JPH02301293A - Electronic still camera - Google Patents

Abstract

PURPOSE:To store a digital picture signal into a memory with high efficiency and to increase the number of picked-up picture sheets by providing a means which separates a digital picture signal from an A/D converter into a luminance signal and a color difference signal and applies data compression to them with a different compression system respectively. CONSTITUTION:A picture is photoelectric-converted by an image pickup device 1 and the picture signal obtained from the image pickup device 1 is converted into a digital picture signal by an A/D converter 2. The digital picture signal from the A/D converter 2 is divided into the luminance signal and the color difference signal and they are subjected respectively to data compression by a data compression means 3 by means of different compression systems and the resulting signals are stored in a memory 4. Thus, more digital picture signals are stored in the memory efficiently to attain the storage of lots of patterns of picture signals thereby increasing the number of picked-up picture sheets.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an electronic still camera.

[Conventional technology]

Conventionally, electronic still cameras have an image sensor that photoelectrically converts images, an analog/digital converter that converts the image signal obtained from the image sensor into a digital image signal, and a digital image signal from the analog/digital converter. JP-A-54-139422 and JP-A-Sho 56 have a memory for storing digital image signals from which the digital image signals are extracted and reproduced on a television monitor, etc.
-158583 publication.

JP-A-57-28480, JP-A-62-2695
Publication No. 81.

This is known from Japanese Patent Application Laid-Open No. 63-146583.

Furthermore, in the electronic still camera known from Japanese Patent Application Laid-Open No. 62-269581, the digital image signal from the analog/digital converter is compressed by an image encoder and then stored in the memory. That's what I do.

[Problem to be solved by the invention]

In the above-mentioned electronic still camera, the digital image signal is stored as it is in a memory with a limited capacity, or the data is compressed using the same method by an image encoder and then stored in a memory with a limited capacity. Signals cannot be stored efficiently, and the number of images that can be captured is limited because the number of digital image signals that can be stored in the memory is small.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electronic still camera that can improve the above-mentioned drawbacks, efficiently store digital image signals in a memory, and increase the number of captured images.

[Means for Solving the Problem] In order to achieve the above object, the invention of claim 1 is provided as shown in FIG.
) as shown in FIG. In an electronic still camera having a data compression means 3 for compressing a signal and a memory 4 for storing the digital image signal compressed by the data compression means 3, the digital image signal from the analog/digital converter 2 is converted into a luminance signal. The data compression means 3 is provided with means for compressing data separately for a color difference signal and a color difference signal using different compression methods. In the electronic chill camera No. 1, the luminance signal is D.
The data compression means 3 includes means for compressing data using the PCM method and for the color difference signal using an extended adaptive delta modulation method.

[For production]

In the invention of claim 1, an image is photoelectrically converted by the image sensor 1, and the image signal obtained from the image sensor 1 is analog/
The digital converter 2 converts it into a digital image signal. The digital image signal from this analog/digital converter 2 is divided into a luminance signal and a color difference signal, each of which is compressed by a data compression means 3 using a different compression method.
It is stored in memory 4.

In the invention of claim 2, in the invention of claim 1, the data compression means 3 performs data compression on the luminance signal using the DPCM method, and performs data compression on the color difference signal using the extended adaptive delta modulation method.

〔Example〕

FIG. 2 shows an embodiment of the present invention, and FIG. 3 shows the processing flow of the system controller 1-roller in this embodiment.

In this embodiment, the camera section 11. Adapter part 12. Medium capacity memory 13. It has an output terminal 14, and the imaging device 15 is a CCD.
It is composed of solid-state image sensors such as The switch 10 is used to turn on/off the power of the system and to switch between image capturing and image reproduction. When performing imaging, the system controller 26 operates the drive section 16 in response to a signal from the switch 10 to drive the imaging device 15. When the imaging device 15 is driven by the drive unit 16, it captures an image of the subject through the lens 17. The photoelectric conversion is performed via the shutter 18 and an analog image signal is output. This analog image signal is subjected to processing such as gamma correction and edge emphasis in the signal processing unit 19, and then converted into a Y signal, which is a luminance signal, and an R-Y signal and a B-Y signal, which are two color difference signals. The signal is A/D converted by an analog/digital (A/D) converter 20 and stored in a page memory 22 by a memory controller 21.
Expanded to fill the screen. R-Y signal from the signal processing unit 19,
The B-Y signal is switched by the multiplexer 23, converted by A/1 by the A/D converter 24, and expanded into the page memory 25 by the memory controller 21 for one screen.

In this case, [KU-Y signal and B-Y signal are A/D converter 24 after one fish at half the sample rate of Y signal.
/D converted.

The memory control unit 21 controls the page memories 22 and 25 and the medium capacity memory 13 based on control signals from the system controller 26.

Small liquid crystal display @29. Enter key 30. A search data input interface (I/F) 31 is used to input search data such as the photographer and the location.
(zip code, area code, etc.) is input from the input key 30 via the search data input I/F 31. Liquid crystal display device 2
Reference numeral 9 displays the date/time and input data using a digital clock 32. This liquid crystal display device 29 is 0 to 9. A”
Six digits are displayed using Z, a"z, and several other symbols, and the six digits are displayed using four buttons 33 to 36 of the input key 30 as shown in FIG. 4(b). The control method for these four buttons is very similar to that used for commercially available digital watches. This is used to start changing and setting display data. The ``+'' button 34 is used to change one character in the display data of the liquid crystal display 29 in the increasing direction in order. If the character is a number, each time the ``+'' button 34 is pressed, the value increases by 2', for example. becomes 3', and 3' becomes 4'.5 The '-' button 35 is the opposite of the '+' button 34, and changes one character in the display data of the liquid crystal display device 29 in the decreasing direction. If the character is a number, for example, 5' becomes 4' and 4' becomes 3' each time the +' button 34 is pressed. ” MOD[E' button 3
6 is for changing the mode of display data on the liquid crystal display device 2129, and each time the 'MODE' button 36 is pressed, the display data on the liquid crystal display device 29 changes to date, time, photographer, postal code of the place where the image was taken, etc. You can change the mode to display various data such as the area code of the shooting location. As for the actual operation, first set the MODE 'button 36 to the mode you want to change and press the SET/1NIEXT' button 33. M, and the area code of the imaging location is T for T E L E P HONE E, so it becomes the letter 2nd from the left] 1).If you want to change it, press the ``10'' button 34. ” Use button 35 to select SET/NEXT according to the desired character.
'Press button 33. Then, the next character in the display data on the liquid crystal display device 29 blinks and can be changed in the same way. Decide on the last character in the display data on the liquid crystal display device 29 and press the SET/NEXT' button 33.
Pressing ends the one character change state. FIG. 4(a) is an example in which the liquid crystal display device 29 displays 10:08:35, FIG. 4(c) is an example in which the liquid crystal display device 29 displays the person taking the image, and FIG. d) and (e) are examples in which the liquid crystal display device 29 displays the postal code of Narutofu and the area code of Yokohama City as the imaging location.

Furthermore, when the character generator 37 displays characters corresponding to the search data on the display screen during playback, the system controller 26 transfers the raster data from the character generator 37 to the page memory and displays it on the output screen. used for.

When the shutter button is pressed, the system controller 2
6 causes the memory control unit 21 to start drawing to the page memory 22.25, and transfers data for one screen to the page memory 22.25.
The Y signal, R-Y signal, and B-Y signal stored in the page memory 22.25 are compressed and expanded by the compression/expansion unit 27
．． The search data from the character generator 37 and the date from the clock 32 are compressed by 28.

It is stored in the medium capacity memory 13 together with the time information.

Therefore, in the medium capacity memory 13, image signals obtained by the imaging device 15 for lri planes are stored with date/time information and search data attached as image data. In this case, the data storage format is as shown in FIG. Here, the file header identifier indicates the beginning of the image data file, and the file data length indicates the number of BYTEs of the image file. The code 1 encoding method attribute code indicates whether the image data is compressed or not, and if so, indicates the method. The search data is the above search data and [Appended 1.
This is time information. The ladder to the image data line is an identifier for each line or block of the image, and the image data is stored immediately after it. The end of file is a file end identifier and indicates the end of the image file.

During playback, the system controller 26 controls the memory control unit 2.
1 reads image data one file at a time from the medium-capacity memo U 13, expands it in compression/expansion sections 27 and 28, expands it in page memory 22 and 25, and transfers this image data to the adapter section 12. In the adapter section 12, the Y signal transferred from the page memory 22.25 and the R-Y
The image data consisting of the signal and the B-Y signal is D/A converted by digital/analog (D/A) converters 38, 39, 40, respectively, and converted into NTSC by the NTSC encoder 41.
The converted video signal is converted into a standard video signal and outputted to a television monitor or the like from the output terminal 14. On a television monitor or the like, images are reproduced using the video signal from the output terminal 14, and for example, as shown in FIG. 4(f), an image in which search data and date and time are embedded is reproduced.

In the above embodiment, if an electronic finder is provided to display the inside of the page memory 22, 25, it becomes possible to view the search data using the electronic finder.

Further, the liquid crystal display device 29 may be replaced with an electronic viewfinder.

Next, the configuration of the compression/expansion sections 27 and 28 will be explained.

The compression/expansion units 27 and 28 are each composed of an image compression unit 51 and an image expansion unit 51 as shown in FIGS. 6(a) and 6(b), and the image compression unit 51 includes DPCMPCM units 3Y and B.
-7 decimation section 54 and extended adaptive delta modulation section 55.56
Consisted of. The image decompression unit 51 includes a DPCM decoding unit 57, extended adaptive delta modulation decoding units 58 and 59, and R-Y
, BY enlarging section 60.

R-Y signal from page memory 22 or 25, B-Y
The signal is thinned out by the R-Y, B-y thinning unit 54 to one pixel per 2×2 pixels as shown in FIG.
O1 old... indicates each pixel. This R-Y.

The R-Y signal and B-Y signal from the B-7 thinning unit 54 are elements for expressing hue, and their visual sensitivity is relatively low and the requirement for reproducibility is not very high. Data compression is performed by extended adaptive delta modulation by 55 and 56. In addition, the Y signal from the page memory 22 or 25 is an element for expressing resolution and gradation, and is required to have relatively high visual sensitivity and good reproducibility. Compression encoding is performed using predictive DPCM. In this encoding, a variable length code (Huffman code) as shown in Table 1 is used.

Table 1: This DPCMPCM part 3 is known as the encoding method, which predicts the current value from the already encoded pixel value using the correlation between one pixel and the correlation between lines.
It encodes the error between it and the actual value, and the difference signal is PCM encoded using 3 to 4 bits.

Further, the Y signal from the medium capacity memory 13 is demodulated by the DPCM decoding section 57, and the RY signal and BY signal from the medium capacity memory 13 are converted to the extended adaptive delta modulation decoding section 58.5.
9, the Y signal from the DPCM decoding section 57, and the R-Y signal from the extended adaptive delta modulation decoding section 58 and 59.
The signal BY is subjected to simple pixel expansion as shown in FIG.

The above extended adaptive delta modulation will be explained.

In delta modulation, a method in which the quantization step width of a differential signal is changed at a constant rate depending on the history of the past few encoded bits is called an adaptive delta modulation method. This adaptive delta modulation method focuses on the fact that the difference between adjacent samples becomes smaller when the sampling frequency is increased, and the system performs sampling at a high frequency and encodes the difference signal with one bit. In the adaptive delta modulation method, during 1-bit encoding, the quantization step width is determined from the past pulse train as described above.

That is, when pulses of the same polarity are consecutive, it is determined that there is an overload and the step width is increased, and when pulses of different polarity are consecutive, the step width is decreased in order to suppress quantization noise. In image data, there is a large proportion of pixels that do not change compared to adjacent pixels, and when this is taken into consideration, a method in which a step width of O is added to the adaptive delta modulation method is effective. A method in which a state in which the step width is O is added to this adaptive delta modulation method is called an extended adaptive delta modulation method, and according to this method, noise in flat areas can be reduced.

FIGS. 7(a) and 7(b) show the configurations of the extended adaptive delta modulation sections 55 and 56 and the extended adaptive delta modulation decoding sections 58 and 59.

The extended adaptive delta modulation sections 55 and 56 include a subtracter 61, a comparator 62, a counter (0) 63, and a counter (1).
The expanded adaptive delta modulation decoding section 58.59 is composed of a 64゜1゛ table 65, a T' child table 6, and a density buffer 67, and the extended adaptive delta modulation decoding section 58.59 has a counter (0) 68 and a counter (1).
69, concentration buffer 70. It is composed of a T' table 71.

On the image compression side, the subtracter 61 is the R-Y, B-Y thinning section 5.
From the R-Y signal and B-Y signal from 4, the density buffer 67
The comparator 62 compares this calculated value with the thresholds T and -T from the 1゛ table 65 to calculate the calculated value. If it is larger than the threshold 'r, the counter (1) 64 is updated based on the comparison result of the comparator 62, outputs 1', and the counter (0) 63 is cleared. and child table 5. T' child table 6 has counter (0) 63. An address is designated by the value of the counter (1) 64, and the threshold values "f" and T' stored at that address are read out. Counter (0) 63
．． Counter (+) 64 (direct and T table 65. T'
The relationship between the threshold values "I' and T' in the child table 6' is as shown in Table 2.

In the second table 4 degree buffer 67, the threshold value T' read from the 1'' table 66' is added to its value.

If the calculated value of the subtracter 61 is smaller than the threshold value - 63, the result of the comparison by the comparator 62 causes the counter (0)
is updated and outputs 0', counter (1) 6
4 is cleared. The addresses of the T table 65 and 'T' table 66 are specified by the values of counter (0) 63 and counter (1) 64, and the threshold values T and T' stored at the addresses are read out and set to 1. The threshold value T' from the T'' table 66' is added to the value in the agricultural yield buffer 67.

If the calculated value of the trial calculator 61 is between the threshold value T and the threshold value -1, then the counter (0) 63 and the counter (1) 64 are set to
;The inverted output code of f is output, and the counter (0) 63 and counter (1) 64 are updated by the output code and cleared by the other. 1゛Table 65. T' child table 6 has counter (0) 63. An address is specified by the value of the counter (1) 64, the threshold values T and T' stored at that address are read out, and the value of the density buffer 67 is set to 1. ′ is added.

On the image decompression side, counter (1) 69 is updated in the same way as counter (1) 64 on the image compression side when 1' is manually input, and outputs 1', and counter (0) 68
is cleared by inputting 1'.

'r' table 70 contains counter (0) 68. counter(
1) An address is specified by the value of 69, the threshold value T' stored at that address is read out, and the threshold value '■' from the T' table 70 is added to the value of the density buffer 71. Ru. 1' table 70 is f on the image compression side.
”It is configured similarly to table 66.

In addition, the counter (0) 68 is updated as well as the counter (0) 63 on the image compression side and outputs 0' when O' is input manually, and the counter (1) 69 is inputted with O'. Cleared by The T' table 70 has a counter (
0)68. An address is specified by the value of the counter (1) 69, and the threshold value T' stored at that address is read out and the value of the sensitivity buffer 71 is added to the T' table 70.
The threshold T' from T' is added.

FIG. 8 shows a processing example of the extended adaptive delta modulation sections 55 and 56.

For example, when the input number is 1, the R-Y, B-Y thinning section 54
This is because the density of the R-Y signal and B-Y signal from the above is 29, and the density value of the density buffer 67 is 29.

The calculated value (difference) of the subtractor 61 becomes 0. Therefore, the output signals from the counter (0) 63 and the counter (1) 64 become O' which is the inversion of the output signal '1' immediately before that (initial state), and the counter (1) 64 is cleared and the counter (0)
)63 is updated. Therefore, the state changes from C to D in Table 2 above, and the value of the density buffer 67 remains at 29.

〔Effect of the invention〕

As described above, according to the invention of claim 1, there are provided an image sensor that photoelectrically converts an image, an A/D converter that converts an image signal obtained from the image sensor into a digital image signal, and an A/D converter that converts an image signal obtained from the image sensor into a digital image signal.
In an electronic still camera having a data compression means for compressing a digital image signal from the converter and a memory for storing the digital image signal compressed by the data compression means, the digital image signal from the A/D converter is compressed. Since the data compression means is equipped with a means for dividing the data into a luminance signal and a color difference signal and compressing the data using different compression methods, the digital image signal can be efficiently stored in the memory, and the digital image signal for more screens can be stored efficiently. Image signals can be stored in memory, and the number of captured images can be increased.

According to the invention of claim 2, in the electronic still camera of claim 1, the luminance signal is data compressed using a DPCM method, and the color difference signal described in vII is data compressed using an extended adaptive delta modulation method. Since it is provided as the data compression means, digital image signals can similarly be efficiently stored in the memory, and digital image signals for more screens can be stored in the memory, thereby increasing the number of captured images. I can do it.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 (a) and (b) are block diagrams showing the invention of claims 1 and 2, Fig. 2 is a block diagram showing an embodiment of the invention, and Fig. 3 is a block diagram showing an embodiment of the invention.
The figure is a flowchart showing the processing flow of the system controller l-roller in the same embodiment, FIGS. 4(a) to (f) are diagrams for explaining the same embodiment, and FIG. 5 is the data storage format of the same embodiment. 6(a) and 6(b) are block diagrams showing the compression/expansion section in the same embodiment, and FIG. 7(a)
) (b) is a block diagram showing an extended adaptive delta modulation section and an extended adaptive delta modulation decoding section of the same compression/expansion section, FIG. 8 is a diagram showing a processing example of the extended adaptive delta modulation section, and FIG. 9 is a block diagram showing the extended adaptive delta modulation section. FIG. 6 is a diagram illustrating an example of data thinning and expansion in a compression/expansion section.

DESCRIPTION OF SYMBOLS 1... Image sensor, 2... A/D converter, 3... Data compression means, 4... Memory.

Figure A Figure 4 (a) (h) l≦UOT
Mountain Figure 5 % 9 Figure (a > Black image (0 thinned out picture (C) 4! Large ti Group A

Claims (1)

[Claims] 1. An image sensor that photoelectrically converts an image, an analog/digital converter that converts the image signal obtained from the image sensor into a digital image signal, and a digital image signal from the analog/digital converter. a data compression means for compressing the
In an electronic still camera having a memory for storing a digital image signal compressed by this data compression means, the digital image signal from the analog/digital converter is divided into a luminance signal and a color difference signal, and the data is converted into data using different compression methods. An electronic still camera characterized in that the data compression means includes means for performing compression. 2. The electronic still camera according to claim 1, wherein the data compression means includes means for compressing the luminance signal using a DPCM method and compressing the color difference signal using an extended adaptive delta modulation method. An electronic still camera.