TW201104299A - Computational photography digital camera - Google Patents

Abstract

The present disclosure relates to a computational photography digital camera. The computational photography digital cameral includes a liquid crystal element placed on the optical path thereof and a digital refocusing processor for post-processing the image obtained thereby. The liquid crystal element includes a periodically patterned electrode formed thereon. The digital refocusing processor is configured for performing Fourier transform to the spatial function of the periodically patterned electrode and the image spatial function (in spatial domain) obtained by the digital camera. The digital refocusing processor is also for performing deconvolution of the spatial function of the periodically patterned electrode from the image spatial function in frequency domain, to obtain an eigen image frequency function. The digital refocusing processor is further configured for performing inverse Fourier transform to the eigen image frequency function, to obtain an eigen image spatial function. Moreover, the digital refocusing processor is capable of determine a focal length of each pixel of the image based upon the eigen image spatial function, thereby refocusing the image. The digital camera uses the liquid crystal element to realize all-focused. The liquid crystal element is easy to manufacture and thereby of low cost.

Description

201104299 VI. Description of the Invention: [Technical Field] The present invention relates to a digital camera, and in particular to a computing digital camera. [Prior Art] [0002] Currently, digital cameras use motor-driven lens zooming and/or focusing to obtain high-definition images. However, on the one hand, the motor is often complicated in structure (such as a common voice coil motor including components such as a voice coil, a permanent magnet element, and a package), which is disadvantageous for assembly and large in size, which is disadvantageous for miniaturization of a digital camera. On the other hand, when shooting close-up, the depth of field of the lens is small' often only achieves single-point focusing, and the overall image clarity is not ideal. [〇〇〇3] To this end, the industry proposes a computing camera type digital camera that incorporates special optical components such as coded aper-ture, mask, wavefront in the imaging optical path. Optical element) to capture the 4-dimension light field message on the image side and perform digital refocusing on the captured 4D light field information. In this way, an all in focus image can be obtained. [0004] However, the manufacturing process of special optical components is very demanding and the manufacturing cost is high. In addition, the addition of a coded aperture or reticle to the optical path can cause a loss of light (Uight loss), resulting in insufficient image brightness. In the optical path of the digital camera, the wavefront is added, and the digital focus processing at the back end is very large. SUMMARY OF THE INVENTION _] There is a need to provide a computing camera type digital camera that can achieve full focus and low production cost. 098125292 Page 4 of 22 Form No. A0101 [0006] Ο q [0007] [0008] [0009] 1 Calculate the county machine, its ~, liquid crystal components and - digital food G-lens, lens, The image is sensed in front of the image sensor, and is shaped by a processor. The liquid crystal cell is provided with a periodic pattern electrode having a periodic* periodic pattern electrode. The detector is used to obtain an electrode function through the lens and the sputum pattern. The image sense-image function: the digital focus, the light field information of the element is obtained - deconvolution, - anti-Fourier: for the Fourier transformer, the leaf transformer is used for the periodic map ―Refocuser. The Fourier transform is performed to obtain a polar function and the image function into an image frequency domain function, respectively. The area of the (four) 11 (four) polar frequency domain function and the line removes the periodic map (4) polar image frequency domain function into a «image frequency domain function. The I product is computed to obtain a function of the frequency domain function of the eigenimage. The focus is used to base = intrinsic image (4) Image is compared to the image = the focal length of each point is achieved to achieve the gold focus of the image sensor. ... :J !:; This calculates the digital phase mechanism of the camera. This liquid crystal element is used as a special optical element and digitally refocusing with the digital focus processor for full focus. Due to the maturity of the liquid crystal element technology and the line #, the liquid crystal display is easy to manufacture and the production cost is low. [Embodiment] Please refer to FIG. 1 'The computing camera type digital camera 100 of the first embodiment of the present invention includes a lens 10, an image sensor 20, a liquid crystal element 30, and a digital focus processor. The lens 10 can be a simple fixed-focus lens, and can include only the lens barrel 12 and the housing 098125292 Form No. A0101 Page 5 / Total 22 pages 0982043276-0 201104299 The lens 14 in the lens barrel 12. Preferably, the lens 14 is an aspherical glass lens for better transmission of light field information on the object side to the image side. In the present embodiment, the lens 10 is a zoom lens, which enables close-up photography and telephoto shooting. [0010] Generally, when shooting in a distant scene, the object distance is large, and correspondingly, the depth of field is very large. It is generally considered that a subject (not shown) can form a clear image on the image sensor 20 via the lens 10 without starting the liquid crystal element 30 and the digital focus processor 40. In close-up shooting, the object distance is small, and correspondingly, the depth of field is small, and it is generally impossible to achieve all in focus of the subject. At this time, it is necessary to activate the liquid crystal element 30 and the digital focus processor 40 for digital refocusing (see below). [0011] The image sensor 20 may be a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) sensor. The image sensor 20 is disposed on the image side of the lens 10. Preferably, the image sensor 20 is placed at the image plane of the lens 10. Referring to FIG. 2 at the same time, the liquid crystal element 30 is a liquid crystal panel on which a periodic pattern electrode 32 is formed. The liquid crystal element 30 is disposed between the lens 10 and the image sensor 20 near the image sensor 20. In addition, the optical axis 镜头 of the lens 10 passes through the center of the periodic pattern electrode 32 and the center of the image sensor 20. If the center of the periodic pattern electrode 32 is the origin, the width direction of the image sensor 20 is λ axis, and the height direction of the image sensor 20 is 098125292. Form number Α 0101 Page 6 / Total 22 pages 0984243276-0 201104299 Axis, A spatial coordinate system is established; the spatial frequency of the periodic pattern electrode 32 at the Λ axis is the spatial frequency of the periodic pattern electrode 32 at the y Ο axis, and the spatial function of the periodic image electrode 32 can be expressed as (1) κ, - Cos 2 + Syy) ο Q [0013] It can be understood that, when a close-up shot is applied, if a voltage is applied to the peripheral pattern electrode 32, the optical characteristics at the periodic pattern electrode 32 will change. For example, the refractive index η at the periodic pattern electrode 32 will change to η - ?^ + Δη , where 098125292 % is the intrinsic refractive index of the liquid crystal element 30, Form No. 1010101 Page 7 / Total 22 Page 0982034276-0 201104299 Δη is the amount of change in refractive index at the periodic pattern electrode 32 after the voltage is applied. Thus, the optical path of the light passing through the periodic pattern electrode 32 changes. Correspondingly, the light field tribute obtained by the sensor 20 is no longer a plane (2_diinension), and the four-dimensional light field tribute can be obtained. In this way, a full-focus image can be obtained by processing the four-dimensional light field information (see the description of the digital focus processor 40 below). Generally, in the space coordinate system, the refractive index of the liquid crystal element 30 can be expressed as (2). [0014] The periodic pattern electrode 32 of the present embodiment is a series of concentric rings 322, and the intervals between the rings 322 are the same. The difference between the inside and outside is equal. Of course, the periodic pattern electrode 32 is not limited to the embodiment, and other periodic pattern electrodes may be employed, such as the rectangular spiral 324 shown in FIG. 3, the circular array 326 shown in FIG. 4, and the oblique line shown in FIG. Square spot array 328. [0015] The digital focus processor 40 includes a Fourier transform-type unit 42, a deconvolution unit 44, an inverse Fourier transform unit 46, and a refocusing unit (refocusing). Uni1:)48. [0016] Fourier Transformer 42 is used for image function R on the spatial domain output to image sensor 20 during close-up shooting. (4) 098125292 Form No. 1010101 Page 8/Total 22 pages 0984243276-0 201104299 (Amplitude function) Performing a Fourier transform to obtain a frequency domain function of the image function, where Λ Λ

These are the variables on the upper and lower y axes of the frequency domain. Specifically, according to Fourier Optics (?0111'丨61'0 port-t i c s ), [0017] (3)

l/rjl ^

Ρ (Λ — · i jk ...W

[0018] where is the imaginary unit, Ά is the working wavelength, 0982043276-0 098125292 Form No. A0101 Page 9 / Total 22 pages 201104299 f For the close-up shooting corresponding to the corresponding focal length of the focus on the image sensor 20 ( It can be noted as [0019] In addition, the Fourier transformer 42 is also used for the spatial function of the periodic image electrode 32.

A Fourier transform is performed to obtain a frequency domain function of the periodic image electrode 32. Generally, it is a known function, so that a certainty can be obtained.

[0020] The deconvolfer 44 is used to perform a deconvolution operation. According to the principle of image processing, 098125292 Form No. A0101 Page 10 / Total 22 Page 0982043276-0 201104299 It should be the convolution of the eigenimage function on the spatial domain with the spatial function of the periodic image electrode 32, ie (4) Oh. Therefore, according to mathematical theory, (5) where the pair is represented by Fourier transform. Thus, the deconvolution operation for removing ί / ν Λ 可 为 ( ( 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 098 The deconvolution operation of page 22111299 is equivalent to filtering out the signal of the periodic pattern electrode 32 in the signal obtained by the image sensor 20 in the frequency domain. [0022] The inverse Fourier transformer 46 is used to perform an inverse Fourier transform to obtain

From the above formulas, especially (1), (3), (6) can be obtained with variables Λ f

The function refocusing device 48 is used to determine points on the image sensor 20 to focus on the corresponding points. Specifically, you can get / by substituting the coordinates of each point 098125292 Form No. A0101 Page 12/22 Page 0982043276-0 201104299. So by calculating the points

f You can get a full-focus image. In addition, by calculating the maximum difference of f of point (4), you can also get the depth of field of the image in full focus.

LL

[0023] The computing-type digital camera 100 uses the liquid crystal element 30 as a special optical element and performs digital refocusing using the digital focus processor 40 to achieve full focus. Due to the maturity of the liquid crystal element technology and the industry, the liquid crystal element 30 is easy to manufacture and has a low manufacturing cost. In addition, the modulation of the light field by the liquid crystal element 30 is achieved by changing the optical path of a specific light (light passing through the periodic pattern electrode 32), rather than by intercepting a specific light like a coded aperture or a mask. It can avoid light loss, and there is no problem of excessive calculation caused by wavefront coding. 098125292 Form No. A0101 Page 13 of 22 0982043276-0 201104299 [0024] [0030] [0030] [0031] It can be understood that the arrangement of the liquid crystal element 30 is not limited to In this embodiment, it can be disposed at any position before the image sensor 20 , such as embedded in the lens 10 or disposed in front of the lens 10 . In summary, the present invention has indeed met the requirements of the invention patent, and the patent application is filed according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by those skilled in the art in light of the spirit of the present invention, for example, the scattering portion may include a lattice pattern surrounded by a plurality of first strip-shaped grooves and distributed along the optical axis of the lens. A spiral pattern composed of a plurality of second strip-shaped grooves in a radial spiral shape, etc., should be included in the following patent application. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing a computing-type digital camera according to a first embodiment of the present invention. FIG. 2 is a schematic diagram of a liquid crystal element of the computing image type digital camera of FIG. 1. FIG. 3 is a schematic view of a liquid crystal element according to a second embodiment of the present invention. 4 is a schematic view of a liquid crystal element according to a third embodiment of the present invention. Fig. 5 is a schematic view of a liquid crystal element according to a fourth embodiment of the present invention. [Main component symbol description] Calculated camera number 100 Rectangular spiral 324 camera lens 10 Circular spot array 326 Lens barrel 12 Squared array 328 Lens 14 Digital focus processing 40 Form No. A0101 Page 14 of 22 0984043276-0 098125292 Image sensor 20 Fourier transformer 42 Liquid crystal element 30 Deconvolution 44 Periodic pattern electric 32 Anti-Fourier transform 46 Transistor concentric ring 322 Refocuser 48 201104299 Ο 098125292 Form No. Α0101 Page 15 of 22 Page 0980243276-0

Claims (1)

201104299 VII. Patent application scope: 1. A computing camera type digital camera, comprising a lens and an image sensor; wherein the computing camera type digital camera further comprises a liquid crystal component and a digital focus processor; the liquid crystal component a periodic pattern electrode is formed on the image sensor; the periodic pattern electrode has a periodic pattern electrode function; and the image sensor is configured to obtain light field information through the lens and the liquid crystal element Obtaining an image function; the digital focus processor is configured to include a Fourier transformer, a deconvolution device, an inverse Fourier transformer, and a refocusing device; the Fourier transformer is used for the periodic pattern electrode function and the image The function performs Fourier transform to obtain a periodic pattern electrode frequency domain function and an image frequency domain function respectively; the deconvolfer is used to remove the frequency domain function from the frequency domain function to deconvolute the frequency domain function of the periodic pattern electrode Computing to obtain an eigenimage frequency domain function; the inverse Fourier transformer is used to perform the eigenimage frequency domain function Inverting the Fourier transform to obtain an eigenimage function; the refocusing device is configured to determine a focal length corresponding to the focus of each image sensor on the image sensor according to the eigenimage function, to achieve full focus of the image sensor . 2. The computing camera type digital camera according to claim 1, wherein the lens is a fixed focus lens or a zoom lens. 3. The computing camera type digital camera of claim 1, wherein the lens comprises a lens barrel and at least one lens disposed in the lens barrel. 4. The computing camera type digital camera of claim 3, wherein the at least one lens comprises at least one aspherical glass lens. 5. The computing camera type digital camera according to claim 1, wherein the image sensor is a charge coupler or a complementary metal oxide semiconductor sensation 098125292. Form No. A0101 Page 16 of 22 page 2084023276-0 201104299 Tester. 6. The computing camera type digital camera of claim 1, wherein the image sensor is disposed at an image plane of the lens. 7. The computing camera type digital camera according to claim 1, wherein the liquid crystal element is a liquid crystal panel. 8. The computing camera type digital camera according to claim 1, wherein the liquid crystal element is disposed between the lens and the image sensor, within the lens or in front of the lens. 9. The computing camera type digital camera of claim 1, wherein the periodic pattern electrode is a plurality of concentric rings, a rectangular spiral, a circular spot array or an oblique square array. 10. The computing camera type digital camera of claim 1, wherein the optical axis of the lens passes through a center of the periodic pattern electrode and a center of the image sensor. ❹ 0982043276-0 098125292 Form No. A0101 Page 17 of 22