JPH09322110A - Digital camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the digital camera by which a compression rate of an image picked up and stored in a recording medium is changed. SOLUTION: A CPU 31 designates an image quality revision object image among image data stored in a flush memory 27 in the FINE mode (low compression rate) through the image quality conversion processing, reads the designated image data and a compression/expansion circuit 26 conducts expansion processing to the data and compresses the data again in the economy mode (high compression rate). Then the compressed image data again are stored in an image data storage area of the flush memory 27 and header information of a header part is revised.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital camera, and more particularly to a digital camera capable of changing a compression rate of an image captured and stored in a storage medium.

[0002]

2. Description of the Related Art In recent years, digital cameras (electronic cameras) that electronically store captured images instead of films have become widespread. In such a digital camera, when a photographer presses a shutter, an image of a subject that has passed through a lens is captured by a CCD element, data is compressed through a circuit inside the camera, and written in an internal recording medium.

[0003] Further, there is also known a digital camera in which an operator selects an image quality level at the time of shooting and compresses and records a captured image at a data compression rate corresponding to the selected image quality level. I have.

[0004]

However, in the conventional digital camera, since the image quality level was selected at the time of shooting as described above, the image quality level was mistakenly taken, or However, because the image quality level was set, there were problems such as missing a photo opportunity.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a digital camera capable of changing the compression ratio after photographing.

[0006]

According to the first aspect of the present invention,
An image pickup means for picking up an image of a subject, a data compression means capable of compressing the image data picked up by the image pickup means at a plurality of compression ratios, and a storage means for storing the image data compressed by the data compression means, Designating means for designating a predetermined image from the image data stored in the storage means, means for decompressing the designated image data, and image data decompressed by the decompressing means for the decompressed image. Control means for controlling the data compression means to re-compress the data at a compression rate different from the compression rate when the data was compressed by the compression means, and to store the re-compressed image data in the storage means. The above-mentioned problem is solved by providing the above.

That is, according to the first aspect of the present invention,
The image capturing unit captures an image of the subject, and the data compressing unit is capable of compressing the captured image data at a plurality of compression rates.
The storage means stores the image data compressed by the data compression means, the designating means designates a predetermined image from the image data stored in the storage means, and the data decompressing means stores the designated predetermined image data. Then, the control means causes the data compression means to recompress the image data decompressed by the decompression means at a compression rate different from the compression rate when the image data was compressed by the compression means, and recompresses the recompressed image data. The image data is controlled to be stored in the storage means.

Therefore, since the compression ratio of the image photographed and stored in the storage means can be changed, even if the image quality level (compression ratio) to be recorded is wrongly selected at the time of photographing, the image quality after photographing is not changed. The level (compression rate) can be changed, which improves the usability of the operator.

In this case, as in the second aspect of the invention, the different compression rates are greater than the compression rates when the expanded image data is compressed by the compression means. A rate is useful.

That is, according to the invention described in claim 2, in the invention described in claim 1, the control means compresses the image data expanded by the expansion means, when the image data is compressed by the compression means. The data compression means is recompressed at a compression rate different from that, and the recompressed image data is controlled to be stored in the storage means.

Therefore, since the image can be recompressed at a compression rate higher than the compression rate of the image photographed and stored in the recording means, the desired image quality level (compression rate) can be erroneously selected at the time of photography. It is possible to change an image recorded at an image quality level (low compression rate) to a lower image quality level (high compression rate). Further, when the amount of memory that can be stored in the storage unit is small, the amount of stored data can be reduced, so that the number of images that can be stored can be secured.

In this case, as in the third aspect of the invention, further, when the compressed image data is stored in the storage means, a selection means for selecting one of a plurality of compression rates of the data compression means is provided. The compression means compresses the image data imaged by the imaging means at a compression rate lower than the compression rate selected by the selection means, and the storage means compresses the compressed image data compressed by the compression means. The decompression means decompresses the image data stored at a compression rate lower than the compression rate designated by the designating means stored in the storage means, and the decompressing means decompresses the image data. The image data stored in the storage unit at a compression rate lower than the compression rate designated by the designation unit is re-stored in the data compression unit at the compression rate selected by the selection unit. By condensation, it is effective to control so as to store the re-compressed image data in the storage means.

That is, according to the invention of claim 3, when the compressed image data is stored in the storage means, there is further provided a selection means for selecting one of a plurality of compression ratios of the data compression means, The compression unit compresses the image data imaged by the imaging unit at a compression rate lower than the compression rate selected by the selection unit, and the storage unit stores the compressed image data compressed by the compression unit. The decompression means decompresses the image data stored in the storage means at a compression rate lower than the compression rate designated by the designation means, and the control means decompresses the storage data decompressed by the decompression means. The image data stored at a compression rate lower than the compression rate designated by the designation means stored in the means is recompressed by the data compression means at the compression rate selected by the selection means. It is effective to control so as to store the re-compressed image data in the storage means.

That is, according to the invention described in claim 3, in the invention described in claim 1, the selecting means selects one of the plurality of compression ratios of the data compressing means when storing the compressed image data in the storing means. The compression means compresses the image data imaged by the imaging means at a compression rate lower than the compression rate selected by the selection means, and the storage means stores the compressed image data compressed by the compression means. The decompressing means decompresses the image data stored in the storage means at a compression rate lower than the compression rate designated by the designating means, and the control means stores in the storage means decompressed by the decompressing means. The image data stored at the compression rate lower than the stored compression rate designated by the designation means is recompressed by the data compression means at the compression rate selected by the selection means, and the recompressed image is recompressed. Controlling so as to store the data in the storage means.

Therefore, the image data is stored at a compression rate lower than the selected compression rate, and at the time of recompression, the image data is recompressed at the selected compression rate. The image data can be stored at a low compression rate, and the usability for the operator is improved.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments to which the present invention is applied will be described below with reference to FIGS. 1 to 4 are diagrams showing an embodiment of a digital camera of the present invention.

First, the structure will be described. FIG. 1 is a perspective view illustrating an external configuration of the digital camera according to the present embodiment.
As shown in FIG. 1, the digital camera 1 includes two blocks divided into a main body 2 and a camera section 3.
An LCD (liquid crystal display) 6 is provided in the case 4 of the main body 2.
Is provided, and the LCD 6 faces the front side of the case 4.

An image pickup lens 7 is provided in the upper part of the case 5 of the camera section 3, and the image pickup lens 7 is provided.
Are directed to the back side of the case 5.

The camera section 3 is arranged on the side surface of the main body section 2 on the left hand operation side by the photographer, and is attached to the main body section 2 so as to be rotatable 90 ° forward and 180 ° rearward. ing. FIG. 1 shows a state of being rotated 180 ° backward.

The main body 2 is provided on the upper surface of the case 4,
Power switch 8, "Shutter" key 9, "DEL" key 10, "+" key 11, "-" key 12, "MOD"
"E" key 13, "DIP (display)" key 1
4, an “image quality conversion” key 15, a conversion execution key 16 and an “image quality mode” key 19 and the like, and an opening / closing lid 17
Inside, an external power supply terminal, a video output terminal, and a digital terminal (not shown) are provided. Further, a function switching key 18 is provided on the front surface of the case 4, and an openable battery lid (not shown) is provided on the lower surface of the case 4.

FIG. 2 is a block diagram showing the circuit configuration of the digital camera 1 shown in FIG. The digital camera 1 shown in FIG. 2 has a CCD (Charge Coupled Divice) 20,
A / D converter 22, drive circuit 23, timing generator 24, DRAM 25, compression / decompression circuit 26, flash memory 27, ROM 28, RAM 29, key input unit 30, CPU 31, signal generator 32, VRA
M (Video RAM) 33, D / A converter 34, LCD (Liq
A uid crystal display) 6, an I / O port 36 and the like.

The CCD 20 receives the image signal of the subject imaged by the image pickup lens 7, accumulates electric charges proportional to the amount of received light for each transfer electrode arranged on the light receiving surface, and supplies them by the drive circuit 23. In response to the drive signal, the accumulated charge accumulated in each transfer electrode is sequentially output to the A / D converter 22 via the buffer 21 as an electric signal (analog signal), one electrode at a time.

The A / D converter 22 converts the electric signal output from the CCD 20 into a digital signal and supplies it to the timing generator 24 as image data.

The drive circuit 23 uses the timing signal supplied from the timing generator 24 to drive the CCD 2
The exposure and readout timing of 0 is drive-controlled.

The timing generator 24 generates a timing signal for controlling the drive circuit 23.

The DRAM 25 is a semiconductor memory for temporarily storing the captured image data.

The compression / expansion circuit 26 compresses the image data stored in the DRAM 25 by encoding. Specifically, for example, JPEG (Joint Photograph) depending on a predetermined encoding method of the image data stored in the DRAM 25, that is, the type of image to be handled (still image in this case).
ic Experts Group) algorithm performs compression processing (coding processing) by DCT (Discrete Cosine Transform), quantization, and Huffman coding for every 8 × 8 pixels, and the compressed image data is stored in the flash memory. To 27. In addition, the compression / expansion circuit 26
When the "FINE mode" is selected by the "image quality mode" key 19, data compression is performed at a low compression rate, while when the "economy mode" is selected, data compression is performed at a high compression rate. . The data compression rate in the compression processing is determined by the relationship with the image quality after decompression.
The compression / expansion circuit 26 also decodes the compressed image data stored in the flash memory 27 and expands it.

The flash memory 27 is a memory for storing the image data compressed by the compression / expansion circuit 26. FIG. 3 is a diagram illustrating an example of a memory configuration of the flash memory 27. As shown in FIG. 3, the flash memory 2
Reference numeral 7 includes a header section (table) 27A that manages information on the captured image, and an image data storage section 27B that stores image data of the captured image. The header section 27A includes an image page number, a start address of the image data storage section 27B in which image data of a captured image is stored, and an image quality mode flag (FINE mode (low "H" in the case of compression rate) and "L" in the case of economy mode (high compression rate) are stored in association with each other, and this header information (data) is newly stored in the image data storage unit 27B. It is updated when data is stored or whenever the mode (compression rate) of the stored image data is changed. The image data storage unit 27B is address-managed by the header unit 27A and stores image data in block units.

The ROM 28 stores various control programs executed in the digital camera 1 and data used in the program processing. The various control programs include, for example, the image quality conversion shown in the flowchart of FIG. There is an image conversion processing program or the like for executing the processing.

The RAM 29 has a work memory used in the program processing executed by the CPU 31.

The key input section 30 includes a "shutter" key 9, a "+" key 11, a "-" key 12, and a "DE" shown in FIG.
"L" key 10, "MODE" key 13, "DSP" key 14, "image quality conversion" key 15, "conversion execution" key 16,
And an “image quality mode” key 19 and the like, which are used by the operator to instruct various processes in the digital camera 1. The "shutter" key 9 is a key for instructing image pickup. The “image quality conversion” key 15 is a key for instructing switching to the image quality conversion mode. The image quality conversion mode is set by first pressing the “image quality conversion” key 15, and the image quality conversion is performed by pressing the “image quality conversion” key again. The mode is canceled. The "conversion execution" key 16 is a key for instructing to change the image quality level, and the "image quality mode" key 19 is a key for setting the image quality level when storing image data in the flash memory 27.

Based on various programs stored in the ROM 28, the CPU 31 uses the work memory of the RAM 29 as a work area and executes a process corresponding to the operation of each key of the key input unit 30 to execute the digital camera 1. Control each part of.

When the "shutter" key 9 of the key input unit 30 is pressed, the CPU 31 executes a photographing process to generate an image capture signal to the timing generator 24 and capture the image from the CCD 20 to the DRAM 2
Store in 5 once. Color calculation processing is performed on the image data stored in the DRAM 25 to create a luminance signal and a color signal from the video signal, and this image data (luminance signal and color signal) is transferred to the compression / expansion circuit 26. And compress it,
The compressed image data is stored in the flash memory 27.

When the "DIP" key 14 of the key input unit 30 is pressed, the CPU 31 executes an image reproduction process and a predetermined compressed image data (compressed luminance signal and color signal) from the flash memory 27. Read and compress /
The image data (luminance signal and chrominance signal) transferred to the expansion circuit 26 and expanded by the compression / expansion circuit 26 is transferred to the signal generator 32, and the signal generator 32 converts the image data into a video signal. To display.

Further, in the image quality conversion process (see FIG. 4) which will be described later, the CPU 31 stores the F in the flash memory 27.
An image to be changed in image quality is designated from the image data stored in the INE mode (low compression rate), the designated image data is read out, and the compression / decompression circuit 26 performs decompression processing. Recompress at the compression rate. Then, the recompressed image data is stored in the image data storage unit 27B of the flash memory 27, and the header information of the header unit 27A is changed.

The signal generator 32 adds a synchronizing signal to the image data to create a video signal.

The VRAM 33 is a signal generator 3
2 is a memory for storing the video signal generated in Step 2.

The D / A converter 34 converts the digital video signal output from the signal generator 32 into an analog video signal.

The LCD (Liquid Crystal Display) 6 is
The liquid crystal is driven based on the input video signal to display an image.

The I / O port 36 is an interface for inputting / outputting image data converted into a serial signal by the CPU 31 and can be connected to an external device such as an FDD device or a personal computer.

Next, the operation of the digital camera of this embodiment will be described. FIG. 4 is a flowchart for explaining the image quality changing process executed by the CPU 31. The image quality changing process will be described below with reference to FIG.

In FIG. 4, first, the CPU 31 waits for a key input (step S1). If there is a key input, the process proceeds to step S2, and the key input is the operation of the "image quality conversion" key 15. If it is the "image quality conversion" key 15, the process proceeds to step S3 to set the processing of the main body of the digital camera 1 to the image quality change mode,
The page number of the image whose image quality mode flag is set to "H" indicating the FINE mode in the header portion 27B of the flash memory 27 is displayed on the display screen of the LCD 6, and the process proceeds to step S4.

On the other hand, in step S2, step S
If the key input made in 1 is not the "image quality conversion" key 15, the process proceeds to step S13, and the capacity of the data storage unit 27B of the flash memory 27 is FULL.
It is determined whether or not there is a remaining memory capacity, and if the capacity is FULL, the process proceeds to step S3,
Even if the "image quality conversion" key 15 is not operated, the image quality conversion mode is automatically set. On the other hand, when the capacity of the data storage unit 27B of the flash memory 27 is not FULL in step S13, the process proceeds to step S14 and step S1.
The process corresponding to the key operation made in step is executed.

In step S4, it is determined whether or not the "image quality conversion" key 15 for instructing the cancellation of the image quality conversion mode has been operated again, and if the "image quality conversion" key 15 has been operated again. Ends the flow.

On the other hand, if it is determined in step S4 that the "image quality conversion" key 15 has not been operated again, the process proceeds to step S5, and the "+" key 11 and "-" key 12 are pressed. When the page number of the image quality conversion target image is selected by the operation, the image data corresponding to the selected page number is read from the flash memory 27 and compressed / compressed.
The data is transferred to the expansion circuit 26 and expanded, and the expanded image data is displayed on the LCD 6 via the VRAM 33 (step S6).

Then, in step S7, it is confirmed whether or not the image quality conversion target image is the image displayed on the LCD 6, and if this image is good, "Y" is selected by the conversion execution key, and the process proceeds to step S8. On the other hand, if this image is not good, "N" is selected with the conversion execution key and step S5 is performed.
Then, the page number of the image to be converted is designated again.

In step S8, the CPU 31 compresses /
The decompression circuit 26 recompresses the decompressed image data of the image quality conversion in the "economy mode", that is, at a high compression rate. Then, the block data of the flash memory 27 in which the data of the conversion target image was stored is erased (step S9), and the recompressed image data is stored in the corresponding location of the data storage unit 27B of the flash memory 27 (step S9). S10). Then, the header information of the header portion 27B of the recompressed image is rewritten and the image quality mode flag is changed from "H" to "L" (step S11).

Next, of the images recorded in the FINE mode, the page number next to the recompressed image to be converted is L.
After displaying on CD6 (step S12), step S4
Then, the process for changing the image quality is executed again.

As described above, in the present embodiment,
Since the image data can be recompressed at the image quality level (economy mode) lower than the image quality level (FINE mode) of the image data captured and stored in the flash memory 27,
It is possible to erroneously select a desired image quality level at the time of shooting and change an image stored at a high image quality level to a lower image quality level. Further, when the amount of memory that can be stored in the flash memory 27 is small, the amount of stored data can be reduced, so that the number of images that can be stored can be ensured, and the usability for the operator is improved.

Further, in the present embodiment, the image quality change candidate image is displayed on the LCD 6 and the image quality level is changed after confirmation, so that the image to be changed can be specified without mistake. it can.

Further, in this embodiment, even if the "image quality conversion" key for instructing the image quality change is not input, if the capacity of the flash memory 27 is FULL, the image quality change mode is automatically set. Therefore, the usability for the operator is improved.

In the above embodiment, the image quality change target image is designated by the operator's instruction and the image quality level of the designated image data is changed. However, the capacity of the flash memory becomes FULL. In this case, the image data recorded at the high image quality level may be automatically converted to the economy image quality level to secure the number of shootable images.

Further, an image in which the economy mode is designated in advance may be finely recorded, and the image quality may be changed only in the image recorded in fine by designating the economy mode in the image quality changing process of FIG. 4 described above. .

[0054]

As described above, according to the first aspect of the invention, since the compression ratio of the image photographed and stored in the recording means can be changed, the image is recorded at the time of photographing. Even if the selection of the image quality level (compression rate) is incorrect, the image quality level (compression rate) can be changed after shooting, which improves the usability for the operator.

Further, according to the second aspect of the invention, since the re-compression is possible at a compression rate higher than the compression rate of the image photographed and stored in the recording means, the desired image quality level ( By mistakenly selecting the compression rate, it is possible to change an image recorded at a high image quality level (low compression rate) to a lower image quality level (high compression rate). Further, when the amount of memory that can be stored in the storage unit is small, the amount of stored data can be reduced, so that the number of images that can be stored can be secured.

According to the third aspect of the invention, the image data is stored at a compression rate lower than the selected compression rate, and at the time of recompression, the image data is recompressed at the selected compression rate. Therefore, at the time of shooting, image data can always be stored with high image quality (low compression rate), which improves the usability for the operator.

[Brief description of drawings]

FIG. 1 is a perspective view of a digital camera according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a circuit configuration of the digital camera shown in FIG.

FIG. 3 is a diagram showing a memory configuration example of the flash memory of FIG.

FIG. 4 is a flowchart for explaining an image quality changing process executed under the control of the CPU.

[Explanation of symbols]

 1 Digital Camera 4, 5 Case 6 LCD 7 Imaging Lens 8 “Power” Key 9 “Shutter” Key 10 “DEL” Key 11 “+” Key 12 “-” Key 13 “MODE” Key 14 “DIS” Key 15 “Image Quality” "Conversion" key 16 "Conversion execution" key 17 Open / close lid 18 Function switching key 19 "Image quality mode" key 20 CCD 22 A / D converter 23 Drive circuit 24 Timing generator 25 DRAM 26 Compression / expansion circuit 27 Flash memory 28 ROM 29 RAM 30 Key Input Section 31 CPU 32 Signal Generator 33 VRAM 34 D / A Converter 35 Amplifier 36 I / O Port

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H04N 7/24

Claims (3)

[Claims] 1. An image pickup means for picking up an image of a subject, a data compressing means capable of compressing image data picked up by the image pickup means at a plurality of compression rates, and image data compressed by the data compressing means. Storage means, a designation means for designating a predetermined image from the image data stored in the storage means, a means for decompressing the designated predetermined image data, and image data decompressed by the decompression means To re-compress the decompressed image data with the data compression unit at a compression rate different from that when the decompressed image data was compressed by the compression unit, and to store the re-compressed image data in the storage unit. A digital camera comprising: a control unit for controlling. 2. The different compression rate is a compression rate higher than a compression rate when the decompressed image data is compressed by the compression means. Digital camera. 3. When the compressed image data is stored in the storage means, the storage means further comprises a selection means for selecting one of a plurality of compression ratios of the data compression means, wherein the compression means picks up an image by the image pickup means. The compressed image data is compressed at a compression rate lower than the compression rate selected by the selection means, the storage means stores the compressed image data compressed by the compression means, and the decompression means stores in the storage means. The image data stored at a compression rate lower than the stored compression rate designated by the designating means is decompressed, and the control means decompresses by the designating means stored in the storage means. The image data stored at a compression rate lower than the compressed compression rate is recompressed by the data compression means at the compression rate selected by the selection means, and the recompressed image data is forwarded. The digital camera according to claim 1, wherein the controller controls so as to store in the memory means.