JP2006094469A - Imaging device and imaging method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device and an imaging method capable of designing a lens without considering the object distance or defocus range and attaining image restoration with a highly accurate calculation. <P>SOLUTION: The imaging device includes: an imaging lens device 200 for imaging an object dispersion image which has passed through an optical system and a phase plate as a light wavefront modulation element; an image processing device 300 for generating an image signal having no dispersion from the dispersion image signal supplied from the imaging element 200; and an object brief distance information detection device 400 for generating information equivalent to the distance to the object. The image processing device 300 generates an image signal having no dispersion according to the information generated from the object outline distance information detection device 400. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus such as a digital still camera, a camera mounted on a mobile phone, a camera mounted on a portable information terminal, and the like using an imaging element and including an optical system and a light wavefront modulation element (phase plate).

In response to the digitization of information, which has been rapidly developing in recent years, the response in the video field is also remarkable.
In particular, as symbolized by a digital camera, a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) sensor, which is a solid-state image sensor, is used in most cases instead of a conventional film.

  As described above, an imaging lens device using a CCD or CMOS sensor as an imaging element is for taking an image of a subject optically by an optical system and extracting it as an electrical signal by the imaging element. In addition to a digital still camera, It is used for a video camera, a digital video unit, a personal computer, a mobile phone, a personal digital assistant (PDA) and the like.

FIG. 14 is a diagram schematically illustrating a configuration and a light flux state of a general imaging lens device.
The imaging lens device 1 includes an optical system 2 and an imaging element 3 such as a CCD or CMOS sensor.
In the optical system, the object side lenses 21 and 22, the diaphragm 23, and the imaging lens 24 are sequentially arranged from the object side (OBJS) toward the image sensor 3 side.

In the imaging lens device 1, as shown in FIG. 14, the best focus surface is matched with the imaging device surface.
FIGS. 15A to 15C show spot images on the light receiving surface of the imaging element 3 of the imaging lens device 1.

In addition, an imaging apparatus has been proposed in which a light beam is regularly dispersed by a phase front (wavefront coding optical element) and restored by digital processing to enable imaging with a deep depth of field (for example, non-patent literature). 1, 2, and patent documents 1 to 5).
"Wavefront Coding; jointly optimized optical and digital imaging systems", Edward R. Dowski, Jr., Robert H. Cormack, Scott D. Sarama. "Wavefront Coding; A modern method of achieving high performance and / or low cost imaging systems", Edward R. Dowski, Jr., Gregory E. Johnson. USP 6,021,005 USP 6,642,504 USP 6,525,302 USP 6,069,738 JP 2003-235794 A

In the imaging devices proposed in the above-mentioned documents, all of them are based on the assumption that the PSF (Point-Spread-Function) when the above-described phase plate is inserted into a normal optical system is constant, When the PSF changes, it is extremely difficult to realize an image with a deep depth of field by convolution using a subsequent kernel.
Therefore, even with a single focal point lens, a regular (non-changing) PSF cannot be realized with a normal optical system in which the spot image changes depending on the object distance. There is a big problem in adopting due to the high accuracy of design and the accompanying cost increase.

  An object of the present invention is to simplify an optical system, reduce costs, perform lens design without worrying about an object distance and a defocus range, and perform image restoration by highly accurate calculation. It is an object of the present invention to provide an imaging apparatus and method capable of performing the above.

  In order to achieve the above object, an image pickup apparatus according to a first aspect of the present invention includes an image pickup element that picks up a subject dispersion image that has passed through at least an optical system and a light wavefront modulation element, and a distributed image signal from the image pickup element. Conversion means for generating a non-dispersed image signal, and subject distance information generation means for generating information corresponding to the distance to the subject, wherein the conversion means includes information generated by the subject distance information generation means. Based on this, a non-dispersed image signal is generated from the dispersed image signal.

  Preferably, at least two conversion coefficients corresponding to dispersion caused by the light wavefront modulation element according to the subject distance are stored in advance, and based on information generated by the subject distance information generation unit. Coefficient conversion means for selecting a conversion coefficient corresponding to the distance from the conversion coefficient storage means to the subject, and the conversion means converts the image signal by the conversion coefficient selected by the coefficient selection means. .

  Preferably, the image processing apparatus includes conversion coefficient calculation means for calculating a conversion coefficient based on the information generated by the subject distance information generation means, and the conversion means uses the conversion coefficient obtained from the conversion coefficient calculation means to generate an image signal. Perform the conversion.

  Preferably, the optical system includes a zoom optical system, at least one correction value storage means for storing in advance at least one correction value corresponding to the zoom position or zoom amount of the zoom optical system, and at least the light wavefront modulation element. Based on the information generated by the second conversion coefficient storage means that stores in advance the conversion coefficient corresponding to the resulting variance and the subject distance information generation means, a correction value corresponding to the distance from the correction value storage means to the subject is obtained. Correction value selection means for selecting, and the conversion means converts an image signal based on the conversion coefficient obtained from the second conversion coefficient storage means and the correction value selected from the correction value selection means. I do.

  Preferably, the correction value stored in the correction value storage means includes the kernel size of the subject dispersion image.

  An imaging method according to a second aspect of the present invention includes a step of imaging a subject dispersion image that has passed through at least an optical system and a light wavefront modulation element, and subject distance information for generating information corresponding to a distance to the subject. A generating step, and a step of converting the dispersed image signal based on the information generated by the subject distance information generating step to generate an image signal having no dispersion.

According to the present invention, there is an advantage that lens design can be performed without worrying about an object distance and a defocus range, and that an image can be restored by calculation such as accurate convolution.
Further, according to the present invention, the optical system can be simplified and the cost can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a block diagram illustrating an embodiment of an imaging apparatus according to the present invention.

  The imaging apparatus 100 according to the present embodiment includes an imaging lens apparatus 200 having a zoom optical system, an image processing apparatus 300, and an object approximate distance information detection apparatus 400 as main components.

  The imaging lens device 200 optically captures an image of an imaging target object (subject) OBJ, and an image captured by the zoom optical system 210 is formed. The image sensor 220 includes a CCD or a CMOS sensor that is output to the image processing apparatus 300 as the next image signal FIM. In FIG. 1, the imaging element 220 is described as a CCD as an example.

  FIG. 2 is a diagram schematically illustrating a configuration example of the optical system of the zoom optical system 210 according to the present embodiment.

The zoom optical system 210 in FIG. 2 is disposed between an object side lens 211 disposed on the object side OBJS, an image forming lens 212 for forming an image on the image sensor 220, and between the object side lens 211 and the image forming lens 212. An optical wavefront modulation element (wavefront forming optical element: Wavefront) made of, for example, a phase plate (Cubic Phase Plate) having a three-dimensional curved surface, which deforms the wavefront of image formation on the light receiving surface of the image sensor 220 by the imaging lens 212. A Coding Optical Element) group 213; A stop (not shown) is disposed between the object side lens 211 and the imaging lens 212.
In the present embodiment, the case where the phase plate is used has been described. However, the optical wavefront modulation element of the present invention may be any element that deforms the wavefront, and an optical element whose thickness changes. (For example, the above-described third-order phase plate), an optical element whose refractive index changes (for example, a gradient index wavefront modulation lens), an optical element whose thickness and refractive index change by coding on the lens surface (for example, wavefront modulation) A light wavefront modulation element such as a hybrid lens) or a liquid crystal element capable of modulating the phase distribution of light (for example, a liquid crystal spatial phase modulation element) may be used.

The zoom optical system 210 in FIG. 2 is an example in which an optical phase plate 213a is inserted into a 3 × zoom used in a digital camera.
The phase plate 213a shown in the figure is an optical lens that regularly splits the light beam converged by the optical system. By inserting this phase plate, an image that does not fit anywhere on the image sensor 220 is realized.
In other words, the phase plate 213a forms a deep luminous flux (which plays a central role in image formation) and a flare (blurred portion).
Means for restoring the regularly dispersed image to a focused image by digital processing is called a wavefront aberration controlling optical system (WFCO), and this processing is performed in the image processing apparatus 300.

  FIG. 3 is a diagram showing a spot image on the infinite side of the zoom optical system 210 that does not include a phase plate. FIG. 4 is a diagram showing a spot image on the near side of the zoom optical system 210 that does not include a phase plate. FIG. 5 is a diagram showing a spot image on the infinite side of the zoom optical system 210 including the phase plate. FIG. 6 is a diagram showing a spot image on the near side of the zoom optical system 210 including the phase plate.

Basically, the spot image of the light passing through the optical lens system not including the phase plate is different depending on whether the object distance is on the close side or on the infinite side, as shown in FIGS. A spot image is shown.
As described above, in an optical system having spot images different in object distance, the H function described later is different.
Naturally, as shown in FIGS. 5 and 6, the spot image passing through the phase plate influenced by the spot image also becomes a different spot image on the near side and the infinite side.

In such an optical system having different spot images at the object position, the conventional apparatus cannot perform an appropriate convolution operation, and astigmatism, coma aberration, spherical aberration, etc. that cause this spot image shift. An optical design that eliminates each aberration is required. However, the optical design that eliminates these aberrations increases the difficulty of optical design, causing problems such as an increase in design man-hours, an increase in cost, and an increase in the size of the lens.
Therefore, in the present embodiment, as shown in FIG. 1, when the imaging apparatus (camera) 100 enters the shooting state, the approximate distance of the object distance of the subject is read from the object approximate distance information detection apparatus 400, and the image It supplies to the processing apparatus 300.

The image processing apparatus 300 generates an image signal having no dispersion from the dispersed image signal from the image sensor 220 based on the approximate distance information of the object distance of the subject read from the object approximate distance information detection apparatus 400.
The object approximate distance information detection apparatus 400 may be an AF sensor such as externally active.

  In the present embodiment, as described above, dispersion means that, by inserting the phase plate 213a, an image that does not fit anywhere on the image sensor 220 is formed, and the phase plate 213a has a deep light flux ( It plays a central role in image formation) and a phenomenon of forming flare (blurred portion), and includes the same meaning as aberration because of the behavior of the image being dispersed to form a blurred portion. Therefore, in this embodiment, it may be described as aberration.

  FIG. 7 is a block diagram illustrating a configuration example of the image processing apparatus 300 that generates an image signal having no dispersion from the dispersion image signal from the image sensor 220.

  As illustrated in FIG. 7, the image processing apparatus 300 includes a convolution apparatus 301, a kernel / numerical operation coefficient storage register 302, and an image processing operation processor 303.

  In this image processing apparatus 300, the image processing arithmetic processor 303 that has obtained information related to the approximate distance of the object distance of the subject read from the object approximate distance information detection apparatus 400 is used in an appropriate calculation for the object separation position. The kernel size and its calculation coefficient are stored in the kernel and numerical calculation coefficient storage register 302, and an appropriate calculation is performed by the convolution device 301 that calculates using the value, thereby restoring the image.

Here, the basic principle of WFCO will be described.
As shown in FIG. 8, when the subject image f enters the WFCO optical system H, a g image is generated.
This can be expressed by the following equation.

(Equation 1)
g = H * f
Here, * represents convolution.

  In order to obtain a subject from the generated image, the following processing is required.

(Equation 2)
f = H ^-1 * g

Here, the kernel size and calculation coefficient regarding the function H will be described.
The individual object approximate distances are AFPn, AFPn-1,..., And the individual zoom positions (zoom positions) are Zpn, Zpn-1,.
The H function is defined as Hn, Hn-1,.
Since each spot is different, each H function is as follows.

  The difference in the number of rows and / or the number of columns in this matrix is the Carney size, and each number is the calculation coefficient.

As described above, in the case of an imaging device including a phase plate (Wavefront Coding optical element) as an optical wavefront modulation element, an image signal without proper aberrations by image processing within the predetermined focal length range However, if it is outside the predetermined focal length range, there is a limit to the correction of the image processing, so that only an object outside the above range has an image signal with aberration.
On the other hand, by performing image processing in which no aberration occurs within a predetermined narrow range, it is possible to bring out a blur to an image outside the predetermined narrow range.
In this embodiment, the distance to the main subject is detected by the object approximate distance information detection device 400 including the distance detection sensor, and different image correction processing is performed according to the detected distance. .

The above image processing is performed by convolution calculation. To realize this, for example, one type of convolution calculation coefficient is stored in common, and a correction coefficient is stored in advance according to the focal length, The correction coefficient is used to correct the calculation coefficient, and an appropriate convolution calculation can be performed using the corrected calculation coefficient.
In addition to this configuration, the following configuration can be employed.

  The kernel size and the convolution calculation coefficient itself are stored in advance according to the focal length, the convolution calculation is performed using the stored kernel size and calculation coefficient, and the calculation coefficient according to the focal length is stored in advance as a function. In addition, it is possible to employ a configuration in which a calculation coefficient is obtained from this function based on the focal length and a convolution calculation is performed using the calculated calculation coefficient.

  When associated with the configuration of FIG. 7, the following configuration can be adopted.

At least two or more conversion coefficients corresponding to the aberration caused by the phase plate 213a are stored in advance in the register 302 as the conversion coefficient storage means in accordance with the subject distance. The image processing arithmetic processor 303 functions as a coefficient selection unit that selects a conversion coefficient corresponding to the distance from the register 302 to the subject based on the information generated by the object approximate distance information detection device 400 as the subject distance information generation unit. .
Then, a convolution device 301 as a conversion unit converts an image signal using the conversion coefficient selected by the image processing arithmetic processor 303 as a coefficient selection unit.

Alternatively, as described above, the image processing calculation processor 303 as the conversion coefficient calculation unit calculates the conversion coefficient based on the information generated by the object approximate distance information detection device 400 as the subject distance information generation unit, and stores it in the register 302. Store.
Then, a convolution device 301 as a conversion unit converts an image signal using a conversion coefficient obtained by an image processing calculation processor 303 as a conversion coefficient calculation unit and stored in the register 302.

Alternatively, at least one correction value corresponding to the zoom position or zoom amount of the zoom optical system 210 is stored in advance in the register 302 serving as a correction value storage unit. This correction value includes the kernel size of the subject aberration image.
A conversion coefficient corresponding to the aberration caused by the phase plate 213a is stored in advance in the register 302 that also functions as the second conversion coefficient storage unit.
Then, based on the distance information generated by the object approximate distance information detection device 400 as the subject distance information generation means, the image processing arithmetic processor 303 as the correction value selection means performs a process from the register 302 as the correction value storage means to the subject. Select a correction value according to the distance.
The convolution device 301 serving as the conversion unit generates an image based on the conversion coefficient obtained from the register 302 serving as the second conversion coefficient storage unit and the correction value selected by the image processing arithmetic processor 303 serving as the correction value selection unit. Perform signal conversion.

  Next, specific processing when the image processing arithmetic processor 303 functions as a conversion coefficient arithmetic means will be described with reference to the flowchart of FIG.

In the approximate object distance information detection apparatus 400, the approximate object distance (AFP) is detected, and the detection information is supplied to the image processing arithmetic processor 303 (ST1).
The image processing arithmetic processor 303 determines whether or not the object approximate distance AFP is n (ST2).
If it is determined in step ST1 that the object approximate distance AFP is n, the kernel size and calculation coefficient of AFP = n are obtained and stored in the register (ST3).

If it is determined in step ST2 that the approximate object distance AFP is not n, it is determined whether or not the approximate object distance AFP is n-1 (ST4).
If it is determined in step ST4 that the approximate object distance AFP is n-1, the kernel size and calculation coefficient of AFP = n-1 are obtained and stored in the register (ST5).
Thereafter, the determination process of step ST2ST4 is performed by the number of the object approximate distances AFP that must be divided in terms of performance, and the kernel size and calculation coefficient are stored in the register.

In the image processing arithmetic processor 303, the set value is transferred to the kernel and numerical arithmetic coefficient storage register 302 (ST6).
Then, a convolution operation is performed on the image data captured by the imaging lens device 200 and input to the convolution device 301 based on the data stored in the register 302, and the calculated and converted data S302 is an image. Transferred to the processing arithmetic processor 303.

In the present embodiment, WFCO is employed to obtain high-definition image quality, and the optical system can be simplified and the cost can be reduced.
Hereinafter, this feature will be described.

10A to 10C show spot images on the light receiving surface of the imaging element 220 of the imaging lens device 200. FIG.
10A shows a case where the focal point is shifted by 0.2 mm (Defocus = 0.2 mm), FIG. 10B shows a case where the focal point is a focal point (Best focus), and FIG. 10C shows a case where the focal point is shifted by −0.2 mm. In this case, each spot image is shown (Defocus = −0.2 mm).
As can be seen from FIGS. 10A to 10C, in the imaging lens device 200 according to the present embodiment, a light beam having a deep depth (a central part of image formation) is formed by the wavefront forming optical element group 213 including the phase plate 213a. Play a role) and flare (blurred part) is formed.

  As described above, the primary image FIM formed in the imaging lens device 200 of the present embodiment has a light beam condition with a very deep depth.

FIGS. 11A and 11B are diagrams for explaining a modulation transfer function (MTF) of a primary image formed by the imaging lens device according to the present embodiment. FIG. 11A is a diagram showing a spot image on the light receiving surface of the imaging element of the imaging lens device, and FIG. 11B shows the MTF characteristics with respect to the spatial frequency.
In the present embodiment, the high-definition final image is left to the correction processing of the image processing apparatus 300 including a digital signal processor (Digital Signal Processor), for example, as shown in FIGS. 11A and 11B. The MTF of the primary image is essentially a low value.

  The image processing apparatus 300 is configured by a DSP, for example, and receives a primary image FIM from the imaging lens apparatus 200 as described above, and performs a predetermined correction process or the like for raising the MTF at the spatial frequency of the primary image. A fine final image FNLIM is formed.

The MTF correction processing of the image processing apparatus 300 is performed after edge enhancement, chroma enhancement, etc., using the MTF of the primary image, which is essentially a low value, as shown by a curve A in FIG. In the process, correction is performed so as to approach (reach) the characteristics indicated by the curve B in FIG.
The characteristic indicated by the curve B in FIG. 12 is a characteristic obtained when the wavefront is not deformed without using the wavefront forming optical element as in the present embodiment, for example.
It should be noted that all corrections in the present embodiment are based on spatial frequency parameters.

In this embodiment, as shown in FIG. 12, in order to achieve the MTF characteristic curve B to be finally realized with respect to the MTF characteristic curve A with respect to the optically obtained spatial frequency, each spatial frequency is changed to each spatial frequency. On the other hand, the original image (primary image) is corrected by applying strength such as edge enhancement.
For example, in the case of the MTF characteristic of FIG. 12, the curve of edge enhancement with respect to the spatial frequency is as shown in FIG.

  That is, a desired MTF characteristic curve B is virtually realized by performing correction by weakening edge enhancement on the low frequency side and high frequency side within a predetermined spatial frequency band and strengthening edge enhancement in the intermediate frequency region. To do.

As described above, the imaging apparatus 100 according to the embodiment includes the imaging lens apparatus 200 including the optical system 210 that forms the primary image and the image processing apparatus 300 that forms the primary image into a high-definition final image. In the system system, the wavefront of the imaging is deformed by providing a new optical element for wavefront shaping, or by providing an optical element such as glass or plastic that has been molded for wavefront shaping. In this image forming system, such a wavefront is imaged on an imaging surface (light receiving surface) of an imaging element 220 including a CCD or a CMOS sensor, and the primary image is obtained through the image processing apparatus 300 to obtain a high-definition image. .
In the present embodiment, the primary image obtained by the imaging lens device 200 has a light beam condition with a very deep depth. Therefore, the MTF of the primary image is essentially a low value, and the image processing apparatus 300 corrects the MTF.

Here, the imaging process in the imaging lens apparatus 200 in the present embodiment will be considered in terms of wave optics.
A spherical wave diverging from one of the object points becomes a convergent wave after passing through the imaging optical system. At that time, aberration occurs if the imaging optical system is not an ideal optical system. The wavefront is not a spherical surface but a complicated shape. Wavefront optics lies between geometric optics and wave optics, which is convenient when dealing with wavefront phenomena.
When dealing with the wave optical MTF on the imaging plane, the wavefront information at the exit pupil position of the imaging optical system is important.
The MTF is calculated by Fourier transform of the wave optical intensity distribution at the imaging point. The wave optical intensity distribution is obtained by squaring the wave optical amplitude distribution, and the wave optical amplitude distribution is obtained from the Fourier transform of the pupil function in the exit pupil.
Further, since the pupil function is exactly from the wavefront information (wavefront aberration) at the exit pupil position itself, if the wavefront aberration can be strictly numerically calculated through the optical system 210, the MTF can be calculated.

Accordingly, if the wavefront information at the exit pupil position is modified by a predetermined method, the MTF value on the imaging plane can be arbitrarily changed.
In this embodiment, the wavefront shape is mainly changed by the wavefront forming optical element, but the target wavefront is formed by increasing or decreasing the phase (phase, optical path length along the light beam). .
Then, if the target wavefront is formed, the light flux emitted from the exit pupil is from the dense and sparse portions of the light, as can be seen from the geometric optical spot images shown in FIGS. It is formed.
The MTF in the luminous flux state shows a low value at a low spatial frequency and a characteristic that the resolving power is managed up to a high spatial frequency.
That is, if this MTF value is low (or such a spot image state in terms of geometrical optics), the phenomenon of aliasing will not occur.
That is, a low-pass filter is not necessary.
Then, the flare-like image that causes the MTF value to be lowered may be removed by the image processing apparatus 300 including a DSP or the like at the subsequent stage. Thereby, the MTF value is significantly improved.

As described above, according to the present embodiment, the imaging lens device 200 that captures the subject dispersion image that has passed through the optical system and the phase plate (light wavefront modulation element), and the dispersion from the dispersed image signal from the imaging element 200. An image processing device 300 that generates an image signal having no image, and an object approximate distance information detection device 400 that generates information corresponding to the distance to the subject. The image processing device 300 includes the object approximate distance information detection device 400. Since the image signal that is less dispersed than the dispersed image signal is generated based on the generated information, the kernel size used in the convolution operation and the coefficient used in the numerical operation are made variable, and the approximate distance of the object distance is measured. By correlating the kernel size and the above-mentioned coefficients corresponding to the object distance, the object distance and defocus range can be considered. Lens design can be, and accurate convolutional without - there is an image restoration becomes possible by Deployment advantages.
The imaging apparatus 100 according to the present embodiment can be used for a WFCO of a zoom lens in consideration of the small size, light weight, and cost of consumer equipment such as a digital camera and a camcorder.

In the present embodiment, the imaging lens device 200 having a wavefront forming optical element that deforms the wavefront of the imaging on the light receiving surface of the imaging device 220 by the imaging lens 212, and the primary image FIM by the imaging lens device 200. Therefore, the image processing apparatus 300 that performs a predetermined correction process for raising the MTF at the spatial frequency of the primary image to form a high-definition final image FNLIM is provided, so that high-definition image quality can be obtained. There is an advantage that it becomes possible.
In addition, the configuration of the optical system 210 of the imaging lens device 200 can be simplified, manufacturing becomes easy, and cost can be reduced.

By the way, when a CCD or CMOS sensor is used as an image sensor, there is a resolution limit determined by the pixel pitch, and if the resolution of the optical system exceeds the limit resolution, a phenomenon such as aliasing occurs, which adversely affects the final image. It is a well-known fact that
In order to improve image quality, it is desirable to increase the contrast as much as possible, but this requires a high-performance lens system.

However, as described above, aliasing occurs when a CCD or CMOS sensor is used as an image sensor.
Currently, in order to avoid the occurrence of aliasing, the imaging lens apparatus uses a low-pass filter made of a uniaxial crystal system to avoid the occurrence of aliasing.
The use of a low-pass filter in this way is correct in principle, but the low-pass filter itself is made of crystal, so it is expensive and difficult to manage. Moreover, there is a disadvantage that the use of the optical system makes the optical system more complicated.

As described above, in order to form a high-definition image, the optical system must be complicated in the conventional imaging lens apparatus in spite of the demand for higher-definition image due to the trend of the times. . If it is complicated, manufacturing becomes difficult, and if an expensive low-pass filter is used, the cost increases.
However, according to the present embodiment, the occurrence of aliasing can be avoided without using a low-pass filter, and high-definition image quality can be obtained.

  In the present embodiment, the example in which the wavefront forming optical element of the optical system 210 is disposed closer to the object side lens than the stop has been described. The effect of this can be obtained.

  Moreover, the lens which comprises the optical system 210 is not limited to the example of FIG. 2, and various aspects are possible for this invention.

1 is a block configuration diagram showing an embodiment of an imaging apparatus according to the present invention. It is a figure which shows typically the structural example of the zoom optical system of the imaging lens apparatus which concerns on this embodiment. It is a figure which shows the spot image of the infinite side of the zoom optical system which does not include a phase plate. FIG. 4 is a diagram showing a spot image on the close side of a zoom optical system that does not include a phase plate. It is a figure which shows the spot image of the infinite side of the zoom optical system containing a phase plate. It is a figure which shows the spot image of the near side of the zoom optical system containing a phase plate. It is a block diagram which shows the specific structural example of the image processing apparatus of this embodiment. It is a figure for demonstrating the principle of WFCO. It is a flowchart for demonstrating operation | movement of this embodiment. It is a figure which shows the spot image in the light-receiving surface of the image pick-up element of the image pick-up lens apparatus which concerns on this embodiment, Comprising: (A) is a case where a focus shifts by 0.2 mm (Defocus = 0.2 mm), (B) is a result. In the case of a focus (Best focus), (C) is a figure which shows each spot image when a focus shifts by -0.2 mm (Defocus = -0.2 mm). It is a figure for demonstrating MTF of the primary image formed with the imaging lens apparatus which concerns on this embodiment, Comprising: (A) is a figure which shows the spot image in the light-receiving surface of the image pick-up element of an imaging lens apparatus, ( B) shows the MTF characteristic with respect to the spatial frequency. It is a figure for demonstrating the MTF correction process in the image processing apparatus which concerns on this embodiment. It is a figure for demonstrating concretely the MTF correction process in the image processing apparatus which concerns on this embodiment. It is a figure which shows typically the structure and light beam state of a general imaging lens apparatus. FIG. 15A is a diagram showing a spot image on the light receiving surface of the image sensor of the imaging lens apparatus of FIG. 14, where FIG. 14A shows a case where the focal point is shifted by 0.2 mm (Defocus = 0.2 mm), and FIG. In the case (Best focus), (C) is a diagram showing each spot image when the focal point is shifted by -0.2 mm (Defocus = -0.2 mm).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Image forming apparatus, 200 ... Imaging lens apparatus, 211 ... Object side lens, 212 ... Imaging lens, 213 ... Optical element for wavefront formation, 213a ... Phase plate (light wavefront modulation element), 300 ... Image processing apparatus, 301 ... Convolution device, 302 ... Kernel, numerical calculation coefficient storage register, 303 ... Image processing calculation processor, 400 ... Object approximate distance information detection device.

Claims (6)

An imaging device that captures a subject dispersion image that has passed through at least the optical system and the light wavefront modulation device;
Conversion means for generating a non-dispersed image signal from the dispersed image signal from the imaging element;
Subject distance information generating means for generating information corresponding to the distance to the subject,
The conversion unit generates an image signal having less dispersion than the dispersion image signal based on information generated by the subject distance information generation unit. Conversion coefficient storage means for preliminarily storing at least two conversion coefficients corresponding to dispersion caused by the light wavefront modulation element according to the subject distance;
Coefficient selection means for selecting a conversion coefficient according to the distance from the conversion coefficient storage means to the subject based on the information generated by the subject distance information generation means,
The imaging apparatus according to claim 1, wherein the conversion unit converts an image signal using the conversion coefficient selected by the coefficient selection unit. Conversion coefficient calculation means for calculating a conversion coefficient based on the information generated by the subject distance information generation means,
The imaging apparatus according to claim 1, wherein the conversion unit converts an image signal using a conversion coefficient obtained from the conversion coefficient calculation unit. The optical system includes a zoom optical system,
Correction value storage means for storing in advance at least one correction value corresponding to the zoom position or zoom amount of the zoom optical system;
Second conversion coefficient storage means for storing in advance a conversion coefficient corresponding to dispersion caused by at least the light wavefront modulation element;
Correction value selection means for selecting a correction value according to the distance from the correction value storage means to the subject based on the information generated by the subject distance information generation means, the conversion means comprising the second conversion coefficient The imaging apparatus according to claim 1, wherein the image signal is converted by the conversion coefficient obtained from the storage unit and the correction value selected from the correction value selection unit. The imaging apparatus according to claim 4, wherein the correction value stored in the correction value storage unit includes a kernel size of the subject dispersion image. Capturing an object dispersion image that has passed through at least the optical system and the light wavefront modulation element with an imaging element;
A subject distance information generation step for generating information corresponding to the distance to the subject;
An imaging method comprising: converting the dispersed image signal based on information generated by the subject distance information generating step to generate an image signal having no dispersion.

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