JP2004048172A - Electronic imaging apparatus and electronic imaging apparatus for microscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic imaging apparatus and an electronic imaging apparatus for microscope which provides a high-quality image with reduced noise or shaggies enhanced due to the counter enhancement while it holds a good resolution feeling. <P>SOLUTION: A piezoelectric driver 5 periodically displaces a CCD 2 for imaging an object to output an image signal for every displaced position. The image signals from the CCD 2 are rearranged to form a composite image. Then the contour enhancing frequency is made variable for the rearranged image according as before and after the displacement of the CCD 2 by the driver 5. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electronic imaging device for electronically recording an image captured by a solid-state imaging device or the like, and an electronic imaging device for a microscope.
[0002]
[Prior art]
2. Description of the Related Art In recent years, an image pickup device such as an image pickup device (CCD) captures an image of a subject formed by a photographing lens, and an electronic camera that electronically records an image signal obtained as an electric signal from the image capturing device. Electronic imaging devices have become popular.
[0003]
In such an electronic imaging apparatus, it is important to display a better image on the display means. For this reason, conventionally, appropriate signal processing is performed on an image signal output as an electric signal from the imaging means. Things have been done.
[0004]
Japanese Patent Laying-Open No. 11-112837 is based on such a concept, and variably controls the degree of contour emphasis by the contour emphasis means according to the gain value by the gain control means at the time of an imaging operation.
[0005]
On the other hand, recently, the subject image formed on the image sensor is optically shifted by a parallel plate provided in the optical path of the taking lens, or the taking lens is shifted in a plane perpendicular to the optical axis. A method of reading a plurality of images and synthesizing the plurality of images to obtain a high-definition still image has been put to practical use.
[0006]
In such a method, an appropriate signal processing is performed on an image signal in order to display a better image on the display means. For example, Japanese Patent Application Laid-Open No. H07-123424 discloses the method. As described above, there is known an image processing apparatus in which the edge enhancement strength is changed based on the relative positional relationship between the shifted images and the image quality is controlled so that a stable resolving power can be felt in any state.
[0007]
[Problems to be solved by the invention]
In Japanese Patent Application Laid-Open No. 07-123424, as the relative positional relationship of the shifted image becomes finer, the spatial frequency characteristic is shifted to the right in the figure as shown in FIG. That is, the spatial frequency characteristic is shifted in the direction of increasing the Nyquist frequency to increase the degree of edge enhancement, thereby trying to secure a stable resolution.
[0008]
However, when the edge enhancement degree is increased in this way, an unnecessary frequency is emphasized, and unnecessary noise and jaggedness due to edge enhancement are generated, which results in an unsightly image. The problem arises.
[0009]
The present invention has been made in view of the above circumstances, and provides an electronic imaging apparatus and an electronic imaging apparatus for a microscope that can obtain a high-quality image with reduced noise and jaggedness by contour enhancement while maintaining a sense of resolution. The purpose is to do.
[0010]
[Means for Solving the Problems]
The invention according to claim 1, an imaging device that captures a subject image, and a displacement unit that periodically displaces the imaging device and outputs an image signal of the subject image from the imaging device for each displacement position. Image processing means for rearranging the image signal of the image sensor for each displacement position by the displacement means and synthesizing the image, and contour enhancement means for performing contour signal processing on the image rearranged by the image processing means; Wherein the contour emphasizing frequency of the contour emphasizing means is made variable in accordance with before and after the displacement of the image pickup device by the displacing means.
[0011]
According to a second aspect of the present invention, in the first aspect of the present invention, the contour emphasizing means is capable of changing the contour emphasizing frequency before and after the cyclic displacement operation of the imaging device by the displacement means. Features.
[0012]
According to a third aspect of the present invention, in the first aspect of the present invention, there is provided a lens system for projecting the subject image onto the image sensor, and a contour emphasis frequency by the contour emphasizing means is set according to a type of the lens system. It is characterized by being variable.
[0013]
According to a fourth aspect of the present invention, in the first aspect of the present invention, there is provided a gain adjusting means for adjusting a signal level of an image output from the image sensor to a predetermined gain, and the gain adjusting means adjusts a gain value of the gain adjusting means. Thus, the contour emphasis frequency by the contour emphasizing means is made variable.
[0014]
According to a fifth aspect of the present invention, there is provided an aperture stop for adjusting a numerical aperture of illumination light and an objective lens, the microscope being connected to a microscope having at least one port for outputting an image from the objective lens, and outputting from the port. An electronic image pickup apparatus for a microscope that picks up an image captured by a microscope, comprising: a contour emphasis unit that enables a contour emphasis intensity for performing a contour signal processing on an image output from the port to be picked up; Is characterized in that the contour emphasis strength by the contour emphasis means is varied in accordance with the state change of.
[0015]
The invention according to claim 6 is connected to a microscope having an aperture stop for adjusting the numerical aperture of illumination light and an objective lens, and having at least one port for outputting an image from the objective lens, and outputting the image from the port. An electronic image pickup apparatus for a microscope that picks up an image obtained by a microscope, comprising: a contour emphasizing means capable of changing a contour emphasizing frequency for performing contour signal processing on an image picked up from the port. Is characterized in that the contour emphasizing frequency by the contour emphasizing means is varied in accordance with the state change.
[0016]
The invention according to claim 7 is connected to a microscope having an aperture stop for adjusting the numerical aperture of illumination light and an objective lens, and having at least one port for outputting an image from the objective lens, and outputting from the port. In an electronic imaging device for a microscope that captures an image of a subject, an image sensor that captures a subject image, and the image sensor is periodically displaced, and an image signal of the subject image is output from the image sensor for each displacement position. Displacing means, image processing means for rearranging an image signal of the image sensor for each displacement position by the displacing means to synthesize an image, and performing contour signal processing on the image rearranged by the image processing means. Contour emphasizing means that makes the contour emphasizing frequency to be applied variable, and wherein the contour emphasizing frequency by the contour emphasizing means is varied according to a change in the state of the aperture stop. To have.
[0017]
As a result, according to the present invention, while maintaining the sense of resolution both before and after the displacement of the imaging device by the displacement means, it is possible to suppress the occurrence of unnecessary noise emphasized by contour emphasis and oblique jaggies due to edge emphasis. it can.
[0018]
Further, according to the present invention, regardless of the MTF of the lens system, it is possible to suppress the occurrence of unnecessary noise emphasized by contour emphasis and the occurrence of jaggedness due to edge emphasis while maintaining a sense of resolution.
[0019]
Further, according to the present invention, unnecessary edge enhancement is not performed in a region with a large amount of noise, and a high-quality image can be obtained.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0021]
(First Embodiment)
FIG. 1 shows a schematic configuration of an electronic imaging apparatus to which the first embodiment of the present invention is applied. In FIG. 1, reference numeral 1 denotes a photographing optical system, which includes a photographing lens, a driving motor for driving the lens, a driving mechanism, and the like. An optical subject image is formed on a solid-state imaging device (hereinafter simply referred to as a CCD) 2 such as a CCD via the photographing optical system 1.
[0022]
The CCD 2 photoelectrically converts the formed optical subject image to generate an image signal of the subject image.
[0023]
In this case, a timing generator (TG) 3 and a signal generator (SG) 4 for generating a synchronization signal such as a drive pulse are connected to the CCD 2 and are driven by a predetermined timing signal. Further, the CCD 2 has an electronic shutter function (means) (not shown) so that the exposure time can be controlled.
[0024]
A piezoelectric driver 5 is connected to the CCD 2 as displacement means. The piezoelectric driver 5 has a piezoelectric element such as a piezo element, and the CCD 2 is periodically displaced by the piezoelectric element to output an image signal in which the subject image at each displacement position is shifted by a pixel. ing.
[0025]
The CCD 2 is connected to a CDS circuit (correlated double sampling circuit; Correlated Double Sampling). The CDS circuit extracts an image signal component from an output signal of the CCD 2.
[0026]
An amplifier (AMP) 7 is connected to the CDS circuit 6 as gain adjustment means. The amplifier (AMP) 7 is composed of gain control means including an AGC circuit for adjusting the output signal level from the CDS circuit 6 to a predetermined gain value.
[0027]
The amplifier (AMP) 7 is connected to a frame memory 9 as an image memory via an A / D converter 8. The A / D converter 8 converts an analog image signal output from the amplifier (AMP) 7 into a digital image signal in synchronization with a timing signal of the timing generator (TG) 3. The frame memory 9 stores a digital signal output from the A / D converter 8. The reading and writing of data in the frame memory 9 is controlled by the memory controller 10. The frame memory 9 includes memories corresponding to a plurality of images obtained by pixel shifting, and stores each image separately in these memories. Then, based on the control of the CPU 28 described later, the plurality of images are rearranged (pixel-shifted) into one image (image processing means).
[0028]
A color separation circuit 11 and a γ correction circuit 12 are connected to the frame memory 9. The color separation circuit 11 separates an image signal read from the frame memory 9 into three primary color signals of an RL signal, a GL signal, and a BL signal. The γ correction circuit 12 performs gamma (γ) correction processing of the color signal.
[0029]
A WB (white balance) circuit 13 for adjusting the white balance of the image signal is connected to the color separation circuit 11. The WB (white balance) circuit 13 is connected to a color correction circuit 16 via a white clip 14 and a clip level detection circuit 15. The color correction circuit 16 performs color correction for improving color reproducibility.
[0030]
A color difference matrix circuit 18 is connected to the color correction circuit 16 via a color γ correction circuit 17. The color γ correction circuit 17 performs γ (γ) correction processing of the color signal corrected by the color correction circuit 16. The color difference matrix circuit 18 converts each of the R, G, and B color signals into a luminance signal YL and two color difference signals (RY signal and BY signal) to adjust hue, color saturation, and the like. is there.
[0031]
On the other hand, a Y signal generation unit 19 is connected to the γ correction circuit 12. The Y signal generation unit 19 extracts and generates only a luminance signal (Y signal) from the image signal subjected to the γ correction processing by the γ correction circuit 12.
[0032]
A band-pass filter (BPF) 20 is connected to the Y signal generator 19. The band pass filter (BPF) 20 forms a part of the contour emphasis means, and removes low frequency components from the Y signal to extract a contour signal (hereinafter, referred to as an edge signal).
[0033]
A coring unit 21 is connected to the band pass filter (BPF) 20. The coring unit 21 also forms part of the contour emphasizing means, and performs coring processing for suppressing or removing noise components of the edge signal generated by the band-pass filter (BPF) 20 and improving the S / N ratio. It is something to give.
[0034]
The coring unit 21 is connected to an edge enhancement degree accumulator 22. The edge enhancement degree integrator 22 performs an edge enhancement process by multiplying the Y signal subjected to the coring process by the coring unit 21 by a predetermined coefficient, and constitutes a part of a contour enhancement unit. .
[0035]
The edge enhanced Y signal output from the edge enhancement degree integrator 22 is input to the adder 23 together with the luminance signal YL output from the color difference matrix circuit 18. The adder 23 adds these signals and outputs a luminance signal YH.
[0036]
Then, the luminance signal YH from the adder is input to the liquid crystal display (LCD) 24 and the DRAM 25 as display means together with the color difference signals (RY signal and BY signal) from the color difference matrix circuit 18 as image signals. . The liquid crystal display (LCD) 24 has a signal processing circuit for processing image signals into a displayable form, and displays an image subjected to signal processing here. The DRAM 25 is a camera built-in storage unit including a memory for temporarily storing image signals.
[0037]
The DRAM 25 is connected to a compression / expansion circuit 26 for performing compression processing and expansion processing on the image signal and a recording medium 27 such as a memory card for storing the image signal.
[0038]
Each of the above-described components is electrically connected to the CPU 28 as a control unit. The CPU 28 controls the entire electronic imaging apparatus. An operation unit 29 is connected to the CPU 28. The operation unit 29 has a plurality of switches such as a trigger switch that can start an AF operation at the time of shooting and generate a trigger signal to start an exposure operation.
[0039]
An operation performed at the time of photographing in the electronic imaging device configured as described above will be described. Here, only the part related to the present invention among the operations performed at the time of photographing is described.
[0040]
In this case, the CCD 2 is vibrated at a constant period by a piezoelectric driver 5 having a piezoelectric element such as a piezo element, and generates an image output in synchronization with the vibration. For example, in the pixel arrangement shown in FIG. 2 (a), (1) → (2) → (3) → (4) at a 2/3 pixel interval from the reference pixel position (1) shown in FIG. 2 (b). In the order of ▼ → ▲ 5 ▼ → ▲ 6 ▼ → ▲ 7 ▼ → ▲ 8 ▼ → ▲ 9 ▼, three pixels are shifted in each of the horizontal and vertical directions, and a total of nine pixels are shifted, and imaging of each displacement position Generate output. As a result, the number of pixels in the X and Y directions is tripled without changing the R, G, and B color arrangements as shown in FIG.
[0041]
From the image signal obtained by the CCD 2, an image signal component is extracted by a CDS circuit 6, and an output signal level is adjusted to a predetermined gain value by an amplifier (AMP) 7, and then converted to a digital signal by an A / D converter 8. Is converted. Then, the image signal converted into the digital signal is temporarily stored in the frame memory 9.
[0042]
The frame memory 9 includes memories corresponding to the nine images (1) to (9) obtained by shifting the pixels, and stores the nine images individually in these memories. Then, under the control of the CPU 28, these nine images are rearranged (pixel-shifted) into one image.
[0043]
Thereafter, the image signal of the rearranged image is split into a main signal output to the color separation circuit 11 and a sub signal output to the γ correction circuit 12. Here, the main signal is subjected to signal processing such as predetermined color correction processing in each circuit after the color separation circuit 11. On the other hand, as for the sub signal, after the γ correction processing is performed by the γ correction circuit 12, the Y signal generation unit 19 extracts and generates only the luminance signal (Y signal). This Y signal is input to a band pass filter (BPF) 20. The band-pass filter (BPF) 20 generates an edge signal from the Y signal and outputs this to the coring unit 21.
[0044]
The coring unit 21 performs a predetermined coring process on the edge signal, and then outputs the result to the edge emphasis degree integrator 22. Then, after the edge enhancement processing is performed in the edge enhancement degree integrator 22, the Y signal subjected to the edge enhancement processing is added to the luminance signal YL of the main signal in the adder 23, output to the LCD 24, and reproduced and displayed. Processing is performed.
[0045]
In the edge enhancement processing performed by the band-pass filter (BPF) 20, a 4 × 4 BPF is usually used to enhance the vicinity of the Nyquist frequency. That is, for the image signal before the pixel shift shown in FIG. 2A, the edge is enhanced near the Nyquist frequency by using a 4 × 4 BPF as shown in FIG. (Contrast reproducibility). .
[0046]
On the other hand, in the image signal after the pixel shift shown in FIG. 2C, by increasing the Nyquist frequency, an improvement in resolution and a reduction in moire due to aliasing are expected.
[0047]
However, in practice, as shown in FIG. 4A, when the opening of the CCD 2 (PD (photodiode) for converting light into an electric signal) has a large shape as shown in FIG. Due to the pixel shift of (9), an overlapping portion occurs with the pixel position before the pixel shifting, and it is difficult to improve the resolution due to the overlapping portion, and it is impossible to secure the MTF up to the Nyquist frequency after the pixel shifting. That is, the resolution limit of the image signal after the pixel shift is determined by the shape of the opening of the CCD 2, and thereafter, even if the pixel is shifted, the Nyquist frequency only shifts. FIG. 5 shows the MTF with respect to the resolution frequency in the case of the CCD 2 having an aperture ratio of 85%, and the MTF can be secured without any problem for the Nyquist frequency F1 before the pixel shift. However, since the resolution of the Nyquist frequency F2 after the pixel shift has already reached the limit of the resolution, further improvement of the resolution cannot be expected.
[0048]
When a 4 × 4 BPF is applied as a band-pass filter (BPF) 20 to the image signal after such pixel shift, as shown in FIG. 6, the frequency characteristic B of the 4 × 4 BPF is as shown in FIG. Since the vicinity of the Nyquist frequency after the pixel shift is emphasized with respect to the MTF of the CCD 2 described in the above section, the emphasis is made to an unnecessary frequency range (a portion indicated by hatching) D in which no improvement in resolution can be expected. Will be. In other words, at the Nyquist frequency after pixel shift, the resolution limit has already been reached, and although further improvement in resolution cannot be expected, extra emphasis will be performed, thereby causing noise and edge emphasis. There is a problem that an oblique jaw or the like is generated.
[0049]
Therefore, in the first embodiment, a 6 × 6 BPF as shown in FIG. 3B is used instead of the 4 × 4 BPF after the pixel is shifted. The frequency characteristic of the 6 × 6 BPF is set so as to emphasize the frequency range up to the resolution limit including the vicinity of the Nyquist frequency before the pixel shift, as shown by C in FIG. As a result, it is not necessary to emphasize an unnecessary frequency range in which an improvement in resolution cannot be expected, and only necessary edge enhancement can be performed. Therefore, it is possible to suppress the generation of noise and oblique jaw due to edge enhancement.
[0050]
For this reason, the band-pass filter (BPF) 20 for edge enhancement is used by switching between 4 × 4 BPF and 6 × 6 BPF without shifting pixels.
[0051]
A timing chart at the time of the photographing operation in this case is as shown in FIG. In this case, the vertical synchronization signal VD shown in FIG. 11A is output at a frame period, and the pixel shift voltages x and y shown in FIGS. 11E and 11F are controlled based on the vertical synchronization signal VD. A shift is performed. The image signal shown in FIG. 9G is read out by the exposure shown in FIG. 9B for each pixel shift. In the case of photographing the image signal before shifting the pixel, the bandpass filter (BPF) 20 shown in FIG. 4D uses a 4 × 4 BPF. Uses a 6 × 6 BPF instead of a 4 × 4 BPF. That is, the edge emphasis processing is executed in a state where the contour intensity frequency is variably controlled by the bandpass filter (BPF) 20 and a predetermined S / N ratio is secured.
[0052]
In this way, for the image signal before the pixel shifting operation shown in FIG. 2A, by using the 4 × 4 BPF, the vicinity of the Nyquist frequency can be enhanced and the MTF can be secured without any problem. . In addition, for the image signal after the pixel shifting operation shown in FIG. 2C, by using a 6 × 6 BPF instead of a 4 × 4 BPF, an unnecessary frequency range where no improvement in resolution can be expected is emphasized. And only necessary edge enhancement can be performed. As a result, it is possible to obtain a high-quality image that can suppress the occurrence of unnecessary noise emphasized by contour emphasis and the occurrence of oblique jaggedness due to edge emphasis, while maintaining the resolution in both cases before and after pixel shift.
[0053]
(Second embodiment)
Next, a second embodiment of the present invention will be described.
[0054]
The schematic configuration of the electronic imaging apparatus according to the second embodiment is the same as that of FIG. 1 described in the first embodiment, and therefore, the drawing is used.
[0055]
The second embodiment is characterized in that the contour intensity frequency is varied by a band-pass filter (BPF) 20 according to the tendency of the MTF of a lens system including an optical system such as the photographing optical system 1 and an objective lens on the microscope side. I have.
[0056]
FIG. 8 shows an example of the MTF of the CCD 2. When a lens system having a relatively high MTF is used for such a CCD 2 as shown in FIG. 9A, the CCD 2 and the lens system are combined. The MTF at this time is as shown in FIG. 10A, and a high MTF can be obtained over the entire range of the resolution frequency.
[0057]
In such a case, a 4 × 4 BPF having a frequency characteristic as shown in FIG. 11A is used as the band-pass filter (BPF) 20. As a result, necessary edge enhancement can be performed over the entire frequency range including the high frequency range.
[0058]
On the other hand, when a lens system having a relatively low MTF as shown in FIG. 9B is used for the MTF CCD 2 as shown in FIG. 8, the MTF when these CCD 2 and the lens system are combined is as shown in FIG. As shown in FIG. 10 (b), especially in a high frequency region, the MTF becomes low, and the improvement of the resolution is hardly expected.
[0059]
In such a case, the bandpass filter (BPF) 20 uses a 6 × 6 BPF instead of a 4 × 4 BPF. The frequency characteristic of the 6 × 6 BPF is set so as to emphasize frequencies in a range excluding a high frequency range where improvement in resolution cannot be expected as shown in FIG. 11B.
[0060]
As a result, it is not necessary to emphasize an unnecessary frequency range where improvement in resolution cannot be expected, and only necessary edge enhancement can be performed. Therefore, it is possible to suppress occurrence of noise and jaggedness due to edge enhancement.
[0061]
Therefore, in this case, the resolution is expected to be improved by switching between the 4 × 4 BPF and the 6 × 6 BPF in the band-pass filter (BPF) 20 according to the MTF of the lens system. There is no need to emphasize unnecessary frequency ranges, and only necessary edge enhancement can be performed. Thereby, regardless of the MTF of the lens system, it is possible to obtain a high-quality image that can suppress the occurrence of unnecessary noise emphasized by contour emphasis or the occurrence of jaggedness due to edge emphasis while maintaining a sense of resolution.
[0062]
(Third embodiment)
Next, a third embodiment of the present invention will be described.
[0063]
The schematic configuration of the electronic imaging apparatus according to the third embodiment is the same as that of FIG. 1 described in the first embodiment, and therefore, the drawing is used.
[0064]
In the above-described first embodiment, the output signal level of the CDS circuit 6 for extracting an image signal component from the output signal of the CCD 2 is adjusted to a predetermined gain by the amplifier (AMP) 7, but the third embodiment is not limited to this. The embodiment is characterized in that the contour intensity frequency is varied by a band-pass filter (BPF) 20 according to the gain value of the amplifier (AMP) 7.
[0065]
FIG. 12 shows the relationship between the gain value of the amplifier (AMP) 7 and the noise amount. In this figure, for example, if the gain value of the amplifier (AMP) 7 is increased because the captured image is dark, it is included from the beginning. This shows how the amount of noise increases.
[0066]
From this state, when the amplifier (AMP) 7 uses the gain region A in which the gain value is relatively small and the noise amount is not so large, the bandpass filter (BPF) 20 is shown in FIG. A 4 × 4 BPF having such frequency characteristics is used.
[0067]
Then, in this case, when the gain area A of the amplifier (AMP) 7 and the 4 × 4 BPF shown in FIG. 13A are combined with the MTF of the CCD 2 shown in FIG. An MTF as shown is obtained, and necessary edge enhancement can be performed under high resolution.
[0068]
On the other hand, when the amplifier (AMP) 7 uses the gain region B where the gain value is large and the noise amount is large, the band-pass filter (BPF) 20 replaces the 4 × 4 BPF with 6 × 6. Is used. As this 6 × 6 BPF, one having a frequency characteristic as shown in FIG. 13B is used.
[0069]
Then, also in this case, when the gain area B of the amplifier (AMP) 7 and the 6 × 6 BPF shown in FIG. 13B are combined with the MTF of the CCD 2 shown in FIG. 14, FIG. The MTF as shown is obtained, and necessary edge enhancement can be performed at a low resolution.
[0070]
Therefore, in this way, the band-pass filter (BPF) 20 switches between 4 × 4 BPF and 6 × 6 BPF in accordance with the gain value of the amplifier (AMP) 7 and uses it. This eliminates unnecessary edge enhancement in a region with a large amount of noise, thereby obtaining a high-quality image.
[0071]
(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described.
[0072]
FIG. 16 shows a schematic configuration of a microscope to which the electronic imaging device for a microscope of the present invention is applied. Note that the schematic configuration of the electronic imaging device for a microscope connected to such a microscope is the same as that of FIG. 1 described in the first embodiment, so that FIG.
[0073]
In FIG. 16, reference numeral 31 denotes a light source. Light emitted from the light source 31 is collected by a collector lens 32, an FS (field stop) 33 for adjusting an illumination range, and an AS for adjusting a numerical aperture of illumination light. The light is radiated to the sample 36 via an (aperture stop) 34 and a condenser lens 35. The transmitted light from the sample 36 is imaged by the CCD 39 via the objective lens 37 and the imaging lens 38. In this case, the CCD 39 corresponds to the CCD 2 of the electronic imaging device for a microscope (see FIG. 1) connected to a port (not shown).
[0074]
By the way, in the microscope configured in this way, it is known that the MTF of the objective lens 37 changes between when the AS (aperture stop) 34 is closed and when it is opened.
[0075]
17A and 17B illustrate this state. FIG. 17A shows the objective lens when the AS (aperture stop) 34 is closed, and FIG. 17B shows the objective lens when the AS (aperture stop) 34 is open. 37 shows the MTF. As can be seen from the figure, when the AS (aperture stop) 34 is closed, the resolution in the middle range is higher than when the AS (aperture stop) 34 is open. On the other hand, when the AS (aperture stop) 34 shown in the figure (B) is open, the limit resolution greatly extends in the high frequency direction as compared with the case where the AS (aperture stop) 34 shown in the figure (A) is closed.
[0076]
Thus, when the MTF of an image acquired with the AS (aperture stop) 34 in the open state is in the state of FIG. 18C, the AS (aperture stop) 3 is adjusted to the closed state, and the image is acquired. As shown in FIG. 3D, the MTF of the image to be processed is excessively high in the MTF in the middle band, resulting in a significantly unnatural image. In addition, noise is generated due to unnecessary high-frequency MTF enhancement. Will be invited.
[0077]
Therefore, in the fourth embodiment, the edge enhancement degree in the edge enhancement degree integrator 22 shown in FIG. 1 is changed according to the state change of the AS (aperture stop) 34. In this case, the edge emphasis degree integrator 22 can change the level of the edge emphasis degree as shown in FIGS. 19A and 19B according to a gain value control command from the CPU 28.
[0078]
In such a configuration, when the AS (aperture stop) 34 is open, the edge emphasis degree integrator 22 selects the normal edge emphasis degree shown in FIG. As a result, the MTF of an image acquired when the AS (aperture stop) 34 is open is maintained at the state shown in FIG. 18C, and a natural and high-quality image can be acquired. On the other hand, when the AS (aperture stop) 34 is closed, the resolution in the middle range is increased as shown in FIG. 18D, so that the edge emphasis degree integrator 22 has the level shown in FIG. A small edge enhancement is selected. As a result, the resolution in the middle range is prevented from becoming too high, and the MTF of an image obtained with the AS (aperture stop) 34 closed is also in the state shown in FIG. High quality images can be obtained.
[0079]
On the other hand, in the fourth embodiment, the contour intensity frequency is varied by the band-pass filter (BPF) 20 according to a change in the state of the AS (aperture stop) 34.
[0080]
In this case, when the AS (aperture stop) 34 shown in FIG. 17A is in the closed state and the limit resolution does not extend in the high frequency direction, the bandpass filter (BPF) 20 is used as shown in FIG. A 6 × 6 BPF having the frequency characteristics shown is used. The frequency characteristics of the 6 × 6 BPF are set so as to emphasize frequencies in a range excluding a high frequency range where improvement in resolution is not expected. This eliminates the need for emphasizing unnecessary frequency regions in which the resolution cannot be improved, and allows only necessary edge emphasis to be performed, thereby suppressing the occurrence of noise.
[0081]
In the case where the AS (aperture stop) 34 shown in FIG. 17B is in the open state and the limit resolution is greatly extended in the high frequency direction, a 6 × 6 BPF is used as the bandpass filter (BPF) 20. Instead, a 4 × 4 BPF having a frequency characteristic as shown in FIG. As a result, necessary edge enhancement can be performed over the entire frequency range including the high frequency range.
[0082]
Therefore, in this way, by changing the contour emphasis degree and the contour strength frequency according to the change in the state of the AS (aperture stop) 34, it is possible to obtain a high-quality image in which the occurrence of noise is suppressed.
[0083]
In addition, the present invention is not limited to the above-described embodiment, and can be variously modified in an implementation stage without departing from the spirit of the invention.
[0084]
Furthermore, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent features. For example, even if some components are deleted from all the components shown in the embodiments, the problem described in the column of the problem to be solved by the invention can be solved, and the problem described in the column of the effect of the invention can be solved. In the case where the effect described above is obtained, a configuration from which this configuration requirement is deleted can be extracted as an invention.
[0085]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an electronic image pickup apparatus and an electronic image pickup apparatus for a microscope that can obtain a high-quality image in which noise emphasized by contour emphasis and diagonal jaws are reduced while maintaining a sense of resolution. .
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an electronic imaging device according to a first embodiment of the present invention.
FIG. 2 is a diagram for explaining pixel shifting according to the first embodiment;
FIG. 3 is a diagram showing 4 × 4 and 6 × 6 BPFs used in the first embodiment;
FIG. 4 is a diagram illustrating an opening of a CCD used in the first embodiment.
FIG. 5 is a diagram illustrating an MTF of a CCD used in the first embodiment.
FIG. 6 is a diagram illustrating a state in which 4 × 4 and 6 × 6 BPFs of the first embodiment are switched.
FIG. 7 is a diagram showing a timing chart during a shooting operation according to the first embodiment.
FIG. 8 is a diagram for explaining an MTF of a CCD used in a second embodiment of the present invention.
FIG. 9 is a diagram illustrating an MTF of a lens system used in the second embodiment.
FIG. 10 is a diagram illustrating a second embodiment.
FIG. 11 is a diagram illustrating frequency characteristics of 4 × 4 and 6 × 6 BPFs according to the second embodiment;
FIG. 12 is a diagram illustrating a relationship between a gain value and an amount of noise of an amplifier (AMP) used in a third embodiment of the present invention.
FIG. 13 is a diagram illustrating frequency characteristics of 4 × 4 and 6 × 6 BPFs according to the third embodiment;
FIG. 14 is a diagram illustrating an MTF of a CCD used in the third embodiment.
FIG. 15 is a diagram illustrating a third embodiment.
FIG. 16 is a diagram showing a schematic configuration of a microscope applied to a fourth embodiment of the present invention.
FIG. 17 is a diagram illustrating an MTF according to a state change of an aperture stop according to a fourth embodiment.
FIG. 18 is a diagram illustrating an MTF of an image obtained according to a change in the state of the aperture stop according to the fourth embodiment.
FIG. 19 is a diagram illustrating an edge emphasis degree of an edge emphasis degree accumulator used in the fourth embodiment.
FIG. 20 is a diagram illustrating frequency characteristics of 4 × 4 and 6 × 6 BPFs according to the fourth embodiment;
[Explanation of symbols]
1. Photographing optical system 2. CCD
3. Timing generator (TG)
4 ... Signal generator (SG) 4
5 Piezoelectric driver 6 CDS circuit 7 Amplifier (AMP)
8 A / D converter 9 Frame memory 10 Memory controller 11 Color separation circuit 12 γ correction circuit 13 WB (white balance) circuit 14 White clip 15 Clip level detection circuit 16 Color correction circuit 17 Gamma correction circuit 18 Color difference matrix circuit 19 Y signal generation unit 21 Coring unit 22 Edge emphasis degree accumulator 23 Adder 24 LCD
25 ... DRAM
26 compression / expansion circuit 27 recording medium 28 CPU
29 ... operation unit 31 ... light source 32 ... collector lens 33 ... FS (field stop)
34 AS (Aperture stop)
35: condenser lens 36: sample 37: objective lens 38: imaging lens 39: CCD

Claims (7)

An image sensor that captures a subject image;
Displacement means for periodically displacing the image sensor, and outputting an image signal of the subject image from the image sensor for each displacement position,
Image processing means for rearranging the image signal of the image sensor for each displacement position by the displacement means and performing image synthesis,
An electronic image pickup apparatus, comprising: a contour emphasis means for making a contour emphasis frequency for performing contour signal processing on an image rearranged by the image processing means variable. 2. The electronic imaging apparatus according to claim 1, wherein the contour emphasizing means is capable of changing the contour emphasizing frequency before and after the cyclic displacement operation of the imaging device by the displacement means. A lens system that projects the subject image onto the image sensor,
2. An electronic image pickup apparatus according to claim 1, wherein an outline emphasis frequency by said outline emphasis means is made variable in accordance with a type of said lens system. A gain adjusting unit that adjusts a signal level of an image output from the image sensor to a predetermined gain,
2. The electronic imaging apparatus according to claim 1, wherein an outline emphasis frequency by said outline emphasis means is made variable according to a gain value of said gain adjustment means. An electron microscope for connecting to a microscope having an aperture stop for adjusting the numerical aperture of illumination light and an objective lens and having at least one port for outputting an image from the objective lens, and capturing an image output from the port. In a typical imaging device,
Comprising a contour emphasis means capable of changing a contour emphasis strength for performing contour signal processing on an image captured and output from the port,
An electronic image pickup apparatus for a microscope, wherein an intensity of an outline emphasized by an outline enhancer is varied according to a change in a state of the aperture stop. An electron microscope for connecting to a microscope having an aperture stop for adjusting the numerical aperture of illumination light and an objective lens and having at least one port for outputting an image from the objective lens, and capturing an image output from the port. In a typical imaging device,
Comprising a contour emphasis means capable of changing a contour emphasis frequency for performing contour signal processing on an image captured and output from the port,
An electronic imaging apparatus for a microscope, wherein an outline emphasis frequency by an outline emphasis means is varied according to a change in the state of the aperture stop. An electron microscope for connecting to a microscope having an aperture stop for adjusting the numerical aperture of illumination light and an objective lens and having at least one port for outputting an image from the objective lens, and capturing an image output from the port. In a typical imaging device,
An image sensor that captures a subject image;
Displacement means for periodically displacing the image sensor, and outputting an image signal of the subject image from the image sensor for each displacement position,
Image processing means for rearranging the image signal of the image sensor for each displacement position by the displacement means and synthesizing the image,
Contour emphasizing means for making a contour emphasizing frequency for performing contour signal processing on an image rearranged by the image processing means variable, and the contour emphasizing frequency by the contour emphasizing means according to a change in the state of the aperture stop. An electronic imaging device for a microscope, wherein the electronic imaging device is configured to change the value of the electronic image.

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