JPH0773570B2 - Image processing method in electronic endoscope apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image processing method in an electronic endoscope apparatus for imaging in a frame sequential method.

[Conventional technology]

The field-sequential method that sequentially obtains color images corresponding to illumination light of each color from one CCD two-dimensional sensor is effective when multiple CCD two-dimensional sensors cannot be mounted, and has recently been applied to medical electronic endoscope systems. Is being done.

Such an electronic endoscope apparatus simultaneously converts color images sequentially captured according to illumination light via red (R), green (G), and blue (B) field memories, and outputs color images as color images. It is configured to play on a TV.

[Problems to be solved by the invention]

However, in an electronic endoscope apparatus that captures images in the frame-sequential method, it is necessary to make each field data of R, G, and B the same field in order to prevent line flicker. Therefore, in the past, odd field and even field were used. Only one of the field data is read out from the CCD, or both field data are added and read out at once from the CCD.

Therefore, the vertical resolution of the CCD was half that of the original CCD.

In addition, a general electronic endoscope device is a full-frame CCD (500 (H)) of 1/2 inch or 1/3 inch optical size of a general TV.
Although × 400 (V) = 200,000 pixels) is used, a CCD applicable to small diameter is a CCD for local observation with an optical size of about 1 mm □ when developing a small diameter endoscope.

Therefore, when the CCD is operated in the current system, the screen size is determined by the area ratio, and the 1 mm □ CCD has a small screen size, which is a practical problem.

The present invention has been made in view of such circumstances, and provides an image processing method in an electronic endoscope apparatus capable of improving the resolution in the vertical direction and quadrupling the screen size in area ratio. The purpose is to provide.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention obtains a color signal of a frame sequential system from a CCD arranged at a distal end portion of an endoscope, and A / D-converts this frame sequential color signal to sequentially store in a memory for each color. , In an electronic endoscope apparatus in which simultaneous reading is performed from each memory and simultaneous conversion is performed and a color image is reproduced by the simultaneous color signal, the odd field and the even field of the CCD are sequentially ordered within one field period. The frame sequential color signals are obtained by inter-line transfer to the memory, and the data for each horizontal scanning line is alternately read from the odd field data and the even field data once stored in each memory to complete the frame data. It is characterized in that the simultaneous color signal is obtained.

Further, the read frequency of the simultaneous color signal from the memory is halved with respect to the writing frequency of the frame sequential color signal to the memory, and the simultaneous color signal (frame data) is sequentially set to an odd field. The feature is that a color image is reproduced by interlacing with even fields.

[Action]

According to the present invention, the odd field data and the even field data of the CCD are sequentially read within one field period and stored in the memory of the corresponding color channel. When reading from each memory, the data for each horizontal scanning line is alternately read from the odd-numbered field data and the even-numbered field data to complete and output the frame data. As a result, the resolution in the vertical direction can be doubled as compared with the conventional method.

In addition, the read frequency is halved with respect to the write frequency to the memory, and the read frame data is interlaced into the odd field and the even field in order to reproduce the color image. It can be quadrupled as a ratio.

〔Example〕

Hereinafter, preferred embodiments of an image processing method in an electronic endoscope apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of an electronic endoscope apparatus to which the method of the present invention is applied. Light from an illumination lamp 10 passes through a near infrared ray removing filter 12, a color filter disc 14 and a light guide 16. The subject 18 is proved from the tip of the endoscope. That is, each of the color filter disks 14 has a central angle of 12
It has a 0 ° red filter, a green filter, and a blue filter, and has a predetermined rotation speed (for example, 20rps) by the motor 20.
It is rotated by. This causes the light from the illumination lamp 10 to pass through this rotating color filter disc 14
Illumination light of each color of red (R), green (G), and blue (B) that changes sequentially in synchronization with the cycle of 60 seconds, that is, the cycle of the VD pulse shown in FIG. B)), light guide 16
It is added to the subject 18 via.

An image pickup lens 22 provided at the tip of the endoscope picks up an image of a subject 18 illuminated by red, green, and blue illumination light and forms an image on a light receiving portion of a CCD 24.

The CCD 24 has, for example, a size of 1 mm □, and has an interline CC of 141 pixels in the vertical direction (V) and 100 pixels in the horizontal direction, for example.
At D, it is driven by a timing pulse applied by a sync circuit 26 via a CCD drive circuit 28. That is, in the photoelectrically converted image information incident on the light receiving portion of the CCD 24, the odd field and the even field of the CCD 24 are sequentially interline-transferred within one field period as shown in FIG. The data and the even field data are applied to the A / D converter 32 via the process amplifier 30.

Here, the interlaced scanning will be described in more detail below.
As shown in the figure, within one field period (16.6 mS), first, horizontal scanning lines forming odd fields (O)
Minute data is transferred, and then data for horizontal scanning lines 'to' constituting the even field (E) is transferred.

Also, the transfer time for one horizontal scanning line is H / 2 (≈.31.7
5 μS) and the transfer time for one frame is approximately 4.61 mS (≈3
It is designed to be shortened to 1.8 μS x 141 + 2H). 2H
Indicates the period of ejection to the vertical transfer path. In this way, by increasing the transfer rate from the CCD 24 and reading it, the light irradiation time is increased and the output voltage of the CCD 24 is obtained.

Further, the horizontal transfer (write) frequency is set to 2fsc≈7.16M Hz.

The A / D converter 32 converts a frame sequential color signal (analog signal of the odd field and even field) corresponding to each input illumination light into a digital signal, and outputs this digital signal to the changeover switch 34.

The changeover switch 34 changes over the input frame sequential color signal to any one of the three memories 40, 42 and 44 and outputs it in synchronization with a timing pulse of one field cycle which is applied from the synchronizing circuit 26. The piece 34E is sequentially switched to the contacts 34A, 34B, 34C, 34A ... And the frame sequential color signals corresponding to the respective illumination lights are sequentially output to the memories 40 to 44.

The three memories 40 to 44 temporarily store frame data (odd field data and even field data) for each color, and writing and reading of frame data are controlled by a control signal from the memory drive circuit 48.

Next, the writing / reading control of the memory will be described.

As shown in FIGS. 2 (C) and 3, the field sequential color signals of the odd field and the even field are sequentially written in the corresponding memories, and at the same time, as shown in FIGS. 2 (D) and 3 (A). As shown in (C) to (C), the R, G, and B color signals are simultaneously read and converted into the simultaneous system.

Further, as shown in FIG. 4, when reading the odd field data and the even field data, the data of the first horizontal scanning line of the odd field, the data of the first horizontal scanning line of the even field, and the second of the odd field are read. Horizontal scan line data, ... even field 70th horizontal scan line data, odd field number
The odd field and the even field are alternately read for each horizontal scanning line in the order of data of 71 horizontal scanning lines to complete one frame data. Of course, during the field period on the TV monitor (16.6ms, 262.5 lines), the readout period of each horizontal scanning line is 1H (63.5μ).
s), and the read period for one frame data is approximately 8.95.
It is ms (≈63.5 μS × 141). Further, the read frequency f _{sc at} this time is 3.58 M Hz, which is ½ of the write frequency.

The simultaneous color signals that are simultaneously read from the memories 40 to 44 and converted into the simultaneous method are output to the D / A converters 52, 54 and 56, respectively. That is, each of the memories 40 to 44 outputs a color signal of a specific color. For example, as shown in FIG. 5, the color signals of R _-1 , G _-1 , and B _-1 are simultaneously read from the memories 40, 42, and 44 and displayed. Then, at the time of the next writing, the frame sequential color signal of R _{0 is written} to the memory 40, and at the time of the next reading, from the memories 40, 42, 44 respectively.
The color signals of R ₀ , G _-1 , and B _-1 are read simultaneously.

The R, G, and B simultaneous color signals converted simultaneously as described above are converted to analog signals by D / A conversion switches 52, 54, and 56, and then added to an encoder 58. Converted to a color video signal. Then, this composite color video signal is added to the color TV and reproduced as a color video.

In this way, since one frame data / one field period data is obtained from the CCD24, the vertical resolution can be doubled, and this one frame data can be converted into an odd field (141 lines), If you interlace to an even field (141 lines), you get an image of 282 lines (double the image in the vertical direction) and 2f in the horizontal direction.
_sc the data written in the _{(7.16M Hz) f sc (3.58M} Hz)
The image size is doubled by reading with, and thus the screen size can be made into a practical size that is four times the area ratio.

〔The invention's effect〕

As described above, according to the image processing method in the electronic endoscope apparatus according to the present invention, the resolution in the vertical direction can be improved, and the screen size can be quadrupled by the area ratio. The small CCD can be applied to electronic endoscopes.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an electronic endoscope apparatus to which the method of the present invention is applied, and FIGS. 2A to 2D are timings of respective parts used for explaining FIG. A chart, FIG. 3 is a timing chart showing details of data transfer by interlaced scanning of CCD, and FIGS. 4 (A) to 4 (C) are used for explaining reading of data from the memory of FIG. 1, respectively. Timing chart, fifth
The figure is a diagram used for explaining writing and reading of each memory in FIG. 24 …… CCD, 26 …… Synchronous circuit, 28 …… CCD drive circuit, 34…
… Changeover switch, 40, 42, 44 …… Memory, 48 …… Memory drive circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-63-123282 (JP, A) JP-A-63-98286 (JP, A) JP-A-62-82888 (JP, A)

Claims (2)

[Claims] 1. A color signal of a frame-sequential system is obtained from a CCD disposed at the tip of an endoscope, the frame-sequential color signal is A / D converted and sequentially stored in a memory for each color, and simultaneously read from each memory. In the electronic endoscope apparatus which is converted into the simultaneous system by the above and reproduces a color image by the simultaneous color signal, the odd field and the even field of the CCD are sequentially interline-transferred within one field period. The frame sequential color signal is obtained by the above method, and the data for each horizontal scanning line is alternately read from the odd field data and the even field data once stored in each of the memories to complete frame data to complete the simultaneous color signal. An image processing method in an electronic endoscope apparatus, characterized in that. 2. A reading frequency of a simultaneous color signal from the memory is halved with respect to a writing frequency of the frame sequential color signal to the memory, and the simultaneous color signal is sequentially set to an odd field. 2. An image processing method in an electronic endoscope apparatus according to claim 1, wherein a color image is reproduced by interlacing with even fields.