JPH0763445B2 - Endoscopic image data recording / reproducing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an endoscope image recording / reproducing apparatus that compresses and records and expands and reproduces endoscopic image data.

[Problems to be Solved by Conventional Techniques and Inventions] In recent years, by inserting an elongated insertion portion into a body cavity, a treatment instrument inserted into a treatment instrument channel can be observed by observing an organ in the body cavity or the like. An endoscope that can be used for various therapeutic treatments is 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 recorded on an image recording device in addition to being observed on a television monitor.
It may be used later for diagnosis and analysis. When recording an endoscopic image in this manner, there is a problem that a large-capacity storage device is required because the image data has a large amount of data. Also, when transmitting an image, there is a problem that the transmission speed is slow.

Therefore, it has been proposed to compress the image data.
For example, Japanese Patent Application No. 62-279599 previously filed by the present applicant discloses a device as shown in FIG. 38 as a prior art.

In this device, RGB signals forming an endoscopic image are input from the input unit 225, converted into digital signals by the A / D converter unit 226, and then input to the compression circuit unit 227. The compression circuit unit 227 compresses the image data by predictive coding or the like, and the compressed image data is recorded in the recording system unit 228. When reproducing an image, the image data on the recording system unit 228 is restored to the original image signal by the expansion circuit unit 229, converted to an analog signal by the D / A converter unit 231, and output via the output unit 232. Is output. The above-mentioned units are controlled by the control signal generation unit 233. In this device, the quantization levels for the R, G, and B signals in the A / D converter unit 226 are the same.

However, in the case of an endoscopic image, the R signal is distributed more on the high brightness side and the B signal is distributed more on the low brightness side, and so on. When the quantization levels are the same, there is a problem in that the R signal and the B signal are not used effectively and the compression efficiency is poor.

Therefore, the applicant of the present application has proposed in Japanese Patent Application No. 62-279599 a device for performing γ correction and quantization in accordance with the characteristics of a plurality of color signals forming an endoscopic image.

However, the characteristics of the endoscopic image change depending on the observation site, the observation method, and the like. In the device, even if the quantization level is different between R, G, B, since the quantization level is always unchanged, it is not always possible to optimally compress various endoscopic images. However, the image quality may deteriorate depending on the image.

The present invention has been made in view of the above circumstances, and an endoscope capable of efficiently performing compression recording / expansion reproduction of image data for various endoscopic images with less deterioration of the image quality. An object is to provide an image recording / reproducing device.

[Means and Actions for Solving the Problems] The endoscopic image recording / reproducing apparatus of the present invention includes an image analyzing means for analyzing characteristics of image data of an endoscopic image obtained by the endoscope, and the image analyzing means. Compression rate switching obtaining means for switching the compression rate according to the analysis result, image compression means for compressing the image data according to the compression rate output by the compression rate switching means, and compression output by the compression rate switching means. A recording unit that records a rate identification signal and image data compressed by the image compression unit on a recording member in association with each other, a compression rate determination unit that reproduces the compression rate identification signal from the recording member, and a recording member. It is characterized by comprising means for reproducing the image data and means for expanding the image data reproduced from the recording member according to the compression rate determined by the compression rate determining means.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

1 to 9 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. 4 is an image analysis unit. FIG. 5 is a block diagram showing the configuration, FIG. 5 is a histogram of a differential signal between a normal image and a dyed image, FIG. 6 is a flowchart showing a recording operation of the image recording apparatus, and FIG. 7 is a flowchart showing a reproducing operation of the image recording apparatus. FIG. 8 is an explanatory diagram for explaining the compression operation of the compression circuit, and FIG. 9 is an explanatory diagram showing the recording system for the recording system section.

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 extended from 1b, the universal cord
A connector 1d connected to the observation device 3 is provided at the end of 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. Further, an objective lens system (not shown) is provided inside the observation window, and a solid-state image pickup device such as CCD 8 is provided at the image forming position of the objective lens system.
Is provided. The output signal of this CCD8 is the insertion section 1a,
Connector 1 inserted through the operation part 1b and universal cord 1c
The signal is input to the observation device 3 via the signal line connected to d.

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 has filters 22R, 22G, and 22B that are arranged along the circumferential direction and that transmit light in the respective wavelength regions of red (R), green (G), and blue (B). By being rotated, the filters 22R, 22G, 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 to a digital signal by the A / D converter 12 and then selectively input to the memories 14R, 14G, and 14B corresponding to R, G, and B by the changeover switch 13, and the memory 14R , 14G, 14B, R image, GG image, B respectively
Images are stored. The memory 14R, 14
The G 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 to the input unit 3
It is inputted from 1 and converted into digital signals by the A / D converters 32, 32, 32, respectively, and temporarily stored in the R frame memory 33R, G frame memory 33G, B frame memory 33B. ing. Each frame memory 33R, 33G, 33
The R, G and B image signals read from B are respectively compressed by the compression circuit section 34 and then recorded in the recording system section 35.

Further, at the time of reproducing the image data, the R, G and B image signals are read from the recording system unit 35 and expanded by the expansion circuit unit 36 to restore the data. The restored R, G, B image data are stored in the R frame memory 37R, G frame memory 37G, B frame memory 37B.
It is supposed to be temporarily stored in. Then, from this frame memory 37R, 37G, 37B, each R, G, B image signal,
It is read out in synchronization with the TV signal, converted into analog signals by the D / A converters 38, 38, 38, respectively, and then output.
It is designed to be output from 39.

In this embodiment, an image analysis unit 51 for analyzing the characteristics of the endoscopic image from the image information stored in the frame memories 33R, 33G, 33B is provided. The output signal of the image analysis unit 51 is input to the compression rate switching circuit 52. The compression rate switching circuit 52 determines the compression rate in the compression circuit section 34 based on the signal from the image analysis section 51, sends the compression rate to the compression circuit section 34, and the image to the recording system section 35. The compression rate identification signal is sent as a compression rate identification signal, and the recording system unit 35 records the compression rate identification signal together with the compressed R, G, B image information.

Also, the compression rate is discriminated from the compression rate identification signal reproduced from the recording system section 35, and the information of the compression rate is obtained from the expansion circuit section 36.
A compression rate determination circuit 53 for sending to the. During playback,
From the recording system unit 35, the compression rate identification signal is reproduced together with the compressed R, G, B image information, and the compression rate determination circuit 53
Determines the compression rate of the image based on the compression rate identification signal, and sends information on the compression rate to the expansion circuit section 36. The decompression circuit section 36 is adapted to perform decompression according to the compression rate.

Next, the image analysis unit 51 will be described with reference to FIGS. 4 and 5.

As shown in FIG. 4, the image analysis unit 51 includes a one-pixel delay line 55 that delays the input image signal by one pixel, a subtractor 56 that obtains a difference between the output of the one-pixel delay line 55 and the input image signal, A comparison circuit 57 that compares the output of the subtracter 56 with a predetermined threshold value, a counter 58 that counts the output of the comparison circuit 57, and a frequency component determination signal that determines the frequency component based on the output of the counter 58. A generation circuit 59 is provided, and the frequency component discrimination signal from the frequency component discrimination signal generation circuit 59 is input to the compression rate switching circuit 52.

In this embodiment, the image analysis unit 51 particularly determines whether the endoscopic image is a stained image or a normal image. In general, the stained image is an image in which details of the endoscopic diagnosis region are emphasized as compared with the normal image. Therefore, the stained image contains many high-frequency components. Therefore, the difference in density value between adjacent pixels is calculated,
When the histogram of the difference values is obtained, the normal image has a large distribution in the vicinity of 0 as shown in FIG. 5 (a), and the stained image has many large absolute values as shown in FIG. 5 (b). , Both images have distinctly different characteristics. Therefore,
As shown in FIG. 5B, a predetermined threshold value is determined, and both images can be discriminated by the magnitude of the cumulative value of pixels having a difference whose absolute value is larger than the threshold value. Fourth
The image analysis unit 51 shown in the figure discriminates the stained image and the normal image in this way. That is, the subtracter 56 calculates the difference between adjacent pixels, the comparison circuit 57 compares the difference with a threshold value, and the counter 58 calculates the cumulative value of pixels having a difference whose absolute value is larger than the threshold value. Then, the frequency component discrimination signal generation circuit 59 outputs the frequency component discrimination signal according to the accumulated value. The image analysis unit 51 is
All the R, G, B images may be analyzed, or one or two images may be analyzed.

Next, referring to FIGS. 6 to 8, the compression circuit section 34,
The operation of the expansion circuit unit 36 will be described.

As shown in FIG. 6, the compression circuit unit 34, in step S1,
The entire input image is divided with a predetermined number of pixels as one block, and the average value of the density values of the pixels in each block is calculated.
Next, in step S2, the average value is recorded in the recording system unit 35 together with the compression identification information by the compression rate identification signal from the compression rate switching circuit 52. In this embodiment, there are three compression methods and three compression ratios. Then, the compression rate is switched between the normal image and the dyed image based on the signal from the compression rate switching circuit 52. The compression method is switched depending on how many pixels are replaced with the average value as one block. For example, if one block consists of 2 pixels, it is about 1 /
It is compressed to 2 and it is compressed to about 1/4 when 4 pixels are 1 block, and it is compressed to 1/9 when 9 pixels is 1 block.

On the other hand, as shown in FIG.
In step S3, the compression identification information and the average value of each block are reproduced from the recording system unit 35, and in step S4, each pixel in the block is formed into a block by using the density value as the average value based on the compression identification information. Restore pixels.

FIG. 8 shows an example of the compression / expansion operation in which specific density values are entered. The figure (a) relates to a compression method (compression NO1) in which two pixels are made into one block, the figure (b) relates to a compression method (compression NO2) in which four pixels are made one block, and the picture (c) is made to include nine pixels as one
It relates to the compression method (compression NO3) that uses blocks. As shown in (a), in compression NO1, the entire input image is divided with two pixels P ₁ and P ₂ as one block, 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, from one average value (4) reproduced from the recording system unit 35,
A density value (4,4) of 2 pixels is created. Similarly, as shown in FIG. 6B, in compression NO2, four pixels P ₁₁ , P ₁₂ , P ₂₁ , and P ₂₂ are set as one block, and the density values (2, 6, 5,
The average value (5) of 7) is recorded in the recording system unit 35, and at the time of reproduction, from the average value (5), the density value of four pixels (5, 5, 5, 5)
To create. Similarly, as shown in FIG.
_{In, P 11 ~P 13, P 21} ~, P 23, P 31 ~P the nine pixels ₃₃ as one block, the density values of the pixels in the block (2,5,6,6,4,7,4,
The average value (5) of 3, 8) 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).

The relationship between the compression identification information and the block size is as shown in the table below.

In the case of such compression and expansion, the larger the number of pixels in one block, the higher the compression rate, and the resolution at the time of reproduction deteriorates. The following table shows the relationship between the number of pixels in one block of compressed NO1, 2, 3 and the compression ratio and the resolution during reproduction.

In normal images, there are few high frequency components, especially the stomach wall is a so-called flat image with few high frequency components,
Even if you select compression NO3, you will hardly notice the deterioration of image quality. Therefore, when the image analysis unit 51 determines that the image is a normal image, the compressed NO3 is selected. On the other hand, in a dyed image, the fine parts become clear, and therefore the deterioration of the image quality becomes noticeable when the compressed NO3 is selected. Therefore, when the image analysis unit 51 determines that the image is a dyed image, the compression NO1 or 2 is selected according to the number of high frequency components of the image.

As shown in FIG. 9, the recording system unit 35 records the compression identification information indicating which compression NO is used for each image at the beginning, and then records the average value for each block. It shall be. During reproduction, decompression is performed based on the compression identification information.

As described above, in this embodiment, the normal image and the stained image are automatically discriminated by analyzing the frequency components of the endoscopic image, and the compression method, that is, the compression ratio is changed according to the discrimination result. It is possible to reduce the deterioration of the image quality according to the characteristics of the endoscopic image and perform high compression suitable for the image.

In many cases, the dyed image has many B components, so R
Alternatively, it may be determined whether the image is a normal image or a dyed image based on the size of the B component with respect to the G component.

Also, the compression method may be changed between the R, G, and B images.

FIG. 10 is a block diagram showing the configuration of the image analysis unit in the second embodiment of the present invention.

This embodiment is an example in which the compression ratio is variable according to the running state of the blood vessel, and only the configuration of the image analysis unit 51 differs from the first embodiment.

An image in which many blood vessels are running has important value for diagnosis, and therefore it is necessary to suppress the compression rate to obtain a good image quality. Therefore, in this embodiment, the running state of the blood vessel is automatically determined and the compression rate is changed.

As shown in FIG. 10, the image analysis unit 51 in this embodiment.
Is a differentiating circuit 61 for differentiating the input image signal, a thinning circuit 62 for thinning the output image of the differentiating circuit 61, a binarizing circuit 63 for binarizing the output image of the thinning circuit 62, A counter 64 that counts the number of H-level pixels in the output image of the binarization circuit 63 and a blood vessel running signal generation circuit 65 that generates a blood vessel running signal according to the output of the counter 64 are provided. The signal is input to the compression rate switching circuit 52.

An R image signal including a large amount of blood vessel information is input to the image analysis unit 51, and a differentiation circuit 61 differentiates the R image signal to further emphasize the blood vessel. Next, the thinning circuit 62 thins the differentiated image, and the binarizing circuit 63 binarizes it.
Next, the counter 64 quantifies the blood vessel volume by counting the number of H-level pixels in the binarized image. Then, the blood vessel running signal generation circuit 65 generates a blood vessel running signal for changing the compression rate based on the quantified blood vessel volume.

The relationship between the blood vessel volume, the compression rate, and the resolution during reproduction is as shown in the table below.

Other configurations, operations and effects are similar to those of the first embodiment.

11 to 14 relate to a third embodiment of the present invention,
FIG. 12 is a block diagram showing the configuration of the compression circuit unit, FIG. 12 is a block diagram showing the configuration of the prediction error calculation circuit, FIG. 13 is an explanatory diagram for explaining the method of calculating the prediction error, and FIG. 14 is smoothing. It is an explanatory view of a filter.

This embodiment is different from the first embodiment in the compression circuit section 34 and the expansion circuit section 36.

The compression circuit unit 34 in the present embodiment has a smoothing circuit 41 and a prediction error calculating circuit 42 as shown in FIG. 11, and the image signals from the frame memories 33R, 33G and 33B are smoothing circuits. It is smoothed by 41, 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 52. The spatial frequency band after smoothing can be determined by arbitrarily setting the value of the smoothing coefficient k. That is, as k is large and the smoothing effect is large, the high frequency component of the image is deteriorated.

As shown in FIG. 12, 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. 13, 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 unit 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.

Here, when the smoothing coefficient k in the smoothing circuit 41 is increased, the high frequency component of the image is deteriorated, but the smoothing effect is large, so the prediction error signal is generally small, and therefore the amount of data to be recorded is small. Become. That is, the compression rate 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 increases. That is, the compression rate is low. Thus, the smoothing circuit
By arbitrarily setting the smoothing coefficient k in 41, the compression rate can also be arbitrarily set. In this embodiment, when there are many high frequency components in the endoscopic image, the smoothing coefficient k
Is reduced to reduce the compression rate, and when there are few high frequency components, the smoothing coefficient k is increased to increase the compression rate.

Other configurations are similar to those of the first embodiment.

In this embodiment, for example, the compression rate can be changed according to the diagnosis site. Generally, there are many distant images when observing the upper digestive tract,
When observing the lower gastrointestinal tract, most of the images are in the near view. Therefore, the image of the lower digestive tract is more clearly displayed in detail than the image of the upper digestive tract is observed. Therefore, when observing the lower digestive tract, it is not preferable to increase the compression rate to deteriorate the image quality.

In the present embodiment, since the high frequency component increases during observation of the lower digestive tract, this is discriminated by the image analysis unit 51, and the compression rate becomes low. On the other hand, when observing the upper gastrointestinal tract, the high-frequency component is small, so this is discriminated by the image analysis unit 51, and the compression rate becomes high.

The relationship between the diagnosis site, compression rate and resolution during reproduction is as shown in the table below.

Other configurations, operations and effects are similar to those of the first embodiment.

15 to 18 relate to a fourth embodiment of the present invention,
FIG. 16 is a block diagram showing the configuration of the image recording device, FIG. 16 is a block diagram showing the configuration of the compression circuit section, FIG. 17 is a block diagram showing the configuration of the band limitation switching circuit, and FIG. 18 is each of FIG.
It is explanatory drawing which shows the pass band of LPF.

As shown in FIG. 15, 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 67R and the G band limit switching circuit 67G are provided. , B band limitation switching circuit 67B is provided. In addition, the image analysis unit 51
The image signal is input to the input section 31 from the input section 31, and the compression rate switching circuit 52 controls the band limit switching circuits 67R, 67G and 67B.

Further, the compression circuit section 34 in the present embodiment has a prediction error calculation circuit 42 similar to that of the third embodiment, as shown in FIG. 16, but unlike the third embodiment, the smoothing circuit 41 is provided. There is no. Further, the expansion circuit section 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 section 35, as in the third embodiment. is there.

The band limit switching circuits 67R, 67G, 67B are configured as shown in FIG.

Each band limitation switching circuit 67 (representative of 67R, 67G, 67B)
The input end of is connected to the input end of a 1-input 2-output changeover switch 70a. A low-pass filter (hereinafter referred to as LPF) (1) 68 and an input end of an LPF (2) 69 are connected to the respective output ends of the changeover switch 70a. The output terminals of the LPFs 68 and 69 are connected to the respective input terminals of a 2-input 1-output changeover switch 70b. The output of the changeover switch 70b is the output of the band limitation changeover circuit 67. The pass bands of the LPFs 68 and 69 are as shown in FIG. That is, LPF (1) 68 has a characteristic of removing high-frequency components, and LPF (2) 69 has a characteristic of not removing high-frequency components too much.

Further, the image analysis unit 51 in this embodiment has the same configuration as that shown in FIG. 4 or FIG. 12 except that it has an A / D converter that converts an analog image signal from the input unit 31 into a digital signal. That is, the frequency component of the image and the running state of the blood vessel are determined.

The switches 70a and 70b are switched by a compression rate switching circuit 52. That is, the image analysis unit
When it is determined in 51 that the image has few high-frequency components or an image with few blood vessels, the switches 70a and 70b select the LPF (1) 68 side, and as a result, the data amount of the prediction error signal in the compression circuit unit 34 is Less. On the other hand, when the image analysis unit 51 determines that the image has many high-frequency components or many blood vessels, the switches 70a and 70b select the LPF (2) 69 side, and as a result, the prediction error in the compression circuit unit 34 is increased. Although the data amount of the signal increases, the image quality does not deteriorate.

In the third embodiment, the band limitation of the image signal is digitally performed by the smoothing circuit 41 in the compression circuit unit 34, but in the present embodiment, the LPFs 68 and 69 in the band limitation switching circuit 67 are used in an analog manner. Is going.

Other configurations, operations and effects are similar to those of the first embodiment.

19 to 23 relate to a fifth embodiment of the present invention,
FIG. 20 is a block diagram showing the configuration of an image analysis unit, FIG. 20 is an explanatory diagram showing a compression rate table, FIG. 21 is a flowchart showing a recording operation, and FIG. 22 is an explanatory diagram showing a recording system for a recording system unit. FIG. 23 is an explanatory diagram showing the block size.

While the first to fourth embodiments make the compression ratio variable for each image unit, the fifth to seventh embodiments are examples in which the compression ratio is made variable for each partial area in the image.

The fifth embodiment is an example in which the compression rate is variable in the central portion and the peripheral portion of the endoscopic image.

In this embodiment, the configuration of the image analysis unit 51 is different from that of the first embodiment. As shown in FIG. 19, the image analysis unit 51 includes a brightness calculation circuit 71 for the central area of the image to which the image signal from the R frame memory 33R is input, and a brightness calculation circuit 72 for the peripheral area of the image. The output of each calculation circuit 71, 72 is input to the flat image / cylindrical image discrimination signal generation circuit 73. The output of the flat image / cylindrical image discrimination signal generating circuit 73 is sent to the compression rate switching circuit 52.

The endoscopic image is roughly divided into two according to the observation state. One is an image in which the distance from the tip of the endoscope is almost the same from the center of the image to the periphery as in the case of observing the stomach wall, and therefore the brightness is also substantially constant in the entire image (hereinafter referred to as a flat image). The other is an image (hereinafter referred to as a cylindrical image) in which the distance from the tip of the endoscope is far from the center of the endoscope and is dark and the periphery is close and therefore bright as in esophageal observation. The image analysis unit 51 distinguishes between the flat image and the cylindrical image.

The recording operation of this embodiment will be described with reference to FIG.

First, step S11 (steps will be omitted hereinafter, simply S11
It is written as. ), The brightness calculation circuit of the central area of the image
From 71, the brightness of the central region of the image is calculated. This brightness is A.

In step S12, the brightness calculation circuit 72 for the peripheral area of the image calculates the brightness of the peripheral area of the image. Let this brightness be B.

Next, in S13, the flat image / cylindrical image discrimination signal generation circuit 73
To determine whether the brightness is A <B,
In the case of S, it is determined that the image is a cylindrical image, and that information is sent to the compression rate switching circuit 52, and this compression rate switching circuit 52
In 4, the compression rate table (a) as shown in FIG.
Select. On the other hand, in the case of NO, it is determined that the image is a flat image, and the information thereof is sent to the compression rate switching circuit 52, and this compression rate switching circuit 52 at S15, the compression rate table as shown in FIG. 20 (b). Select (b).

In the compression rate table, the image is divided into, for example, 64, and the compression rate of each divided image is determined. The numbers in the figure are
The compression ratio is shown. The larger the value, the higher the compression ratio. Therefore,
In the compression rate table (a), the central portion has high compression and the peripheral portion has low compression. Further, in the compression rate table (b), the entire image is low compressed.

Next, in S16, the compression circuit unit 34 compresses each divided image according to the compression rate table selected in S14 or S15.

Then, in S17, the compressed image information together with the compressed identification information,
Record in the recording system unit 35.

In the present embodiment, since the compression rate, that is, the block size, differs for each area in one image, the recording method for the recording system unit 35 is, as shown in FIG. The compression identification information indicating the compression rate of the block is added to. Also, the block size is the 23rd
As shown in the figure, there are three types, 1 × 2, 2 × 2, and 3 × 2.

The following table shows the relationship between the observed portion, the compression ratio, and the resolution during reproduction when it is determined that the image is a cylindrical image.

Other configurations, operations and effects are similar to those of the first embodiment.

24 to 26 relate to a sixth embodiment of the present invention,
Figure is a block diagram showing the structure of the image analysis unit. Figure 25 shows (R
FIG. 26 is a flow chart showing the recording operation.

This embodiment is an example in which the compression rate is variable according to the color.

In this embodiment, the configuration of the image analysis unit 51 is different from that of the first embodiment. As shown in FIG. 24, the image analysis unit 51
It has a matrix conversion circuit 81 to which the RGB image signals from the respective frame memories 33R, 33G, 33B for use are input, and in this matrix conversion circuit 81, the R, G, B signals are a luminance signal Y and two color difference signals. It is designed to be converted into RY and BY. The Y, RY, and BY signals are recorded in the divided image frame memory 82 and then input to the calculation circuit 83, Is calculated. The l calculated by the calculating circuit 83 is input to the calculating circuit 84, and the cumulative value Σl of l in the divided image is calculated. The calculation circuit
The Σl calculated in 84 is input to the compression rate determination circuit 85.

In the case of endoscopic diagnosis, color information is very important for diagnosis. That is, information with low saturation such as halation and shadow, which is close to black and white, has little meaning in diagnosis. In particular, the halation part becomes a white area and is meaningless for diagnosis. Therefore, divide the image, calculate the saturation of the image in the divided area,
If the saturation is low, increasing the compression rate and slightly lowering the image quality has little effect on diagnosis.

The recording operation of this embodiment will be described with reference to FIG.

First, in S21, the matrix conversion circuit 81 converts the RGB coordinates into Y (RY) (BY).

Next, in S22, the image is divided into, for example, 64 by the divided image frame memory 82.

Next, in S23, the calculation circuit 83 Ask for. That is, the saturation information is obtained.

Next, in S24, the calculation circuit 84 accumulates 1 in the divided images.

Next, in S25, the compression rate determination circuit 85 causes the cumulative value Σ of l
The compression rate for each divided image is determined according to l.

Next, in S26, according to the determined compression ratio, the compression circuit unit 34
The inside of each divided image is compressed by.

Then, in S27, the compressed image information is sent together with the compressed identification information.
Record in the recording system unit 35.

The relationship between the saturation, the compression rate, and the resolution during reproduction is as shown in the table below.

Further, the range of the compression ratio (0,1,2,3) in the above table is (R-
Y) (B-Y) plane shows, for example, a broken line in FIG.

Other configurations, operations and effects are similar to those of the first embodiment.

27 to 30 relate to a seventh embodiment of the present invention,
Figure is a block diagram showing the structure of the image analysis unit. Figure 28 shows (R
-Y) (B-Y) plane explanatory view, FIG. 29 is an explanatory view showing divided images, and FIG. 30 is a flowchart showing a recording operation.

Similar to the sixth embodiment, this embodiment is an example in which the compression ratio is variable according to the color, but in this embodiment, the compression ratio of the area close to the average color is increased.

In this embodiment, the configuration of the image analysis unit 51 is different from that of the first embodiment. As shown in FIG. 27, the image analysis unit 51 is
It has a matrix conversion circuit 91 to which the RGB image signals from the respective frame memories 33R, 33G, 33B for use are inputted, and in this matrix conversion circuit 91, the R, G, B signals are a luminance signal Y and two color difference signals. It is designed to be converted into RY and BY. The Y, RY and BY signals are sent to the average color calculation circuit 92 and the divided image frame memory 93 for the entire area. The output of the divided image frame memory 93 is sent to the average color calculation circuit 94 in the divided image.
The average color (x ₀ , y ₀ ) calculated by the average color calculation circuit 92 and the average color (xij, yij) calculated by the average color calculation circuit 94 are
Input to the calculation circuit 95, Is calculated. The l calculated by the calculating circuit 93 is input to the compression rate determining circuit 96.

In the case of endoscopic diagnosis, the color of the entire image, that is, a region close to the average color is not so important for diagnosis, and a region having a color apart from the average color generally indicates a lesion site. Therefore, in the region close to the average color, even if the compression rate is increased and the image quality is slightly deteriorated, the diagnosis is hardly affected.

The recording operation of this embodiment will be described with reference to FIG.

First, in S31, the matrix conversion circuit 91 converts the RGB coordinates into Y (RY) (BY).

Next, in S32, the calculation circuit 92 causes (RY) (BY).
Obtain the average color (x ₀ , y ₀ ) of all pixels on the plane. still,
(X ₀ , y ₀ ) is the average color (RY) as shown in FIG.
The coordinates on the (BY) plane are shown.

Further, in S33, the image is divided into, for example, 64 by the divided image frame memory 93, and in S34, the average color calculation circuit 94 averages the pixels in each divided image on the (RY) (BY) plane. Find the color (xij, yij). As shown in FIG. 29, the divided image at the i-th row and the j-th column when the image is divided is
j, and the average color of the divided images Bij is (RY) (B-
Y) The coordinates on the plane are (xij, yij).

Next, in S35, the calculation circuit 95 causes (RY) (B-
Y) Find the distance 1 between the average color of each divided image and the average color of all pixels on the plane.

Next, in S36, the compression rate determination circuit 96 determines the compression rate of each divided image according to the distance l.

Next, in S37, the compression circuit unit 34 is operated according to the determined compression ratio.
The inside of each divided image is compressed by.

Then, in S38, the compressed image information together with the compressed identification information,
Record in the recording system unit 35.

The following table shows the relationship between the distance from the average color, the compression rate, and the resolution during reproduction.

In addition, the range of the compression rate in the above table is (RY) (B-
Y) When shown on a plane, it becomes as shown by the broken line in FIG. 26, for example.

Other configurations, operations and effects are similar to those of the first embodiment.

31 to 34 relate to an eighth embodiment of the present invention,
Figure is a block diagram showing the configuration of the endoscope apparatus, FIG. 32 is a block diagram showing the configuration of the image compression recording unit, FIG. 33 is an explanatory diagram showing a histogram of a general endoscopic image, and FIG. It is explanatory drawing which shows the histogram of an endoscopic image.

As shown in FIG. 31, a CCD 101 for converting an image of a living body into an electric signal is provided at the tip of the insertion portion of the endoscope.
The output electric signal of the CCD 101 is input to an amplifier 102 for amplifying the electric signal in a predetermined range (for example, 0 to 1 volt). The output electric signal of the amplifier 102 is input to the selector 105 after passing through the γ correction circuit 103 and the A / D converter 104. The selector 105 has three output terminals, which are respectively connected to the R memory 106R, the G memory 106G, and the B memory 106B. Each memory 106R, 106G, 106B is a D / A converter 107R, 107G, 107
B is also connected to the image compression recording unit 108. The image compression recording unit 108 includes an image determination unit 121, an image compression unit 122, and an image recording unit 123. The D / A converter 107R, 107G, 10
7B is connected to the RGB signal output terminals 109, 110, and 111, respectively.

Further, a control signal generation unit 112 for controlling the destination of the image signal and the transfer timing at the time of image signal transfer is provided, and the control signal generation unit 112 includes the A / D converter 104, the selector 105, and the RG.
B Memomi 106R, 106G, 106B, D / A converter 107R, 107G, 107
B, connected to the image compression recording unit 108. The control signal generation unit 112 is also connected to a synchronization signal generation circuit 113, and the synchronization signal generation circuit 113 outputs a synchronization signal SYNC for the RGB signal output to a synchronization signal output terminal 114.

The control signal generator 112 is also connected to a motor 115 that drives the RGB rotary filter 116. The light from the lamp 118 passes through the RGB rotary filter 116 and the light guide 117 of the endoscope and is emitted from the tip of the insertion portion of the endoscope.

Next, the image compression recording unit 108 will be described with reference to FIG.

Each RGB input signal is a histogram creation unit 139R,
After passing through 139G and 139B, it is guided to the peak position detection circuit 140. The output of the peak position detection circuit 140 is the selector 1
32, the selector 136, and the compression information ROM 141.
An image determination unit 121 by the histogram creation units 139R, 139G, 139B, the peak position detection circuit 140, and the compression information ROM 141.
Is configured. Further, each RGB input signal is led to the selector 132 after passing through the working R memory 131R, G memory 131G, and B memory 131B. The output of this selector 132 is the blocking circuit (1) 1
33, blocking circuit (2) 134, blocking circuit (3) 135
It is connected to the. The outputs of the blocking circuits 133, 134, 135 are input to the predictive encoder 137 via the selector 136. The memory 131R, 131G, 131B,
Selector 132, blocking circuit 133, 134, 135, selector 136,
The predictive encoder 137 constitutes the image compression unit 122. Then, the predictive encoder 137 and the compression information ROM 141
Each output of is recorded in the image recording unit 123.

Next, the operation of this embodiment will be described.

The flow of signals will be described with reference to FIG. The image signal from the CCD 101 is converted by the amplifier 102 into a voltage in a predetermined range, that is, 0 to 1 volt in this embodiment. This image signal is
It is input to the γ correction circuit 103 and converted into an image signal having a predetermined γ characteristic. Then, in the A / D converter 104, it is digitized at a predetermined quantization level (for example, 8 bits). After that, the image input to the CCD 101 is stored in the R memory 106R when the image entering the CCD 101 is stored in the R memory 106R, and the image when the green (G) illumination is stored is stored in the G memory according to the control signal from the control signal generating unit 112 via the selector 105. Images under blue (B) illumination are recorded in B memory 106B in 106G, respectively. Each memory 106R, 106
The signals read from the G and 106B are transferred to the image compression recording unit 108 and D
Transferred to the / A converters 107R, 107G, 107B. The RGB image signals from the D / A converters 107R, 107G, 107B are output to the RGB image signal output terminals 109, 110, 1 together with the synchronization signal SYNC generated by the synchronization signal generation circuit 113 under the control of the control signal generation unit 112.
It is output from 11. On the other hand, the control signal generator 112 outputs RGB
A motor control signal is sent to the motor 115 that rotationally drives the rotary filter 116. The motor 115 rotates the RGB rotary filter 116 according to the switching timing of the selector 105 by the control signal. By the RGB rotary filter 116, the illumination light from the lamp 118 is time-sequentially separated into three colors of R, G and B, and is guided to the light guide 117 of the endoscope, and the distal end portion of the insertion portion of the endoscope. Is emitted from. This lighting system is
This is the so-called RGB frame sequential color system.

Next, the operation of the image compression recording unit 108 will be described. The signals read from the RGB memories 106R, 106G, and 106B are image compression recording units 1 under the control of the control signal generation unit 112.
R memory 131R, G memory 131G, B memory 131B for work in 08
And recorded in the histogram creation units 139R, 139G, 139B. Histogram creation units 139R, 139G, and 139B create histograms of RGB signals. After that, the peak position detection circuit
At 140, the peak position of each histogram is calculated, and the RGB position
Based on the magnitude relationship of the peak positions of the three signals, the selector 132,
A control signal is output to the selector 136 and the compression information ROM 141.

On the other hand, the signals read from the memories 131R, 131G, 131B are guided to the selector 132. The selector 132 guides the RGB signal to any one of the blocking circuit (1) 133, the blocking circuit (2) 134, and the blocking circuit (3) 135 based on the control signal of the peak position detection circuit 140. The three blocking circuits 133, 134, 135 are, for example, 1 × 2, 2 ×, respectively.
It outputs a 2,3 × 3 size blocked video signal. The larger the block size, the better the compression ratio,
On the contrary, the image quality deteriorates. The selector 136 guides the output of the selected blocking circuit to the predictive encoder 137 based on the control signal of the peak position detection circuit 140. Predictive encoder 137
Calculates a prediction error by the predictive coding method described in “Shokoido Image Processing Handbook, pages 217 to 219” and outputs it to the image recording unit 123. This image recording unit 123
Data is recorded on a large-capacity recording medium such as an optical disk or a magnetic disk.

Further, the peak position detection circuit 140 sends a control signal to the compression information ROM 141 in order to simultaneously record information such as a block size required for image restoration in the image recording unit 123. The compression information ROM 141 outputs information such as a block size corresponding to the selected output signal to the image recording unit 123.

33 (a), (b), and (c) show histograms of RGB components of a general endoscopic image, and FIGS. 34 (a), (b), and (c) respectively show The histogram of each RGB component of the stained endoscopic image is shown. As shown in FIG. 33, in a general endoscopic image, the R component is biased to a high brightness level, and the B component is biased to a low brightness part. Therefore, RG
When the peak position of the B3 signal histogram is obtained and the magnitude relation is checked, R>G> B. On the other hand, when blue-based dyeing such as methylene blue is performed, as shown in FIG.
At the peak position of the histogram, B and R are almost equal,
G becomes a low level. That is, the magnitude relationship is B ≧ R
> G. In this way, it is possible to easily distinguish between the general endoscopic image and the stained endoscopic image from the peak position of the RGB histogram.

In a general endoscopic image, the R component has few high-frequency components, and the B component is
The component has a low brightness level. Therefore, with respect to R and B, even if the resolution is reduced, it is difficult to visually detect the deterioration in image quality. Therefore, high compression can be performed by dividing the R component into 2 × 2 blocks and the B component into 3 × 3 blocks. On the other hand, the G component has many high-frequency components and the brightness level is high. That is, since the image quality deterioration is easily detected visually,
It is possible to compress with high image quality by forming a block of 1 × 2 size. Moreover, in the stained endoscopic image, there are many high-frequency components in the RGB3 components. Therefore, all three components are compressed with high image quality by forming blocks of 1 × 2 size.

Thus, in this embodiment, according to the characteristics of the input image,
Three types of blocking processing are selected. Then, after that, predictive coding processing is performed to perform further compression.
For this reason, it is possible to select large-size block formation and perform high compression for an image having a high correlation between adjacent pixels and having a small number of high-frequency components, such as a normal endoscopic image. on the other hand,
Regarding a special image such as when dyeing, the correlation between adjacent pixels is low and there are many high frequency components. For this reason, it is possible to select a small-sized block and perform compression without degrading the image quality.

As described above, since compression suitable for various characteristics of endoscopic images is performed, it is possible to compress image data with little deterioration in image quality. Moreover, since three types of compression processing are performed in parallel, the processing time is always constant.

35 to 37 relate to a ninth embodiment of the present invention,
Fig. 36 is a block diagram showing the configuration of the image compression / recording unit. Fig. 36 is an explanatory diagram showing an endoscopic image and its frequency distribution in a distant view.
FIG. 37 is an explanatory diagram showing an endoscopic image and its frequency distribution in a close view.

The present embodiment is the same as the eighth embodiment except that the configuration of the image compression recording unit 108 is different.

The configuration of the image compression recording unit 108 will be described with reference to FIG. Each RGB input signal is FFT circuit 159R, 159G, 159B
After passing through, the signal is guided to the frequency distribution detection circuit 160. The output of this frequency distribution detection circuit 160 is
It is adapted to be input to the selector 153, the selector 157, and the compression information ROM 161. The FFT circuits 159R, 159G, 159B, the frequency distribution detection circuit 160, and the compression information ROM 161 constitute an image determination unit 121. Further, each RGB input signal is a work R memory 151R, a G memory 151G, a B memory 151B,
After passing through the DCT circuits 152R, 152G, 152B, it is guided to the selector 153. The output of the selector 153 is input to the filter circuit (1) 154, the filter circuit (2) 155, and the filter circuit (3) 156. The outputs of the filter circuits 154, 155, 156 are input to the selector 157. The memories 151R, 151G, 151B, DCT circuits 152R, 152G, 152B, selector 153, filter circuits 154, 155, 1
The image compression unit 122 is composed of the 56 and the selector 157. The outputs of the selector 157 and the compression information ROM 161 are
The image recording unit 123 is adapted to be recorded.

Next, the operation of the image compression recording unit 108 will be described. RGB
The signals read from the memories 106R, 106G, and 106B are controlled by the control signal generator 112, and are used as a working R memory 151R, a G memory 151G, a B memory 151B, and an FFT circuit 159 in the image compression unit 108.
Recorded in R, 159G, 159B. In the FFT circuits 159R, 159G and 159B, Fourier transform is performed on each RGB signal and the power spectrum thereof is calculated. Then, in the frequency distribution detection circuit 160, the frequency distribution range of each signal is obtained,
Based on this distribution range, control signals are output to the selector 153, the selector 157, and the compression information ROM 161.

On the other hand, the signals read from the memories 151R, 151G, 151B are guided to the DCT circuits 152R, 152G, 152B. Here, for example, 8 × 8 size discrete cos conversion described in “IEEE Trans Vol. 1C-23, pages 90 to 93” is performed and output to the selector 153. This selector 153
RGB signal based on the control signal of the frequency distribution detection circuit 160,
It is led to any one of the filter circuit (1) 154, the filter circuit (2) 155, and the filter circuit (3) 156. The three filter circuits 154, 155, 156 are, for example, 2 × with the upper left as the origin.
It is a 2,3 × 3,4 × 4 size transmissive filter. The smaller the filter size, the higher the compression ratio and, conversely, the lower the image quality. The selector 157 outputs the output of the selected filter circuit to the image recording unit 123 based on the control signal of the frequency distribution detection circuit 160. On the other hand, the frequency distribution detection circuit 160 sends a control signal to the compression information ROM 161 in order to simultaneously record information such as the filter size necessary for the restoration. The compression information ROM 161 outputs information such as the filter size corresponding to the selected output signal to the image recording unit 123.

Here, the frequency distribution of the endoscopic image will be described with reference to FIGS. 36 and 37. In the present example, for example, consider a case where the same subject is observed at different observation distances. 36 (a) and 36 (b) respectively show an endoscopic image at the time of distant view,
The power spectrum showing the frequency distribution is shown in FIGS. 37 (a) and 37 (b), respectively, and an endoscopic image at the time of near view,
The power spectrum which shows the frequency distribution is shown.
In the distant view, the high frequency component in the structure of the mucous membrane of the living body is masked by the resolution of the optical system or the like and is not detected. When the frequency distribution in this case is imaged as a power spectrum,
As shown in FIG. 36 (b), the image is focused on the origin, that is, the low frequency component. On the other hand, in a close view, high frequency components such as the mucous membrane structure of the living body are detected. In this case, the frequency distribution is distributed in a wide range around the origin, as shown in FIG. 37 (b). Thus, by obtaining the power spectrum, the proportion of high frequency components can be determined.

In an endoscopic image, the amount of information included in a video signal varies depending on the observation distance even when the same subject is projected. That is, when the observation distance is short and there are many high frequency components, it is possible to compress with high image quality by setting the filter size to 4 × 4. On the contrary, when the observation distance is long and the high frequency component is small, high compression can be performed by setting the filter size to 2 × 2. Further, even at the same observation distance, there is a large difference in the amount of information between the upper digestive tract and the lower digestive tract. This is because almost no blood vessel image is detected in the upper digestive tract such as the stomach, but a blood vessel image is detected in the lower digestive tract such as the large intestine. The lower digestive tract where the blood vessel image is detected has many high-frequency components, and the upper digestive tract where the blood vessel image is not detected has few high-frequency components. As a result, the filter size is set to, for example, 2 × 2 in the upper digestive tract and 3 × 3 in the lower digestive tract, so that the image quality and the compression rate can be balanced.

Other configurations, operations and effects are similar to those of the eighth 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. Also, the endoscope
Either a type having an image pickup device at the tip or a type receiving an image by the image pickup device after guiding an image to the outside of the object to be observed via an image guide by an optical fiber may be used.

EFFECTS OF THE INVENTION As described above, according to the present invention, the compression method can be changed according to the characteristics of the endoscopic image, so that the deterioration of the image quality can be reduced for various endoscopic images. The effect is that high compression is possible.

[Brief description of drawings]

1 to 9 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. 4 is an image analysis unit. FIG. 5 is a block diagram showing the configuration, FIG. 5 is a histogram of a differential signal between a normal image and a dyed image, FIG. 6 is a flowchart showing a recording operation of the image recording apparatus, and FIG. 7 is a flowchart showing a reproducing operation of the image recording apparatus. FIG. 8 is an explanatory diagram for explaining the compression operation of the compression circuit, FIG. 9 is an explanatory diagram showing the recording method for the recording system unit, and FIG. 10 is a configuration of the image analysis unit in the second embodiment of the present invention. FIG. 11 is a block diagram showing a third embodiment of the present invention.
FIG. 11 is a block diagram showing the configuration of the compression circuit section, FIG. 12 is a block diagram showing the configuration of the prediction error calculation circuit, FIG. 13 is an explanatory diagram for explaining the method of calculating the prediction error, and FIG. 14 is FIGS. 15 to 18 relate to a fourth embodiment of the present invention, FIG. 15 is a block diagram showing the construction of an image recording apparatus, and FIG. 16 is a construction of a compression circuit section. Block, FIG. 17 is a block diagram showing the configuration of the band limit switching circuit, FIG. 18 is an explanatory diagram showing the pass band of each LPF of FIG. 17,
19 to 23 relate to a fifth embodiment of the present invention,
FIG. 20 is a block diagram showing the configuration of an image analysis unit, FIG. 20 is an explanatory diagram showing a compression rate table, FIG. 21 is a flowchart showing a recording operation, and FIG. 22 is an explanatory diagram showing a recording system for a recording system unit. FIG. 23 is an explanatory view showing the block size, FIG.
26 to 26 relate to the sixth embodiment of the present invention, FIG. 24 is a block diagram showing the configuration of the image analysis unit, and FIG. 25 is (R-
Y) (B-Y) plane explanatory view, FIG. 26 is a flowchart showing a recording operation, FIGS. 27 to 30 are related to a seventh embodiment of the present invention, and FIG. 27 is a configuration of an image analysis unit. 28, FIG. 28 is an explanatory view showing the (RY) and (BY) planes, FIG. 29 is an explanatory view showing divided images, FIG. 30 is a flowchart showing a recording operation, and FIG. 31 to FIG. FIG. 34 relates to an eighth embodiment of the present invention, FIG. 31 is a block diagram showing a constitution of an endoscope apparatus, FIG. 32 is a block diagram showing a constitution of an image compression recording unit, and FIG. FIG. 34 is an explanatory view showing a histogram of an endoscopic image, FIG. 34 is an explanatory view showing a histogram of a stained endoscopic image, FIGS. 35 to 37 are related to a ninth embodiment of the present invention, and FIG. Block diagram showing the configuration of the recording unit,
FIG. 36 is an explanatory diagram showing an endoscopic image and its frequency distribution in a distant view, FIG. 37 is an explanatory diagram showing an endoscopic image in a near view and its frequency distribution, and FIG. 38 is a conventional image compression device. It is a block diagram shown. 1 ... Electronic endoscope, 5 ... Image recording device 34 ... Compression circuit unit, 35 ... Recording system unit 51 ... Image analysis unit, 52 ... Compression ratio switching circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yu Konomura 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside 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-61-92073 (JP, A)

Claims (1)

[Claims] 1. An image analysis means for analyzing characteristics of image data of an endoscopic image obtained by an endoscope; a compression rate switching means for switching a compression rate according to an analysis result of the image analysis means; The image compression means for compressing the image data according to the compression rate output by the rate switching means, the compression rate identification signal output by the compression rate switching means, and the image data compressed by the image compression means are associated with each other. Recording means for recording on a recording member, compression rate determining means for reproducing the compression rate identifying signal from the recording member, means for reproducing image data from the recording member, compression rate determined by the compression rate determining means And a means for expanding the image data reproduced from the recording member according to the above.