JPH05504038A - Scanning speed compensation - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Scanning speed compensation field of invention The present invention relates to the field of image processing, and more particularly to the field of image processing of CCD image scanners ( Relates to a system for compensating for variations in the speed of scanning (original documents).

Background of the invention The present invention relaxes the tolerances required on the (original) scanning mechanism and This was done in response to the problem of reducing the effects of fluctuations in scanning speed. . (Hereinafter, the movement of the document will be referred to as scanning, and the movement of the original will be referred to as scanning. The scanning of each photosensitive element is called a "scan". ) Linear currently in practical use At the technical level of the canning system, images (information N) on the same straight line can be input at the same time. the media or scanning head (linearly relative to the original) to It has been moved or the path of the light has been modified. scanning head Variations in the movement between the camera and the object (of the scan) will cause The image is distorted. Such distortions can be solved by compressing or enlarging various parts of the image, and by adjusting the brightness. There are wobbles, edge distortions, etc.

U.S. Pat. No. 4,591,727, Gaebeljn et al. d 5tate 5canner ForA Variable 5peed Solid state scanner for variable speed transport (of documents) ), the scanning timing (of the CCD) depends on the transponder that moves the document being scanned. synchronized to the default speed. According to this, the amplification factor of the output signal depends on the scanning linear velocity. Since the integration time (electrons of the CCD) varies (note, the output signal of the CCD is generally proportional to the integration time). Therefore, the brightness of the screen may become uneven. It is possible to prevent this from happening. If the document speed drops below a certain threshold, This system selects only part of the scan (of the CCD) and removes the data from the other (scan of the CCD). data is thrown away.

U.S. Patent No. 4.8711.119, 13ystaa by Belkirch et al. For 5ynchron+ztnglt+tegratlon Pu1s es With Integration Signal 1n an Asy nchronous Ra5te Chichi@Input 5 ” (“Synchronization using integrated signals in an asynchronous rask-input scanner”) In the ``Nokulus System''), a scanning array containing rusks is maintained at a constant value. The integration time (electronic of the CCD) is different from that of an asynchronously driven system. ζ4° to compensate for accumulated errors in the speed of scanning (documents) In order to A signal is generated at a predetermined time. One effect of such adjustments is the There is an occurrence of artifacts in the force image. The artifact is a line on the image. It often occurs as enlargement or compression in random areas.

Summary of the invention The present invention is capable of capturing pixel light from each pixel area of the print on the original screen from the correct position. Some use sensor arrays with multiple scan lines to ensure that each The sensor array captures light from the relevant pixel area of the screen of the media being scanned. In order to capture the image, M photosensitive elements are provided which are located exactly adjacent to each other. one of the screens taking the sum of the light values sensed by each of the N photosensitive elements observing one pixel area; The desired value (for one pixel area) can be obtained.

In another variation of the invention, a weighted average of the pixel capture signals from each pixel region of interest on the screen is provided. The target pixel value is determined by the average value. Scan line at the correct position among the sensor scan lines The motion-induced image is calculated by summing the products of the signals from the Image quality deterioration is reduced.

In this system, an image is generated for a fixed time corresponding to the scan line (pixel data) capture rate. During the interval, it is necessary to reduce (signal) the amount of movement of the mechanism. It is. By selecting appropriate pixels in the image and summing the accumulated electrons, Tolerances in mechanical drive and positioning of objects (by drive) are greatly simplified This significantly improves the economic efficiency of the entire system.

As mentioned above, the first purpose of the present invention is to scan images in an image scanner. It consists in providing compensation (for variations in speed).

Furthermore, it is an object of the present invention to During capture (of pixel data), the position sensor (of the document) Provides a system for determining which scan line is at the correct position among a plurality of scan lines That's true.

Another object of the invention is to determine the weighting factors applied for each scan line. It is important to effectively utilize the position feedback function from position sensors to .

The foregoing and other objects of the present invention, where like symbols indicate like parts, are used throughout the specification. This will become even clearer by matching the drawings in the section with the descriptions below. Ru.

Brief description of the drawing FIG. 1 shows a preferred embodiment of the invention in block diagram form.

Figure 2 shows a scanning line linear sensor with multiple scanning lines arranged in a matrix array. It is shown with an exploded view showing the individual photosensitive elements.

FIG. 3 shows the apparent positions of photosensitive elements corresponding to pixels on the original screen.

Figure 4 shows the right deviation due to mechanical tolerance in the object positioning mechanism. This is what is shown.

Figure 5 shows the left deviation due to mechanical tolerance in the object positioning mechanism. This is what is shown.

Figure 6 shows the apparent position of the photosensitive element corresponding to the pixel of the original screen by applying the weighted average. This is what is shown.

Figure 7 shows a mechanism for determining the position of an object with the aim of reducing system costs. Calculation of the weighted average value ( values).

Figure 8 shows a more detailed feedback block diagram for scan line selection. be. This feedbank provides the necessary A signal is generated.

In FIG. 1, a screen 30 is imaged onto a CCD image sensor 33 by a lens 31. It will be done.

The infrared cutoff filter 42 is located between the screen 30 and the lens 31. CCD image The analog output of the sensor 33 is processed and digitized in block 36. Ru. The position sensor 34 generates a signal corresponding to the absolute position of the screen 30, and this signal is An input to the scan line selection feedback program 38 is provided. CCD image sensor 33 appropriate scan lines utilize the output from the scan line selection feedback block 38. to the scanline store (buffer of data from the scanline) and ALU block 37. , and the sum of the signals from the selected scan lines is calculated. captured picture Final reconstruction and storage of the image takes place in block 39. This accumulation area (Bro From the back 39), the image can be output to a hardcopy device 40 and a display device 41, and the image quality can be improved using image manipulation software. Ru.

In FIG. 2, the CCD image sensor 33 is a linear sensor array type. It is composed of a plurality of M scanning lines 14, and each scanning line has a plurality of photosensitive elements. It is made up of (pixels). In a preferred embodiment (the CCD image sensor has ) The number of scanning lines 14 is seven. Sensor scan 1! ■There is a similar center below 4. Horizontal shift register consisting of multiple elements along the length of the array There is a ta 17. One row of photosensitive elements is indicated at 20 in the figure. in row 20 The photosensitive elements (hereinafter also referred to as pixel elements) are numbered 21 to 27, and are indicated by the arrow 19. is the relative movement between the object to be scanned 30 and the CCD image sensor 33. It defines the direction.

In FIG. 3, the photosensitive elements 24 in column 20 and each corresponding pixel in each other column of the sensor The child defines the center position of the sensor, which is indicated by the center line denoted by CL. be done. The center line of the linear array is the screen pixel SP on the screen 30 to be scanned. It coincides with the center of 2. For any given screen, many pixels cover the screen. It is located in the grid matrix that is created. In the (screen) scanning process, At any particular time (of the scan), only one screen pixel (of the scan) This becomes the target pixel. The (target) pixel is indicated by SF3. The picture before the target pixel The pixel (that is, the pixel that has already been scanned) is indicated by SF3, and the next pixel (all pixels) is indicated by SF3. In other words, the next pixel to be scanned) is indicated by SPI. In the state shown in Figure 3, the movement The position sensor 34 detects that the pixel elements 23, 24, and 25 are This shows that the illuminance from the correct pixels of the surface can be accurately sensed. In the preferred embodiment In this case, a photosensitive element corresponding to one pixel SP2 of the screen, for example 23.24.2 The number of photosensitive elements such as 5 is equal to 3. This number is defined (in the text) as N. It will be done. In other words, three image sensor pixels cover one pixel on the screen. It is used for. The scanning speed (of documents) remains constant at normal speed. If held, the feedback signal (from position sensor 34) When scanning, the signals from (signals from) these three central pixels are always recorded.

Under conditions where the speed of the mechanism varies, the aiming position will also vary. example For example, if the screen slows down temporarily, the normal centerline CL will change to the next scanned image. The plane point is not reached, but the preceding series of scan lines (to the center line CL) come to the correct position. .

In this case, the position sensor 34 indicates that the photosensitive (pixel) elements 24, 25, 26 are It generates a signal indicating that it is accurately sensing the illuminance from a large pixel. This is shown in Figure 4. Shown below.

A similar situation occurs when the scanning mechanism is accelerated. In this case, the position The sensor 34 allows the pixel elements 22, 23, 24 to accurately measure the illuminance from the correct pixel of the screen. It generates a signal indicating that it is sensing something. This state is shown in FIG.

The weighted average approach is shown in Figures 6 and 7. In Figure 6, column 2 (of scan lines) The center line of the 0 pixel element 24, that is, the linear array, is the center of the pixel on the screen 30. matches.

In this position (shown in Figure 6), no errors have occurred regarding the movement and the position The position sensor 34 detects that the pixel elements 23, 24, 25 correct the illuminance from the correct pixel of the screen. Indicates that it is accurately sensed (generates a signal).

In FIG. 7 the scanning mechanism is accelerated again. any photosensitive element (signal of) is selected and (signal of selected photosensitive element) is adjusted by weighting factor. The operation shown in FIGS. 4 and 5 is improved by receiving the following information. in this case , position sensor 34 detects that all pixel elements 22, 23, 24, 25 are correctly displayed on the screen. It generates a signal indicating that it senses a portion of the natural illuminance. (The position sensor 34 ) position, the pixel elements 21.22.23.24.25.26 . A weighting factor for each of the 27 is generated. For example, as shown in FIG. The table below represents the weighting factors for each photosensitive element.

Element number weighting factor 23 100% 27 0% The above table can be converted and the pixel value of the screen can be determined from the following formula.

(pix 1 zero 0%) + (pix 2 0%) + (pix 3 * 1 00%) + (4 pix 100%) + (5 pLx 100%) + (pix 6 * 0%) + (pix 7 0%) Same as pixel value of one screen By using the approach, the pixel value of the screen in the case of Fig. 7 can be calculated by the following formula: Explain the weighted average (value) that represents. That is, each signal from the 7 rows of scan lines is After each (each pixel of) is multiplied by a weighting factor, their sum is taken.

(pix 1 zero 0%) + (pix 2 20%) + (+) IX 3 Books 100%) + (pix 4*100%) + (pix 5 books 80 %) 10 (pix 600%) + (pix T00%) Pixel value diagram of one screen To determine the correct pixel selection in the operations shown in 4 and 5, or To determine the weighting factors needed for the operations shown in Figures 6 and 7, the scan line selection in Figure 8 A feedback block 38 can be used. Constant scanning speed , the sensor represents the optimal pulse velocity that would be observed from the position sensor 34. Based on timing (document scanning), a stable reference frequency is generated (obtained) ). The signal denoted A (in Figure 8) generated in this way is at the reference frequency. It is generated by number generator 81 and sent to counter 79. Signal A is the subtractor stay. The difference B-A is subtracted from the position sensor signal B at step 82, and the difference B-A is Represents the relative position (difference) when compared with. Decoding, which is a lookup table, etc. A double block 83 determines the weighting factor required for each photosensitive element, so that B-A The signal is used by the scan line store (scan line data buffer) and the ALU block 37. Convert it into a usable form. The encoder output signal is converted to a counter of the same type as counter 79. A signal B is generated by inputting the signal to the printer 80. The table below provides the weighting factors. This is part of an example lookup table.

input 83 pjxl pix2 pjx3 pjx4 pix5 pix8 pix 7+1 0 0 90100100 10 0+2 0 0 80100100 20 0 + 3 0 0 70100100 30 0 or more Preferred implementation of the present invention As mentioned above, many variations and modifications may be made without departing from the essential spirit of the invention. It is obvious that you can do two things. Therefore, the scope of the appended claims is is intended to cover all such alterations and modifications that fall within the true scope of There is.

abstract The present invention provides a sensor having multiple scan lines to capture a target pixel in an object. I'm using saare. Each sensor detects the screen of the scanned media (document). are substantially adjacent to each other so that light from one pixel area of the photosensitive element can be captured by a plurality of photosensitive elements. It is equipped with a plurality of photosensitive elements located at the same location. Monitoring the absolute position of an object This generates a feedback signal, and by using this signal, it is possible to determine which sensation Determine whether the light element senses the desired screen pixel area. As a result, (of the object ) Compensation is made for changes in the speed of movement during the scan. Other modifications of the present invention to calculate the (brightness) value for the desired screen pixel position. There is a configuration that uses a weighted average of (signals from) elements. According to this, the correct position signal from the scanning line of the sensor that The sum of the products with the correct weighting factor determined by the feedback signal from the This reduces image quality deterioration caused by changes in scanning speed. It will be done.

international search report -Ku Yiyi-h, m, ua-11@PCT/IJS 91108539AN)- IAFJG A+Nr’JfX MNNI:XE

Claims (14)

[Claims] 1. Scanning speed compensator, including: intensity of light hitting each photosensitive element (brightness) an image sensor array consisting of a plurality of photosensitive elements that provides an electronic signal indicative of the A means for forming an image on the aforementioned image sensor array; detects the relative position between the image sensor array and the screen to be scanned, and In order to provide a position signal indicating the position of the target pixel area from the screen formed on the means of The signal provided by the photosensitive element corresponding to the position of the desired pixel area in the original screen is means for selecting as a compensation signal (for fluctuations) said selected signal for subsequent A means of accumulating for use. 2. The scanning speed compensator of claim 1, comprising: for each pixel area of the screen; The desired pixel area and location on the scanned screen to calculate the weighted average value of In order to assign a weight value to each signal output from a group of photosensitive elements that are aligned in a means of. 3. The aforementioned image sensor array is formed from M scanning lines of photosensitive elements, Among the M scanning lines, there is one on each of N (N≦M) scanning lines; A scanning line is one line of the screen for a column of N photosensitive elements (forming a vertical column). 2. The scanning rate compensator of claim 1, wherein pixels are formed. 4. The aforementioned image sensor array is formed from seven scanning lines of photosensitive elements (front Among the seven scanning lines, there is one on each of the three scanning lines, and there is a (forming vertical rows) of three photosensitive elements (forming vertical columns); 2. The scanning speed compensator of claim 1, wherein the pixels of the screen are formed by: 5. Detects the relative position between the aforementioned image sensor array and the screen being scanned 2. The scanning speed compensator of claim 1, wherein said means for Motion sensing that provides signals representing movement between the sensor array and the screen being scanned knowledge means, In conjunction with the aforementioned motion sensing means, the aforementioned motion signal is received and the magnitude of the aforementioned motion signal is detected. The size is compared with the size of a reference signal, and an image is formed from the screen onto the image sensor array. A function of (the result of) comparing the aforementioned position signals representing the position of the desired pixel region being as a position signal output means. 6. The above-mentioned position signal output means linked to the above-mentioned motion sensing means comprises: the scanning speed compensator of item 5; It has an input end for receiving the above-mentioned motion signal, and a count (receiver) representing the magnitude of the motion signal. counter means for providing (No.); Means to generate a stable reference count (signal), representing the magnitude of the movement signal Receive the aforementioned count (signal) and the aforementioned reference count (signal), and display the aforementioned count (signal) from the screen. The above-mentioned position represents the position of the target pixel area being imaged on the image sensor array. Comparison means for providing position signals. 7. 7. The scanning speed compensator of claim 6, wherein said comparing means comprises: The above-mentioned count (signal) representing the magnitude of the signal and the above-mentioned stable reference count (signal) ), and an output representing the difference between the two input signals. a subtractor to provide the value, Enter the output value from the aforementioned subtractor and add it to each of the selected signals (to be multiplied) Decoder means for providing weighting factors. 8. used in systems where the image and image sensor means move in conjunction with each other. , a scanning speed compensator containing the following configuration, input the image and convert it into an analog signal. The image sensor means for converting, digitizing the photosensitive element to provide the signal, means for digitizing the aforementioned analog signal; means for generating positional information (position signal) regarding the relative movement of the image and the sensor; Means for selecting a group of photosensitive elements corresponding to a particular pixel of an image, representing said pixel of an image combining the aforementioned digitized photosensitive element signals from the aforementioned selected photosensitive element groups. to generate image pixel values that are compensated (for variations in) velocity by processing means. 9. The scanning speed compensator of claim 8, comprising: for each pixel region of the image; pixel area and location of interest on the scanned image to form a weighted average value of The signal output from the selected photosensitive element that is aligned (corresponding) with the means for assigning weight values (to be multiplied by). 10. The aforementioned image sensor means is formed from M scanning lines of the photosensitive element, Among the M scanning lines, there is one on each of N (N<M) scanning lines. A scanning line is one line of the screen for a column of N photosensitive elements (forming a vertical column). 9. The scanning rate compensator of claim 8, wherein pixels are formed. 11. The aforementioned image sensor means is formed from seven scanning lines of the photosensitive element (front Among the seven scanning lines, there is one on each of the three scanning lines, and there is a (forms a vertical column) for each column of three photosensitive elements, one pixel of pixels forms 9. The scanning speed compensator of claim 8. 12. Detecting the relative position between the aforementioned image sensor means and the image being scanned 9. The scanning speed compensator, image sensor of claim 8, wherein said means for: motion sensing for providing a motion signal representative of motion between the sensor means and the image being scanned; means, In conjunction with the aforementioned motion sensing means, the aforementioned motion signal is received and the magnitude of the aforementioned motion signal is detected. The image formed on the image sensor means is compared with the magnitude of the reference signal. We present the aforementioned position signal representing the position of the pixel region of interest as a (resulting) function of the comparison. position signal output means for providing 13. The above-mentioned position signal output means linked to the above-mentioned motion sensing means includes the following: The scanning speed compensator of claim 12, It has an input end for receiving the above-mentioned motion signal, and a count (receiver) representing the magnitude of the motion signal. counter means for providing (No.); Means to generate a stable reference count (signal), representing the magnitude of the movement signal The above count (signal) and the above reference count (signal) are received, and the image sensor The aforementioned position signal representing the position of the desired pixel area of the image being imaged on the sensor means. Comparison means to provide. 14. 14. The scanning speed compensator of claim 13, wherein said comparing means comprises: The above-mentioned count (signal) representing the magnitude of the signal and the above-mentioned stable reference count ( has an input end for receiving a signal) and represents the difference between the two input signals. a subtractor to provide the output value, Enter the output value from the aforementioned subtractor and add it to each of the selected signals (to be multiplied) Decoder means for providing weighting factors.