KR930010023B1 - Sampling system for fax - Google Patents

Abstract

The method for improving the image resolution in the image acquisition and recording parts of the facsimile comprises the steps of: (a) sampling and scanning the present line with a period of delta X; (b) shifting the sampling position of the image data in the neighbor line of the present line as much as half of the delta X in a first direction with the period of delta X; (c) sampling and recording the present line with the certain period of delta X; and (d) shifting the sampling position of the image data in the neighbor line of the present line as much as half of the delta X in the first direction with the period of delta X.

Description

Diagonal Sampling Method of Facsimile

1 is an explanatory diagram of a conventional rectangular sampling.

2 is a distribution diagram of spatial frequency components according to FIG.

3 is an explanatory diagram of diagonal sampling according to the present invention;

4 is a distribution diagram of spatial frequency components according to FIG.

The present invention relates to a method for sampling image data of a facsimile, and more particularly, to an image reading unit and a quincunx sampling or diagonal sampling method capable of improving the resolution of an image or reducing the amount of image data to be transmitted. .

In general, a facsimile is an image data transmission / reception terminal that converts a character, a picture, or a picture into an electrical signal and transmits and receives with an opposite party. Generic term for picture transmission to transmit and receive data. Such a facsimile includes an image acquisition patter for sampling and binarizing an image such as an original, a picture or a picture, and an image recording patter for reproducing the image. The resolution of the facsimile and the amount of data are determined according to the sampling methods of the image reading unit and the image recording unit.

FIG. 1 is a diagram for explaining sampling of a commonly used facsimile, which represents orthognal sampling. Fig. 1A shows a sampling of an image reading unit located inside the facsimile, and Fig. 1B shows an image recording unit and sampling. That is, (1b) shows the image reproduction state of the image recording unit.

2 is a distribution diagram of spatial frequency components according to FIG. 1.

A conventional rectangular sampling method will be described with reference to FIGS. 1 and 2 above.

When the horizontal axis is the horizontal space axis and the vertical axis is the vertical space axis as shown in the first diagram, the "X" symbol represents the sampling point of the image reading portion. In addition, as shown in the diagram 1b, the "O" tabular represents a reproduction point of the image recording section, where ΔX and ΔY represent horizontal resolution and vertical resolution, respectively.

In a conventional facsimile, a CCD (Charge Coupled Device) or a CIS (Contact Image Sensor) arranged in a line is used in a conventional facsimile to sample an image on the rectangular grid as shown in FIG. 1A. For the image as shown in (IB), a TPH (Thermal Print Head) or a light emitting diode in which a plurality of heat generating elements are arranged in a line has been used, or a photo scanner.

Accordingly, a method of sampling an image of a document to be transmitted on a rectangular grid as shown in the 1a diagram, and taking a black point or a white point on the rectangular grid as shown in the 1b diagram to record the sampled document image on a recording sheet. This is represented by the second frequency as the spatial frequency component of the sampled document image. In FIG. 2, the spatial frequency component of the image is shown as the second degree in consideration of the visual effect of the human being. In FIG. 2, when considering the visual effects of humans, the distribution of the spatial frequency components of the image is limited to the inside of the rhombus rectangle, and if the horizontal and vertical sampling intervals are ΔX and ΔY, respectively, the spatial frequency of the sampled image. The distribution of components in the horizontal and vertical directions respectively At the period of, the fundamental frequency components of the original image are repeated.

Therefore, when recorded on the recording sheet by the image recording unit of the sampled image, the spatial frequency components reproduced without error have their bandwidths in the horizontal and vertical directions, respectively. Become. That is, the maximum resolution that can be reproduced is 2ΔX and 2ΔY in the horizontal and vertical directions, respectively.

As described above, the conventional rectangular sampling method has a problem that the minimum spatial resolution of an image that can be reproduced when the spacing between sampling points is ΔX and ΔY in the vertical and horizontal directions is 2ΔX and 2ΔY, respectively. Therefore, the resolution is reduced and there is a disadvantage that can not reduce the amount of image data.

Accordingly, an object of the present invention is to provide a diagonal sampling method of an image reading unit and a recording unit capable of improving the resolution of an image in a facsimile.

Another object of the present invention is to provide a diagonal sampling method of an image reading unit and a recording unit of a facsimile capable of reducing the amount of image data.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

3 is an explanatory diagram of a diagonal sampling according to the present invention, where (3a) shows a sampling of an image reading unit, and a sampling point of an "X" tabular shape is shown in a rhombus lattice form. This means that when the interval between sampling points in the nth scan line is ΔX, the interval between the sampling points in the n-1th scan line and the n + 1th scan line is equal to ΔX. Uniformly position the points Left or right.

(3b) shows the image reproducing method of the image recording section. When recording the sampled image on the recording paper, recording is performed on a grid of the same shape as that used for the sampling of the image reading section. It is shown in the form of a grid. In order to perform the sampling of the image recording unit in this manner, it is shown in the nth recording line in the same manner as in (3a). In order to perform sampling of the image recording unit in this manner, as shown in (3a), when the interval between sampling points in the nth recording line is ΔX, between the sampling points in the n-1th recording line and the n + 1th recording line, The interval of is equal to ΔX, but the positions of sampling points are uniformly Should be moved left or right.

4 is a distribution diagram of the spatial frequency components of FIG. 3 according to the present invention, in which the spatial frequency components of the original image are periodically repeated on a rhombus lattice.

Hereinafter, the present invention will be described in detail with reference to FIGS. 3 and 4.

First, the image reading unit must sample an image on a rhombus lattice as shown in FIG. 3A.

When reading the image of the initial first line, the image data is scanned by sampling at ΔX period, and sampling point is read when reading the image of the next line. The image data is scanned by shifting the sample by sampling and sampling at a period of ΔX. For example, when the interval between the sampling points of the nth scan line is ΔX, the interval between the n−1th and n + 1th scan line sampling points is ΔX, which is the same as the nth scan line. Uniformly position the sampling points Move left or right by That is, the image reading unit samples and shifts the odd-numbered scan line at an interval of [Delta] X and samples at an interval of [Delta] X. Here, a method of sampling an image on a rhombus lattice will be referred to as diagonal sampling. In FIG. 3A, ΔX represents a horizontal interval of sampling points, and ΔY represents a vertical space of sampling points.

On the other hand, the image recording unit records the image on the grid having the same shape as that used when sampling in the image reading unit as shown in the third diagram.

First, when recording (reproducing) an image of a line, image data is recorded by sampling at a period of ΔX, and a sampling point is recorded when an image of the next line is recorded. Image data is recorded by sampling by a period of? X. That is, when the interval between reproduction points (or recording points) in the odd line is ΔX, the interval between the recording points in the even line, which is the next line, is ΔX in the same way as the nth line. The position of the record points To the left or to the right. However, the direction in which the positions of the recording points are moved here should be the same as when sampling at the reading part. In FIG. 3B, ΔX denotes a horizontal gap between recording points and ΔY denotes a vertical gap between recording points.

Accordingly, the distribution of the spatial frequency components of the image sampled by the diagonal sampling method as shown in the third diagram is shown as the fourth diagram. In FIG. 4, the spatial frequency components of the sampled image have a form in which the spatial frequency components of the original image are periodically repeated on a rhombus lattice. In consideration of this, it is assumed to have a rhombus distribution.

In FIG. 4, the repetition period of the spatial frequency component in the horizontal spatial frequency axis direction is Since the minimum resolution of the image that can be reproduced is ΔX. In other words, the resolution of an image that can be reproduced is improved twice in the horizontal direction than in the conventional method of sampling an image on a rectangular grid. In this case, the data amount of the image to be transmitted is the same as the above-described method of FIG. 1 and the third method, and the minimum resolution of the reproduction function in the vertical direction is 2?

However, when the sampling point spacing in the horizontal direction is 2ΔX in FIGS. 3A and 3B, the minimum resolution that can be reproduced in the horizontal and vertical directions is 2ΔX and 2ΔY, respectively. The amount of image data to be reduced is doubled.

Therefore, when the amount of image data to be transmitted is equal to the conventional facsimile, the horizontal spatial resolution of the reproduced image is improved, and when the horizontal spatial resolution of the reproduced image is the same as the conventional facsimile, the amount of image data to be transmitted is reduced. You can do it.

As described above, the present invention has the advantage of improving the resolution of an image or reducing the amount of image data to be transmitted by a diagonal sampling method.

Claims (2)

In a facsimile image data sampling method including an image reading unit and an image recording unit, the current line is sampled and scanned at a period of ΔX, and a sampling position of image data of a line adjacent to the current line is predetermined in the first direction. A read diagonal sampling process of shifting by position and sampling and scanning at a period of ΔX, sampling and recording the current line at a period of ΔX, and specifying a sampling position of image data of a line adjacent to the current line in a first direction. A diagonal sampling method of a facsimile, characterized in that it consists of a read diagonal sampling process of shifting by position and sampling and scanning with a period of ΔX. The method of claim 1, wherein the shift by the predetermined position is performed by the sampling period ΔX from the initial sampling point of the previous line. A facsimile diagonal sampling method, characterized in that shifted by an interval of.