JPH02113683A - Digital electronic still camera - Google Patents

Abstract

PURPOSE:To efficiently use a storage area and to execute high-speed consecutive photographing by controlling a data compressing means and making the data compressing means compress data for a block in which significant difference is detected by a detecting means. CONSTITUTION:When a consecutive photographing mode is designated by a mode signal 48, for the picture data of the first one frame in the consecutive photographing, a moving block detecting part 44 instructs an orthogonal transform encoding part 32 to compress the picture data of all the blocks 102 included in the frame. Further, for the picture data of the second and succeeding frame, the moving block detecting part 44 instructs the orthogonal transform encoding part 32 to compress only the picture data of some blocks 102 in which 'movement' is detected. Consequently, for the second and succeeding frame in the consecutive photographing, the quantity of the picture data per one frame is minimized. Thus, processing time for compressing the data can be shortened, a consecutive photographing speed can be improved, and the storage area per one frame occupying a picture data storage medium 12 can be also minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a digital electronic still camera, and more particularly to a digital electronic still camera having a continuous shooting function.

L+L') Xura Digital 1 Shiko still camera is a photographic device that photographs the subject using a solid-state imaging system, such as COD, and stores the image signal representing it in the memory in the form of digital data. be. The memory often takes the form of a memory card equipped with a RAM such as a semiconductor memory. In this case, data compression such as orthogonal transform encoding and 45-r encoding is often performed in order to efficiently use the memory storage area.

2. Description of the Related Art Conventionally, in image processing systems that record and reproduce image signals, image data has been compressed in order to avoid an increase in memory element f due to a large amount of image data. For example, in the image data compression apparatus disclosed in Japanese Patent Application Laid-Open No. 61-13528 [1], data is compressed by performing two-dimensional Tisread cosine transformation, as shown in FIG. In particular, such two-dimensional discrete cosine transformation is complicated in processing, and requires a processing time of, for example, several hundred milliseconds to process one frame of image data.

One of the characteristics of electronic still cameras is that they are capable of high-speed continuous shooting. At least 413 for continuous shooting
A continuous shooting speed of about 5 to 6 frames per second is required, but a system that requires processing time for data compression is not suitable for continuous shooting.

The object of the present invention is to eliminate the drawbacks of the prior art and provide a digital/electronic still camera that can achieve high-speed continuous shooting while making efficient use of storage space. do.

Summary of the Invention According to the present invention, a digital still camera that photographs a subject and stores image data representing the scene in a memory is divided into blocks in which both sides of the image taken are divided into a plurality of blocks. Image day divided into means and bronc.

data compression means for compressing data in blocks;
a recording means for storing compressed image data in a memory; a temporary storage means for storing image data divided into blocks; read the data,
The detecting means includes a detecting means for comparing the read image take with the image data output from the blocking means block by block to detect blocks having a significant difference, and the detecting means includes:
For blocks in which a significant difference has been detected, the data compression means is controlled to perform data compression.

DESCRIPTION OF EMBODIMENTS Next, embodiments of a still camera according to the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, the embodiment of the digital still camera has an imaging device 10, which photographs a subject and converts an image signal representing the scene into digital data. This is a photographing device that stores images in a memory car 1512. For example, a solid-state image sensor such as a CCD is advantageously applied to the imaging device IO, which photographs the field with the imaging lens 14 and outputs color image signals representing the field, such as red (R) and green (G). and blue (B) color component signals at its output 16. This color component signal is output in a rask scanning format similar to a TV signal. Other functional units necessary for photographing, such as an exposure mechanism and a focusing mechanism, are not directly related to the understanding of the present invention, and therefore their explanation will be omitted. The memory card 12 is a storage device in which a semiconductor memory device such as a RAM is carried on a card-like base, and is preferably removably attached to the device.

The output 16 of the imaging device 10 is connected to an analog-to-digital converter (ADC) 18, which converts an input analog image signal into corresponding digital data and outputs it to its output 20. It is a circuit. This digital converter encodes each of the color components RGB into, for example, 8 bits. This digital data output 20 is connected to a signal processing section 22.

In this embodiment, the signal processing unit 22 subjects the image data to pre-processing such as white balance adjustment and gradation correction, and luminance and color difference processing that converts the color component value data into luminance signal and two-phase color difference signals. , performs signal processing to output this to its output 24.

An output 24 of the signal processing section 22 is connected to a professional digitization section 26. The image signal output from the imaging device 10 is in the form of a normal rask scan sequential signal.

As shown in FIG. 2, the blocking unit 26 divides the one-frame screen 100 represented by the image confidence into a plurality of areas of a predetermined size, that is, blocks 102, and expresses which of the blocks 102 in the image data. This is a functional unit that asks for identification data, such as the flock number, to identify whether the Each block 102 may have a size of, for example, 8 pixels in the horizontal scanning (H) direction and 8 pixels in the vertical scanning (V) direction,
Alternatively, the number of pixels may be different in the vertical and horizontal directions. Therefore, the blocking section 28 has a line buffer that stores image data for eight horizontal scanning lines. The image data thus divided into blocks 102 are passed from the output 28 to the frame memory 30 and the orthogonal transform encoding section 32.

The frame memory 30 is a storage device that stores image data of 1 frame in the example, and has a storage capacity of 1. is read out.

The orthogonal transform encoding unit 32 inputs the human power 2 from the blocking unit 26.
The image data manually inputted in 8 is subjected to orthogonal transformation and clockwise conversion in units of each block 102, and the function of outputting it to the output 36 is destroyed. As the orthogonal transform encoding, for example, two-dimensional discrete cosine transform (OCT) is applied to the supplement. As a result, the image data of each block 102 is converted into frequency domain data for each block 102, and data is arranged in the horizontal (H) direction and vertical (V) direction of the screen 100 starting from the lowest frequency. The encoding is a certain V! Data with frequencies below the A value are discarded, and a large number of pitches are assigned to low frequency components, thereby performing nonlinear data compression. The image data compressed in this way is, as illustrated in FIG.
20 and an image data section 122. The header 120 includes management data such as data type, frame number, and photographing conditions, and the image data section 122 includes the identification number 124 of the block 102 and compressed image data 126.

An output 36 of the orthogonal transform encoder 32 is connected to a quantizer 38. The quantity f converting unit 38 is connected to the memory card 12 and has a quantization and recording function of quantizing the compressed image data by J■ and storing it in the memory card 12.

The frame memory 30 has a readout output 31, which is connected to one input of the difference detection section 34.

The difference detection unit 34 also has the other input, which is connected to the (11 input 28) of the blocking unit 2G.
The image data of block +02 is compared with the image data of the same block 102 read from the frame memory 30, and a difference calculation function is activated to detect whether the difference between the two exceeds a threshold value. This threshold value is input to the input 40. When a difference exceeding the threshold value 40 is detected in the image data of block +02, the difference detection section 34 outputs a difference detection signal to its output 42.

For example, the difference detection unit 34 may be configured to integrate the absolute value of the difference value of the image data in the corresponding block 102 between two such frames on a block-by-block basis, and obtain the integrated value. In other words, since the image data compared by the difference detection unit 34 indicates the density of the color component value -q RGB, the difference between the current frame and the previous frame for one block 102 can be calculated by calculating the difference between the current frame and the previous frame.
It is possible to detect whether or not there is a change in the picture, that is, a pa movement "'".

The motion front block detection section 44 includes one or more circuits for incrementing the number of the image data block in synchronization with the output operation of image communication from the imaging device 10, and includes a differential detection section 42 from the difference detection section 34. This is a functional unit that responds to the output 4B and provides the counted value to the orthogonal transform encoding unit 32 from the output 4B. In other words,
The motion flow detection unit 44 cooperates with the difference detection unit 34 so that the image data of the block 102 in the current frame output from the blocking unit 26 is stored in the frame memory 3.
A motion detection function is realized to detect that the image data of the corresponding block 102 in the previous frame read from 0 has changed significantly, that is, that there is "movement" in the picture. The motion block detection section 44 notifies the orthogonal transform encoding section 32 of the identification number representing the block 102 in which the motion has been detected, together with an instruction signal instructing orthogonal transformation. In order to activate this function only in the case of continuous shooting, that is, quick shooting, the motion bronc detection section 44 inputs a mode signal specifying the continuous shooting operation mode to its human power 48.

In the case of the normal single-shot mode, a mode signal specifying the single-shot mode is input to the mode input 48 of the motion block detection section 44 . In response to this, the detection unit 44 outputs 4
An instruction signal for instructing orthogonal transformation is output from 6 to orthogonal transformation instruction ¥1132. As a result, the encoding unit 32
The image data manually inputted from the blocking unit 26 is always orthogonally transformed and encoded.

When instructed to photograph, the imaging device 10 photographs the scene and outputs a one-frame image signal representing the scene. This image signal is output from the imaging device 10 to an analog-to-digital converter 18, where it is converted into corresponding digital data. This image data is subjected to preprocessing and brightness/color difference processing in the signal processing section 22, and is divided into predetermined blocks 102 in the blocking section 26. The blocked image data is compressed for each block 102 in the orthogonal transform encoding section 32, converted into a quantity f-1 by the quantization section 38, and stored in the storage area of the memory car 1/12.

In the continuous shooting mode, when the continuous shooting mode is designated by the mode signal 48, the motion block detection section 44 is set to an operable state. In the quick shooting mode, the motion bronc detection unit 44 compresses the image data of all blocks 102 included in the first frame of continuous shooting in the same manner as described above. The power exchange encoding unit 32 is instructed. Therefore, all blocks of image data of the first frame are written to the memory card 12 in the same manner as described above.

In the continuous shooting mode, the imaging device 10 is driven so as to continuously shoot the scene. At its output 16, image signals of a series of frames are outputted one after another. Therefore,
Regarding the image data from the second frame onward, the motion block detection section 44 instructs the orthogonal transform encoding section 32 to perform data compression only on the block 102 in which 'motion' has been detected.

To explain in more detail, the difference detection unit 34 receives the image data of one bronc 102 of the current frame input from the blocking unit 2B to the input 28, and in synchronization with this, the difference detection unit 34 receives the image data of the previous frame 1\ from the frame memory 30. The image data of the same block 102 is read out. When the two names are compared and the difference exceeds the threshold value 4o, the difference detection section 34 outputs a difference detection signal to its output 42.

The motion block detection unit 44 increments the number of the block 102 in one frame Iy-1-100 by 91 in synchronization with the image signal output from the imaging device 10. Difference detection section 3
When the motion block detection section 44 receives the difference detection signal 42 from the motion block detection section 4, the motion block detection section 44 supplies the counted value, that is, the blocking section, to the orthogonal transformation encoding section 32 from the output 46 along with an orthogonal transformation instruction. This means that the image data of block 102 in the current frame is the same as that of the corresponding block 102 in the previous frame.
Image data from No. 2 shows that the intention has changed.

When the orthogonal transform encoding unit 32 receives this instruction,
The image data of the block 102 currently inputted manually from the blocking unit 26 is subjected to alternating transform and encoded, thereby compressing the image data of the block 102 of the current frame. The compressed image data is
The block identification number +24 is sent to the quantization unit 38, where it is quantized and stored in the storage area of the memory cart 12.

In this way, the image data from the second frame onward shot in the continuous shooting mode is
Data compression is performed in the orthogonal transform encoding unit 32 only for the data. For the block 102 that is determined to have no movement of the right foot, image data 1 is stored in the memory cart 12.
26 is not stored. Therefore, for frames after the second frame of continuous shooting, the amount of image data per J frame is small, so the processing time for data compression in the orthogonal transform encoding unit 32 is also short, and the memory card 12 is not occupied. The storage area per frame is also small. For example, even with currently available circuit elements, it is more than 5 frames per second, and if future element technology is taken into account, it is 10 frames per second.
A continuous shooting speed of ~20 frames is achieved.

Note that the mode signal 48 given to the motion block detection section 44 is generated by a system control section (not shown) in response to a mode setting operation or a shirt release operation of the camera. For example, the shirt release button is configured to operate in two steps, and the system control section generates the mode signal 48 for the normal single-shot mode in the first step, and the second step.
The mode signal 48 for the continuous shooting mode may be generated in the step. In this way, in continuous shooting operation, the first
All the image data of the frame is compressed as in the case of the single shot mode, and the image data of the second and subsequent frames can be data compressed only for the block 102 in which motion has been detected.

Effects As described above, according to the present invention, image data from the second frame onwards captured in a continuous shooting operation is subjected to data compression only for blocks in which motion has been detected. Therefore, after the second frame of quick shooting, the amount of image data per frame decreases. Therefore, the processing time for data compression is reduced, so that the speed of quick shooting is improved and the storage area per frame occupied in the image data storage medium is also reduced.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram showing an embodiment of a digital electronic still camera according to the present invention. FIG. 2 is an explanatory diagram showing an example of a screen bronc configuration in the embodiment shown in FIG. 1. It is an explanatory view showing an example of a format composition of image data in an example. Explanation of symbols of main parts 10, Imaging device +2. ,,Memory card 2G... Pro-linking section 30, Frame memory 32,..., Orthogonal transform encoding section 343. Difference detection unit 38, quantization unit 44, motion block detection unit Patent applicant: Fuji Photo Film Co., Ltd. Agent: Takashi Katori [Takao Maruyama]

Claims (1)

[Scope of Claims] A digital electronic still camera that photographs a scene and stores image data representing the scene in a memory, the camera comprising: a block that divides a screen represented by the image data into a plurality of blocks; data compression means for compressing the image data divided into blocks in block units; recording means for storing the compressed image data in the memory; and storage means for compressing the image data divided into blocks. temporary storage means for temporarily accumulating; controlling the data compression means, reading out the image data stored therein from the temporary storage means, and combining the read image data with the image data output from the blocking means; detecting means for detecting a block with a significant difference by comparing each block, the detecting means controlling the data compression means for the blocks in which the significant difference has been detected; A digital electronic still camera characterized in that the data compression is performed.