JPH0519351A - Microfilm reader - Google Patents

Abstract

PURPOSE:To facilitate the automatic correction of the position of a sentence by vignetting the line of the sentence of an original to the wide-width line and detecting a rotational angle for errecting an image by the inclination of the line. CONSTITUTION:By a vignetting means 18, the focus of a lens 18 is moved from a focusing position so as to be defocued as much as fixed amount which is previously decided and a threshold value for binarizing is changed to be the smaller value. As the result, the images of the respective sentences are blurred and they become the wide-width lines. By a CPU 38, the inclination of the line is obtained by an inclination detection means, next. Besides, the image is rotated by a prism 20 forming an image rotation means 78 and a motor 64 by the CPU 38 so that the inclination becomes zero. As the result, the projected image is errected and correctly positioned.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microfilm reader for reading an image containing a document printed on a microfilm with a scanner.

[0002]

BACKGROUND OF THE INVENTION A reader for projecting an image on a microfilm onto a screen or outputting it to a printer is known. The image projected on the microfilm here is not always the correct tilt, and some images are tilted greatly. In such a case, not only the projected image appearing on the screen is tilted, but also when the image is output to a printer, the printed image is tilted.

Therefore, an image rotating prism is usually interposed in the optical system so that the image can be rotated so that the projected image is erect. However, in this case, it is necessary for the operator to constantly monitor the screen. Further, when the image selected in advance is automatically searched and is automatically printed out, the inclination cannot be corrected.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and a microfilm reader capable of automatically detecting the inclination of a projected image and automatically correcting a sentence to a correct horizontal or vertical position. The purpose is to provide da.

[0005]

According to the present invention, the object is to binarize the image signal output by the scanner in a microfilm reader in which an image containing a document recorded in the microfilm reader is read by the scanner. A binarizing means, a focus control means, a blur control means for rendering at least a part of the projected image out of focus and changing the binarization level to make the document line of the original document a continuous wide line; The present invention is achieved by a microfilm reader characterized by comprising inclination detecting means for obtaining the inclination of a line, and image rotating means for rotating the projection image so that the line becomes horizontal or vertical from the obtained inclination. .

Here, the inclination detecting means can obtain the inclination by using a straight line passing through the intermediate value of the line width or a straight line passing through the average value of the coordinates of the pixels included in the predetermined length of the line. . For the straight line, the least squares method that minimizes the sum of squares of the error between these intermediate values and the average value is used, or the minimax approximation method that minimizes the maximum absolute value of this error (maximum (Approximation method) and the like.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a functional block diagram of its main part, FIG. 3 is a view showing a projected image on a screen, and FIG. 5 is a flow chart of the operation.

In FIG. 1, reference numeral 10 is a microfilm, which is wound from one of the two reels 12 and 14 to the other and runs. Light from a light source 16 is guided to the film 10 from below, and transmitted light from the film 10 is projected by a projection lens 18, an image rotation prism 20, reflection mirrors 22, 24, and
It is led to the screen 28 from the back side via 26. A vertically movable plate 30 is provided on the back surface of the screen 28 so as to be movable in the horizontal direction, and a CCD line sensor 32 is attached to the movable plate 30. Therefore, the movable plate 3 is read by these while reading the image incident on the line sensor 32.
By moving 0 in the horizontal direction, a scanner 32A for reading the projected image on the screen 28 is formed.

As shown in FIG. 1, the device of this embodiment has two components.
One data transfer bus 34, 36, one bus 34
Is for CPU, and the other bus 36 is for image data. The CPU bus 34 has a CPU (processor chip)
38, ROM 40, RAM 42, etc. are connected.
The image data read by the line sensor 32 is digitized and then input to the scanner input interface (I
F) 44 and the image data bus 36 are sent to each unit.

Reference numeral 46 is a memory for image data (hereinafter referred to as I-ME).
M), and a semiconductor memory capable of high-speed writing and reading is used. This I-MEM46 is bus 3
6 is connected.

Reference numeral 48 denotes a compression / decompression processing unit, which is used for both buses 3
4 and 36. This compression / decompression processing unit 48
Compresses the read image data when transferring it to an external device such as a facsimile or other microfilm reader, and decompresses and restores the data transferred with the compressed data from the external device. And so on.

An image processing unit 50 includes both buses 34 and 3
Connected to 6. This processing unit 50 performs various spatial filtering processes such as edge enhancement by differentiation process, thinning process, and dither process based on the read raw data.

Reference numeral 52 denotes image data transfer (I-DMA;
Image Direct Memory Access) control unit, which controls the direct data transfer between various input / output interfaces and memories, or between memories. That is, in this embodiment, the transfer of the image data is performed without the intervention of the CPU 38 by the DMA.
By adopting the method, the CPU 38 does not need to perform any processing until the transfer is completed after setting the predetermined parameters such as the transfer start memory address and the number of transfers to the I-DMA control unit 52.

Reference numeral 54 denotes a disk input / output interface, which is an external memory device 56 such as an optical disk and a bus 36.
Intervenes between. Reference numeral 58 denotes a printer output interface, which is interposed between the printer 60 and the bus 36.

The focus of the projection lens 18 can be adjusted by a motor 62 forming a focus control means. The image rotating prism 20 can be rotated by a motor 64, and an image rotating means is formed by these. These motors 62 and 64 are interfaced by a command from the CPU 38.
It is controlled via the face 66 and a drive circuit (not shown).

The CPU 38 obtains the inclination of the projected image according to the operation program stored in the ROM 42 and rotates the image. The function of the CPU 38 that performs the series of operations is shown in FIG. 2, and the flow of the operation is shown in FIG.

In FIG. 2, reference numeral 68 denotes a signal processing means, which performs waveform shaping of the output signal a of the line sensor 32, unevenness of illumination, unevenness of output level due to unevenness of characteristics of each pixel of the line sensor 32, and the like. The signals b are aligned and output to the binarizing means 70 (step 100 in FIG. 5). The binarizing means 70 binarizes the signal b by comparing it with the threshold value Vth ₀ (step 102). The binarized signal c, that is, a signal indicating black and white, is sent to the focus control means 72, where, for example, the contrast of the signal c is obtained, and the position of the projection lens 18 where this contrast becomes maximum, that is, the focus position is searched (step 104).

Once the in-focus position of the lens 18 has been obtained in this way, the blurring control means 74 blurs the projected image to make a wide line in which each line of the text of the image is continuous (FIG. 4).
To That is, the blurring control means 74 controls the lens 1
The focus of No. 8 is moved from the focus position by a predetermined fixed amount Δf so as to be out of focus (step 106),
The threshold for binarization is changed from Vth ₀ to V smaller than Vth _0.
Change to th (step 108). As a result, the image of each line of the sentence is blurred, and the blurred area is read as black. Therefore, the image obtained at this time is shown in FIG.
It becomes a wide line indicated by B.

Next, the CPU 38 obtains the inclination of the line B by the inclination detecting means 76 (step 110). Various algorithms can be applied to the detection of this inclination.
For example, as shown in FIG. 4, the x and y coordinates are taken, and on the line B at appropriate x-direction positions x ₁ , x ₂ , x ₃ , x ₄ .
Coordinates of lower edge (y ₁ ^U , y ₁ ^L ), (y ₂ ^U , y ₂ ^L ), (y ₃ ^U ,
y ₃ ^L ), (y ₄ ^U , y ₄ ^L ), and these midpoints P ₁ ,
The coordinates (intermediate value) of P ₂ , P ₃ , and P ₄ are P ₁ = (y ₁ ^U + y
^{Calculate as} ₁ ^L ) / 2. Therefore, these intermediate points P ₁ ~
The straight line C closest to P ₂ may be obtained and the slope of this straight line C may be obtained.

Here, the straight line C can be obtained so that the sum of the squares of the errors with the intermediate points P _{1 to} P ₄ is minimized, that is, by the least squares method. The straight line C is the intermediate point P ₁
So that the largest of the errors with ~ P ₄ is the smallest,
That is, it can be obtained by the minimax approximation method. Also, instead of using the y coordinates of the intermediate points P _{1 to} P ₄ ,
A point Q ₁ , which is an average value of xy coordinates of all pixels included in the regions Z ₁ and Z ₂ of appropriate lengths L ₁ and L ₂ on the line B,
It suffices to find a straight line D that is close to Q ₂ .

When the inclination α of the line B is thus obtained, the CPU 38 rotates the image by the prism 20 and the motor 64 forming the image rotating means 78 so that the inclination α becomes 0 (step 112). ). As a result, the projected image is in an upright and correct position. In this state, the scanner 32A is operated again to read an image, compression / decompression processing and image processing are performed, and then the image is sent to the printer 60, the external memory device 56, or an external device.

In the above embodiment, the blurring control means 74 optically blurs the focal point and changes the binarization threshold value Vth ₀ to obtain the line B. This operation is performed by an electronic circuit by electrical processing. It is also possible to do so. For example, a spatial filtering process using an average value matrix for averaging pixel densities in the x direction can produce the same effect even if the image is blurred in the line direction of the sentence.

The image rotating means is a prism 20 and a motor 6.
Instead of forming at 4, it can be done electrically. For example, as shown in FIG. 1, it is possible to provide an image rotation LSI 78. Although the above sentence is described as having horizontal lines, it is exactly the same in the case of a vertically written sentence when it is considered to be rotated by 90 °.

[0024]

As described above, according to the first aspect of the present invention, the lines of the document of the original are blurred to make a wide line, and the rotation angle for making the image upright by determining the inclination of the line is determined. Knowing that, since the image is rotated by this angle, the image can be automatically read in the correct state without inclination even if the operator does not monitor it.

In order to obtain the inclination of a wide line, for example, a straight line which is close to the median value of the width of this line or a straight line which is close to the average value of the coordinates of the pixels within the predetermined length of this line is obtained. The slope of the straight line may be obtained (claims 2 and 3). Various approximation methods such as the least-squares method and the minimax approximation method can be used to determine a straight line close to these intermediate values and average values (claims 4 and 5).

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a functional block diagram of the main part.

FIG. 3 is a diagram showing a projected image on a screen.

FIG. 4 is a diagram showing blurring processing of a partial area A thereof.

[Fig. 5] Flow chart of operation

[Explanation of symbols]

10 microfilm 20 Prism as image rotation means 32A scanner 70 Binarization means 72 Focus control means 74 blur control means 76 Tilt detection means 78 LSI as image rotation means B wide line C straight line

Claims (5)

[Claims] 1. A microfilm reader in which an image including a document recorded in a microfilm reader is read by a scanner, a binarizing means for binarizing an image signal output from the scanner, and a focus control means. Blurring control means for making at least a part of the projected image out of focus and changing the binarization level to make the document line of the original document a continuous wide line; and inclination detection means for obtaining the inclination of the line. An image rotating means for rotating the projected image so that the line becomes horizontal or vertical from the obtained inclination, the microfilm reader. 2. The microfilm reader according to claim 1, wherein the inclination detecting means obtains an inclination of a straight line which is close to an intermediate value of widths at a plurality of points of the line. 3. The microfilm reader according to claim 1, wherein the inclination detecting means obtains an inclination of a straight line which is close to an average value of coordinates of pixels included in a predetermined length at a plurality of positions of the line. 4. The microfilm reader according to claim 2, wherein the straight line for obtaining the inclination is determined so that the sum of squares of the error from the intermediate value or the average value is minimized. 5. The microfilm reader according to claim 2, wherein the straight line for obtaining the slope is determined so that the one having the maximum absolute value of the error from the intermediate value or the average value is the minimum.