JPH03209976A - Detecting circuit for variation point of binary image - Google Patents

Abstract

PURPOSE:To detect the variation point of a binary image without necessitating a subtracter by providing an input image register, an image variation point detector, and an adder. CONSTITUTION:In an initial state, an absolute variation point coordinate latch 104 is '0'. In a step 1, image data shown in the figure is latched by an input latch 101. A variation point detector 102 outputs a first color variation point '2' looked at from the left of an image. An adder 103 outputs an addition output '2' of the variation point detector 102 and an absolute variation point coordinate latch 104. This value is a first absolute variation point coordinate of an input. Subsequently, in a step 2, the detector 102 outputs the next variation point '7', and the adder 103 outputs '7'. In a step 3, '8' is outputted from the detector 102, but as for this value, its true variation point is unknown unless the next image is inputted. In a step 4, the value of the adder 103 is latched by a coordinate latch 104, and only at the time point when a processing of a one-word portion of an input is ended, the latch is executed. Accordingly, a subtracter of a conventional circuit becomes unnecessary, and one adder is enough.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a binary image change point detection circuit, and more particularly to a binary image compression/decompression circuit. [Background Art] With the development of the information society, the need to transmit large amounts of binary images at high speed has been rapidly increasing in recent years. Along with this, technologies for compressing, transmitting, and storing binary images are being developed. As a compression/expansion method for binary images, a method called the MH method has been established as an international standard. This method scans the binary image from the left, finds the coordinates that change from white to black or from black to white, and calculates the length of the white line and the length of the black run in the binary image from the coordinates. , a system that assigns an optimal code to each run trap.In order to realize MI encoding according to this standard, a circuit that quickly calculates the coordinates of the change point where a binary image changes from white to black or from black to white is required. Fig. 5 shows a conventionally used change point detection circuit. In Fig. 5, the conventional change point detection circuit includes an input image latch 301 and a change point detector 302 of the input image latch. , a subtracter 303, a change point latch 304 that latches the output of the change point detector 302, an adder 305, and an absolute change point coordinate latch 306. Next, FIGS. The operation will be explained using: In the initial state (step O), the absolute change point coordinate latch 306 is

It is [0]. First, in step 1, the image data example [00
1111103 (binary) is latched into input latch 301. At this time, the change point latch 304 is cleared at the same time. The change point detector 302 outputs the first color change point 2 when viewed from the left of the input image. A subtracter 303 subtracts the value of the change point latch 304 from the value of the change point detector 302 and outputs a value 2. The adder 305 inputs the subtracter 303 and the absolute change point coordinate latch 306, and outputs the added value [2]. This value becomes the first absolute change point coordinate of the input image. Next, in step 2, the output of the change point detector 302 is doubled to the change point latch 304, and at the same time the adder 305
The output of is latched into the absolute change point coordinate latch 306. Next, in step 3, the change point detector 302 outputs [7], which is the next change point of the input image. Therefore, the subtracter 303 outputs [5] which is obtained by subtracting the value [2] of the change point latch 304 from [7], and the adder 305 outputs [7]. This value becomes the second absolute change point coordinate. Next, in step 4, the value of 302 is latched into the coordinate latch 304, and the value of the adder 305 is latched into the coordinate latch 306. Next, in step 5, the next change point [8] is output from the detector 302 (however, since the next image has not been input yet, it is not known whether this value is the real change point or not). At this time, the subtracter 303 outputs [1], and the adder 305 outputs [8]. However, this value is not the true absolute change point coordinate. In the next step 6, the value of the detector 302 is latched into the change point latch 304, and the value of the adder 305 is latched into the coordinate latch 306. In this way, adder 30
5, absolute change point coordinates are output one after another. [Problems to be Solved by the Invention] However, this conventional circuit requires one adder 305 and two subtracters 303 in order to obtain the changing point coordinates of a binary image, and the hardware is It has the disadvantage of being large. SUMMARY OF THE INVENTION An object of the present invention is to provide a binary image change point detection circuit which solves the above-mentioned drawbacks and eliminates the need for a conventional subtracter. [Means for Solving the Problems] The configuration of the present invention is such that, in a binary image change point detection circuit that detects change point coordinates that change from white to black or from black to white in a binary image, an input register that latches in fixed units, a change point detector that sequentially outputs the image change points counted from the end of the input image latched in the input register, and an absolute change point coordinate that stores the change point coordinates. a latch - an adder for adding the value of the change point detector and the value of the absolute change point coordinate latch, and the absolute change point coordinate latch is configured to add the value of the change point detector and the value of the absolute change point coordinate latch, and the absolute change point coordinate latch is configured to add the value of the change point detector and the value of the absolute change point coordinate latch. The present invention is characterized in that the output of the adder is latched only at the end of the change point detection process. [Example] Next, the present invention will be explained using the drawings. FIG. 1 is a flowchart showing a change point detection circuit according to an embodiment of the present invention. In FIG. 1, an input image latch 101, a change point detector 102 of the input image latch 101, an adder 103,
and an absolute change point coordinate latch 104. Next, the operation will be explained using FIG. 2 as well. In the initial state (step O), the absolute change point coordinate latch 104 is [0
]. First, in step 1, the image data [0011
1110 (binary)] is latched into the input switch 101. The change point detector 102 outputs the first color change point [2] when viewed from the left of the input -6, - force surface image. The adder 103 inputs the change point detector 102 and the absolute change point coordinate latch 104, and outputs the added value [2]. This value becomes the first absolute change point coordinate of the input image. Next, in step 2, the change point detector 102 outputs [7], which is the next change point of the input image. Therefore, the adder 103 outputs [7]. This value becomes the second absolute change point coordinate. Next, in step 3, the next change point [8] is output from the detector ] 02 (however, since the next image has not been input yet, it is not known whether this value is the real change point or not. ). At this time, the adder 103 outputs [8]. However, this value is not the true absolute change point coordinate. (In the next step 4, the value of the adder 103 is latched in the coordinate latch 104. In this way, in this embodiment, the absolute change point coordinate latch 104
is executed only when processing for one word of the input image is completed,
The value of adder 103 is latched. Therefore, there is an advantage that a subtracter is not required as in conventional circuits. Further, a change point detection circuit according to another embodiment of the present invention will be explained using FIGS. 3 and 4. FIG. FIG. 3 is a flowchart showing a change point detection circuit according to another embodiment of the present invention. In FIG. 3, this embodiment includes an input image latch 201, a change point detector 202 of this input image latch 201,
It is configured to include an adder 203, an absolute change point coordinate latch 204, and an output latch 205. Next, the operation will be explained using FIG. 4 as well. In the initial state, the absolute change point coordinate latch 204 is

[0]
It is. First, in step l, the image data [001
11110 (binary)] is latched into the input latch 201. The change point detector 202 outputs the first color change point [2] when viewed from the left of the input image. The adder 203 is
The change point detector 202 and the absolute change point coordinate latch 204 are input, and the added value [2] is output. This value becomes the first absolute change point coordinate of the input image. Next, in step 2, output 2 of adder 203 is latched into output latch 205. The detector 202 outputs [7], which is the next changing point of the input image. Therefore, the adder 203 outputs [7]. This value becomes the second absolute change point coordinate. Next, in step 3, the next change point [8] is output from the detector 202 (however, since the next image has not been input yet, we do not know whether this value is the real change point or not) . At this time, the adder 203 outputs [8]. However, this value is not the true absolute change point coordinate. In the next step 4, the value of the adder 203 is latched into the coordinate latch 204. In this manner, in this embodiment, the absolute change point coordinate latch 203 latches the coordinates of the adder 203 only when processing for one word of the input image is completed. Therefore, there is an advantage that a subtracter is not required compared to the conventional circuit. [Effects of the Invention] As described above, the present invention requires only one adder, whereas conventionally one subtracter and one adder were required to detect the changing point coordinates of a binary image. There is an effect.

[Brief explanation of drawings]

FIG. 1 is a flow chart showing a change point detection circuit according to an embodiment of the present invention, FIG. 2 is a diagram showing the logical operation of each part in FIG. 1, and FIG. 3 is a flow chart showing a change point detection circuit according to another embodiment of the present invention. a flowchart showing the circuit;
FIG. 4 is a diagram showing the logical operation of each part in FIG. 3, FIG. 5 is a flowchart showing a conventional change point detection circuit, and FIG. 6 is a diagram showing the logical operation of each part in FIG. 101.201,301...Input image latch, 102.202,302...Change point detector,
103゜203.305 ・・・・・・Adder, 10
4,204,306 --- Absolute change point coordinate latch, 205,304 ... Change point latte, 30
3...Subtractor.

Claims (1)

[Claims] In a binary image change point detection circuit that detects change point coordinates that change from white to black or from black to white in a binary image, an input register that latches an input image in fixed units;
a change point detector that sequentially outputs the image change points counted from the end of the input image latched in the input register; an absolute change point coordinate latch that stores the change point coordinates; and a value of the change point detector. The absolute change point coordinate latch includes an adder that adds values to the absolute change point coordinate latch, and the absolute change point coordinate latch adds the output of the adder only at the end of change point detection processing for each fixed unit image in the input register. A change point detection circuit for a binary image, characterized in that it is configured to latch.