JPH077258B2 - Image processing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image processing apparatus for enlarging an image by increasing the number of pixels forming an image formed by image data and overlay data by interpolation pixels.

(Prior Art) A high-definition CRT with a large number of pixels, for example, to capture and observe an analog video signal of a still image displayed on a cathode ray tube display device (hereinafter referred to as a CRT) with a multi-format camera and to store it. To convert the video tape to analog-to-digital (hereinafter referred to as A / D conversion)
After that, enlargement interpolation is performed to increase the number of pixels with a device as shown in FIG. In the figure, reference numeral 1 is an analog-digital converter (hereinafter referred to as A / D) that converts an analog video signal input into a digital signal, and the output is stored in a data memory 2. An enlargement interpolation processing circuit 3 enlarges and interpolates the image data output from the data memory 2, and enlarges and interpolates the image data by a method described later. The expansion interpolation processing circuit 3 is usually composed of dedicated hardware or a programmable microprocessor,
The output is stored in the recording storage device 4.

There are two methods of enlarging interpolation performed by the enlarging interpolation processing circuit 3 described below, and either one of them is used, or only one is selected by a switch and used.

A method of simply connecting the areas of pixels A method of approximating from the data of neighboring points (a) Linear interpolation The average value of two adjacent points is set as the intermediate pixel.

(B) Cubic interpolation The interpolation shown in FIG. 3 is performed. In the figure, 20 is a pixel of the original image, 21 is a pixel obtained by weighting and averaging four pixels in the horizontal direction, and four pixels 21 are weighted and averaged to obtain the interpolation point 22 to be obtained.

(Problems to be Solved by the Invention) By the way, the method in the above method has an advantage of high processing speed, but since the image is simply enlarged, a mosaic screen is obtained. In particular, as the magnification increases, the mosaic shape becomes more noticeable, giving a rough feel. Since the method of (1) takes an average of neighboring point data, a natural magnified image can be obtained, but the image lacks sharpness. This method requires a longer processing time.

When enlarging data in which images and characters and graphics (circles, closed curve graphs, etc.) are mixed, the method of () is not limited to data such as characters and graphics (often binary data, but not limited to this). Boundary and outline are sharp and sharp in enlarged interpolation, but there is a problem that roughness is conspicuous in the image part. With this method, a soft enlarged interpolation image with a natural feeling can be obtained in the image part, but the character part is a boundary. ， There was a problem that the outline was blurred.

The present invention has been made in view of the above points, and an object thereof is to perform an interpolation process suitable for each data on image data and data such as characters and graphics, and to obtain a good enlarged image. It is to realize the obtained image processing device.

(Means for Solving Problems) The present invention for solving the above problems is an image processing apparatus for increasing the number of pixels forming an image formed by image data and overlay data by interpolation pixels to enlarge the image. In the above, a comparison / determination unit that receives data of each pixel forming the image, compares the value of the data with a reference value, and determines whether the data is the image data or the overlay data, Selecting means for separating each pixel data forming the image into the image data and the overlay data based on the output signal of the comparing and judging means; and the data separated as the overlay data by the selecting means, Pixel enlargement interpolation processing means for performing enlargement interpolation by pixels having the value of the data, and the image by the selecting means. And an approximate value enlargement interpolation processing means for receiving data separated as image data and performing enlargement interpolation by pixels having values obtained by weighting data values of a plurality of neighboring pixels. It is a thing.

(Operation) The comparison / determination means receives data of each pixel forming an image, compares the value of the data with a reference value, and determines whether the data is image data or overlay data. In accordance with the result of this discrimination, the selection means classifies the data of each pixel into overlay data and image data, the overlay data is input to the pixel enlargement interpolation processing means, and the image data is input to the approximate value enlargement interpolation processing means. The interpolation processing means performs interpolation processing suitable for each data.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic block diagram of an embodiment of the present invention. In the figure, the same parts as those in FIG. 2 are designated by the same reference numerals. In the figure, 11 is set with image data and data such as characters on the overlay plane (hereinafter, the case where the overlay data is binary data will be described as an example) in the input digital data from the data memory 2. White signal data that exceeds the reference value in comparison with the reference value is determined to be binary data, and if the data is less than the reference value, it is determined to be image data and binary data and image data are determined. The comparison discriminator performs on / off control by a comparator control signal from a controller (not shown). Also, it is possible to change the reference value. 12 indicates the data from the data memory 2 according to the discrimination result signal from the comparison discriminator 11.
With a selector that selectively separates image data and binary data,
The value data is output to a pixel expansion interpolation processing circuit (hereinafter referred to as a pixel interpolation circuit) 13 and the image data is output to an approximate value expansion interpolation processing circuit (hereinafter referred to as an approximate value interpolation circuit) 14. The outputs from the pixel interpolating circuit 13 and the approximate value interpolating circuit 14 are output from the respective interpolating circuits in the pixel address order as enlarged interpolating data and are combined.

Next, the operation of the embodiment configured as described above will be described. The analog video signal is converted into a digital signal at the timing of the sampling clock in the A / D 1 and stored in the data memory 2. This analog video signal is converted into an analog signal by, for example, a DA converter (hereinafter referred to as D / A) as shown in FIG. 4, and a signal having a difference in signal level such as image data and binary data on overlay is generated. It is a synthesized signal. In the figure, 31 is a D / A having a data input terminal 32 and a reference white terminal 33.
, Input image data to the data input terminal 32, and
The conversion is performed, and the data on the overlay input to the reference white terminal 33 outputs the analog signal of the highest brightness. Therefore, in the analog video signal input to the A / D1, the binary data has a clear level difference as compared with the image data.

The data stored in the data memory 2 is sequentially read and input to the comparison / determination unit 11. The comparison discriminator 11 compares the input image data with a reference value, discriminates between the image data and the binary data, and inputs the signal of the discrimination result to the selector 12. The selector 12 opens the gate to the pixel interpolation circuit 13 if the determination result is the white level, and opens the gate to the approximate value interpolation circuit 14 if the determination result is the image data level. The video data from the data memory 2 are simultaneously input to the selector 12, and the pixel interpolating circuit 13 or the approximate value interpolating circuit 14 is respectively opened by the gate opened for each data type.
Entered in. The pixel interpolation circuit 13 performs interpolation by a method of simply connecting the pixel areas as described above. or,
The approximate value interpolation circuit 14 performs interpolation by linear interpolation or cubic interpolation. The enlargement ratio by interpolation in this case is designated by the enlargement ratio signal from the controller.

As described above, the video data interpolated by different methods depending on the type of data are combined in pixel order after being output from the interpolation circuit, and are output and stored in the recording storage device 4.

When the comparison discriminator 11 is turned off by the comparator control signal, the interpolation method (that is, the gate to the interpolation circuit) is set in the selector 12 in advance, and the pixel interpolation circuit 13 or the approximation circuit is set based on the interpolation method. The data is output to the value interpolation circuit 14.

As described above, according to the present embodiment, binary data and image data are separated and enlarged interpolation is performed by an interpolating method suitable for each, and compared to the case where the conventional method is fixed to one method. As a result, a natural enlarged interpolation image can be obtained as the image data, and a binary image on the overlay plane can have a sharp boundary and contour. Further, since the degree of discrimination and the selection of the method are given a degree of freedom, it is possible to obtain an enlarged interpolated image suitable for the intended use.

The present invention is not limited to the above embodiment. Although monochrome data has been described in the embodiment, it is also applicable to color data.

(Effect of the Invention) As described in detail above, according to the present invention, the data value of each pixel forming an image is compared with a reference value, and whether the data is image data or overlay data. By distinguishing, the data of each pixel is classified into overlay data and image data, the overlay data is input to the pixel enlargement interpolation processing means and interpolation processing is performed, and the image data is input to the approximate value enlargement interpolation processing means. I am trying to do the interpolation processing, so
Interpolation processing suitable for each data is performed, so that an image processing apparatus that can obtain a good enlarged image can be realized.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of an embodiment of the present invention, and FIG.
FIG. 3 is a diagram of a conventional image processing apparatus, FIG. 3 is an explanatory diagram of cubic interpolation, and FIG. 4 is a diagram of setting of data level at DA conversion. 1 ... A / D, 2 ... data memory 3 ... expansion interpolation processing circuit, 4 ... recording storage device 11 ... comparison discriminator, 12 ... selector 13 ... pixel expansion interpolation processing circuit 14 ... approximation Value expansion interpolation processing circuit

Claims (4)

[Claims] 1. An image processing apparatus for enlarging an image by increasing the number of pixels forming an image formed by image data and overlay data by interpolation pixels, and receiving the data of each pixel forming the image, Of the image based on the output signal of the comparison / determination means, which compares the value of 1 with a reference value to determine whether the data is the image data or the overlay data. Selection means for separating the pixel data into the image data and the overlay data, and pixel expansion interpolation processing for receiving the data separated as the overlay data by the selection means and expanding and interpolating by the pixel having the value of the data Means for receiving the data separated as the image data by the selecting means, And an approximate value enlargement interpolation processing means for performing enlargement interpolation with pixels having values obtained by weighting data values of several pixels. 2. The image processing apparatus according to claim 1, wherein the value of the overlay data is selected to be a value showing higher brightness than the value of the image data. 3. The image processing apparatus according to claim 1, wherein the image formed by the image data and the overlay data is a still image. 4. The approximation value expanding interpolation processing means for performing at least one of linear interpolation and cubic interpolation is used, as claimed in claim 1, claim 2 or claim 3. Image processing device.