JPH01138877A - Color picture analyzer - Google Patents

Abstract

PURPOSE:To facilitate picture analysis by converting each picture element of a color video signal into an LUV display color system being a nearly uniform color space in terms of perception so as to apply expanding and emphasis processing to the difference in hue and inverting the result again into the original color video signal. CONSTITUTION:The video signal of an object picked-up by a CCD camera 2 at the tip of a scope 1 introduced into a coelom is sent to a main body. Signal processing such as color correction is applied in the inside of main body by a camera control section 4 and the signal is converted into a video signal comprising R, G, B signals and a synchronizing signal and the result is outputted to a control section 5. The signal is sent to an RGB-XYZ-LUV conversion section 11 from the control section 5, the RGB signal is converted into the XYZ display color system and further into the LUV display color system signal and emphasis processing is applied in a color stimulus emphasis processing section 15. At first, emphasis is added to at first stimulus, the difference of hue is expended to emphasize the lightness. Thus, the minute difference of the color of tissue structure is analyzed and diagnosis is facilitated.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a color image analysis device that processes and displays captured color images for analysis, and particularly relates to a color image analysis device that processes and displays a captured color image for analysis. The present invention relates to a color image analysis device that performs image processing such as enhancement processing to facilitate image analysis by converting into a color space of a color system that is approximately uniform in space.

(Prior art) In a color image analysis device that processes and displays a color image of a subject and provides it for analysis, emphasis processing is performed on specific components of the color image in order to make image analysis easier. Various processing methods are used to clarify the features on the image that are of interest.

Conventional processing methods include, for example, performing non-linear density conversion on the brightness information of the target image data to expand and emphasize areas near a specific brightness, rotate the hue, or expand and emphasize a specific hue range. etc.

However, all of these conventional enhancement processes are based on color systems derived from equipment such as imaging devices,
For example, H8I color system (H is Hev; hue, ■ is xnte
Image processing is based on numerical data using the RGB color system (R represents red, G represents green, and B represents the color of fruits and vegetables). Ta.

In such conventional processing using the H3I color space or the RGB color space, there is a large discrepancy between each value and how people perceive color. Therefore, even if appropriate values are selected and processed, there is no correspondence between the actual color and the value, and the human sense of judgment is different from that of the naked eye, so it is not always possible to emphasize the color as desired. I was unable to obtain the correct image.

Taking an electronic endoscope as an example, the original image of an organ etc. captured by introducing an endoscope into a body cavity etc. is, for example, RG.
The B image data is held in each image memory and displayed on the screen of a display device such as a color monitor for observation and diagnosis by a doctor or the like. At this time, if there is a lesion site such as cancer in the object to be imaged, for example, an organ in a body cavity, the doctor diagnoses the lesion by distinguishing it based on subtle differences in the color of the site.

However, in the past, electronic systems equipped with appropriate conversion processing means were used to more clearly identify the differences between normal and diseased areas in endoscopic images and to facilitate diagnosis. Endoscopic equipment generally did not exist. However, various types of image processing such as those described above, such as converting endoscopic image data into an image space consisting of hue, saturation, and brightness and performing enhancement processing, have only been carried out experimentally.

Furthermore, the scope of the target endoscope, such as the stomach wall, has a similar reddish color throughout, and the difference in color between normal tissue and diseased areas such as cancer is small. It is extremely small. When this was expressed on a hue histogram, these two parts were so close that they were difficult to separate, and it was difficult to distinguish them with the naked eye.

Therefore, even if various types of image processing such as those described above are performed, the minute color differences mentioned above cannot be emphasized as desired because the processing method is different from how the human eye distinguishes color differences. Therefore, it is difficult to distinguish between these with the naked eye, making diagnosis using endoscopic images difficult.

(Problems to be Solved by the Invention) As described above, image enhancement processing in conventional color image analysis devices is based on numerical data that does not originate from the equipment system such as the imaging device. However, since this is a different type of sense than humans, who visually judge the displayed image processed in this way, there is a problem in that it is not always possible to obtain an image that is enhanced as desired.

In particular, in diagnosis using images of internal organs, etc. in body cavities using electronic endoscopes, organ mucous membranes, etc. are reddish overall, and the color of normal tissues and diseased areas such as cancer. Since the difference in color is extremely small, it is difficult to discern the difference in color with the naked eye.

However, until now, electronic endoscope devices with appropriate conversion processing means did not generally exist.
Even in the experimental enhancement processing, etc., the process was based on a color system derived from equipment that does not necessarily match the color difference perceived by humans, so this slight color difference was not as expected. However, there was a problem in that the diagnosis was difficult to make because it was difficult to distinguish between these two types.

This invention was made in view of the above-mentioned conventional problems, and its purpose is to utilize a color space in which color differences seen by the human eye are represented as substantially equal spatial differences. An object of the present invention is to provide a color image analysis device that can perform color enhancement processing under conditions close to human senses.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the color image analysis device according to the present invention is capable of analyzing perceptual color differences based on the distance within the color space. A conversion means converts each pixel of a color image signal into the LUV color system using the uniform color space LUV color system shown in FIG. an image processing means for enlarging the difference in hue and emphasizing the difference in color; and an inverse conversion means for inversely converting each pixel on the LUV color system image-processed by the image processing means into an original color video signal; It is characterized by having the following.

(Function) If the color image analysis device has such a configuration,
Using the conversion means, each pixel of the color video signal is converted into the LUV color system, which is a color space with a perceptually almost uniform frequency, and at least By magnifying the difference in hue to emphasize the difference in color, and then inversely converting it back to the original color video signal using an inverse conversion means and displaying it, we can create a space where the difference in color seen by the human eye is almost uniform. LUV as expressed as the difference between
Enhancement processing is now performed on the color space, and an image that is enhanced almost as desired can be obtained, making image analysis and the like easier.

(Example) Below, each example of the color image analysis device according to the present invention will be described in detail based on the drawings.

FIG. 1 shows a block diagram of essential parts of an electronic endoscope device as an embodiment of a color image analysis device to which the present invention is applied.

A scope 1 introduced into the object, and a CC installed at one end of the scope 1 to image the object and obtain its video signal.
There is a D-camera 2 and a connector 3 disposed at the other end of the scope 1 for connecting video signals and the like to an endoscope body (not shown).

Also, inside the endoscope body, there is a camera control unit 4 that performs signal processing such as color correction and outputs R (red), G (green), and B (blue) signals and a video signal converted into a synchronization signal. There are a control unit 5, a control console 6, and image memories 7 to 9 that store R, G, and B image signals.

Furthermore, inside the endoscope body, there is an RGB-XY7-LUV conversion unit 11 that converts each pixel of image data from RGB image signals to the LUV color system via the XYZ color system and vice versa, and There are provided U and V multivalued image memories 12 to 14 for temporarily storing and holding pixel data related to the image data, and a color stimulation enhancement processing section 15 for performing image processing such as enhancement.

A color monitor 10 for displaying images is provided outside the endoscope.

Further, FIG. 2 shows a detailed block diagram of the color stimulus enhancement processing section 15 mentioned above.

A chromaticity coordinate calculation circuit 151 that receives the value of each pixel from the multivalued image memories 12 to 14 and calculates the chromaticity coordinates of that pixel;
There is a parameter register 152 that holds each image processing parameter instructed by. Also, a stimulus purity enhancement circuit 153 that performs stimulus purity enhancement processing, and a hue range expansion circuit 154 that performs hue range expansion processing.
2, which executes two-dimensional discrete fast Fourier transform processing.
A dimensional DFT conversion circuit 155 and a brightness enhancement circuit 156 that performs brightness enhancement processing are provided. Furthermore, a LUVUV ratio calculation circuit 157 calculates a new LUV value from the chromaticity coordinate values of pixels subjected to various image processing in this way.
Ru.

In addition, FIGS. 3 to 6 show the stimulus purity enhancement circuit 1, respectively.
53, hue range expansion circuit 154, two-dimensional DFT conversion circuit 155, and brightness enhancement circuit 156. FIG.

Next, the operation of the apparatus of this embodiment will be explained based on these figures.

A CCD camera 2 is disposed at the tip of the scope 1 introduced into a subject's body, for example, a body cavity.
A video signal of the subject imaged by the D camera 2 is sent to the endoscope body via the connector 3.

Then, inside the endoscope body, signal processing such as color correction is performed in the camera control unit 4, and the video signal is converted into a video signal consisting of R, G, B signals and a synchronization signal, and is output to the control unit 5. . From the control unit 5, each R, G, B image memory 7
The data is sent to the color monitor 10 and displayed on the screen, and is sent to the RGB-XY7-LUV conversion unit 11 for each pixel on the other hand. The RGB-XY7-LUV conversion unit 11 converts each pixel from the RGB signal into the XYZ color system and further into the LU
Each of the L, U, and V values stored in each of the image memories 12 to 14 is converted into a color value of the V color system and stored in each of the L, U, and V@ image memories 12 to 14. Enhancement processing is performed on pixel values in a color stimulus enhancement processing section 15, which is a main part of the present invention, under the control of a control section 5 and according to instructions from a control console 6.

That is, in FIG. 2, the chromaticity coordinate calculation circuit 151 calculates the chromaticity coordinates of each pixel stored in the image memories 12 to 14 for I7, U, and ■. Then, processes such as emphasis and conversion are sequentially executed according to the contents of the parameter register 152 that holds each parameter instructed via the control console 6.

Some colors are difficult to distinguish unless they have a certain level of saturation or brightness. To do this, first, the stimulation purity of the pixel is emphasized in the stimulation purity emphasizing circuit 153 based on the value of the processing parameter A1 for stimulation purity, that is, saturation and brightness. At this time, as shown in FIG. 3, the closer to the effective boundary line of the chromaticity coordinates, the higher the stimulus purity becomes.

Next, the hue range expansion circuit 154 expands the hue range based on the value of parameter B1. The wavelength of each pixel of an image of an internal organ, etc. in a body cavity captured by an endoscope is approximately within the range of 560 to 590 nanometers, that is, almost all wavelengths are between A1 and A2 of the chromaticity coordinates shown in Fig. 4. is included.

The image as a whole has a reddish tinge, and there does not seem to be much difference in hue. It is difficult for the human eye to discern this slight difference in hue. Therefore, the difference in hue is enlarged so that the difference in hue can be easily distinguished. Through this enlargement process, as shown in FIG. 4, the difference between adjacent pixels is enlarged, and the difference in hue is emphasized, resulting in a large difference in hue.

Further, the two-dimensional DFT conversion circuit 155 reduces changes in brightness due to differences in distance from the illumination position during photographing according to the value of the parameter C1. In this way, for example, by using a filter as shown in FIG. 5, the influence of illumination is removed, and subtle changes in organ mucous membranes can be easily identified. At this time, by changing the parameters of this two-dimensional Fourier transform filter, it is possible to emphasize tissues and blood vessels, or to use it for various other purposes.

After I&, in the brightness emphasis circuit 156, the parameter C
FIG. 6 shows the effect of this emphasizing process, in which brightness is emphasized based on the relationship between saturation, which is stimulus purity, and brightness using a value of 1.

From the new chromaticity coordinate values obtained in this way, a new LUV value is calculated in the LUV value calculation circuit 157,
This value is output from the color stimulus enhancement processing section 15.

Then, the value of each pixel as a result of processing by the color stimulus emphasis processing section 15 is converted to RG again under the control of the control section 5 shown in FIG.
The B-XYZ-LUV conversion unit 11 converts R from the LUV color system.
The signals are inversely converted into GB signals and stored in each of the R, G, and B image memories.

When the emphasis processing for all pixels is completed in this way, the image after the emphasis processing is displayed on the color monitor 10 and can be observed.

In this way, in the electronic endoscope device of this embodiment, the uniformity of the color difference is guaranteed for the color image based on the RGB color system captured from the COD camera 2 at the tip of the endoscope 1. Convert to LUV color space, which is a uniform color space,
After emphasizing hue, saturation, and lightness, two-dimensional Fourier transform is used to remove the effects of illumination during imaging with an endoscope, and also enables tissue and blood vessel enhancement processing.

In this way, by analyzing subtle differences in tissue color and adding various enhancements, it becomes possible to more clearly express differences between normal tissue and lesions such as cancer, which were difficult to distinguish in the original image. In addition, subtle changes in fine blood vessels and mucous membranes are emphasized,
Furthermore, the effects of variations in brightness and darkness due to differences in illumination during imaging are removed, making it possible to distinguish subtle changes in mucous membranes, making diagnosis etc. easier.

Note that this invention is not limited to the above-mentioned embodiments, and can of course be implemented in other embodiments.
In the LUV space, it is also possible to perform emphasis processing such as changing the stretch width when expressed in a histogram of hue, saturation, brightness, etc., and to change the coordinate position within the same space. Furthermore, the present invention is not limited to color images in which the image signals are provided by the RGB signal system, but can also be implemented in H8I display or image processing devices using color difference signals. Of course, it goes without saying that the present invention is effective not only in endoscope devices but also in other color image analysis devices.

[Effects of the Invention] As explained in detail above, the color image analysis device according to the present invention uses the LUV color system, which is a uniform color space in which the distance in the color space directly indicates the perceptual color difference. Since image processing such as enhancement is performed using It becomes possible to easily magnify and emphasize the differences between the two.

[Brief explanation of the drawing]

1 to 6 are diagrams relating to an electronic endoscope device as an embodiment of a color image analysis device according to the present invention,
FIG. 1 is a block diagram of the main part, and FIG. 2 is a detailed block diagram of the color stimulus enhancement processing section. Further, FIG. 3 is an explanatory diagram of the stimulus purity emphasizing process, FIG. 4 is an explanatory diagram of the hue range expanding process, FIG. 5 is an explanatory diagram of the two-dimensional DFT filter, and FIG. 6 is an explanatory diagram of the brightness emphasizing process. 1... Scope 2... CCD camera 3... Connector 4... Camera control section 5... Control section 6.
...Control console 7-9...R, G, B image memory 10...Color monitor 11...RGB-X
YZ-LUV conversion units 12 to 14... L, U, V multi-value image memory 1... Color stimulation enhancement processing unit 151...
Chromaticity coordinate calculation circuit 152...parameter register 1
53... Stimulus purity enhancement port 8154... Hue range expansion circuit 155... Two-dimensional DFT conversion circuit 156.
...Lightness enhancement circuit 157...LUV value calculation circuit

Claims (1)

[Claims] (1) A conversion means for converting each pixel of a color video signal into the LUV color system in which the color difference is approximately equal in the color space, and at least the hue of each pixel converted to the LUV color system by the conversion means. an image processing means for emphasizing the color difference by enlarging the difference between the images;
A color image analysis device comprising: inverse conversion means for inversely converting each pixel on a UV color system into an original color video signal.