JP2694027B2 - Endoscope image data compression device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an endoscopic image data compression apparatus that compresses endoscopic image data.

[Problems to be solved by conventional technology and invention] In recent years, by inserting an elongated insertion portion into a body cavity,
2. Description of the Related Art Endoscopes capable of observing organs in a body cavity and the like and performing various treatments using a treatment tool inserted into a treatment tool channel as necessary are widely used.

Further, an electronic endoscope in which a solid-state image pickup device such as a CCD is provided at the tip of the insertion part is also in practical use.

By the way, the electronic endoscope and the endoscopic image taken by the television camera connected to the eyepiece of the fiberscope are:
In addition to observing on a television monitor, it may be recorded on an image recording device for later use in diagnosis and analysis. When an endoscope image is recorded in this manner, there is a problem that a large-capacity storage device is required because the amount of image data is large. Also, when transmitting images, there is a problem that the transmission speed is low.

Therefore, it has been proposed to compress the image data. In this case, various compression techniques can be applied. For example, the applicant of the present application filed in Japanese Patent Application No. 62-279599 previously filed according to the characteristics of a plurality of color signals forming an endoscopic image. We have proposed a device that performs gamma correction and quantization. The structure of this device is shown in FIG.

In this device, an observation device 1 to which the electronic endoscope 144 is connected
A light source unit 152 and an image data compression unit 161 are provided in the 46. The light emitted from the lamp 153 in the light source unit 152 is
After passing through a rotary filter 155 that is driven to rotate by a motor 154,
The light of each wavelength region of R, G, B is time-sequentially separated, passes through the light guide 151 of the electronic endoscope 144, and is emitted from the tip of the insertion portion 143 of the electronic endoscope 144. The image of the subject illuminated by this light is the objective lens 1 provided at the tip of the insertion portion 143.
An image is formed on the image pickup surface of the CCD 158 by 57 and converted into an electric signal. This CCD 158 is a driver 159 in the observation device 146.
Driven by the image data compression unit.
After being amplified by the amplifier 162 in the 161, it is selectively inputted to the γ correction circuits 164, 165 and 166 via the changeover switch 163. The γ correction circuits 164, 165, 166 respectively correspond to R, G, B color signals, and have γ characteristics in consideration of the luminance distribution of each color signal. For example, for the R signal, the slope is increased in the high brightness level part to increase the data amount of the high brightness level part, and for the B signal, the slope is increased in the low brightness level part to increase the data amount of the low brightness level part. The data amount is increased, and the G signal has a normal characteristic. γ correction circuit 164,165,
The outputs of 166 are input to A / D converters 167, 168 and 169, respectively, and are digitized at different quantization levels, for example, R and B are 4 bits and G is 8 bits. A / D
The outputs of the converters 167, 168 and 169 are respectively stored in the memory 171.
It is stored in R, 171G, 171B. This memory 171R, 171G, 171B
The signals read out from the D / A converters 172, 173 and 174 are converted into analog signals, and then only the R and B signals are reverse γ corrected by the reverse γ correction circuits 175 and 176, and the data output terminals 177, 178 and 1 are output.
It is output from 79. The signals read from the memories 171R, 171G, 171B are also recorded in the image recording device 150.
The control signal generator 181 controls the timing of the motor 154, the driver 159, the changeover switch 163, the memories 171R, 171G, 171B, the image recording device 150, and the like, and outputs a synchronization signal from the SYNC output terminal 182.

As described above, the apparatus shown in FIG. 17 performs γ correction on the R, G, and B color signals with different γ characteristics and records them in the image recording apparatus 150, and performs inverse γ correction during reproduction, The original signal before γ correction is restored and then displayed on a monitor or the like.

However, in this case, the characteristic of the inverse γ correction circuit is γ
When the characteristic of the correction circuit is γ ₀ , it is necessary to match the characteristic of 1 / γ ₀ , and it is very difficult to match it accurately. In particular, when the γ correction and the inverse γ correction are performed in an analog manner, there is a possibility that the characteristics may change with temperature.

The present invention has been made in view of the above circumstances, and utilizes the features of an endoscopic image, has a simple configuration, and is capable of highly compressing endoscopic image data. Is intended to provide.

[Means for Solving the Problems] An endoscopic image data compression apparatus according to the present invention is the same in the endoscopic image data compression apparatus for compressing image data of an endoscopic image obtained by an endoscope. In order to compress one color information including the component on the longest wavelength side among a plurality of color information forming the endoscopic image captured in 1. at a higher compression rate than the other color information, the one color information The calculation between adjacent pixel signals is performed so that the resolution of is lower than the resolution of the other color information,
A data compression means for compressing data is provided.

[Operation] In the present invention, by lowering the resolving power of one color information including the component on the longest wavelength side among the plurality of color information forming the endoscopic image as compared with the resolving power of the other color information, One color information is data-compressed with a higher compression rate than the other color information. In a normal endoscopic image, the color information including the component on the longest wavelength side has less high-frequency components than other color information. Therefore, the diagnosis is not affected even if the resolution of the color information is lowered and the compression rate is increased.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

1 to 6 relate to a first embodiment of the present invention, FIG. 1 is a block diagram showing a configuration of an image recording apparatus, and FIG. 2 is an explanatory diagram showing an entire endoscopic image filing system,
FIG. 3 is a block diagram showing the structure of the observation apparatus, FIG. 4 is a flow chart showing the recording operation of the image recording apparatus, FIG. 5 is a flow chart showing the reproducing operation of the image recording apparatus, and FIG. 6 is a compression operation of the compression circuit. It is an explanatory view for explaining.

As shown in FIG. 2, the endoscopic image filing system is connected to the electronic endoscope 1, the observation device 3 and the aspirator 6 to which the electronic endoscope 1 is connected, and the observation device 3. The monitor 4 and the image recording device 5 are provided.

The electronic endoscope 1 includes a slender and flexible insertion portion 1a to be inserted into a living body 2, a large-diameter operation portion 1b connected to a rear end of the insertion portion 1a, and the operation portion. It has a universal cord 1c extending from 1b, and a connector 1d connected to the observation device 3 is provided at the end of the universal cord 1c.

An illumination window and an observation window are provided at the tip of the insertion portion 1a of the electronic endoscope 1. A light distribution lens (not shown) is mounted inside the illumination window, and a light guide 18 is connected to the rear end of the light distribution lens. This light guide
18 is inserted through the insertion portion 1a, the operation portion 1b, and the universal cord 1c, and is connected to the connector 1d. An objective lens system (not shown) is provided inside the observation window, and a solid-state image sensor, such as a CC, is provided at the image forming position of the objective lens system.
D8 is provided. The output signal of this CCD8 is
It is adapted to be inputted to the observation device 3 through a signal line which is inserted through a, the operation portion 1b and the universal cord 1c and is connected to the connector 1d.

The observation device 3 is configured as shown in FIG.

The observation device 3 includes a lamp 19 that emits white light, and includes the lamp 19 and a rotary filter 21 that is provided between the lamp 19 and the incident end of the light guide 18 and is driven to rotate by a motor 20. There is. The rotary filter 21 includes red (R), green (G), and blue (B) arranged in the circumferential direction.
The filters 22R, 22G, and 22B that transmit light in the respective wavelength regions are provided, and by being rotated by the motor 20, the filters 22R, 22G, and 22B are sequentially inserted in the illumination optical path. Then, by the rotary filter 21, R, G, B
The light that is time-sequentially separated into the respective wavelength regions is emitted from the tip end portion of the insertion portion 1a of the electronic endoscope 1 via the light guide 18 and the light distribution lens.

The observing device 3 has an amplifier 9, and the output signal of the CCD 8 is amplified by the amplifier 9 to a voltage level within a predetermined range, and γ corrected by a γ correction circuit 11. The γ-corrected signal is converted into a digital signal by the A / D converter 12 and then converted by the changeover switch 13 into R, G, B
Are selectively input to the memories 14R, 14G, and 14B respectively corresponding to the memory 14R, 14G, and 14B.
B images are stored. The memory 14R, 1
4G and 14B are read simultaneously at the timing of the television signal, and are converted into analog signals by the D / A converters 15, 15 and 15, respectively. This analog R, G, B
Each image signal of is the sync signal SY from the sync signal generation circuit 16.
Output from RGB signal output terminal 17 together with NC, monitor 4,
The data is input to the image recording device 5 or the like. The motor 20, A / D converter 12, changeover switch 13, memory 14R,
The 14G, 14B, D / A converter 15, and the synchronization signal generation circuit 16 are controlled by the control signal generation unit 23.

Next, the image recording device 5 including the image data compression device will be described with reference to FIG.

The R, G, and B image signals output from the observation device 3 are input from the input unit 31, and the A / D converters 32, 32, and 32, respectively.
Is converted into a digital signal by the R frame memory 33R, G
The frame memories 33G and 33B for B are temporarily stored in the frame memory 33B. Each frame memory 33R, 33
R, G, B image signals read from G, 33B, respectively,
The R compression circuit 34R, the G compression circuit 34G, and the B compression circuit 34B are respectively compressed at different compression rates and then recorded on the recording system unit 35 such as an optical disk or a magnetic disk.

When reproducing image data, the recording system unit 35
The R, G, B image signals are read out from the R, G, B expansion circuits 36R, G expansion circuits 36G, B expansion circuits 36B, respectively, and the data are restored separately. ing. The restored R, G, and B image data are temporarily stored in the R frame memory 37R, the G frame memory 37G, and the B frame memory 37B. Then, from this frame memory 37R, 37G, 37B, the respective R, G, B image signals are read out in synchronization with the television signal and converted into analog signals by the D / A converters 38, 38, 38, respectively. After that, the output section 39 outputs the data.

Next, referring to FIGS. 4 to 6, compression circuits 34R, 34
The operation of G, 34B and the expansion circuits 36R, 36G, 36B will be described.

As shown in FIG. 4, in step S1, the compression circuit 34 (representing 34R, 34G, and 34B) divides the entire input image with a predetermined number of pixels as one block, and determines the density of pixels in each block. Calculate the average of the values. Next, in step S2, the average value is recorded in the recording system unit 35 together with the color identification information. In this embodiment, the number of pixels in one block is 9 pixels for the R image, 2 pixels for the G pixel, and 4 pixels for the B pixel. Therefore, about R image is about 1 /
This means that the image data is recorded by compressing it to 9, compressing it to about 1/2 for the G image, and compressing it to about 1/4 for the B image.

On the other hand, as shown in FIG. 5, the expansion circuit 36 (36R, 36G, 36
Represent B. ), In step S3, the recording system unit 35
Then, the color identification information and the average value of each block are reproduced, and in step S4, the pixels constituting the block are restored based on the color identification information by using the density value of each pixel in the block as the average value.

FIG. 6 shows an example of the compression / expansion operation in which specific density values are entered. (A) figure relates to G image, (b) figure relates to B image, (c) figure relates to R image. As shown in (a), in the G image, two pixels P ₁ and P ₂ are set as one block, and the entire input image is divided, and the average value (4) of the density values (3, 5) of the pixels in the block is divided. Is calculated, and this average value (4) is recorded in the recording system unit 35. At the time of reproduction, the density value (4,4) of two pixels is created from one average value (4) reproduced from the recording system unit 35. Similarly, as shown in FIG. 7B, in the B image, the four pixels P ₁₁ , P ₁₂ , P ₂₁ , and P ₂₂ are set as one block, and the density values (2, 6, 5, 7) of the pixels in the block are set. The average value (5) of 4) is recorded in the recording system unit 35, and at the time of reproduction, the density value (5,5,5,5) of 4 pixels is created from the average value (5). Further, as shown in FIG. 7C, in the R image, P _{11 to} P _{11
13, P 21 ~P 23, P} 31 9 pixels as one block to P _33, the average value of the density values of the pixels in the block (2,5,6,6,4,7,4,3,8) (5) is recorded in the recording system unit 35, and at the time of reproduction, the density value of 9 pixels is created from the average value (5).

In the case of such compression and decompression, the larger the number of pixels in one block, the higher the compression ratio and the lower the resolution at the time of reproduction.
The relationship between the number of pixels in one block of each R, G, B image, the compression ratio, and the resolution during reproduction is as shown in the table below.

Thus, in the present embodiment, R, which constitutes an endoscopic image,
Of the G and B images, the R image containing the longest wavelength component is
Data is compressed at a higher compression rate than other G and B images. Generally, the R image in the endoscopic image has a so-called flat shape with few high frequency components. Therefore, to display the color and shape of a lesion that is diagnostically heavy, R
The images do not contribute much, rather the G and B images carry important information. Therefore, even if the compression ratio of the R image is increased and the resolution during reproduction is lowered to some extent, it does not affect the diagnosis.

Further, since the G image has the most important information for diagnosis, in the present embodiment, with respect to the G image, the resolution at the time of reproduction is emphasized and the compression rate is kept low.

As described above, according to the present embodiment, by utilizing the characteristics of the endoscopic image, the structure is simple, and the deterioration of the image quality during reproduction does not affect the diagnosis. It is possible to compress the endoscopic image data.

7 to 10 relate to the second embodiment of the present invention, FIG. 7 is a block diagram showing the configuration of a compression circuit, FIG. 8 is a block diagram showing the configuration of a prediction error calculation circuit, and FIG. FIG. 10 is an explanatory diagram for explaining the method of calculating the prediction error, and FIG. 10 is an explanatory diagram of the smoothing filter.

The present embodiment differs from the first embodiment in the compression circuit 34 and the expansion circuit 36 provided for the R, G, B image signals.

As shown in FIG. 7, the compression circuit 34 in this embodiment has a smoothing circuit 41 and a prediction error calculating circuit 42, and the image signals from the frame memories 33R, 33G, 33B are smoothed by the smoothing circuit 41. Are smoothed by, and are predictively coded by the prediction error calculation circuit 42, and stored in the recording system unit 35.

The smoothing circuit 41 is configured to smooth by a 3 × 3 (pixel) two-dimensional filter as shown in FIG. This filter uses (1-k) times the density value of the pixel as the smoothed density value of each pixel, and (k / 8) times each of the density values of the eight pixels in the vicinity of that pixel. It is the value obtained by adding the value obtained. It should be noted that k (0 <k <1) is a smoothing coefficient. A large value of this indicates a large smoothing effect, and a small value indicates a small smoothing effect. The value of the smoothing coefficient k is switched by the compression rate switching circuit. By arbitrarily determining the value of the smoothing coefficient k, the spatial frequency band after smoothing can be determined. That is, the higher the value of k and the greater the smoothing effect, the more the high-frequency components of the image deteriorate.

As shown in FIG. 8, the prediction error calculation circuit 42 delays the input data by one pixel by the one-pixel delay line 43, and subtracts this data from the original input data by the subtractor 44 to obtain one pixel. It is designed to find the difference from the previous data. As shown in FIG. 9, when the density value of the pixel (i, j) is x (i, j), the prediction error signal Δx (i, j) output from the prediction error calculation circuit 42 is Δx (i , j) = x (i, j) -x (i-1, j).
Since this prediction error signal has a smaller value than the input data, the amount of data recorded in the recording system unit 35 can be small.

On the other hand, the expansion circuit 36 restores the original data by adding the prediction signal, that is, the data of one pixel before to the prediction error signal reproduced from the recording system unit 35. In the present embodiment, unlike the first embodiment, the decompression circuit 36 uses R, G, B
Have the same circuit configuration and operation.

Here, if the smoothing coefficient k in the smoothing circuit 41 is increased, the high-frequency component of the image is deteriorated, but since the smoothing effect is large, the prediction error signal becomes small overall,
Therefore, the amount of data to be recorded is small. That is, the compression ratio is high. On the other hand, when k is small and the smoothing effect is small, the high frequency component of the image does not deteriorate, but the prediction error signal becomes large overall, and therefore the amount of data to be recorded is small. That is, the compression ratio is low. Thus, by setting the smoothing coefficient k in the smoothing circuit 41 to any value, the compression rate can also be set to any value.

In the present embodiment, similar to the first embodiment, the smoothing coefficient in the smoothing circuit 41 in the compression circuit 34 corresponding to each image signal is arranged in the order of R, B, G from the highest compression rate. k is set. The relationship between the smoothing coefficient k of each R, G, B image, the compression rate, and the resolution during reproduction is as shown in the following table.

As described above, in this embodiment, similarly to the first embodiment, the resolution of the G image that is important for diagnosis does not decrease, and the resolution of the R image that causes no problem even if the resolution decreases for diagnosis is decreased and the compression ratio is reduced. Is high.

Other configurations, operations and effects are the same as those of the first embodiment.

FIGS. 11 to 14 relate to a third embodiment of the present invention.
FIG. 11 is a block diagram showing the configuration of the image recording apparatus, FIG. 12 is a block diagram showing the configuration of the prediction error calculation circuit, FIG. 13 is a block diagram showing the configuration of the band limitation switching circuit, and FIG.
It is explanatory drawing which shows the pass band of each LPF of the figure.

As shown in FIG. 11, in this embodiment, between the input section 31 and the A / D converters 32, 32, 32 in the first embodiment, the R band limit switching circuit 51R and the G band limit switching circuit 51G are provided. , B band limitation switching circuit 51B is provided.

Further, the compression circuit 34 in the present embodiment has a prediction error calculation circuit 42 similar to that of the second embodiment as shown in FIG. 12, but unlike the second embodiment, R, G, B Have the same circuit configuration and operation. In addition, the expansion circuit 36 has a second
Similar to the embodiment, the original data is restored by adding the prediction signal, that is, the data of one pixel before to the prediction error signal reproduced from the recording system unit 35.
G and B have the same circuit configuration and operation.

The band limit switching circuits 51R, 51G, 51B are configured as shown in FIG.

The input terminals of the band limiting switching circuits 51R, 51G, 51B are respectively connected to the input terminals of the 1-input 2-output switching switches 53R, 53G, 53B. One output end of each changeover switch 53R, 53G, 53B is connected to the input end of an R low-pass filter (hereinafter referred to as LPF) 54R, G LPF 54G, and B LPF 54B, respectively. The output terminals of the LPFs 54R, 54G, 54B are connected to one input terminals of 2-input 1-output changeover switches 55R, 55G, 55B, respectively. In addition, the changeover switch 53R,
The other output end of 53G, 53B and the other input end of the changeover switches 55R, 55G, 55B are connected. And the changeover switch
55R, 55G, 55B output is the band limit switching circuit 51R, 51G, 51B
Is output. The pass band of each of the LPFs 54R, 54G and 54B is as shown in FIG. That is, LPF5 for R
4R removes high-frequency components, G-use LPF54G hardly removes high-frequency components, and B-use LPF54B has intermediate characteristics.

The changeover switches 53R, 53G, 53B and the changeover switches 55R, 5
5G and 55B can be switched by a signal from the dyed image signal generation circuit 52. The dyed image signal generation circuit 52 has a switch 57, a power supply voltage is applied to one end of the switch 57 via a resistor 58, and the other end is grounded. Then, depending on the voltage at one end of the switch 57, the changeover switches 53R, 53G, 53B and the changeover switches 55R, 55
G and 55B can be switched.

 Next, the operation of the present embodiment will be described.

When recording a normal image, the dyed image signal generation circuit
Turn off the switch 57 of 52. Then, in response to the signal, the changeover switches 53R, 53G, 53B and the changeover switches 55R, 55G, 5
5B selects the LPF 54R, 54G, 54B side, respectively. As a result, the R, G, and B image signals are all LPF54R, 54G, and 54B.
Pass through. Therefore, the high frequency component is removed from the R image,
The amount of data of the prediction error signal by the compression circuit 34R becomes small. High-frequency components higher than those of the R signal are removed from the B signal, and the data amount of the prediction error signal is slightly reduced. Further, since the high frequency component is hardly removed from the G signal, the data amount of the prediction error signal is large, but the resolution does not deteriorate.

In the second embodiment, the compression circuit 3 limits the band of R, G, B signals.
Digitally performed by the smoothing circuit 41 in 4R, 34G, 34B, in the present embodiment, the band limit switching circuit 51R, 51G,
The LPF 54R, 54G, and 54B in the 51B are used to perform analog processing.

Next, when recording a dyed image, the switch 57 of the dyed image signal generation circuit 52 is turned on. Then, in response to the signal, the changeover switches 53R, 53G, 53B and the changeover switches 55R, 5
5G and 55B select the circuit side bypassing LPF54R, 54G, and 54B, respectively. As a result, the R, G, and B image signals are output as they are without passing through the LPFs 54R, 54G, and 54B, and the band is not limited. Therefore, the compression ratio in the compression circuit 34 is smaller than that in the normal image.

The reason why the band limitation is not provided in the dyed image is as follows.

In the normal image, each of the R, G, and B images, especially the R image, has few high-frequency components, and therefore even if the band limitation is applied, the difference from the original image can hardly be discriminated. On the other hand, in the dyed image, the shape of details is conspicuous, and therefore, if band limitation is performed, deterioration in image quality can be clearly discriminated as compared with the original image.

As described above, according to this embodiment, it is possible to switch the resolution and compression rate of an image according to the characteristics of the image.

Other configurations, operations and effects are the same as those of the first embodiment.

Incidentally, also in the first and second embodiments, the original image may be recorded as it is without performing compression for blocking or compression by smoothing at the time of a dyed image.

15 and 16 relate to a fourth embodiment of the present invention,
FIG. 16 is a block diagram showing the configuration of the image recording apparatus, and FIG. 16 is an explanatory diagram for explaining thinning.

The present embodiment is an example of performing compression by thinning out sample points.

As shown in FIG. 15, in this embodiment, the output terminals of the frame memories 33R, 33G, 33B in the first embodiment are connected to the respective input terminals of a 3-input 1-output changeover switch 61. The output terminal of the changeover switch 61 is a thinning circuit.
Connected to 62. The output of the thinning circuit 62 is recorded in the recording system unit 35.

The output end of the recording system section 35 is connected to an expansion circuit 63, and the output end of the expansion circuit 63 is connected to the input end of a 1-input / 3-output changeover switch 64. This changeover switch 64
The respective output terminals of are respectively connected to the frame memories 37R, 37G, 37B in the first embodiment.

The frame memories 33R, 33G, 33B, 37R, 37G, 37B, changeover switches 61, 64, thinning circuit 62, recording system unit 35, decompression circuit
63 is controlled by the control circuit 66.

In the present embodiment, the frame memories 33R, 33G, 33B are sequentially read, and the R, G, B signals are input to the thinning circuit 62 in time series through the changeover switch 61 that is switched for each R, G, B. It The thinning circuit 62 changes the number of thinned pixels according to the input signal and processes the R, G, B signals in time series. For example, as shown in FIG.
One signal is recorded for every 4 × 4 pixels (16 pixels), one signal is recorded for every 2 × 2 pixels (4 pixels) for the B signal, and the G signal is thinned out as shown in FIG. 16 (b). Record everything without leaving. still,
In FIG. 16, black circles indicate pixels to be recorded and white circles indicate pixels to be thinned out.

Further, the recording system unit 35 sequentially reproduces the R, G, B signals, and the decompression circuit 63 to which this signal is inputted changes the decompression pixel number according to the inputted signal to obtain the R, G, B signals. Are processed in time series. That is, 16-pixel data is created from one data for the R signal, four-pixel data is created from the one-pixel data for the B signal, and the G signal is output without being expanded. The R, G, B signals output in time series from the expansion circuit 63 are
It is stored in each frame memory 37R, 37G, 37B via the changeover switch 64 which can be switched for each of R, G, B.

As described above, even if the R signal is recorded and reproduced by thinning out the sampling points, the quality of the reproduced image is hardly deteriorated. Therefore, in this embodiment, the decimation rate of the R signal, that is, the data compression rate is set to be higher than that of the other signals.

Other configurations, operations and effects are the same as those of the first embodiment.

The present invention can be applied not only to the frame-sequential electronic endoscope using RGB signals but also to a single-panel electronic endoscope that decodes a composite video signal. Further, the endoscope may be either of a type having an image pickup element at the distal end portion or a type of receiving an image by the image pickup element after guiding an image to the outside of the object to be observed via an image guide by an optical fiber.

[Effects of the Invention] As described above, according to the present invention, by utilizing the characteristics of an endoscopic image, one of a plurality of color information forming an endoscopic image including a component on the longest wavelength side is included. Since the resolution of the color information is set lower than that of the other color information, the one color information is compressed at a higher compression rate than the other color information. This has the effect of enabling high compression of endoscopic image data.

[Brief description of the drawings]

FIGS. 1 to 6 relate to a first embodiment of the present invention.
FIG. 1 is a block diagram showing the configuration of an image recording device, FIG. 2 is an explanatory diagram showing the entire endoscopic image filing system, FIG. 3 is a block diagram showing the configuration of an observation device, and FIG. FIG. 5 is a flow chart showing a recording operation, FIG. 5 is a flow chart showing a reproducing operation of the image recording apparatus, FIG. 6 is an explanatory diagram for explaining the compression operation of the compression circuit, and FIGS. 7 to 10 are second diagrams of the present invention. FIG. 7 is a block diagram showing a configuration of a compression circuit, FIG. 8 is a block diagram showing a configuration of a prediction error calculating circuit, and FIG. 9 is an explanatory diagram for explaining a method of calculating a prediction error according to the embodiment. FIG. 10 is an explanatory view of a smoothing filter, FIGS. 11 to 14 relate to a third embodiment of the present invention, and FIG. 11 is a block diagram showing a configuration of an image recording apparatus.
Figure 12 is a block diagram showing the configuration of the prediction error calculation circuit,
FIG. 14 is a block diagram showing the configuration of a band limitation switching circuit, FIG. 14 is an explanatory diagram showing the pass band of each LPF in FIG. 13, and FIGS. 15 and 16 are related to the fourth embodiment of the present invention. FIG. 15 is a block diagram showing the configuration of the image recording device, FIG. 16 is an explanatory diagram for explaining thinning-out, and FIG. 17 is a block diagram showing an example of an endoscope system including an image data compression device. 1 ... Electronic endoscope, 5 ... Image recording device 34R, 34G, 34B ... Compression circuit 35 ... Recording system section 36R, 36G, 36B ... Expansion circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yu Konomura 2-34-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. (72) Inventor Issei Nakamura 2-43 Hatagaya, Shibuya-ku, Tokyo No. 2 Olympus Optical Co., Ltd. (72) Inventor Shinichiro Hattori 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. (56) Reference JP-A-63-290539 (JP, A)

Claims (1)

(57) [Claims] 1. An endoscopic image data compression apparatus for compressing image data of an endoscopic image obtained by an endoscope, of a plurality of color information constituting an endoscopic image taken by the same image pickup device. In order to compress one color information including the component on the longest wavelength side at a higher compression rate than the other color information, the resolution of the one color information is set to be lower than the resolution of the other color information. An endoscopic image data compression apparatus comprising a data compression unit that performs a calculation between pixel signals adjacent to each other to compress the data.