JPH03121037A - Endoscope image data compressing device - Google Patents

Abstract

PURPOSE:To obtain the superior image quality with the less number of bits by varying the compression rate at a bright part and dark part of a compressed image. CONSTITUTION:The brightness information supplied from a brightness information detector 43 is inputted into a selection part 44, and a quantumizing device 33 or 34 is selected by selecting switches 39 and 40 according to the brightness information. When the brightness is at a level of 0-30 in 8-bit (256) gradation, the quantumiZing device 33 is selected, and when the brightness is at a level of 31-256, the quantumizing device 34 is selected. With this constitution, the quantumizing device 33 or 34 is selected according to the brightness information of each color of R, G, and B, and the image signal which is dark in a certain degree is quantumizied by the less number of bits, while in case of the bright image signal, quantumization is performed with the much number of bits, and quantumization is weighted according to the brightness of the image signal. Thus, the superior image quality can be obtained with the less number of bits.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an endoscopic image data compression device that compresses endoscopic image data.

[Prior Art and Problems to be Solved by the Invention] In recent years, treatment instruments have been developed that allow observation of internal organs in the body cavity by inserting an elongated insertion section into the body cavity, and when necessary, treatment instruments inserted into the treatment instrument channel. Endoscopes that can perform various therapeutic procedures are widely used.

Furthermore, electronic endoscopes in which a solid-state imaging device such as a COD is provided at the distal end of the insertion portion have also been put into practical use.

By the way, endoscopic images carried by the electronic endoscope or the TV camera connected to the eyepiece of the fiberscope are not only observed on the TV monitor, but also recorded in an image recording device for later diagnosis. It may be used for analysis. When recording endoscopic images in this manner, there is a problem in that a large capacity storage device is required because the amount of image data is large. Furthermore, when transmitting images, there is a problem that the transmission speed is slow.

Therefore, various image compression means have been proposed as methods for reducing the information amount of the image signal. Is there no movement on the screen in these, or is it small enough? ! For mirror image compression, there is a means to digitize the image, predict the pixel to be encoded from neighboring pixels, and convert the prediction error into an ω child, or a method such as discrete cosine transform (DCT). Are suitable.

However, for example, when compressing an endoscopic image using predictive encoding, the prediction errors resulting from the predictive encoding of each of RGB are quantized as they are in one density gradation of, for example, 5 bits. By the way, when examining endoscopic images, there are bright areas such as nearby body walls and dark areas such as relatively distant body walls in or around the foramen, which can be memorized in detail and used later. The areas necessary for observation and consideration are bright areas, and there will be a lot of noise in areas that are dark to a certain extent, so the prediction error may not need to be small, or details cannot be clearly observed in dark areas, so even if the compression rate is increased. There is no support.

The present invention has been developed in view of these circumstances, and is an internal method that changes the compression ratio between bright and dark areas of an endoscopic image, thereby achieving good image quality with a small number of bits. The purpose of this invention is to provide an endoscopic data compression device.

[Means for Solving the Problems] In order to achieve the above object, an endoscopic image data compression device according to the present invention changes the compression ratio depending on the brightness and darkness of the endoscopic image.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

Figures 1 to 3 relate to the first embodiment of the present invention.
FIG. 2 is a block diagram showing the compression device, FIG. 2 is an explanatory diagram showing the entire endoscope filing system, and FIG. 3 is an explanatory diagram showing the configuration of the observation device.

As shown in Figure 2, inside? ! The mirror image filling system includes an electronic endoscope 1, an observation device 3 and a suction device 6 to which the electronic endoscope 1 is connected, and a monitor 4 and an image recording device 5 connected to the observation device 3. We are prepared.

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

The distal end of the insertion section 1a of the electronic endoscope 1 is provided with an illumination window and an observation window. 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 section 1a, the operation section 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, for example, a CCD 8, is disposed at the imaging position of this objective lens system.

The output signal of this CCD 8 is transmitted to the insertion section 1a, the operation section 1b,
The signal is input to the observation device 3 via a signal line inserted through the universal cord 1C and connected to the connector 1d.

The observation device 3 is constructed as shown in FIG.

The observation device @ 3 includes a lamp 19 that emits white light, and a rotary filter 21 that is provided between this lamp and the incident end of the light guide 18 and is rotationally driven by a motor 20. ing. The rotating filter 21 has red (R) and green (G) filters arranged along the circumferential direction.
), and a filter 22 that transmits light in each wavelength range of blue (B).
R, 22G, 22B, and is rotated by the motor 20 to insert a filter 22R122 into the illumination optical path.
G and 22B are inserted sequentially. The light separated in time series into the R2G and B wavelength regions by the rotating filter 21 is transmitted to the light guide 18. The light is emitted from the distal end of the insertion section 1a of the electronic endoscope 111 through a light distribution lens.

Furthermore, the observation device 3 has an amplifier 9, and the output signal of the CCD 8 is amplified by this amplifier to a voltage level within a predetermined range, and subjected to γ correction in a γ correction circuit 11. The γ-corrected signal is converted into a digital signal by the A/D converter 12, and then is transferred to memories 14R and 14G corresponding to R, G, and B, respectively, by the changeover switch 13.
, 14B, and the memories 14R, 14G,
14B, 8 images, G11tii image, and 8 images are respectively stored. The memory 14R11
4, G, 14. B is read out at the same time as the television signal, and is converted into an analog signal by the D/A converters 15, 15.15. These analog R, G, and B image signals are output from the RGB signal output terminal 17 together with the synchronization signal 5YNC from the II signal generation circuit 16, and are outputted to the monitor 41 and the image recording device 5.
etc. are entered. Said motor 20. A
/D converter 12. Changeover switch 13. Memory 14R
114, G, 14B, D/A converter 15. The synchronizing signal generating circuit 16 is controlled by a control signal generating section 23.

The image recording device 5 shown in FIG. 2 includes the image data compression device shown in FIG. The image data compression device will be described below with reference to FIG.

The R, G, and B image signals outputted from the observation device 3 are input to predictive encoders 32a, 32b, and 32c via image input units 31a, 31b, and 31C, respectively, where they are predictively encoded to form an image. It is designed to output to a recording device 5. Also, the above R,G.

Each B image signal is sent to a suspender 33, which will be described later, after receiving brightness information.
34 is inputted to a switching input section 35 for switching.

The predictive encoders 32a, 32b, 32c include a subtracter 3
6, a plurality of quantizers 33 and 34 with different quantization gradations, in this embodiment two types of suspenders 33 and 34, and these two types of quantizers 3.
3.34 on the input side and output side, respectively, an adder 41, and a predictor 42. The R signal input to the predictive encoder 32a is input to one input end of the subtracter 36, where one pixel (or one horizontal line, one field/frame, the same applies hereinafter) is extracted from the input signal. The previous signal is subtracted to obtain a difference signal, which is input to the next stage quantizer 33 or 34. The difference signal is converted into an ω signal by the hanger generators 33 and 34, and the hanger-formed R signal is outputted to the image recording device, and a part of the difference signal is output to the adder 41.
For example, 1 is input to the predictor 42 and stored in the predictor 42.
The signal is added to the signal before the pixel. This added signal is stored in the predictor 42, and is also input to the other input terminal of the subtracter 36, and the next R imaging signal input from the image input section 31a is subtracted to obtain the difference signal. It looks like this.

By the way, in this embodiment, there are two types of quantizers 33 and 34 with different quantization gradations, and one of the suspender 33 is the first one.
The sign assignment of the prediction error shown in the table is
The prediction error codes shown in Table 2 are assigned.

Table 1 Table 2 On the other hand, the R, G, and B color signals are input to the switching input section 35, and the brightness information detector 43 in this switching input section 35
It is now converted to brightness information.

This conversion is performed using a conversion formula of brightness -0, 3R-Fo, 5G+0.2B, which is the same as the method for calculating a normal luminance signal. The brightness information from the brightness information detector 43 is input to the switching section 44, and depending on the brightness information, the switch 39.
40 is switched and operated to select either the m-quantizer 33 or the suspender 34.

That is, in this example, the brightness is 8 bits < 256).
Quantum unit 33 is selected at the 0-30 level of the Iil'i scale, and quantum unit 3 is selected at the brightness level of 31-255.
4 is now selected.

In this configuration, the suspender 33 or 34 is selected depending on the brightness information of each color signal of R, G, and B, and a somewhat dark image signal is converted into a 1d signal with a small number of bits, and a bright image signal is suspended with a large number of bits. The quantization is weighted according to the brightness of the image signal, and good image quality can be obtained with a small number of bits.

FIG. 4 is a block diagram of a second embodiment of the device of the present invention.

In this embodiment, instead of creating and converting brightness information from each color signal of RG[3 with a brightness information detector, G (ffi
The G signal is used as a substitute for brightness information, and the switching section 44 uses this G signal.
is operating. The other configurations and effects are the same as in the first embodiment.

FIG. 5 is a block diagram of a third embodiment of the device of the present invention. In this embodiment, the gradation of the quantization error of only the R signal is changed and selected based on the brightness information that is converted by the brightness information detection unit using the RGB signals. Therefore, there is only one omega converter 34 for the G signal and the B signal, which constitutes the predictive encoders 32b' and 32G', respectively, and the other configurations and effects are the same as in the first embodiment. .

6 to 11 relate to a fourth embodiment of the device of the present invention, FIG. 6 is a block diagram showing the configuration of the image recording device, and FIG. 7 is a block diagram showing the configuration of the image recording device.
The figure is a block diagram showing the configuration of the image analysis unit, Figure 8 is a flowchart for determining the compression rate, Figure 9 is an explanatory diagram for determining the compression rate according to the brightness of the original image, and Figure 10 is the brightness and compression rate. FIG. 11 is an explanatory diagram showing the relationship between image quality and image quality, and FIG. 11 is an explanatory diagram showing the recording method in the recording system unit.

In each of the above-mentioned embodiments, the brightness is calculated from the RGB values, and a plurality of quantizers with different n-th gradations are selected based on this brightness information, but in this embodiment, one screen is divided into many blocks. The compression ratio of each block is set according to the average brightness of each block.

In the image recording device 5 shown in FIG. 6, the R, G, and B image signals outputted from the observation device 3 shown in FIG.
52.52, it is converted into digital No. 16 and is temporarily stored in the R frame memory 53R, the G frame memory 53G, and the B frame memory 53B. The R, G, and B image signals read out from the frame memories 53R, 53G, and 53B are respectively compressed by the compression circuit section 34 and then stored in the recording system section 55.

Furthermore, when reproducing image data, the recording system section 55
The R, G, and B image signals are read out from
The data is decompressed and restored by the decompression circuit section 56. The restored RlG and B image data are 1
(Frame memory 57R, G frame memory 57G
, and are temporarily stored in the B frame memory 57B. This frame memory 57R, 5
7G.

R, G, and B image signals are read out from 57B in synchronization with the television signal, and are then sent to D/Δ converters 58 and 57B, respectively.
58. After being converted to an analog signal in 58, output) 3 parts 5
It is designed to be output from 9.

In this embodiment, each of the frame memories 53R253G,
An image analysis unit 61 is provided to analyze the characteristics of the endoscopic image from the image information stored in the image information stored in the image information storage unit 53B. The output signal of this image analysis section 61 is input to a compression rate switching circuit 62. This compression rate switching circuit 62 is
Based on the signal from the image analysis unit 61, the compression rate in the compression circuit unit 54 is determined, and the compression rate is sent to the compression circuit unit 54, and information on the compression rate of the image is compressed in the recording system unit 55. The recording system unit 55 sends this compression ratio identification signal as a compression ratio identification signal to the compressed R, G,
It is designed to be stored together with the image information of B.

Further, a compression rate determination circuit 63 is provided which determines the compression rate from the compression rate identification signal reproduced from the recording system unit 55 and sends information on the compression rate to the decompression circuit unit 56. During playback, the recording system unit 55 records compressed R, G, and B data.
A compression ratio identification signal is reproduced together with the image information of the image, and the compression ratio determination circuit 63 determines the compression ratio of the image based on the compression ratio identification signal, and transmits the compression ratio information to the decompression circuit section 5.
Send to 6. The decompression circuit section 56 is configured to perform decompression according to this compression ratio.

The image analysis section 61 shown in FIG. 6 is arranged as shown in FIG. 7. That is, the input image signals from the R, G, and B frame memories are input to the matrix circuit 71, where a luminance signal (Y signal @) is formed, and this luminance signal is input to the divided image frame memory 72. , one side for example 16
It is designed to be divided.

Each divided image (, i is the brightness average value calculation circuit 7 in the divided image) divided by the divided image frame memory 72.
3, the average value of the brightness within each divided image is calculated and inputted to the compression rate determination circuit 74. In this compression rate determination circuit 74, depending on the SIL average value of the brightness in each divided image, for example, if the average brightness in the divided image is one of the four gradations of O<1<2×3,
Deciding on the compression ratio of the corresponding gradation in 4 stages of 0, 1, 2 and 3,
This decision information is input to a compression ratio switching circuit 62 shown in FIG.

Next, the compression ratio determination flow will be explained with reference to the flowchart shown in FIG. First, the matrix circuit 71 inputs image signals from the R, G, and B frame memories, as shown in step S1.<R, G.

A brightness signal is generated from each B image, and the brightness signal is input to the frame memory 72 for the next divided image, and in step S2, one image is divided into, for example, 16 as shown in FIG. 9(A). Then, it is input to the brightness average value calculation circuit 73 in the next divided image, and as shown in step S3 and FIG. 9(B), the brightness average for each divided image is determined, for example, in O to 3 gradations. Based on the brightness information for each divided image, the compression rate determining circuit 74 in the next stage determines the compression rate according to the brightness as shown in step $4, for example, in stages O to 3 as shown in FIG. 9(C). is determined, and according to this determination, each divided image is compressed in step S5, and the compressed identification information and compressed image information are roughly recorded in step S6.

Furthermore, as shown in FIG. 11, the recording method in the recording system unit 55 is to record compression identification information indicating which compression number was used for compression for each image at the beginning, and then record the average value for each block. It shall be.

During playback, decompression is performed based on the compression identification information.

By doing this, as shown in Figure 10, the compression ratio of each block in one image is changed depending on the brightness within each block, and the darker the image, the higher the compression becomes, and the image quality during playback also changes accordingly. to degrade. However, since details cannot be clearly observed in such a dark region within one image, even if the compression ratio is increased and the image quality is (slightly) degraded, it will have little effect on diagnosis by reproducing the image.

For example, the compression ratio in stages O to 3 is
- A plurality of different quantization gradations as shown in the third embodiment, here four types of suspenders are provided, and one of them is selected and determined according to Akimaro information. Note that in this fourth embodiment, this image compression method is not limited to the predictive coding method;
Various methods such as the DCT method are implemented as necessary.

Note that the present invention is not limited to a frame-sequential electronic endoscope using RGB signals, but can also be applied to a single-panel electronic endoscope that decodes a composite video signal. Further, the endoscope may be of a type having an image pickup element at its tip or of a type having an image guided to the outside of the object to be observed via an image guide using an optical fiber and then received by an image recording element.

[Advantageous Effects of the Invention 1] As explained above, according to the present invention, the compression ratio is changed between the bright parts and the dark parts of the compressed image, and good image quality can be obtained with a small number of bits.

[Brief explanation of drawings]

Figures 1 to 3 relate to the first embodiment of the present invention.
Figure 2 is a block diagram showing the compression device, Figure 2 is an explanatory diagram showing the entire endoscope filling system, Figure 3 is an explanatory diagram showing the configuration of the observation device, and Figure 4 is a second embodiment of the device of the present invention. FIG. 5 is a block diagram of the third embodiment of the apparatus of the present invention, FIGS. 6 to 11 are of the fourth embodiment of the apparatus of the present invention, and FIG. 6 is a block diagram of the image recording apparatus of the present invention. FIG. 7 is a block diagram showing the configuration of the image analysis section; FIG. 8 is a flowchart for determining the compression ratio; FIG. 9 is an explanatory diagram for determining the compression ratio according to the brightness of the original image; 1st
FIG. 0 is an explanatory diagram showing the relationship between brightness, compression ratio, and image quality, and FIG. 11 is an explanatory diagram showing the recording method for the recording system section. 32... Predictive encoder 33. 34... Hanging device 42... Predictor 35... Switching input section 7
1...7 tricks circuit 72...Divided image frame memory 73...Average (1 output circuit 74...Compression ratio determination circuit Fig. 2, Fig. 3

Claims (1)

[Claims] An image compression device for compressing endoscopic images, characterized in that the compression rate is changed depending on the brightness of the endoscopic image.