermined band. Thus, only necessary frequency components are obtained, and are FM-modulated and recorded on a magnetic recording medium.

However, in such a conventional electronic still camera, the process from imaging to recording is performed by analog signal processing, and there is a limit to the improvement in image quality due to variations in characteristics of a matrix circuit and a low-pass filter. I was

On the other hand, in recent years, digital electronic still cameras have been proposed to solve the above-mentioned problems, and are gradually becoming popular.

Although various proposals have been made for the digital electronic still camera, an outline thereof will be described with reference to FIGS. 3 to 5. FIG.

That is, in FIG. 3, a subject optical image incident through an optical system 1 having a photographing lens, an aperture, a shutter, and the like is received by a color image sensor 2 composed of a CCD, and is subjected to well-known horizontal and vertical read scanning. The color signals R, G, and B are read from each pixel of the color image sensor 2, and are converted into digital signals indicating, for example, 8-bit (that is, 256 steps) gradations by the A / D converter 3. The cell array of the color image sensor 2 includes FIGS. 4 (a) and 4 (b).
As shown in the figure, the green (G) portion and the red (R) and blue (B)
The color signals R, G, and B are output by forming pixels by providing a color filter having a ratio of 2: 1: 1 and performing horizontal scanning for each row.

These digitized color signals R, G, and B are input to a matrix circuit including a wide-range luminance signal generation circuit 4, a bottom-range luminance signal generation circuit 5, color difference signal generation circuits 6, 7, and an adder 9, and the luminance signal Y And the color difference signals RY and BY are formed.

The high-frequency luminance signal generation circuit 4 calculates the following equation (1) based on each color signal Rd, Gd, Bd delayed by one horizontal period (1H) and each color signal R, G, B currently read horizontally. The high-frequency luminance signal Yh is generated by performing the operation of (2).

Yh = 0.25 (B + Rd) +0.25 (G + Gd) (1) Yh = 0.25 (R + Bd) +0.25 (G + Gd) (2) In the above equation, the image that is currently being read by horizontal scanning is shown. When the color signal from the sensor 1 is a blue signal B and a green signal G, the above equation (1) is operated, and when the output signal is a red signal R and a green signal G, the above equation (2) is used.
Is calculated.

The high-frequency luminance signal Yh is supplied to a digital low-pass filter 8 having a pass band of 0 to 4.2 MHz shown in FIG.

The low-frequency luminance signal generation circuit 5 calculates the following equations (3) and (4) based on each color signal Rd, Gd, Bd delayed by one horizontal period (1H) and each color signal R, G, B obtained by the current horizontal scanning readout. ) To generate a bottom-range luminance signal YL.

YL = 0.11 (B−G) +0.30 (Rd−Gd) + G (3) YL = 0.11 (Bd + Gd) +0.30 (R−G) + G (4) The current horizontal scanning readout is performed. When the color signals from the image sensor 1 are the blue signal B and the green signal G, the calculation of the above equation (3) is performed. When the output signals are the red signal R and the green signal G, the calculation of the above equation (4) is performed. I do.

Then, the baseband luminance signal YL is subtracted from the highband luminance signal Yh in the adder 9, and the luminance signal YL-YH generated by the subtraction processing is 0 to 0.7 MHz shown in FIG. 5 (b).
, And is output as a luminance signal Yc.

The color difference signal generation circuit 6 calculates the following equation (5) based on each color signal Rd, Gd, Bd delayed by one horizontal period (1H) and each color signal R, G, B by the current horizontal scanning readout. Generates a color difference signal RY.

R−Y = 0.7 (R−G) −0.11 (Bd−Gd) (5) Then, this color difference signal R−Y is 0 shown in FIG.
The signal is supplied to a digital low-pass filter 11 having a pass band of about 0.7 MHz.

The color difference signal generating circuit 7 calculates the following equation (6) based on each color signal Rd, Gd, Bd delayed by one horizontal scanning period (1H) and each color signal R, G, B obtained by the current horizontal scanning reading. Generates the equation difference signal BY.

BY = 0.89 (BG) -0.30 (Rd-Gd) (6) The color difference signal BY is a digital signal having a pass band of 0 to 0.7 MHz, also shown in FIG. 5 (c).・ Supplied to the low-pass filter 12.

Further, the adder 13 performs an addition operation of the luminance signals YH and Yc from the digital low-pass filters 8 and 10,
As shown in FIG. 5D, a luminance signal Y including a high-frequency component and a reduced luminance component is formed.

The generated signal Y of the predetermined frequency component and the color difference signals RY and BY are input to the data compression circuit 14 to reduce the number of bits, thereby reducing the storage capacity.
Data-compressed luminance signal Y and color difference signals RY and B
-Y is output to the connector 16 via the input / output interface 15.

The luminance signal Y and the color difference signals RY and BY are stored in a memory card 18 having a semiconductor memory (static RAM), and an input / output interface connected to the memory card 18 is provided. Recording and reproduction are enabled by attaching 17 to the connector 16.

The memory card 18 records, for example, image data for 26 frames, and can be edited and deleted freely, which is very convenient.

[Problems to be solved by the invention]

Incidentally, the solid-state memory 18 has an image data area A and memory information, that is, a type of memory, as shown in FIG.
An area B in which the storage capacity, the expiration date of the power supply battery, and the like are stored.

Then, the image data is converted to NO1, NO2, NO3
... If the unnecessary image data is intermittently erased as indicated by NO2 and NO4 after sequentially storing NOn, the data erase area remains discontinuously.

On the other hand, the electronic still camera having the above-described configuration includes a data compression circuit, and can change the size of various image data depending on a data compression mode.
Since the image data area A cannot be changed, image data larger than the erasure area cannot be recorded in the erasure area.

In addition, it is desirable that data such as the size of the image data, recorded or erased is written in the image information area B for each image data so that a search can be performed during recording and reproduction.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a digital electronic still camera capable of effectively utilizing a memory by reducing an empty area of a memory for recording image data. is there.

[Means for solving the problem]

In order to achieve such an object, the present invention relates to a digital electronic still camera, wherein a garbage means for detecting a free area of a memory for storing image data in conjunction with a data input means and sequentially transferring the image data to the free area. And a garbage mode selection means for selectively enabling a garbage operation, so as to fill the area where the image data is stored and simultaneously form a free area following the recording area.

(Operation)

According to the present invention having such a configuration, the garbage means operates by operating the data input means provided in the digital electronic still camera, and the storage area of the memory is reduced, so that a new image is generated by shooting. The obtained image data is stored in a free area formed following the storage area in accordance with the size of the image data, so that the memory can be effectively used.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a circuit diagram of a digital electronic still camera to which the present invention is applied, and the same or corresponding parts as those in FIG. 3 are denoted by the same reference numerals.

First, the configuration will be described with reference to FIG. 1. A CCD image sensor 2 provided with a color filter having an arrangement as shown in FIG. The color signals R (red), G (green), and B (blue) of each pixel are output by horizontal and vertical scanning readout.

Since these color signals R, G, B are low-level analog signals, they are amplified to a desired level by the preprocessing circuit 21 and subjected to γ correction, white balance correction and the like.

The A / D converter 3 converts the color signals R, G, B into 8-bit digital signals, and stores them in a first buffer memory (not shown) for each hue.

The signal processing circuit 23 is configured as a matrix circuit in the same manner as the high-frequency luminance signal generating circuit 4, the low-frequency luminance signal generating circuit 5, the color difference signal generating circuits 6, 7 and the adder 9, and has a color memory stored in a buffer memory. High-range luminance signal Y based on signals R, G, B
H, low-frequency luminance signal YL, and color difference signals RY and BY. That is, the signal processing circuit 23 performs the calculations described in the equations (1) to (6), and calculates the color difference signals RY, BY and YL.
It generates a luminance signal of -YH.

The data compression circuit 14 outputs a luminance signal Y and color difference signals R-Y, B-
It is provided to reduce the number of bits of Y and to reduce the storage capacity of a memory cartridge described later. Then, the luminance signal Y and the color difference signals RY, B-
Y is output to the connector 16 via the input / output interface 15.

On the other hand, a memory cartridge 31 is connected to the connector 16 and is configured to store a luminance signal Y and color difference signals RY and BY. That is, the memory cartridge 31 includes the interface 32 and the semiconductor memory (for example, static
RAM), a power supply battery (not shown), and the like.

Then, by connecting the memory cartridge 31 to the connector 16, the luminance signal Y, the color difference signals RY, and BY supplied via the interface 32 during shooting are stored in the image data area A of the memory card 33. . At the time of reproduction, image data stored by operation of a system controller 42 described later can be read and displayed on a display (not shown).

In addition to the image data area A, the memory card 33 also has an image information area B for storing a storage capacity, storage contents, a battery expiration date, and the like, so that the image data and the memory card 33 can be easily managed. . The memory card 33 will be described later in detail together with the garbage operation with reference to FIG.

The data input operation 41 is attached as a garbage mode selection means to an easily operable position on the side surface of the case of the electronic still camera, and is configured so that a garbage operation can be selected by a push button or the like.

The system controller 42 (control circuit) is composed of a microprocessor or the like that centrally manages operation timings from photographing to storage in the memory card 33, reading from the memory card 33, and garbage and the like. That is, when garbage is selected by operating the data input device 41, the system controller reads the image information area B of the memory card 33 and performs a garbage operation.

Next, the circuit operation of the digital electronic still camera configured as described above will be described.

First, when a shutter release button (not shown) is pressed to instruct shooting, the optical system 1 is set to an optimum shooting state, and the system controller 42 instructs the image sensor 2 to start scanning and reading.

The color signals R, G, and B from each pixel output in time series by the scanning readout are amplified to a desired level in the preprocessing circuit 21, and γ correction, white balance correction, and the like are performed. The digital signal is converted into a digital signal by the A / D converter 3, and R, G, and B color signals corresponding to the pixel arrangement are supplied to the signal processing circuit 23.

In the signal processing circuit 23, the equations (1) to (6) are used.
Is performed to generate the luminance signal Y and the color difference signals RY and BY, which are stored in the buffer memory.
The data compression circuit 14 includes a luminance signal Y and color difference signals RY, B
Data compression is performed for -Y as described above.

During shooting, the interface 14 is controlled by the system controller 42 to output image data to the connector 16 side, and the compressed image data is stored in the image data area A of the memory card 33 via the connector 16 and the interface 32. .

The present embodiment is configured so that the following garbage operation can be performed on the image data captured and stored as described above.

Next, the garbage operation will be described with reference to FIG. In this case, the system controller 42 is selected to be garbage-operable by operating, for example, a push button of the data input device 41.

On the other hand, in the image information area B of the memory card 33, recorded or erased information for each image data, as well as information such as the size of the image data, the start address and the end address of the image data, are recorded.

When the controller 42 is selected for the garbage operation, the control signal controls the interface 15 so that the data in the memory card 33 can be read, and the system controller 42 reads the area B via the data bus 43 to read the free space in the area A. Search for the presence of

At this time, since the presence / absence of the free area of the image data area A is registered in the image information area B, the free area is searched from the presence / absence of the registration.

If a free area is found, the system controller 42 transfers the image data stored in the next area NO3 to the erased free area, for example, the free area NO2 shown in FIG. The image data stored in the next area NO5 is transferred to the empty area NO4.

In this way, by sequentially transferring the image data stored in the next area to the free area, the image data is packed in the image data area A following the area B as shown in FIG. Will be remembered. Then, the free space is formed in a continuous state following the final storage area of the image data area A, so that the free area is completely separated from the storage area and is substantially enlarged.

As a result, the image data newly supplied by shooting is sequentially stored in the enlarged free area,
Even if the size of the image data is changed by the data compression circuit 14, the image data can be stored.

The transfer of image data described above, that is, garbage collection, is usually performed using a microprocessor, but the speed can be increased using a DMA controller.

Furthermore, it is also possible to control with a microcomputer using firmware, and the above processing may be performed by a random logic circuit. Further, if the garbage collection is performed immediately after the erasure of the image data, the storage area of the image data does not reverse even without the information of the photographing order, and the image can be easily searched during the reproduction.

Also, regardless of whether the data compression is a fixed-length encoding or a variable-length encoding, the garbage collection can be applied to effectively use the memory.

In this embodiment, the case where the mosaic color filters of R, G, and B are used has been described. However, the present invention is applied to an image sensor using other types of color filters, such as a complementary color or a striped filter. Needless to say, the cut-off frequencies of the luminance signal and the color difference signal are appropriately set according to the case where another type of color filter is used or the number of pixels is different. Further, another method can be applied to the method of forming the luminance signal and the color difference signal.

〔The invention's effect〕

As described above, according to the digital electronic still camera of the present invention, the empty area of the memory is searched for by erasing or the like, and the image data of the next area is sequentially transferred to the empty area. An empty area is continuously formed separately from the final storage area, and the image data can be stored in the empty area regardless of the size of the image data, and the memory is effectively used. In particular, since the garbage mode selecting means capable of selectively switching the garbage operation is provided, it is possible to respond to an emergency operation by selectively using the garbage mode selecting means in response to an unexpected memory shortage during photographing.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a digital electronic still camera showing one embodiment of the present invention; FIG. 2 is a memory card diagram illustrating garbage collection; FIG. 3 is a circuit diagram showing an example of a conventional digital electronic still camera; FIG. 4 is an explanatory diagram showing an arrangement of color filters; FIG. 5 is a characteristic curve diagram showing frequency characteristics of a digital filter; FIG. 6 is an explanatory diagram for explaining a memory map of a memory card. 1 in the figure; optical system 2; image sensor 3; A / D converter 14; data compression circuit 15; interface 16; connector 23; signal processing circuit 31; memory cartridge 32; interface 33; memory card 41; Device 42; System controller 43; Data bus A; Image data area B; Information recording area

Claims (1)

(57) [Claims] 1. A solid-state imaging device, an A / D converter for converting a video signal read from the solid-state imaging device into a digital signal, and a luminance / color difference signal for forming a luminance signal and a color difference signal based on the digital signal. A digital electronic still camera having a color difference separation circuit and storing the luminance and color difference signals in a solid-state memory, wherein garbage processing is performed on image data stored in the solid-state memory to make unused areas continuous, A digital electronic still camera, comprising: garbage means for effective use of a memory; and garbage mode selection means for selectively enabling garbage operation.