JPH1117892A - Image processor - Google Patents

Abstract

(57) Abstract: An image processing apparatus executes a correction process according to the inclination between a document surface and a reading unit, and obtains a good image without distortion. An image having an image input unit capable of inclining a reading surface of a document and a reading unit that reads the reading surface by a specified angle, and a processing unit that processes image information input by the input unit In the processing device, there is provided a means for performing correction at the time of image processing in accordance with the designated angle, which is a tilt between the moving reading direction of the document and the reading unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus for processing an image input from a scanner.

[0002]

2. Description of the Related Art In recent years, scanners have been increasingly used for personal use. In the use of scanners for personal use, there are a wide range of reading ranges and required reading resolutions, such as capturing image data such as photographs, capturing ordinary text data-oriented documents, and capturing small and very small printed characters such as business cards. Range.

The size of the scanner itself is also
Somewhat smaller is preferred.

At present, the mainstream scanner satisfies the resolution required for reading a document or the like.
A line-type CCD image sensor capable of taking many image pickup elements in one direction is used.

In this case, the entire document is scanned by adjusting the horizontal direction of the document to the direction of the arrangement of the image sensors and scanning the reading unit in the vertical direction of the document (vertical direction of the array of the image sensors). The same applies to a hand-type scanner, in which the orientation of the image sensor is aligned in the horizontal direction of the original, and the original is scanned by scanning the hand scanner in the vertical direction of the original.

There is also a self-propelled type hand scanner, and the scanner self-propelled in a direction perpendicular to the direction in which the imaging devices are arranged.

A sheet feeder-type scanner performs reading by moving a document, not by moving the reading portion of the scanner. However, the principle is the same only with a relative difference.

Normally, the maximum optical resolution in the main scanning direction of a scanner using a line-type image sensor, that is, in the horizontal direction with respect to a document, is determined by the number of image pickup elements of the image sensor and the reading width. Assuming that the number of imaging elements is N and the width read by the imaging elements is L, the maximum optical resolution in the main scanning direction is N / L.

The sub-scanning direction, that is, the vertical direction of the document, is affected by the speed of document feeding and the timing of image pickup by the image pickup device. Assuming that the relative scanning speed between the original and the image sensor is V, and the timing cycle of imaging by the image sensor is T,
The maximum optical resolution in the sub-scanning direction is 1 / (VT).

This maximum optical resolution determines the resolution which is the basic performance of the scanner device. The easiest way to increase the maximum optical resolution in the sub-scanning direction is to reduce (slow) the scanning speed of the document while keeping the imaging timing constant.

Further, since the scanning speed of the document can be arbitrarily changed to some extent, when the resolution is to be changed, an image having an arbitrary resolution can be obtained by controlling the scanning speed of the document.

To increase the maximum optical resolution in the main scanning direction, use an image sensor having a large number of image pickup devices,
It is necessary to reduce the reading width. Increasing the number of image sensors in the image sensor has technical limitations and costs.

For this reason, the input image is devised to obtain a higher resolution by performing interpolation between pixels and the like in a software manner. In order to reduce the reading width, for example, use of a zoom is conceivable. However, it is rarely used because the lens system becomes complicated and the size of the apparatus cannot be reduced.

In order to increase the resolution by reducing the reading width, for example, Japanese Utility Model Application Laid-Open No. 62-196455
In the gazette, in an electronic blackboard of a type in which a scanner moves and reads on a blackboard, the scanner itself including a line-type image sensor is configured to rotate in a plane parallel to a plate surface to be read. It describes a method of reducing the reading width and increasing the resolution in the main scanning direction.

Normally, the direction in which the line-type image sensors are arranged is set at a right angle to the moving direction of the scanner. However, when the scanner rotated by the angle α is moved,
Since the reading width is cos α times, the resolution in the main scanning direction can be reduced to 1 / cos α times. In this embodiment, an angle detection mechanism is provided, and the resolution in the sub-scanning direction is adjusted to the resolution in the main scanning direction by changing the moving speed of the scanner on the blackboard according to the detected angle.

[0016]

According to the above prior art,
Higher accuracy in the sub-scanning direction of the scanner or setting of an arbitrary resolution can be performed relatively easily.

However, in terms of improving the accuracy in the main scanning direction, the maximum optical resolution cannot be as large as that in the sub-scanning direction for technical and cost reasons. Therefore,
When it is desired to increase the resolution in the main scanning direction, a method of interpolating the pixels in the main scanning direction by software is used to increase the resolution.

However, this is an interpolation to the last, and the resolution is not optically large. Therefore, the quality of the obtained image is inferior to that obtained at the same optical resolution.

In addition to the case where the resolution is increased, for example, when the maximum optical resolution is 200 dpi, 170 d
When an input image of pi is desired, an image is obtained by software correction. First, after inputting the image at 200 dpi, the image is converted to 170 dpi for soft correction.
Convert to Also in this case, purely optical resolution 170 dp
More than 200 dpi to 170 dpi than the image taken with i
An image obtained by software-converting the image into the software has inferior image quality.

In the example of the electronic whiteboard disclosed in Japanese Utility Model Application Laid-Open No. 62-196455, a method is described in which the resolution in the main scanning direction is arbitrarily increased by reducing the reading width.

According to this method, although the reading range is reduced, the optical resolution can be arbitrarily increased. Mechanically, it can be easily realized technically only by adding a rotating part and an angle detecting part.

However, in practice, when reading is performed by moving the tilted line-type image sensor, the obtained image has a distorted shape such as a parallelogram when scanning a rectangle, for example. Will be obtained.

This utility model states that by changing the angle of the scanner, it becomes possible to read at an arbitrary resolution, and by recording the input data as it is, an arbitrarily enlarged image can be recorded. But
No image correction for restoring a parallelogram as an input image to a rectangular image as an original image is performed.

Since only the angle is detected and no means for specifying the angle is provided, the angle of the required tilt is calculated in accordance with the resolution specified by the operator, and the reading unit is tilted. Can not.

In general, when inputting an image, the resolution is designated. If there is no means for specifying the resolution or angle, the operator needs to calculate the required rotation angle from the resolution required by himself and rotate the scanner by that angle,
It will be very burdensome.

According to the present invention, when the operator specifies a required resolution, a line type image sensor tilted by a required angle according to the resolution is obtained by reading obliquely. The purpose of the present invention is to correct the image using the angle in order to restore the original image from the existing image.

The purpose of this correction is to obtain an image designated to be read at a resolution lower than the maximum optical resolution with higher image quality. When the resolution specified by the operator is smaller than the maximum optical resolution, image input is performed at a resolution that is an integral multiple of the specified resolution, and then the pixel values are averaged to obtain a high-quality image.

When an original is scanned with a hand scanner or the like inclined obliquely, the inclination angle between the original scanning direction and the direction of the line-type image sensor is detected, and the angle is used to obtain the image. It is intended to correct. At this time, since the operator merely operates the scanner at an arbitrary angle, the operator cannot know the resolution in the sub-scanning direction. An object of the present invention is to obtain an image resolution from the detection angle.

Although a line-type image sensor like a color line CCD is arranged in three rows of RGB, if the document is scanned while tilted obliquely, the difference in the reading position for each row becomes large. Will happen. An object of the present invention is to correct a distortion after correcting a shift of an input image that occurs when an image sensor arranged in a plurality of rows is used.

[0030]

An image processing apparatus according to claim 1, wherein an image input section capable of inclining a read surface of a document and a reading section for reading the read surface by a specified angle, and the input section. A processing unit for processing image information input by the image processing apparatus, wherein a means for performing correction at the time of image processing in accordance with the movement reading direction of the document and the designated angle that is the inclination of the reading unit. An image processing apparatus comprising:

According to a second aspect of the present invention, there is provided an image processing apparatus, comprising: means for detecting an inclination angle between a read surface of a document and a reading unit for reading the read surface; a processing unit for processing input image information; Means for performing correction at the time of image processing in accordance with the tilt angle detected by the means.

According to a third aspect of the present invention, the image processing apparatus further comprises means for determining a resolution to be given to the image data according to the inclination angle detected by the detecting means or the correction amount executed by the correction executing means. An image processing apparatus according to claim 2, wherein:

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A reading section having a line type image sensor, moving means for allowing the reading section to scan the entire original, and a plane parallel to a surface to be read of the original are described below.
An image input device including a rotation unit that can rotate the reading unit, a control unit that controls the rotation angle and the moving speed of the reading unit, a storage unit for input image data, and processes the image data Assume that there is an image processing unit.

In the present invention, in order to achieve the above object,
When scanning is performed by rotating the scanning unit diagonally,
Although the resolution becomes higher than when the image is not rotated, the image processing unit corrects the image by using the rotation angle to correct the image distortion.

In an input image obtained by the operator moving the reading unit itself, as in a hand scanner, the angle between the arrangement direction of the image sensors in the reading unit and the scanning direction of the image input device of the operator is accurately determined. Since it cannot be known, accurate image correction cannot be performed. In this case, an angle detection mechanism is provided, and image distortion is corrected by using the detection angle obtained from the angle detection mechanism to correct image distortion.

The angle detecting mechanism may be one that directly knows the moving direction of the document or one that knows the moving direction of the document by image processing.

In the example of the hand scanner, the operator does not directly specify the resolution of the image. But,
Using the detection angle or the correction value of the image, the resolution of the image can be calculated, and information on the resolution can be given to the image.

When a plurality of lines of image sensors are arranged like a line CCD for color, and when the document is scanned while being tilted obliquely, the distance for each line of the image sensor and the rotation of the image sensor are determined. An image at a shifted position is read in the sub-scanning direction for each column according to the angle. In this case, the image read in each column is subjected to image processing for aligning the sub-scanning direction using the distance of the column and the angle, and then the image distorted using the angle is processed. to correct.

FIG. 1 is a block diagram of an image input device and an image processing portion.

The image input device 7 includes a reading unit 4 capable of reading an image by a line-type image sensor, a rotation mechanism unit 2 capable of rotating the reading unit 4 in a plane parallel to a surface to be read of a document, and a document. The driving unit 3 is capable of moving the reading unit 4 so that the whole can be scanned.

When the operator specifies the resolution, the control unit 1 transmits the rotation angle of the reading unit 4 to the rotation mechanism unit 2 and the speed of movement to the drive unit 3 based on the resolution.
The image input device 7 inputs an image of a document. Reading unit 4
The input image data read by is stored in the image data storage unit 5.

At this time, the input image is distorted according to the rotation angle of the reading unit 4. The image processing unit 6 corrects the image based on the angle and moving speed given by the control unit 1.

Next, a correction method will be described.

FIG. 2 shows the concept of the distortion of the input image and the correction when the original is scanned while the reading section is inclined.

When the original 8 is read, the reading section 4 is tilted, and only the reading range 9 is scanned in the reading direction.
Input image data 10 is obtained. The reading range 9 represents a scanning range of the reading unit necessary for scanning the entire original 8.

The input image data 10 becomes an image distorted only in the vertical direction according to the inclination of the reading unit 4, the moving speed of the reading unit 4, and the timing of image pickup by the image sensor.

Normally, the image pickup timing of the image sensor is constant, so that the moving speed is determined according to the resolution in the sub-scanning direction. The resolution in the main scanning direction corresponds to the inclination of the reading unit 4. Therefore, when the resolution in the main scanning direction and the resolution in the sub-scanning direction are matched, if the inclination angle of the reading unit 4 is determined, it is determined how much the image should be corrected in the vertical direction.

L is the length of the reading width of the reading unit 4, α
Represents the angle of inclination between the moving direction of the reading unit 4 and the direction in which the image sensors of the reading unit 4 are arranged, and the width of the reading range when the angle is inclined _α is set to Lα.

FIG. 3 is a flowchart from the time when the operator specifies the resolution to the time when the corrected image is obtained in the image input device / image processing of FIG.

Hereinafter, the maximum optical resolution in the main scanning direction is D
_MAX , the resolution specified by the operator is D _OPE , the rotation angle of the reading unit 4 is α, the moving speed for sub-scanning is V, and the image sensor timing is T. The reading width is L, the reading width when the reading unit 4 is rotated by _α is L _α , and the number of imaging elements of the line-type image sensor of the reading unit is N.

According to the flowchart of FIG. An operator specifies a resolution for reading a document on the personal computer 1.

102. Confirm that the reading mode is the oblique reading mode (in the case of oblique reading, the reading width is narrow, so it is necessary to check whether the reading mode is the oblique reading mode).

103. It is determined whether the designated resolution D _OPE is larger than the maximum optical resolution D _{MAX in} the main scanning direction or not.

104. When D _MAX is equal to an integral multiple of D _OPE , the reading section does not need to be tilted. For example, D
When there is a relation of _MAX = k × D _OPE (k is an integer greater than 1), in the process of 109, the image input is performed by averaging the pixels for every k pixels in the horizontal direction or by thinning out at the time of reading Will be done.

105. Adjust the resolution in the sub-scanning direction according to D _OPE . The imaging timing T and the reading speed V are adjusted so that D _OPE = 1 / ( _VT ). Normally, V is adjusted because T is a constant value. As a result, the resolution in the main scanning and sub-scanning directions is matched. The angle α is set to 0.

106. From D _OPE , the angle α at which the reading unit is inclined is determined. D _MAX = N / L, D _OPE = N / L _α ,
From the relationship of cos α = L _α / L, α = Cos ⁻¹ (D _MAX
/ D _OPE ) (see FIG. 1).

107. The imaging timing T and the reading speed V are adjusted so that D _OPE = 1 / ( _VT ). Normally, V is adjusted because T is a constant value. As a result, the resolution in the main scanning and sub-scanning directions is the same. D _OPE =
As can be seen from the relationship of N / L _α = 1 / (V · T), the moving speed V is also determined from the angle α.

108. The reading unit 4 is tilted at an angle α, and an image is read while scanning the document at a speed V. The read image is recorded in the image data storage unit 5. D
_{When MAX} is equal to an integer multiple of D _OPE , pixels may be thinned out at the time of reading.

109. The image is corrected in the vertical direction based on the resolution D _OPE or the angle α (see FIG. 2). D _MAX
And when the integer multiple of D _OPE is equal and pixels are not decimated at the time of reading, it is possible to adjust the resolution in the main scanning direction by averaging the pixels after correcting the image in the vertical direction. . Also, as can be seen from FIG. 2, there is a portion other than the necessary image (the portion of the original 8) when obliquely reading. This may be deleted from the image data storage unit.

The rotation mechanism 2 is not mechanical but may be optical means using a prism or the like.

The rotating mechanism 2 may be a mechanism for rotating the entire scanner, or a rotating mechanism inside the reading section.
A mechanism for rotating only the line type image sensor may be used.

The driving section 3 may move a document instead of moving a reading section, as in a sheet feed type scanner. Further, manual driving such as a hand scanner may be used. In this case, since the moving speed V is determined by the operation of the operator, it is necessary to adjust the imaging timing T.

FIG. 4 is a block diagram of the image input device and the image processing part.

The image input device 18 includes a reading unit 15 capable of reading an image by a line type image sensor, a moving speed detecting mechanism 14 for moving the reading unit 15 to operate the entire original, a moving direction, and a moving direction of the image sensor. An angle detection mechanism 13 detects how much the line is inclined from the vertical.

When the operator operates the document by moving the image input device 18, the control unit 12 controls the moving speed detecting mechanism 1.
4, the reading timing is transmitted to the reading unit 15 using the speed.

Thus, the resolution in the sub-scanning direction is kept constant. The image read by the reading unit 15 is recorded in the image data storage unit 16. The image processing unit 17 obtains the detected angle and the moving speed from the control unit 12, corrects the image data in the image data storage unit 16, and adds resolution information.

FIG. 5 is a flowchart showing a process in which the operator operates the image input device and obtains a corrected image in the image input device and image processing of FIG.

Hereinafter, the maximum optical resolution in the main scanning direction is D
_MAX , the detection angle of the angle detection mechanism 12 is α, the detection movement speed of the movement speed detection mechanism 14 is V, and the imaging timing of the image sensor is T. The reading width is L, the reading width when the reading unit 4 is rotated by _α is L _α , and the number of imaging elements of the line-type image sensor of the reading unit is N.

110. Confirm that the reading mode is the oblique reading mode (in the case of oblique reading, the reading width is narrow, so it is necessary to check whether the reading mode is the oblique reading mode).

111. The moving speed V at which the operator operates the image input device 18 is detected. Here, it is determined that the image input has been completed when the moving speed stops.

112. The reading timing T is changed according to the moving speed V. That is, D _MAX = 1 /
The control unit 12 transmits the reading timing to the reading unit 15 so that the reading timing becomes (V · T), and the reading is performed. Thus, the resolution in the sub-scanning direction can be kept constant.

113. The reading unit 15 reads an image in accordance with the reading timing and records the image in the image data storage unit 16.

114. The angle detection mechanism 13 detects the reading unit 15 and the angle α in the movement direction. Here, detection is performed only once at the beginning of reading. The resolution in the main scanning direction is determined by the angle α (the determined resolution is set as D _OPE ).

115. The moving speed V at which the operator operates the image input device 18 is detected. Here, it is determined that the image input has been completed when the moving speed stops.

[0075] The angle α at 116.114, determines the D _OPE, and which, from the moving speed _{V, D O PE = 1 (} V ·
T is changed to become T). Thus, the resolution in the main scanning direction and the resolution in the sub-scanning direction can be made uniform.

117. The reading unit 14 reads an image according to the reading timing and records the image in the image data storage unit 16.

118. Based on D _OPE or angle α,
The image processing unit 17 corrects an image distorted by oblique reading. The correction method is the same as 109.

119. After the correction, _DOPE is given to the image.

At step 114, the angle detecting mechanism 13 detects the angle at the beginning of reading. However, during reading, the image may be corrected using the average value of the angle at the image correction stage while always reading the angle. .

The angle detecting mechanism 13 may be a mechanical mechanism such as a trackball, or may be a mechanism for detecting using image processing.

FIG. 6 is a conceptual diagram showing an image correction method when a color line CCD is used.

The structure of the apparatus and the flow up to the correction are the same as in FIGS.

When an image is read by moving the reading section 19 composed of color line CCDs in three rows of RGB on the original 20, the input image data 21 to 2 are read.
As shown in 3, the reading position is shifted in RGB.

This shift is affected by the angle α and the column width d of the image sensor. Therefore, by using α and d, position correction is performed on the read image data 21 and 22 so as to match the reading position of B, and images 23 to 25 having the same position are obtained. Thereafter, similarly to FIG. 2, correction is performed in the vertical direction to obtain a final, corrected image 25.

These corrections are performed by the image processing unit 6 in FIG.
In FIG. 4, the image processing unit 16, and in the flowchart 3, 10
9. In the flowchart of FIG.

[0086]

According to the first aspect of the present invention, an image input with the reading unit tilted has a high optical resolution according to the tilt, but is distorted. This distorted image can be restored to the state of the original image, and an image with high definition and arbitrary resolution can be obtained.

According to the second aspect of the present invention, since the angle control section for tilting the reading section is not required, the configuration of the image input section is simplified.

According to the third aspect of the present invention, since the resolution can be calculated and given to this image, the operator can know the resolution of the input image.

[Brief description of the drawings]

FIG. 1 is a block diagram (No. 1) of the present invention.

FIG. 2 is a diagram (part 1) illustrating a point of a correction process according to the present invention;

FIG. 3 is a flowchart showing the operation of the present invention (part 1);
It is.

FIG. 4 is a block diagram (No. 2) of the present invention.

FIG. 5 is a flowchart showing the operation of the present invention (part 2);
It is.

FIG. 6 is a diagram (part 2) illustrating a point of the correction processing of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 control unit 2 rotation mechanism unit 3 drive unit 4 reading unit 5 image data storage unit 6 image processing unit 7 image input device 8 read original 9 read range 10 read image data 11 corrected image data 12 control unit 13 angle detection mechanism 14 Moving speed detecting mechanism 15 Reading unit 16 Image data storage unit 17 Image processing unit 18 Image input device 19 Reading unit 20 Original 21 Read image data 22 Read image data 23 Read image data 24 Position corrected image data 25 Position corrected image data 26 Corrected image data

Claims (3)

[Claims] An image input unit capable of inclining a read surface of a document and a reading unit that reads the read surface by a specified angle, and a processing unit that processes image information input by the input unit The image processing apparatus according to claim 1, further comprising: means for performing correction at the time of image processing in accordance with the designated angle, which is a direction of movement of the document and the inclination of the reading unit. 2. A means for detecting an inclination angle between a surface to be read of a document and a reading unit for reading the reading surface; a processing unit for processing input image information; Means for executing correction at the time of image processing in response to the request. 3. The image processing apparatus according to claim 2, further comprising: means for determining a resolution to be given to the image data according to the inclination angle detected by the detection means or a correction amount executed by the correction execution means. Image processing device.