JP2912371B2 - Image processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention reads an image projected on a negative image having a substantially convex quadrangular outer shape, such as a microfilm, with an image sensor, and erases a black frame appearing around a document. The present invention relates to an image processing device that outputs the image data.

(Technical Background of the Invention) Originals (images)
Is read by an image sensor. In this case, a background is included around the document to be read. For example, in the case of a negative microfilm, a black frame background is generated around a substantially convex square document. For this reason, when a document is read by an image sensor, the black frame portion is read as it is, and when an image is printed or output to a CRT (cathode ray tube, cathode ray tube) using the image signal, the black frame appears as it is. Was. Further, when a PPC printer is used, there is a problem that the amount of toner used increases.

Therefore, various methods have been proposed for eliminating the black frame. For example, Japanese Patent Application Laid-Open No. Sho 62-144463 proposes an image signal processing device in which document position data is stored in a memory for each main scanning line, and only signals within the document position are extracted from an input serial image signal. Have been.

However, according to this apparatus, there is a problem that noise is easily caused by dust adhering to the microfilm or scratches on the microfilm, and the line of the trimming edge is not beautiful.

(Object of the Invention) The present invention has been made in view of such circumstances,
It is less susceptible to dust and scratches on the microfilm, so that the black frame appearing around the original can be neatly erased or trimmed, and the operation time of the first image reading for black frame detection can be shortened. It is an object of the present invention to provide an image processing device that is enabled.

(Constitution of the Invention) According to the present invention, an object of the present invention is to scan and read a projection image obtained by projecting a negative image whose outer peripheral shape is recorded on a film and having a substantially convex quadrangle by an image sensor and include the projection image in the projection image. In the image processing apparatus for detecting, erasing and outputting the black frame, the image sensor obtains an image signal obtained at every first main scanning in the first image reading as appropriate and continuously outputs the image signal in the main scanning direction of the image sensor. Since it is first detected that a number of pixels become white, the coordinates obtained by returning a predetermined distance in the anti-main scanning direction from the coordinates of the last pixel of the continuous pixels are used as the starting point of the black frame in the main scanning direction. Since it is detected for the first time that a certain number of pixels consecutive in the main scanning direction become black, the coordinates returned by a predetermined distance in the anti-main scanning direction from the coordinates of the last pixel of this continuous pixel are Black-and-white discriminating means for repeating the operation of setting the end point of the black frame in the main scanning direction in the sub-scanning direction, memory means for storing the coordinates of the obtained end point and start point, and four lines using the stored coordinates of the end point and start point of the black frame. A straight line calculating means for obtaining a straight line equation of an edge of a black frame by a straight line approximation method; a trimming range calculating means for obtaining a trimming range using the obtained straight line equation; a memory means for storing the obtained trimming range; An image processing apparatus comprising: a trimming unit that erases, as a black frame, an image within the trimming range among images read by the second and subsequent image readings.

That is, from the coordinates from the edge of the black frame on the main scanning line, the equations of the straight lines on each side of the document are obtained by a straight-line approximation method, and the edges of the black frame are determined by the equations of these straight lines. The trimming range is erased as a trimming range.

(Embodiment) FIG. 1 is a functional block diagram of the present invention, FIG. 1 is an overall configuration diagram of a microfilm reader to which the present invention is applied, FIG. 3 is an explanatory diagram of main / sub scanning directions on a screen, and FIG. FIG. 5 is a flow chart of a white determination operation, FIG. 6 is a flowchart of a black determination operation, FIG. 7 is a circuit diagram for obtaining coordinates of four corners of a document, FIG. FIG. 9A is a flowchart of the trimming range calculation operation, and FIG. 9B is an explanatory diagram of the coordinate system.

First, the overall configuration will be described with reference to FIG. In this figure, reference numeral 10 denotes a light source, and light from the light source 10 passes through a condenser lens 12, a heat-insulating glass 14, a cold mirror 16, a microfilm 18, a projection lens 20, an image reversing prism 22, mirrors 24 and 26. The screen 28 is guided to a mold screen 28 and forms an enlarged image of the microfilm 18 on the screen 28.

On the back of the screen 28, a CCD line sensor 30 as an example of an image sensor is provided so as to be movable left and right. That is, the line sensor 30 is arranged long in the direction that passes through the screen 28, and the line sensor 30 reads out an image in the length direction (main scanning direction) and sequentially outputs the image signal α as a time series signal to perform main scanning. The sub-scanning is performed by moving the line sensor 28 in the left-right direction by the motor 31. This line sensor 30
Image signal α is input to the CPU 34 via the input interface 32.
, Where various processes are performed, and the image signal is binarized. The binarized image signal β is output to the printer 38 via the output interface 36, where the image is printed out and a hard copy is obtained. In addition, the binarized signal β output from the CPU 34 can be recorded in an external storage device such as the optical disk device 40. Further, an image may be displayed on a CRT or the like. Therefore, a necessary document image may be read out from the optical disc device 40 and printed out by the printer 38 or displayed on the CRT as necessary. 42
Is a ROM for storing an operation program and the like of the CPU 34, and 44 is a RAM as memory means.

First, the CPU 34 obtains the coordinates of the edge of the black frame for each main scanning line by the first image reading by the image sensor 30. The first image reading for detecting the black frame is performed every other main scanning. Detection of this edge is ROM4
This is performed by the black-and-white discriminating means A of the CPU 34 previously stored as an operation program in FIG.

The black-and-white discriminating means A is determined based on the coordinates x at which the image signal α changes from white to black or from black to white on the main scanning line. That is, as shown in FIG. 3, assuming that the 走 査 axis is in the main scanning direction and the y axis is in the sub scanning direction, the coordinates α (χ) of the coordinates 上 の on a certain main scanning line are white or black over a certain distance l or more. In such a case, it is determined that it is an edge. Here, the distance 1 corresponds to N ₀ pixels on the line sensor 30.

FIG. 5 shows a coordinate X at which the signal α changes from black to white during the main scanning.
Is a flowchart for obtaining the point Xa in FIG. 4, that is, the end point of the black frame. First, χ =
Main scanning starts upward from position 0 (step 100A),
If the signal by the next position chi = 1 pixel alpha (1) is not a white (step 102A, 104A), and N = N ₀ (step 106
A). If α (χ) is white, subtract 1 from N (step 108)
A), if white continues for N ₀ pixels (step 110A), N
Determines that the original document exists before ₀ pixels, employing a chi-N _0/2 as the coordinate X of the edge (step 112A). This constant value N ₀ is assumed to be equal to the distance 1 on the screen.

FIG. 6 is a flowchart for obtaining a coordinate X at which the signal α changes from white to black, which is for obtaining a point Xb in FIG. 4, that is, a starting point of a black frame. That is, χ gradually increases in the main scanning line (step 120A), and if the signal α (χ) is not black (step 120A).
122A) N = N ₀ is returned (step 124A).
1 is subtracted (step 126A), if continued number N ₀ black corresponds to a predetermined distance l (step 128A) is determined from the N ₀ pixels prior document and no white x- (3/2) N ₀ Is adopted as the coordinate X of the edge that turns black.

As described above, the coordinates of the edge of the black frame, that is, the coordinates of the end point and the start point of the black frame are obtained for each main scanning line, and are stored in the RAM 44 as the image edge coordinate memory means B. As described above, the line sensor 30 is moved in the y-direction while the edge of the black frame is stored in the memory to perform sub-scanning. The CPU 34 calculates a straight line equation of each side of the document from the coordinates of the edge of the image thus obtained by the least square method. For example, from the state of continuous increase or decrease in the movement of the coordinates of the end point and the start point of the black frame in the y direction, the set of the end points and the set of the start points are divided into four sets each of which is considered to be located near the same straight line.
For each of these four sets, the coordinates of the edge and a certain straight line X = aY +
The distance .DELTA.X to b is determined, and the coefficients a and b are determined so that the sum of the squares of .DELTA.X is minimized. The straight lines on the four sides are X = a ₁ Y + b ₁ , X = a ₂ Y + b ₂ , X = a ₃ Y + b ₃ , X = a ₄ Y
+ B ₄ and stored. This operation is shown in FIG. This means C can be stored in the ROM 42 as an operation program of the CPU 34.

On the other hand, the CPU 34 also obtains the coordinates of the four corners of the document. The four corners are determined in order to determine the trimming range using the linear equation of the four sides as described above. The four corners may be obtained as intersections of these four straight lines, but here, the image signal α
Seeking from. This operation is shown in FIG.
And can be configured as shown in FIG. 7, for example. This means D can be stored in the ROM 42 as an operation program of the CPU 34, but may be constituted by discrete components according to this circuit diagram.

In FIG. 7, reference numeral 50 denotes a main counter for obtaining coordinates X during main scanning, and reference numeral 52 denotes a sub-counter for obtaining coordinates Y during sub-scanning. The main counter 50 accumulates a clock pulse CK for sequentially reading data of each pixel of the line sensor 30, and the accumulated value X is stored in a register R (X
1), forwarded to F (X2), F (X3), R (X4). The main counter 50 is cleared (returned to zero) each time scanning of one main scanning line is completed. That is, as indicated by LSYC in FIG. 3, the main counter 50 is cleared by a signal obtained by inverting the LSYC signal, which becomes H level in the screen 28 during the main scanning for a corresponding time, by the inverter 56. Secondary counter 52 is LSYC
The signals are integrated, and the integrated value Y is transferred by the bus 58 to the registers R (Y1), R (Y2), R (Y3), and R (Y4). The sub-counter 52 is cleared by a READY / BUSY (hereinafter simply abbreviated as R / B) signal indicating that scanning of the entire area of the screen has been completed.

60 subtraction counter, 62 is a setter set number N _0, the monochrome determination unit A These are formed. That is, the counter 60 subtracts 1 from the set number N ₀ each time the image signal α continues to be white, and returns the counter 60 to N ₀ each time the image signal α changes to black and white. And the beginning edge of After that, the counter 60 similarly inverts the image signal α and also performs the same subtraction. When the counter 60 becomes zero, the counter 60 determines the end edge of the document in the main scanning direction. This results in counter 60
The W / B (white / black) signal, which is the output signal of, is at the H level only during the period when the document is located on the main scanning line as shown in FIG.

This W / B signal is initially H until the sub-scan is completed.
The coordinates that become the level are detected by the flip-flop FF.
The coordinates (X ₁ , Y ₁ ) are the minimum corner of Y as shown in FIG. 9B, and are stored in the registers R (X1) and R (Y1). Further, the rise of the W / B signal is detected by the rise detection circuit 64, and the fall is detected by the fall detection circuit 66. In synchronization with the falling signal dwn of the rising signal up which is each output, the coordinates X ₂ and X ₃ at that time are stored in the registers F (X2) F (X3).
Is stored in the memory. The coordinates X ₂ and X ₃ are rewritten every other main scanning line. Coordinate X ₂ are the coordinates X ₂ in the main scanning line read image immediately before is compared in the context of the comparator COM1 of the memory by the register R (X2),
P <while when namely the X ₂ of Q is slide into decreased every time the main scan register R (X2), continue rewriting the contents of the R (Y2). As a result, the registers R (X2) and R (Y2) have x in FIG. 9B.
The coordinates of the minimum corner (X ₂ , Y ₂ ) are stored.

Register F stored in synchronization with falling of W / B position
The contents of (X3) is immediately before the coordinate X ₃ in the main scanning line read image is compared in the context of the comparator COM2 of the memory by the register R (X3) to, P> between Q register R (X3), Continue to rewrite the contents of R (Y3). As a result, the coordinates (X ₃ , Y ₃ ) of the x-maximum corner in FIG. 9B are stored in the registers R (X3) and R (Y3).

Further, each time the W / B signal goes high, the coordinates X and Y are rewritten in the registers R (X4) and R (Y4). If the W / B signal does not go high again, the last coordinate goes high. X ₄ , Y ₄
Is stored as it is.

The operation for obtaining the coordinates of the four corners in this manner is as shown in FIG. The coordinates of the four corners thus obtained are stored in the memory means E which is a part of the RAM 44.

The CPU 34 calculates the coordinates of the obtained corner and the straight line calculating means C.
The trimming range is obtained using the linear equation obtained in (1) (FIG. 1, trimming range calculating means F). This means F performs the operation shown in FIG. 9A. When obtaining these four corners in accordance with FIG. 7, the last coordinate in the X direction when the image signal α becomes white or black continuously N ₀ times is used. That four corners of the coordinate on the main scanning line, when entering the image from black frame enters a distance l of N ₀ pixels in the image. It contains a distance l of N ₀ pixels in the black frame when similarly entering from the image to the black frame. Therefore, the CPU 34 performs a process of moving the coordinates of the corner by N _0/2 pixels (corresponding to a distance of l / 2) to the inside of the image in the same manner as when the straight line equation is obtained.

This processing is performed as follows. First, X on the main scanning line
0 position X ₁ of the side edge, X ₂ and new coordinates _{N 2/2 (= l /} 2) only by subtracting _{X 1 = X 1 -l / 2} X 2 = X 2 -l / 2 is the I do. Exactly similar position of the edge on the increasing side of x
From _{X 3, X 4 (3/2)} N 0 {= (3/2) l} only subtracts _{X 3 = X 3 - (3/2} ) l X 4 = X 4 - (3/2) Let l be the new coordinates (FIG. 9A, step 300). The trimming range is obtained as follows using the coordinates of the four new corners determined in this way and the above four linear equations. That is, as shown in FIG. 9B, when Y ₁ <Y <Y ₂ (step
302), a straight line X = a ₁ Y + connecting (X ₁ , Y ₁ ) and (X ₂ , Y ₂ )
The b ₁ used (step 304). In this range, X <a ₁ Y + b ₁ is set as a trimming range (step 306).

In Y ₁ <Y <Y ₃ (step _{308), X> a 2 Y} + b 2 a and trimming range (step 310, 312). Likewise
If Y ₂ <Y <Y ₄ , Y ₃ <Y <Y ₄ , steps (316, 318),
The trimming range is determined as in (322, 324).

In this way, the trimming ranges of the four sides of the original shown in FIG. 9B are determined, and these are stored in the memory means G comprising the RAM 44.

In the present embodiment, the straight line equation is obtained by the least square method. However, the present invention may of course be obtained by using another known approximation method such as the Tubyshev approximation method.

The CPU 34 determines the trimming range as in steps 306, 312, 318, and 324 using the coordinates of the four corners obtained by the first scan and the linear equation.

In the subsequent scanning, the image signal α within this range is extracted and is changed to a predetermined signal level, for example, a signal having the same brightness as the background portion of the document or white (trimming means H in FIG. 1). The image signal α thus corrected is output to the CPU 34
Then, the image data is binarized and output to printing means I such as a printer 38 for printing.

As the image sensor, a two-dimensional area sensor can be used instead of the line sensor. In this case, the area sensor may be fixed without moving.

Further, when the edge of the image is obtained, the edge may be obtained every other main scan as in the present embodiment. However, the operation time can be further shortened if the image edge is obtained every other main scan. The present invention also includes such a device.

Further, in this embodiment, the coordinates of the four corners of the document are obtained by the circuit shown in FIG. 7. However, the coordinates may be obtained by calculation as intersections of respective linear equations obtained by a linear approximation method such as the least square method.

(Effect of the Invention) As described above, the present invention determines the edge of an image (original document) from the fact that a certain number of continuous pixels on the main scanning line become white or black by the first scan, Iteratively, the straight line equation of the edge of the image (document) is obtained by a straight line approximation method, and the outside of the range surrounded by these straight lines is stored as a trimming range including a black frame. Since the signal, that is, the signal in the black frame range is extracted and is changed to a predetermined signal level, for example, the brightness or white of the background portion of the original, the coordinates of the edge of the black frame are stored in memory for every main scanning line. Therefore, even if the coordinates of the edge of the black frame fluctuate due to dust or scratches on the microfilm, the equation of the edge of the image can be determined neatly with a straight line without being substantially affected, and output to a printer or the like. This makes it possible to trim the edge of the black frame beautifully.

In addition, the first image reading for obtaining a black frame uses the image signal obtained for each main scan at an appropriate number of times, so that the operation time required for image reading for detecting the black frame can be reduced.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of the present invention, FIG. 2 is an overall configuration diagram of a microfilm reader to which the present invention is applied, FIG. 3 is an explanatory diagram of main and sub scanning directions on a screen, and FIG. FIG. 5 is a flowchart of a white determination operation, FIG. 6 is a flowchart of a black determination operation, FIG. 7 is a circuit diagram for obtaining coordinates of four corners of a document, FIG. 8 is an operation flowchart thereof, and FIG. FIG. 9B is a flowchart of the range calculation operation, and FIG. 9B is an explanatory diagram of the coordinate system. A: black-and-white discriminating means, B: image edge coordinate memory means, C: edge straight line calculating means, F: trimming range calculating means, G: memory means, H: trimming means, α: image signal, 30 …… Line sensor.

Claims (1)

(57) [Claims] An image sensor scans and reads a projection image obtained by projecting a negative image whose outer peripheral shape is substantially a convex quadrangle recorded on a film, and detects and erases a black frame included in the projection image. In the image processing device for outputting, a certain number of pixels continuous in the main scanning direction of the image sensor become white from an image signal obtained at every other main scanning in the first image reading by the image sensor as appropriate. Coordinates returned by a predetermined distance in the main scanning direction from the coordinates of the last pixel of the continuous pixels from the first detection are used as the starting point of the black frame in the main scanning direction, and a fixed number of Since it is detected for the first time that the pixel becomes black, the coordinates obtained by returning a predetermined distance in the anti-main scanning direction from the coordinates of the last pixel of this continuous pixel are set as the end points of the black frame in the main scanning direction. Black-and-white discriminating means for repeating the operation in the sub-scanning direction, memory means for recording the coordinates of the obtained end point and start point, and linear approximation of the straight line equations of the edges of the four black frames using the stored coordinates of the end point and start point of the black frame. Straight line calculating means, a trimming range calculating means for obtaining a trimming range by using the obtained straight line equation, a memory means for storing the obtained trimming range, and an image read by the image sensor for the second and subsequent times. An image processing apparatus comprising: a trimming unit that erases an image within the trimming range as a black frame.