JPH02202264A - Picture reading device - Google Patents

Abstract

PURPOSE:To attain the high speed and accurate automatic focus control by moving a projection lens to compute a parameter which reflects the sharpness of an input picture signal, then moving the projection lens more finely to compute a parameter which reflects the sharpness of the picture signal respectively. CONSTITUTION:A projection lens 1018 is turned up to the position of a limit switch 1019, and the sampling data (AF data = S value) is calculated for execution of the automatic focus control. The AF data calculates the square sum S of the difference between adjacent picture elements for a G(Green) signal with use of a parameter which reflects the sharpness of a subject picture. A 3-line parallel sensor is used to an input color sensor. Then a stepping motor 1014 is driven by an N pulse and the lens 1018 is turned. Then the sampling data (AF data) is calculated for automatic focus control. The AF data calculated previously is compared with the AF data calculated presently. Thus rotational position of the lens 1018 is controlled.

Description

Detailed Description of the Invention [Field of Application in Business A] The present invention relates to an image reading device that reads an image of a light-transmitting original such as a film by photoelectric conversion and performs digital image processing, and particularly relates to an image reading device that performs digital image processing by reading an image of a light-transmitting original such as a film. Regarding reading devices.

[Prior Art] When reading a light-transmitting original such as a film using a color sensor, in a color image reading device that performs automatic focus control, as shown in FIG. Autofocus data reflecting sharpness was sampled, and autofocus was controlled based on that data.

[Problems to be Solved by the Invention] However, calculating data for autofocus for all projection lens angles requires a large amount of calculation time. Control methods are needed.

[Means for Solving the Problems] The present invention provides a sensor for reading an image obtained through a projection lens for focus control, a movement control means for controlling eight shifts of the projection lens, and a movement control means for controlling the projection by the movement control means. A first calculation means for calculating a parameter reflecting the sharpness of the image signal from the sensor while controlling the lens, and a movement control means for calculating the image signal from the sensor while controlling the movement of the projection lens more finely than the first calculation means. 6) Claim 1 further comprising: a second calculation means for calculating a parameter reflecting the sharpness of the projection lens; and an automatic focus control means for controlling the g-motion control means using the parameter to automatically control the focus of the projection lens. It is as described.

[Function] According to the present invention, the parameters that reflect the sharpness of the input image signal are calculated while moving the projection lens, and the sharpness of the image signal is reflected while moving the projection lens more finely. By calculating parameters and using the parameters thus obtained, automatic focus control is performed quickly and accurately.

[Example] The present invention will be explained below with reference to Examples.

1 to 12 show a first embodiment of the present invention.
2 and 2 are drawings that best represent the features of the present invention.

Figure 1 is a block diagram of the image reading device*'1
001 reads 8 (blue) of the three primary colors from the input optical image C00% 1002 reads the same <G (green) CC9% 1003 reads the same < R (red) CC0% 1004 to 1006 are the three CCDs mentioned above Amplifiers for input color CCD signals from, 1007-1009
is an analog/digital C^/D) converter for the analog signals from the three amplifiers, and N1012 is an analog/digital C^/D) converter for the analog signals from the three amplifiers, and N1012 transfers the^/D-converted color digital signals from the three^/D converters to the microprocessor 1015. It is a buffer American sled for. 1013 uses masking calculations, gamma conversion, etc. to create three ^/Dll & device 1007
~100! The input color signal from l is sent to the printer (101
7) is a color signal processing circuit that converts the signal into a signal for output. Reference numeral 1014 is a stepping unit, which performs focus control by rotationally driving the projection lens TOIA. Reference numeral 1015 is a microprocessor, which calculates the sampling parameter S for automatic focus control, controls the lamp light amount power supply 101L, and drives the stepping motor 1014. do other things,
1016 is a power source that controls the amount of light of the lamp 1018^;
1017 is a color printer, 10151 is a projection lens that controls the focal length, and 1019 is a limit switch that provides a reference point when rotating the projection lens.

FIG. 2 is a process flow diagram relating to microprocessor 1015 for automatic control.

First, set the scanner motor ate (201L)
8) to set the reading position at the center of the Fresnel lens 708.

Then, at 202 (in the procedure shown in FIG. 12 described later)
Controls the amount of lamp light that illuminates the film.

Next, in step 203, the projection lens 1016 is rotated to the position of the limit switch 101g.

Next, in step 204, sampling data (^Fday-S value) for autofocus @group is calculated. AF mode is a parameter that reflects the sharpness of the target image, and in this embodiment, the sum of squares S of the difference between adjacent pixels shown in FIG.
In this embodiment, the input color sensor 809 uses a 3-line parallel sensor as shown in FIG. The light is focused on the CCD 809 by a lens 80B shown in FIG. 8, and the lens 808 is controlled to focus on the middle sensor (G signal in this embodiment) among the three sensors arranged in parallel.

Therefore, the G signal has the highest spatial resolution, and the number of pixels in the main scanning direction on the sensor corresponding to the projection surface of the Fresnel lens 708 is approximately 3000 fi elements, and the SOO pixel at the center of the main scanning direction of the Fresnel projection surface is used for calculation. It is targeted.

Next, in step 205, the stepping motor 1014 is driven with N pulses to rotate the projection lens 1014. In this embodiment, the projection lens 1014 is rotated by 3 degrees, which is N-10 in this embodiment.
14 rotates.

Next, in 206, sampling data (F data) for automatic focus control is calculated.

Next, in step 207, the magnitude of the AF data calculated last time and the F data calculated this time are compared, and if the F data value decreases L times (L-3 in this embodiment) consecutively (the third
13 points shown in the figure) performs the process 209, otherwise (until the above is executed M times (208)) 205
Return to processing.

This allows you to project! If the rotation angle of O14 deviates from the in-focus position by a large amount, calculation for automatic focus control can be omitted.

The rotational position of the projection lens 1014 is controlled to the position corresponding to the next sample point (22 points shown in FIG. 3) after the point (18 points shown in FIG. 3) showing the maximum value of the AF data calculated in 2011. .

ASmax-MA
It is determined whether X[1S(I+1)S(1)11 is larger than a predetermined constant value α, and if ΔSMAX>α, the process of 211 is performed, and if the above condition is not satisfied, the process of 212 is performed.
Process.

In step 211, the number of pixels for which AF data is calculated is set to 5oo pixels.

In step 212, the number of pixels to be subjected to F data calculation is set to 3000 pixels.

ΔSMAX is ΔSMA if the target image is completely flat.
x40, and takes a large value when a sharp edge exists in the target image. Therefore, if ΔSMAX<α, go to F
It can be assumed that sharp edges do not exist in the data calculation target pixels, and in that case, automatic focus control can be performed more accurately by increasing the number of data calculation target pixels.

In 213, the F data S value is calculated according to the number of pixels for which F data is calculated, which was set in 211 or 212.

At 214, the stepping motor 1014 is driven to rotate the projection lens 1014 by one pulse.

In step 215, the processes of steps 213 to 214 are repeated once (T-20 in this embodiment).

In step 216, the projection lens is rotated to the projection lens position (8 points in FIG. 3) that has the maximum value among the F data S values determined in steps 213 to 215.

FIG. 3 is a line graph showing values of the AF data S value (sum of squares of differences between adjacent pixels) corresponding to the rotation angle of the projection lens. The line graph at the top of Figure 3 is from 204 to Figure 2.
This is a graphical representation of the AF data S value calculated while coarsely rotating the projection lens 1018 in the process 208, and the line graph at the bottom of FIG. data S
This is a graphical representation of the values.

FIG. 4 is an external view of the 3-line parallel color sensor 809. The imaging lens 80 is installed parallel to the surface of the original to be read, and is focused on the G signal in the middle.
8 has been adjusted.

FIG. 5 shows the size of the aperture of each pixel of the 3-line parallel color sensor 809. 501 is a B (blue) line sensor, 502 is a G (green) line sensor, and 503 is an R (red) line sensor. B
The line sensor has low sensitivity, and to compensate for this, the opening size in the sub-scanning direction is larger than other R and G line sensors, so the spatial resolution in the sub-scanning direction is low.

FIG. 7 is an external view of the film reading device. 7
01 is the main body (scanner part) of the reading device, 702 is a projector unit with a built-in lamp, condensing lens, etc., 703 is a film holder for setting the film, 7
05 is a projection lens 1018 that controls the rotation of the stepping motor.
The belt 704 is the stepping motor 101.
The pulley directly connected to 4, 706 is the document table glass, 70
7 is a reflecting mirror, and 708 is a Fresnel lens for focusing a film image on a reading section inside the scanner.

FIG. 8 is a sectional view of the film projection system of the embodiment. A film image projected from the projector unit 702 is reflected by a reflecting mirror 707 and focused onto a mirror 805 by a Fresnel lens 708 . The images reflected by mirrors 805 to 807 are sent to an imaging lens 808 and sent to a CCD sensor 809.
is imaged. The CCD 809 is a 3-line parallel color sensor shown in FIG. A scanner motor 810 drives mirrors 805 to 807 to move the document reading position in the sub-scanning direction.

Figure 1O is ^F when the original image shown in Figure 9 is read.
This is an example of a graph displaying the Deday S value.

FIG. 11 is a timing chart of the drive pulse of the stepping motor 1014 and the calculation of the F data S value.

FIG. 12 is a processing flowchart of the microprocessor 1015 regarding lamp light amount control of the halogen lamp 803.

In step 1201, the lamp power supply 1016 is controlled to set the lamp voltage for irradiating the film to a predetermined value. The average value of the sensor signal values read in step 1202 is calculated, and a given value β (β-200 in this example) is calculated.
The light intensity of the halogen lamp 803 is reduced until the above-mentioned condition is satisfied.
(1203, 1204).

[Other Embodiments] FIGS. 14 and 15 are drawings relating to a second embodiment of the present invention.

In the first embodiment, one of the aa color sensor signals is used as the signal for extracting the parameters for performing the iJJjgA point control.

In the second embodiment, automatic focus control is performed using parameters extracted from three RGB signals.

In the case of the first embodiment, if edge components are unevenly present in a specific color signal of the film image (for example, an edge signal exists only in highly saturated blue), the parameters for automatic focus control are determined to have good values. In the second embodiment, automatic focus control is performed using parameters extracted from the three RGII signals, so that edge components may be unevenly present in specific color signals of the film image. The aim is to enable good automatic focus control.

FIG. 14 is a processing flowchart of the second embodiment.

At 1401 and 1402, the sum of squares of the difference between adjacent pixels for each of the R signal, G signal, and B signal 5IIs Sa
Find wS- (!4^, 14B, 1.4C, 14
0' is the same as Fig. 2 201゜202.203, 205)
.

At 1403, Swwax−(Ss + s, + S
If the value of s) decreases L times in a row, the process of 1404 is performed (after that, 140.1412.1403 should be executed M times (14E) and the process proceeds to 1404).

At 14o4, the projection lens 10 is placed at the next sample value V= of the maximum value v2 of the F data as shown in FIG.
18 rotation angles are controlled.

The F data value measured 1(i-0,1,,,M) at 1405 is 5s(i), 5o(1),
S! 1(i), A Swwax −MAX [
I So (ill)-S+1(i)11ΔS(IMA
II -MAX [I So (l order x) - saO)
I] Δ5III AX - MAX [I Ss (1
◆g-ss(t) ΔSl defined as 11? MAX'
Determine the signal that gives the maximum value among the values of eΔS(IMAX +ΔSIIMAI. In 1406, 1
The F data S value of the single signal determined in step 405 is calculated. F data (14F) calculated from the signal value
, 14G, 14H) to finely project the projection lens 1018.
(141 to 14, these are the same as 214 to 216 in FIG. 2).

Although the above processing requires more execution time than the first embodiment, it is possible to perform good automatic focus control even when edge components are present unevenly in a specific color signal of a film image.

FIG. 16 relates to a third embodiment of the present invention.

In the second embodiment, when finely controlling the rotation of the projection lens 1018 using the F data, automatic focus control was performed using one of the plurality of color sensor signals. In the third embodiment, FIG.
01 (the previous 16A to 161 are shown in Fig. 14
4A Same as P-1404) MAX (ΔS RM A
X +ΔSOMAX*Δ5avax,) > 2
...(1) (2 is a fixed value given in advance) It is determined whether or not the conditions are satisfied, and if the condition of equation 1 is not satisfied, the projection lens 30111 is finely adjusted using the three color signals of RGB signals. The rotation control is performed. That is, in 1602, from each of the R, G, and B signals to F
After sampling the data and driving the stepping motor with N pulses at 1603 and executing these M times (160
4) In step 1805, the projection lens is rotated to the maximum AF value determined in steps 1602 to 1604.

On the other hand, if 1601 satisfies the condition of formula 1, then 16
In steps 06-1610, the same processing as shown in FIGS.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide an image reading device that can perform autofocus fi4J control at high speed and accurately.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the first embodiment of the present invention, FIG. 2 is a processing flowchart regarding the microprocessor 1015, and FIG. 3 is a line graph showing values of F data S values corresponding to projection lens rotation angles. Figure 4 is an external view of the 3-line parallel color sensor 809. Figure 5 is a diagram showing the aperture size of each pixel of the 3-line parallel color sensor 809. Figure 6 is the sum of squares of the difference between adjacent pixels. Fig. 7 is an external view of the film reading device, Fig. 8 is a sectional view of the film projection system, Fig. 9 is a film original image, Fig. 1O is a graphical representation of the AF day S value, Fig. Fig. 11 is a diagram showing a timing chart of driving pulses of the stepping motor 1014 and F data S value calculation, Fig. 12 is a processing flowchart regarding lamp light amount control, 'fS
Figure 13 is a process flowchart of the conventional example, Figure 14 is a process flowchart of the second embodiment, and Figure 15 is a process flowchart of the second embodiment.
FIG. 16 is a processing flowchart of the third embodiment. The square of the four colors of the M art room] Mutori hakama! Figure 9, Figure 10 on the left side of the helmet, Figure 12.

Claims (1)

[Scope of Claims] 1) A sensor for reading an image obtained through a projection lens for performing focus control, a movement control means for controlling movement of the projection lens, and a movement control means for controlling the projection lens by the movement control means. a first calculation means for calculating a parameter reflecting the sharpness of the image signal from the sensor while controlling the movement;
a second calculation means for calculating a parameter reflecting the sharpness of the image signal from the sensor while controlling the movement more precisely than the calculation means; and automatic focusing control of the projection lens by controlling the movement control means using the parameter. An image reading device comprising an automatic focus control means. 2) The image reading device according to claim 1, wherein the parameter is a sum of squares of differences between adjacent pixels. 3) The image reading device according to claim 1, wherein the first and second calculation means calculate a parameter that reflects the sharpness of the signal near the center of the image from the sensor. . 4) In the image reading device according to claim 1, the first calculation means calculates a parameter that reflects the sharpness of the image signal regarding a specific pixel near the center of the image, and the second calculation means calculates a parameter that reflects the sharpness of the image signal regarding a specific pixel near the center of the image. An image reading device that calculates a parameter that reflects the sharpness of an image signal for a large number of pixels. 5) In the image reading device according to claim 1, when the value of the parameter in the first calculation means monotonically decreases a predetermined number of times in succession, the automatic focus control means adjusts the value of the parameter in the second calculation means. An image reading device characterized in that this is applied to focus control. 6) The image reading device according to claim 1, wherein the sensor is a color sensor. 7) In the image reading device according to claim 6, the first calculation means calculates a parameter reflecting the sharpness of the image signal from the plurality of signals from the color sensor, and the second calculation means calculates a parameter reflecting the sharpness of the image signal from the plurality of signals from the color sensor. An image reading device that calculates a parameter that reflects the sharpness of an image signal from a single signal. 8) The image reading device according to claim 1, wherein the sensor is a plurality of line sensors arranged in parallel and reading mutually different color information.