JPS5977369A - Image interpolation apparatus - Google Patents

Abstract

PURPOSE:To prevent deterioration in the quality of picture by performing interpolation at the writing into or reading from a digital scan converter. CONSTITUTION:In a sector scan ultrasonic diagnosing equipment having a digital scan converter, an ultrasound echo signal returned from a body is inputted into an A/D converter 1 after amplifier and detected to make a digital sample data. The data is written into a frame memory 3 through a lateral direction writing interpolation device 2. The lateral direction writing interpolation device 2 is a circuit which is adapted to perform a writing on real time into a frame memory 3 interolating several subscan lines between original scan lines and a data to be interpolated is done so from those at the same depth of the original scan line. This interpolation may be performed at the reading from or writing into the frame memory and at the time of both writing into the reading from the frame memory.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an image interpolation circuit that interpolates between scanning lines of sectors in a sector scanning ultrasonic diagnostic apparatus having a digital scan converter for raster display.

[Prior art to the invention]

In a sector-scanning ultrasonic diagnostic system equipped with a digital scan converter, the scanning line position is quantized when writing to the frame memory, so the scanning line that should normally be a straight line is displayed as a polygonal line, resulting in moiré patterns. This has the disadvantage that it is very difficult to see.

[Purpose of the invention]

An object of the present invention is to completely interpolate between scanning lines of sectors in order to eliminate moiré fringes, and to provide an ultrasonic section N4 image that is easy to view and has good image quality.

[Key points of the invention]

The present invention eliminates image quality deterioration by performing interpolation operations when writing or reading a digital scan comparator, or at both times, and, as in a two-beam simultaneous scanning ultrasound diagnostic apparatus, This allows perfect interpolation between scanning lines no matter where the sector image is displayed.

[Embodiments of the invention]

FIG. 1 shows a circuit for writing unfired BJJ into the frame memory. Ultrasonic echo signals that come from the body are amplified and
After detection, it enters the A/I converter (■) and becomes digital data. This data enters the lateral direction write interpolator (2) and is written to the frame memory (2) at t7. The write address and control signal to the frame memory (2) are generated from the write control circuit (2).

Next, the operation of the lateral direction writing interpolator (2) will be explained.

This is a circuit that interpolates one sub-scanning m'fcal+a2m...al between the original scanning lines A and B, as shown in FIG. 2, and writes it into the frame memory in real time.

Therefore, the scanning net density is increased by (1+1) times η. At this time, the data to be interpolated is interpolated from data at the same depth of the original scanning line.

LA(m)L
B (m): La+ (m), La2 (m), = l
Let La i (m) (where k=1, 2...
, 1) gives sub-scanning line data.

Next, FIG. 3 shows an interpolation method in the raster direction when reading from the frame memory. The data read out from the frame memory ■ in one direction in a manner consistent with standard TV is
Enter the read data interpolator ■. interpolated data V
iD/A converter - D/A conversion is performed and displayed on the CRT.

The horizontal interpolation method during readout is shown below.

The data read from the frame memory l on the raster A-A' in Fig. 3 is discrete as shown in the hatched area in Fig. 41A (the vertical axis in Fig. 4 is the luminance It is.

) Interpolate the linearly interpolated values of that data. Interpolated data is shown in white. An embodiment of this tree direction interpolation circuit is shown in FIG.

The data read from the frame memory enters the 7 section length detection circuit (2) of the interpolator 51J. Here, the section length where data exists and is small is opened. For example, in the case of Figure 4, t/':r
, ■ After the data f is read out, a no-signal interval between two dots is detected. The data is delayed by this output (2 dot length) by the delay circuit (2).

Therefore, the input X of the differential/difference circuit [phase] is
data (luminance L1') is given to input Y, and data of O (luminance #, L2) is given to input Y.

The difference/difference circuit [phase] is used to calculate the difference between interpolated data (Δ in Figure 4).
Subtract L). Its output is the output of the delay circuit (
(2) data) is multiplied by n and the unit (2) is sequentially integrated by 1 to create interpolated data. .

Data interpolator (61st article about vertical interpolation method)
This will be explained in Fig. 7. In standard TV, interlacing is performed, so vertical interpolation F'j is used to calculate (n+
1) Create scanning line data. .

In the 7th scan, the lines are switched every t-1 horizontal scan. That is, when writing to the line buffer @, the data from the other line buffer O is also read from one horizontal scan ago, and is input into the arithmetic circuit (2) together with the data currently being written to the line buffer @ for calculation.

An example of an operation is (1) Choose the larger of the present and the past.

(2) Take the average of the present and past.

(3) If there is a present value (as a Zamburu point), take the present value; if not, take the past value.

etc. are possible. − Writing and reading are controlled by Waribyou 1 Doro (■).

Each of the interpolation methods described above may be used alone or in combination.

Although linear interpolation is illustrated in FIG. 5, zero-order interpolation or quadratic interpolation may also be used.

Furthermore, in order to prevent deterioration of image quality, interpolation in the horizontal direction may not be performed or may be aborted at locations where the data interval is greater than a certain value.

Although the vertical interpolation is calculated using every other horizontal scanning line in FIGS. 6 and 7, it may also be calculated by reading out even scanning lines and odd scanning lines from the frame memory at the same time.

〔Effect of the invention〕

According to the present invention, interpolation can be performed between scanning lines of sectors without deteriorating image quality, and moire fringes can be removed. Therefore, ultrasonic tomographic images become easier to see and become a powerful tool for diagnosis.

[Brief explanation of drawings]

1 to 2 show one embodiment of the present invention, FIGS. 3 to 5 show another embodiment of the invention, and FIGS. 1 to 2 show still another embodiment of the invention. In the figure, ■ is an A/D converter, ■, ■ are m-to-i,
■ is frame memory, ■ is D/A converter, ■ is CR
It is a T indicator. Hermitage 1 'J! -Do figure 4I! 1

Claims (3)

[Claims] (1) In the digital scan converter that converts the image signal obtained by sector scanning into a rask scanning display signal, W writes the image signal obtained by sector scanning to the frame memory,
An image interpolation device that writes a sub-scanning line having data interpolated from the original scans It and # of a sector scan image. (2) In a digital scan converter that converts an image signal obtained by sector scanning into a rask scan display signal, an image interpolation device performs all data interpolation in the rask direction when reading from a frame memory in the rask direction. (3) In a digital scan converter that converts an image signal obtained by sector scanning into a full raster scan display signal, an image is created in which data is interpolated in a direction perpendicular to the raster direction when reading from the frame memory in the raster direction. Interpolator.