JPH04205680A - Intra-frame area detection device - Google Patents

Abstract

PURPOSE:To rationally detect an intra-frame area as against a double frame and the frame of a lower recessed part by calculating the level signals of the frame and ground and detecting the nest level of the frame, namely, how many numbered fold frame against the outermost side. CONSTITUTION:An intra-frame area detection device consists of a picture input part 1, a binarization circuit 2, a temporary level signal calculation circuit 3, a representative level signal calculation circuit 4 and an in-frame/out-frame judgement circuit 5. The attributes of levels are given to both the frame line part constituting the frame and a around part being a part excepting the above part and they are set to be frame signals. The level signal showing the nest level are sequentially calculated by connection relation with a former raster and the depth of the ground or the frame is detected in accordance with the calculated level signal. Thus, the intra-frame area is detected. Thus, the intra- frame area can easily be detected from the frame line of a complicated shape such as the lower recessed part and the multiplex frame, and a processing becomes simple, whereby a circuit scale can be reduced.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an image processing device, and in particular, the present invention relates to an image processing device, and particularly to an image processing device for specifying an area to be edited or processed using a frame line. The present invention relates to a frame area detection device that detects an area surrounded by a frame line (frame area).

(Prior art) As a method for specifying an area for image processing and editing, the □ method using frame lines is known (for example, Document 1: Nishimura et al.
Picture magazine vol1.17. PP328-338.

(see 1988). This creates a frame line that represents the boundary of an area, and specifies the area inside this frame line. Compared to the conventional area specification method using a tablet or coordinate input, this method has the advantage that a free-shaped area can be specified easily, and since the area can be specified on the same plane as the original image, it is easy to understand the correspondence with the original image. There is.

In such an area designation method, a technique for detecting an area inside a frame line (intra-frame area) is essential. For example, the following method is known as a method for detecting a frame area. First, the outermost part of the image is defined as an out-of-frame part, and the presence or absence of pixels adjacent to this out-of-frame part is sequentially checked. Pixels adjacent to the outside-of-frame portion are determined to be outside-of-frame pixels, pixels that are not determined to be outside-of-frame pixels are determined to be within-frame pixels, and areas of pixels within the frame are detected as within-frame regions. With this method, a frame area can be detected by simple processing from an image signal obtained by raster scanning an image.

However, the frame lines that can be detected are limited to figures that are topologically quite simple, and the area within the frame can be detected from frames with complex shapes such as so-called lower parts (shapes with four parts at the bottom on the screen) and multiple frames. It was difficult to detect correctly.

Therefore, a method of detecting a frame area using a nesting level is also known. This gives a level attribute to the frame line part and other ground parts of the image signal, generates a binary frame signal, and also indicates the nesting level of each pixel of the current raster sequentially based on the connection relationship with the previous raster. In this method, a level signal is calculated, and based on this level signal, it is determined whether the pixel is inside the frame or outside the frame. According to this method, it is possible to correctly detect the area within the frame using simple raster-based processing even from frames with shapes such as question marks or multiple frames, and the detection stability for frame lines is also highly stable. . However, in this method, it is necessary to simultaneously calculate the level signal of the current raster and convert the frame signal into a level signal in units of connected regions (runs) in which the values are equal and continuous, and the processing is complicated. Since within-frame detection is usually applied to image signals obtained by raster scanning, the complexity of such processing directly leads to an increase in circuit scale.

(Question 8 to be solved by the invention) As mentioned above, in the conventional method of detecting frame line areas using nest levels, it is difficult to detect frame areas even from frames with complex shapes such as lower questions and multiple frames. Although it is relatively easy to detect, it requires complex processing of simultaneously calculating the level signal and converting the level signal into connected area units, resulting in an increase in circuit scale.

SUMMARY OF THE INVENTION An object of the present invention is to provide an in-frame area detection device that can easily detect an in-frame area even from a frame line with a complicated shape such as a question mark or multiple frames, and can perform simple processing and reduce the circuit scale. .

[Structure of the Invention] (Means for Solving the Problems) In the present invention, level attributes are given to both the frame line portion constituting the frame and the ground portion which is the other portion to form a frame signal,
A level signal indicating the nest level is sequentially calculated based on the connection relationship with the previous raster, and the nest depth of the ground or frame is detected according to the calculated level signal, thereby detecting the area within the frame. Further, the calculation of the level signal is divided into calculation of a temporary level signal that refers only to adjacent pixels of the previous raster, and calculation of a level signal (representative level signal) within the same raster.

That is, the present invention provides an apparatus for detecting a frame area surrounded by a frame line on an image from an input image signal obtained by raster scanning an image including a frame line. Determine whether it is a line part or not, and the determination result is 2.
a frame signal generating means for generating a frame signal of a value, and calculating a temporary level signal from a frame signal and a level signal of an adjacent pixel of a previous raster and a frame signal of a pixel of the current raster for a pixel of the current raster of the input image signal. a temporary level signal calculation means; detecting a connected area in which the value of the frame signal is continuous and equal from the pixel row on the current raster for which the temporary level signal has been calculated by the means;
A level signal calculation means for calculating the level signal (representative level signal) of all pixels in the connected region from the value of the temporary level signal of each pixel in the connected region, and a frame line from the value of the level signal calculated by this means. The device is characterized by comprising a means for determining whether it is inside or outside.

Level signal correction means for correcting the level signal calculated by the level signal calculation means using the relationship between the level signal and frame signal of mutually adjacent connected areas is added, and the frame line is calculated from the value of the level signal corrected by this means. It may also be possible to determine whether the object is inside or outside.

In addition, calculating the representative level signal of each pixel is equivalent to calculating the downward distance from the image scanning start edge for each pixel, so from the value of this downward distance, it is determined whether the pixel is inside or outside the frame line. Good too. Here, "downward distance from the image scanning start edge" refers to the path that sequentially traces adjacent pixels downward from the image scanning start edge, the one that has the least number of movements from a pixel in the frame line area to a pixel that is not in the frame line area. Defined by the number of movements on the route. "Tracing downward" means to move from a frame pixel to a frame pixel, or from another pixel to another pixel, in any direction other than the reverse direction of the sub-scanning direction, from a frame pixel to another pixel or from another pixel to a frame pixel. When moving to , it means tracing in the sub-scanning direction.

(Function) By calculating the frame and ground level signals in this way, the nest level of the frame, that is, how many layers of the frame it is in relation to the outermost frame, is detected, which allows for double frames and lower For frames such as ``times'', it is possible to rationally detect areas within the frame, and the effects of "whiskers" that occur when forming handwritten frames are also removed. Furthermore, calculating a temporary level signal by referring to the previous raster when calculating the level signal;
By performing the calculation of the level signal that refers to the same raster separately, the calculation process is simplified and the circuit scale is reduced.

(Embodiment) FIG. 1 is a block diagram showing a schematic configuration of an in-frame area detection device according to a first embodiment of the present invention.

This in-frame area detection device includes an image input section 1, a binarization circuit 2
, temporary level signal calculation circuit 3, representative level signal calculation circuit 4
and an in-frame/out-of-frame determination circuit 5.

An image input unit 1 reads an image on a document by raster scanning with a line image sensor, and converts the obtained image signal into an A/D converter.
This is a device that performs correction processing such as shading correction after conversion and then outputs it. The frame signal generation circuit 2 is the image input section 1
The image signal from 2 is divided into the frame line part and the other ground part based on appropriate criteria such as density or chromaticity, and the value is "1" for the frame line part and "0" for the ground part2. A frame signal P (x, y) consisting of value signals is output.

However, the frame line part is the part where the frame line is drawn, and the ground part is the other part. Moreover, X and y represent coordinates. The temporary level signal calculation circuit 3, the representative level signal calculation circuit 4, and the inside/outside-frame determination circuit 5 use the following algorithm to calculate the area within the frame from the frame signal, that is, to surround the document with a frame line drawn in a specific color, for example. Detect areas where

FIG. 2 and FIG. 3 show an algorithm for in-frame area detection processing in this embodiment. For convenience of explanation, as shown in Figure 4, the upper left corner of the image is taken as the origin, and the left and right direction is
The axis (right is positive), the vertical direction is the y-axis (bottom is positive), and the range of the image is 1≦−10=X≦xmax, 1≦y≦ymax. Further, one line in the X-axis direction is called a raster, and the raster 12 at the y coordinate or yO is called the yO-th raster. Furthermore, a raster 11 with a y-coordinate of O at the top end of the image is hypothetically considered, and this is called the top end of the image. Hereinafter, all the figures used for explanation use this coordinate axis.

As shown in Figure 2, this algorithm defines a level signal L (x, y) representing the nest level for each pixel of the image, and recursively uses the frame signal and the level signal of the already calculated area. The level signal L (
x, y). That is, first, the level signal L (x, 0) of raster 11 is set to 0 (step 511).
, from the frame signals P (x, 1), P (X, 0) and the level signal L (X, 0), the level signal L (x, l
) is calculated (steps 312-813). However, the frame signal P (x, 0) at the upper end of the image is set to all 0, that is, other pixels, and the level signal L (x, 0) at the upper end is also set to O.

Next, the calculated level signal L (X, 1) and frame signal -1
] - Based on the number P(x, I), it is determined whether the pixel Q is inside the frame or outside the frame (step 514). Next, the calculated level signal L(X, l) and frame signal P(x, l).

With reference to P(X', 2), the level signal L (X, 2)
Calculate. Below, level signal L (x, y-1
) and the frame signals P (x, y-1) and P (x, y) to calculate the level signal L (x, y) and determine whether it is inside the frame or outside the frame while increasing y by 1. , Y =
Repeat sequentially up to ymaX (step 813
~516).

Level signal calculation within the raster, that is, the frame signal P (x, y-1) and level signal L (x
, y-1) and the frame signal P (x, y) of the y-th raster to calculate the level signal L (x, y) (step 813) in detail in FIG.

This calculation consists of two main steps. First, as the first main step, the frame signal of pixel Q at coordinates (x, y) and the coordinates (x, y-
]), and compare the frame signals of the pixel QO of
(see figure), the coordinates (x, y
) A temporary level signal L (x,
y).

This is done for each pixel in the X-axis direction (step 821
~524).

Rule 1> (a) When pixel Q is a frame and the adjacent pixel QO is also a frame, the nest level of pixel QO is set to the nest level of pixel Q.

If P (X, y) = 1, P O(x
, yl) = 1then L (x, y) = L
(x, y-1) (b) When pixel Q is a frame and adjacent pixel QO is ground, the nest level of pixel QO is set to the nest level of pixel Q.

B P (x, y) = 1, P O (x,
y-1) = 0then L (x, y) = L
(x, y-1>(C) If pixel Q is large and the adjacent pixel QO is a frame, set the nesting level of pixel QO + 1 to pixel Q
Let the nesting level be .

HP (x, y) = 0, PO (x, y-1
)−1then L (x, y) = L (x, y
-1) + 1(d) When pixel Q is ground and the adjacent pixel QO is also ground, the nest level of pixel QO is set as the nest level of pixel Q.

i[P (X,!/) = O, P O(x, y-1)
= 0ihen L (x, y) = L (x, y
-1) After the temporary level signal L(x, y) of each pixel of the y-th raster is determined by the above processing, as a second main step, the A representative level signal is calculated based on the relationship between the frame signal of the pixel adjacent to and the temporary level signal (see FIG. 6) (steps 825 to 526).

<Rule 2> A set of adjacent pixels (x, y
), (x+1.y), process 1 is performed on those pixels. This process is repeated until there are no more pairs of pixels that satisfy condition 1.

Condition 1: Both the pixel Q1 and the horizontally adjacent pixel Q2 are frame pixels or other pixels, and their levels are different.

Process 2: Change the level signal of the pixel with the larger level signal among the pixels Ql and Q2 to the smaller level signal.

ifP (x, y) = [P (x+l, y)]an
d[L (x, y)≠L (x+1.y)] This process divides one raster into connected regions (runs) with equal frame signal values, and calculates the minimum value of the level signal of each pixel in each connected region. This corresponds to making the signal a representative level signal representing the nest level of each pixel in the connected region.

Finally, from the value of the calculated representative level signal L(x,y), it is determined whether the pixel is inside or outside the frame according to the following rule 3> (step 514 in FIG. 3).

Rule 3: ■If pixel Q is another pixel and its level is an even number, then pixel Q is an area outside the frame.■If pixel Q is another pixel and its level is an odd number, then pixel Q is an area within the frame.■Pixel Q is an area within the frame. If it is a pixel, the pixel Q is an area within the frame; however, in the case of ■, it may be determined to be an area outside the frame depending on whether or not the area on the frame line is considered to be within the frame. Here, the area on the frame line is considered to be within the frame.

Description and processing example of frame detection using this algorithm> (Definition of distance and downward distance) First, the "distance" between another pixel P and another pixel Q is defined as follows. Among the routes that lead from other pixels P to pixel Q by sequentially tracing adjacent pixels, the route that crosses the frame line the least number of times is called the minimum frame crossing route.
, Q is defined as the distance between Q. Here, "Number of times the frame is exceeded"
means the number of times a frame pixel moves to another pixel. for example,
In FIG. 18, the minimum frame-crossing path from pixel P1 to pixel Q1 is Ll, and since this path does not cross the frame line, the distance between pixels PO and QO is 0. Further, the minimum frame-crossing path from pixel P2 to pixel Q2 is L2, and the distance is 1 because L2 crosses the frame once. Similarly, pixel P3
The minimum frame crossing path and distance from to pixel Q3 are L3 and 2.

As a definition of the inside and outside of a frame line figure, here, pixels with an even number of distances from a certain reference point on the outermost side of the image are considered to be outside-frame areas, and pixels with odd-numbered distances are considered to be inside-frame areas. According to this, the inside of a simple closed curve becomes an in-frame area, and the area surrounded by multiple frames becomes an in-frame area and an out-frame area alternately from the outer frame. This definition is considered to be appropriate as a definition of inside and outside the framework.

However, calculating the above definition for a general frame line image requires an enormous amount of calculation, and it is difficult to apply it to a rask scan signal.

Therefore, in this process, a lower minimum frame-crossing route and a lower distance are defined as follows, as concepts similar to the above-mentioned minimum frame-crossing route and distance. In other words, among the routes tracing "downward" from pixel P to pixel Q below pixel P (larger y coordinate), the route that crosses the frame line the least number of times is defined as the lower minimum frame crossing route, and that route is the frame line. The number of times the line is crossed is the downward distance. Here, the route followed "downward" is a route that complies with Definition 1 below.

Definition 1: A downward path is a path for pixels of the same type (other pixels or frame pixels) to the adjacent left/right direction or downward direction.
For different types of pixels (other pixels and frame pixels), the path is taken to follow the adjacent pixel in the downward direction.

Pixels whose downward distance from the top of the image is an even number are defined as outside the frame, and pixels whose downward distance from the top of the image is an odd number are defined as inside the frame. The downward distance according to this definition has a similar concept to distance.

In particular, if the frame line is a closed curve, determining whether it is inside or outside the frame based on the downward distance is the same as determining whether it is inside or outside the frame based on the distance described above. FIG. 19 shows an example of the minimum downward border crossing route and downward distance for an actual frame line figure.

In the figure, the minimum downward border crossing path from pixel P1 to pixel Q1 is Ll, and its downward distance is "0". Similarly, from pixel P2 to pixel Q2, L2 and "
1”.

(Explanation of equivalence between level and downward distance) The level signal of each pixel calculated in this process is equivalent to the downward distance from the upper end of the image. The reason for this will be explained. First, a pixel P whose downward distance from the top of the image is n
think of. FIG. 7 shows an example where n=1. In the same figure,
Each square corresponds to one pixel, the area surrounded by diagonal lines represents frame pixels, and the other areas represent other pixels. By definition, there is a path from the pixel 22 at the top of the image to the pixel 21(P) by crossing the frame line n times (indicated by a row of arrows in the figure). Consider the level of each pixel on the path. By the premise, the starting point 22 of the route
The level of is "0". When following this route, if pixels of the same type are traced in the horizontal direction 23, the level will be the same as or smaller than the previous pixel due to rule 2>. Also,
24 stripping rule 1 when tracing pixel type downwards
>(a) and (d), the level becomes the same as the previous pixel. In addition, when the path is transferred from another pixel to a frame pixel, 25 is always downward according to definition 1, so (b
), the level remains the same as the previous pixel. In addition, when the path moves from a frame pixel to another pixel, 26 is defined as (26) in Rule 1>.
C) makes the level of the pixel 1 higher than the previous pixel.

Therefore, the level of each pixel on the path increases by 1 only when moving from a frame pixel to another pixel, and otherwise remains unchanged, or
Otherwise, the level becomes n at most after crossing the frame line part n times. Therefore, the level of other pixels P whose downward distance from the upper end is n is equal to or less than n.

In the figure, the numbers inside the pixels indicate the calculated levels.

Conversely, if the level of another pixel P is n, it is shown using FIG. 8 that the downward distance from the upper end to the other pixel P is less than or equal to n. This indicates that there is a path from the upper end to another pixel Q that crosses the frame pixel n times. First, consider a connected region 32 of other pixels that includes a certain other pixel 31 (Q) and is connected within the same rask. In this area 32, the previous step S25. There is a pixel R whose level is n before the correction process in S26. Pixel Q2 adjacent to this pixel Q
is defined as the upper pixel of pixel Q. When pixel Q2 is another pixel, the level of pixel Q2 becomes n according to Rule 1>(d).

Further, when the pixel Q2 is a frame pixel, the level of the pixel Q2 is n-1 according to Rule 1> (C).

However, if the level n is 0, the pixel Q2 will always be another pixel at level 0. Similarly, consider a connected region of frame pixels including the frame pixel S and connected within the same rask. As before, within this connected region, step S25. There is a pixel T whose level is n before the correction process in S26. The pixel S2 above and adjacent to the pixel T is defined as the upper pixel of the pixel S.

According to (a) and (b) of Rule 1, the level of S2 is n regardless of whether S2 is a frame pixel or another pixel.

By setting the upper pixel of pixel P as P2, and then setting the upper pixel of P2 as P3, the upper end of the image is reached. The level of the path traced through these pixels decreases by one each time it moves from the ground to the frame. Since the level at the upper end is "0", this path -21= crosses the frame line part n times. Therefore, the downward distance from the upper end to the pixel P is n.

In this way, it is equivalent that the level of the other pixel P is n and that the downward distance from the upper end of the image to the other pixel P is n. That is, the level determined by this process represents the downward distance from the top of the image.

Next, with reference to Figures 9 to 14, we will give specific examples of nest level calculation and inside/outside frame determination using this process for frame lines of several shapes, and explain the effects of this process and the intuitive Indicates that there is consistency with the area within the frame.

(Case of Circular Frame Line) First, an example of a simple circular frame (FIG. 9) will be explained. In the figure,
The solid line or hatched part represents the frame line part, the number surrounded by a circle represents the level of other pixels, and the number surrounded by a square represents the level of the frame pixel.

The following examples are expressed similarly. All pixels outside the frame line 41 have a path from the top of the image to reach the pixels without crossing the frame, so the level becomes "0" and becomes an area outside the frame. Further, since the area inside the frame line needs to cross the frame line at least once from the top of the image, the level is "1" and is determined to be an area within the frame.

(In case of lower shape) Next, an example of a frame line (FIG. 10) having four parts on the lower side will be explained. Among the pixels outside the frame line 51, the level of pixels other than the area sandwiched between the lath 52 and the frame line 51 is "0". To reach the area inside the frame line 51, it is necessary to cross the frame line at least once from the top edge, so the level of this area is "1".
''. Also, in order to reach the area between the frame line 51 and the raster 52, it is necessary to cross the frame line twice, so the level of this area is "2". Therefore, if the level is an odd number Only the area inside the frame line is determined to be an in-frame area.

(In the case of multiple frames) If multiple frame lines overlap, the determination is made as follows. The case of the triple frame shown in FIG. 11 will be explained as an example. As in the case of one frame, the outermost frame 61
The level outside is "0". outermost frames 61 and 2
Since the area 64 between the th frame 62 needs to cross at least one frame from the top end, the level of the pixel in this area is "1". Similarly, the level of the area 65 between the second frame line 62 and the third frame line 63 is "2", and the level of the area 66 inside the third frame line is "3". Therefore, regions 64 and 66 whose levels are odd numbers are determined to be within-frame regions. This example is an example of a triple frame, but if there are many overlapping frames, the level increases by 1 each time the frame enters the inner frame, and is alternately determined to be an inside frame area and an outside frame area. As a result, it is possible to easily designate areas such as donut-shaped areas indicated by diagonal lines and areas with isolated islands inside the donut holes using the frame lines.

(When the frame line is not ideal) In all of the above examples, the shape of the frame line is an ideal closed curve, but the frame line actually drawn by hand has "whiskers", "
In many cases, a "faint" noise is added. This process can stably detect some of these noises.

Next, as an example of noise, an example in which "whiskers", "nests", etc. occur in the frame line will be shown.

FIG. 12 shows a case where a "whisker" 72 occurs outside the frame line. Similar to the above example, the level of the area outside the frame line and the level of the area inside the frame line are "0" and "1", respectively. In addition, an area 73 surrounded by the "beard" part of the frame line, the frame line, and the raster of the lowest point of the "beard" of the frame line (indicated by a broken line in the figure) is at least one frame line away from the top of the image. Since it is necessary to exceed the level, the level becomes "1". Therefore, the area 73, which should originally be regarded as an out-of-frame area, is also determined to be an in-frame area. However, since such a region 73 is limited to a minute region between the "whisker" and the frame line and above the lowest point of the "whisker", there is no practical problem with this determination error.

Moreover, as shown in FIG. 13, small holes (hereinafter referred to as nests) 81 and 82 that are determined to be ground may occur inside the frame line. This occurs, for example, due to unevenness in drawing the frame lines.

Note that in FIG. 13, the diagonal line portion represents the frame line portion. In the case of a small nest 81, the level inside the nest is "1," and it is determined that the area is within the frame, and other parts are not affected. In addition, if the nest is extremely large and the bottom of the nest is below the top of the inner area of the frame line, such as nest 82, the area inside the frame line and above the bottom raster 83 of the nest 85
The level of is "2", and it is determined that it is outside the frame. but,
In the area below the raster 83, there is a route 84 that crosses the frame line only once from the top edge, so the level is "1",
This part is determined to be an area within the frame. Such a nest is usually not large, and the region of misjudgment will not be larger than the size of the nest, so there is no problem in practice.

As described above, the within-frame detection processing of this embodiment has the following advantages.

(1) Basically, if it is a normal frame line, the area inside the frame can be detected even if it is below or multiple frames.

(2) Of the various noises that occur when writing frame lines, whiskers, nests, etc. are hardly affected.

(3) Regarding the break in the frame line, if it is located below the frame line, the area within the frame is correctly detected.

That is, it can handle complex frames such as lower questions and multiple frames, and is also resistant to noise when writing frame lines. When drawing a frame line, it is difficult for humans to accurately match the start and end points to create an ideal closed curve (no breaks or whiskers). The frame detection processing of this embodiment is resistant to noise such as small whiskers and nests as long as care is taken not to break the frame line, so there are fewer restrictions on writing the frame line, making it easier to use. will improve.

Next, a specific configuration of the in-frame area detection device based on this embodiment will be explained. FIG. 15 shows an example of the circuit configuration of a frame area detection device that implements the algorithms shown in FIGS. 2 and 3, and FIG. 16 is a time chart of each part for explaining its operation.

-27= In FIG. 15, a frame signal (P) 101 from the frame signal generation circuit 2 of FIG. 1 is input to a terminal 100. This frame signal 101 is determined from the input image signal obtained by scanning the image in the image input unit 1 shown in FIG. This is a binary signal in which the frame line portion is “1” and the other portions are “0”.

This frame signal 101 is input in synchronization with a clock signal (CLK) 102.

Negation of this frame signal 101 and frame signal (PO) 1 rask before
10B is taken by the gate circuit 104, and the result is sent to the adder 105 as the level signal of the previous raster (LO
)106. Output signal 1 of this adder 105
07 corresponds to the temporary level signal calculated by the first main step of the inside-frame detection algorithm described in FIGS. 1 and 2.

Next, the gate circuit 109 calculates the exclusive OR of the frame signal 101 and a signal delayed by one pixel by the latch 108.
It is taken by. Since the output signal 110 of this gate circuit 109 represents the end of the connected region, it will be referred to as a region end signal hereinafter. Then, the coordinate signal 112 which is the output of the counter ]]0 which counts up in synchronization with the clock signal 102 is latched by the latch circuit 113 when the area end signal 110 is "1", and is output as the area position signal 114. The area end signal 110 represents the boundary from the frame to the ground or from the ground to the frame, and the area position signal 114 indicates the position (X coordinate) of the boundary.
represents.

On the other hand, the area minimum value calculation circuit 115 calculates the level signal 10.
The minimum value within the 7 connected regions, that is, the representative level signal is calculated. This region minimum value calculation circuit 115 is specifically composed of a minimum value circuit 116 and a latch circuit 117, and each time the region end signal 110 becomes "1", the latch circuit 117 receives the maximum level value (in this embodiment, “15”). The smaller of the output of the latch circuit 117 and the level signal 107 is detected by the minimum value circuit 116, latched by the latch circuit 117 and updated, thereby calculating the minimum value of the level signal within the connected region.

The output signal 118 of the area minimum value calculation circuit 115 corresponds to the representative level signal calculated by the second main step of the inside-frame detection algorithm described in FIGS. 1 and 2.

This representative level signal 118 is synchronized with the region end signal 110, and is a signal for each connected region. In order to convert this signal for each connected area into a signal for each pixel, the level signal 118 for one rask is written into the memory section 119.

That is, the area end signal 110 is stored in the memory unit 119 as “
1'', the frame signal 101, representative level signal 118 and area position signal 114 are written. Therefore, the number of words written to the memory section 119 is the number of areas of one raster. Information stored in the memory section 119 is read out as a pixel-by-pixel signal while referring to the area position signal 114 during the next raster processing.Specifically, the area position signal 124 read out from the memory unit 119 and the coordinate signal 112 from the counter 111 are compared. The address of RAM 120 in memory unit 119 is incremented by one each time the two become equal.
Frame signal 103 and level signal 10 read from 19
6 is a signal in pixel units. These frame signal 103 and level signal 106 represent information one raster before, and are used for calculation of the next raster. Here, the memory unit 119 requires two rasks, but in this embodiment, two address counters 121 and 122 for reading and writing are used, and the address is switched in time division by the switch 123. I only need 120 RAM for Rusk.

Finally, the gate circuit 126 uses the lowest bit of the level signal 106 read from the memory section 119 and the frame signal 10.
3, and this logical sum output is output as the in-frame/out-of-frame determination signal 127. In-frame/out-of-frame determination signal 1
27, "1" indicates inside the frame, and "0" indicates outside the frame.

In this embodiment, the area on the frame line is considered to be outside the area, but by changing the gate circuit 126, it is also possible to configure the area on the frame line to be considered as inside the area.

In this way, the in-frame area detection device based on the present invention can be realized with a simple configuration. In particular, by storing the representative level signal of one raster in the memory unit 119 in units of connected regions, that is, in the form of a run, the memory unit 119 can share the one-rast delay for decoding the run and referring to the next raster. It has the advantage of requiring only a small capacity.

FIG. 20 is a block diagram of an in-frame area detection device according to a second embodiment of the present invention, in which a representative level signal correction circuit 6 is inserted after the representative level signal calculation circuit 4. In other words, this embodiment is a modification of the second main step for determining the level in the rask, that is, calculating the representative level signal in the first embodiment, as shown in Rule 4 below.

Rule 4> If frame pixels or other pixels are adjacent to each other in the same raster and the level signals of those pixels are different,
The smaller of the level signals is taken as the representative level signal of those pixels. The calculation up to this point is the same as the calculation of the representative level signal in the first embodiment. In this embodiment, as a correction process for the representative level signal, if a frame pixel and another pixel are adjacent to each other and the level signal of the frame pixel is larger than the level signal of the other pixel, the level signal of the other pixel is changed to the level signal of the frame pixel. shall be. Also, if the frame pixel and another pixel are adjacent, and the level signal of the other pixel is greater than the level signal of the frame pixel + 1,
Set the level signal of the frame pixel +1 as the level signal of other pixels (
(See Figure 21).

The above rules can be expressed as the following formula.

jf [(P (x, y) ”” P (x+l, y)]
and[L (x, y) ≠ L (X+t, y
) then L (x, y) = L (x+l,
y) - old n[L (x, y), L (x+l, y)
]5f [P (x, y) = 1] an
d[P (x+l, y) −〇 ]and[L (
x, y) > L (x+l, y) then
L (X, y) = L (x+L, y) if
[P (x, y) = 1
d[P (x+1., y) = 0 1and
[L (X, y) + 1. < L (x+
1. , y) ko1hen L (x+l, y) =
L (X, y) + 1if [P (x, y)
) = O] and [P (x+l, y) −
1] and [L (x, y) < L (x+
l, y) then L (x+I, y) −
L (x, y) if [P (X, y) = 0
] and[P (x+1.y) = 1 ]
and[L (x, y) > L (x+1., y)
+1] then L (x, y) −L (x
+I, y) + The above process is repeated until there are no pairs of pixels satisfying the condition of 1 or more in the rask. In this embodiment, the determination operation in the in-frame/out-of-frame determination circuit 7 in FIG. 20 is the in-frame/out-of-frame determination circuit 7 in FIG.
This is slightly different from that in the out-of-frame determination circuit 5. The level signal of the pixel P determined according to this embodiment represents the downward distance from the upper end of the image to the pixel P, and the definition of the downward path is based on the following definition 2.

Definition 2: A downward path is a path that is traced to adjacent pixels in the horizontal or downward direction.

That is, whereas in the first embodiment, paths in the left and right directions were not allowed between pixels of different types, this restriction is removed in the present embodiment. Therefore, in the first embodiment, correct determination is possible even in the case of a frame line figure that is difficult to accurately determine. This will be explained using the example shown in FIG. In this example, the "whisker" of the frame line is extremely large, and both the dividing line 92 of the "whisker" portion and the tip 93 of the "whisker" extend to the point below the frame line. In this case, according to the first embodiment, the path from the top end to the area inside the frame line must cross the frame line at least twice, so the nesting level inside this frame line is all "2". It is judged to be outside the frame. However, it is thought that it is rare for such a frame line to occur, and there is no major problem in practice. In contrast, according to the second embodiment, for example, the area below the raster 94 within the frame line is determined to be within the frame. Therefore, it is possible to detect the area within the frame that is more resistant to noise than in the first embodiment.

Note that in the first and second embodiments, only one pixel of all the tests directly above the relevant pixel in the current raster shown in FIG. 17(a) is defined as the upward adjacency relationship; Examples of relationships include two pixels directly above and diagonally above the right (or diagonally above the left) as shown in Figure (B), and three pixels directly above, diagonally above the right, and diagonally above the left as shown in Figure (C). You can also think of it as a pixel. In this case, the level signal calculation algorithm in the first main step is to first calculate a provisional level signal of the pixel from multiple upper adjacent pixels according to Rule 1>, and then use the minimum value as the representative level signal of the pixel. do it. In particular, FIG. 17(b) has a feature that when a frame area and another area intersect, one of the areas is always adjacent to each other.

In addition, the present invention can be implemented with various modifications.

[Effects of the Invention] According to the present invention, even in an area surrounded by double or more multiple frame lines or a lower-shaped frame line, the part of the lower question or the inside of the double frame can be determined to be outside the frame. , and "beards" caused by handwriting.
It is possible to perform stable determination even against noise such as. Furthermore, in the present invention, when calculating the minimum value of the nest level in the main scanning direction, that is, the representative level signal, conversion into connected area units can be used, and it can be realized with a simple circuit. Therefore, it is possible to provide a frame detecting device that has fewer restrictions on the user when drawing a frame line and has a small circuit scale.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of a frame area detection device according to a first embodiment of the present invention, FIG. 2 is a diagram schematically showing an algorithm for detecting a frame in the same embodiment, and FIG. A diagram showing a part of the algorithm in Figure 2 in detail, Figure 4 is a diagram to explain the setting of coordinate axes on an image, and Figure 5 is a diagram to explain the contents of the first main step of the algorithm. FIG. 6 is a diagram for explaining the contents of the second main step, FIGS. 7 and 8 are diagrams for explaining that the level signal and the downward distance are equivalent, and FIGS. FIG. 14 is a diagram for explaining a specific example of frame area detection according to the same embodiment, FIG. 15 is a circuit diagram showing in detail the main part of the frame area detection device of FIG. 1, and FIG. Figure 17 is a diagram to explain the definition of the vertical adjacency relationship of pixels, Figure 18 is a diagram to explain the minimum frame crossing route and distance, Figure 19 is a time chart to explain the operation of the figure. 20 is a block diagram showing a schematic configuration of an in-frame area detection device according to a second embodiment of the present invention, and FIG. 21 is a diagram for explaining the minimum downward border crossing route and the downward distance. FIG. 7 is a diagram for explaining the second main step. 1... Image input section 2... Frame signal generation circuit 3... Temporary level signal calculation circuit 4... Representative level signal calculation circuit 5, 7... Frame/outside area determination circuit 6... Representative level signal correction circuit 101...Current raster frame signal 103...One raster previous frame signal 106...One raster previous representative level signal 107...
Temporary level signal 118...Representative level signal of current raster 127...Inside/outside frame determination signal Applicant's agent Patent attorney Takehiko Suzue > eu ε 〉h Table Poem Figure 9 Figure 10 Figure 13 Figure 14 Figure 18 Figure 19 Figure Q 2nd

Claims (2)

[Claims] (1) In a device that detects a frame area surrounded by a frame line on an image from an input image signal obtained by raster scanning an image including a frame line, the frame line is determined for each pixel of the input image signal. a frame signal generating means for determining whether or not a portion is a part, and generating a binary frame signal as a result of the determination; Temporary level signal calculating means for calculating a temporary level signal from frame signals of pixels of a raster; a level signal calculation means for detecting and calculating the level signals of all pixels in the connected region from the value of the temporary level signal of each pixel in the connected region; What is claimed is: 1. A frame area detection device comprising: means for determining. (2) In a device that detects a frame area surrounded by a frame line on an image from an input image signal obtained by raster scanning an image including a frame line, the frame line is determined for each pixel of the input image signal. a frame signal generating means for determining whether or not a portion is a part, and generating a binary frame signal as a result of the determination; Temporary level signal calculation means for calculating a temporary level signal from frame signals of pixels of a raster; , a level signal calculation means for calculating the level signals of all pixels in the connected region from the value of the temporary level signal of each pixel in the connected region; 1. A frame area detection device comprising: a level signal correcting means for correcting the level signal using the relationship between the frame signal and the frame signal; and a means for determining whether the level signal is inside or outside the frame line from the value of the level signal corrected by the means.