Hyperspectral optical system and auto-focusing method using same

Abstract

The present invention relates to a hyperspectral optical device and an auto-focusing method using same. More specifically, an auto-focusing technique is employed in which an object to be photographed by the hyperspectral optical device is divided into a plurality of individual regions, a plurality of depths of field are selected for the object to be photographed, and images captured at the respective depths of field are combined and corrected, thereby alleviating blurring in the image captured by the hyperspectral optical device resulting from non-uniform depth of the object.

Description

Hyperspectral optical system and autofocusing method using the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2024-0069400, dated May 28, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a hyperspectral optical system and an auto-focusing method using the same.

[0005] "Hyperspectral" refers to a technology that finely divides the visible and near-infrared spectrum into approximately 200 wavelengths, unlike conventional imaging, which distinguishes only the three primary colors of light. While the human eye primarily perceives visible light in three bands, hyperspectral imaging technology can divide the spectrum into even more bands.

[0006] Therefore, hyperspectral optical devices, such as hyperspectral cameras or hyperspectral sensors utilizing hyperspectral imaging technology, have a large number of detection wavelength bands and narrowly segmented ranges within each wavelength band, allowing for greater information to be extracted from captured images. Accordingly, research into utilizing hyperspectral imaging technology is ongoing.

[0007] However, when the subject being photographed is uneven and the depth of field is uneven in the Z-axis direction, images captured with currently commercialized hyperspectral optical devices have a problem of defocusing. The Z-axis direction refers to the depth or thickness direction.

[0008] Accordingly, it is necessary to develop a technology that prevents focus blur from occurring in images captured with the hyperspectral optical device even when the subject of the photograph is uneven and the depth of field is uneven in the Z-axis direction.

[0009] [Prior Art Literature]

[0010] [Patent Document]

[0011] (Patent Document 1) U.S. Patent Publication No. 2020-0200606

[0012] The inventors of the present invention have conducted multifaceted research to solve the above problems and have confirmed that when an auto focusing technology is introduced that selects multiple depths of field for a subject to be photographed by a hyperspectral optical system and then combines and corrects images photographed at each of these depths, the focus blurring phenomenon due to uneven depth of field of the subject in the images photographed by the hyperspectral optical system is improved.

[0013] Accordingly, an object of the present invention is to provide a hyperspectral optical system capable of providing an image with improved defocus phenomenon.

[0014] In addition, another object of the present invention is to provide an auto-focusing method using the hyperspectral optical system.

[0015] To achieve the above purpose, the present invention relates to a hyperspectral optical system,

[0016] (a) A viewfinder shooting unit that divides a shooting subject into a plurality of individual areas and then captures depth-specific images of the shooting subject including the individual areas using a view finder;

[0017] (b) A representative depth derivation unit for each area of ​​the photographing subject that calculates the focus for each viewfinder image captured at each depth and then selects the depth corresponding to the viewfinder image with excellent focus as the representative depth for each individual area;

[0018] (c) a hyperspectral image capturing unit that captures individual areas corresponding to the representative depth selected above using a hyperspectral CCD (Charge Coupled Device); and

[0019] (d) A hyperspectral optical system is provided, including an image correction unit that combines hyperspectral images of individual areas corresponding to the representative depth, captured by the hyperspectral CCD, to correct a focus blur phenomenon caused by depth unevenness of the subject being captured.

[0020] In one embodiment of the present invention, the photographing target may be divided into 5 to 20 individual areas.

[0021] In one embodiment of the present invention, 3 to 10 depth-specific images may be captured for each individual area.

[0022] In one embodiment of the present invention, in the representative depth derivation unit for each individual area of ​​the photographing target (b), the focus may be calculated in the viewfinder.

[0023]

[0024] The present invention also relates to an auto-focusing method using a hyperspectral optical system, comprising: (A) a viewfinder shooting step of dividing a shooting subject into a plurality of individual areas and then shooting depth-specific images of the individual areas using a view finder;

[0025] (B) A representative depth derivation step for each area of ​​the photographed subject, which calculates the focus for each depth-based image of each individual area photographed above and then selects the depth corresponding to the calculated focus as the representative depth for each individual area;

[0026] (C) a hyperspectral image capturing step of repeatedly capturing individual areas corresponding to the representative depth selected above using a hyperspectral CCD (Charge Coupled Device); and

[0027] (D) An auto-focusing method using a hyperspectral optical system, including an image correction step of combining hyperspectral images of individual areas corresponding to the representative depth, captured by the hyperspectral CCD, to correct a focus blur phenomenon caused by uneven depth of the subject being captured.

[0028] In one embodiment of the present invention, the photographing target may be divided into 5 to 20 individual areas.

[0029] In one embodiment of the present invention, 3 to 10 depth-specific images may be captured for each individual area.

[0030] In one embodiment of the present invention, in the step (B), the focus may be calculated in the viewfinder.

[0031] According to the present invention, even if the subject of a photograph of a hyperspectral optical system has an uneven depth in the thickness or depth direction, there is an effect of providing an image with improved focus blur by auto-focusing technology.

[0032] Fig. 1a is a schematic diagram showing a viewfinder shooting unit of a hyperspectral optical system for shooting individual areas of a shooting subject using a viewfinder, and Fig. 1b shows viewfinder image data by depth of individual areas shot using the viewfinder.

[0033] Figure 2a shows individual areas divided by depth of the subject of the photograph, and Figure 2b shows a graph for selecting a representative depth for each individual area by using the focus of the viewfinder image for each area at a specific depth.

[0034] Figure 3a is a schematic diagram showing how to repeatedly capture individual areas by path according to a representative depth using a hyperspectral CCD, and Figure 3b shows a hyperspectral CCD image (scanned image) captured by path.

[0035] Figure 4a shows the process of combining the correction images for each path, and Figure 4b shows the hyperspectral CCD image corrected by combining the correction images for each path.

[0036] FIG. 5 illustrates an image captured by a hyperspectral optical system to which an auto-focusing technique is applied according to a preferred embodiment of the present invention.

[0037] Figure 6 shows an image captured by a conventional hyperspectral optical system to which autofocusing technology is not applied.

[0038] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0039] The terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0040] The term “hyperspectral optical system” as used herein means an optical system including a hyperspectral CCD (Charge Coupled Device), and the hyperspectral optical system may be understood as a hyperspectral CCD having an auto-focusing function.

[0041] The term “AUTO FOCUSING” used in this specification refers to a technology that selects multiple depths for a subject to be photographed by a hyperspectral optical device, photographs images of the subject corresponding to each depth, and then combines them to improve the focal flow phenomenon caused by the difference in depth.

[0042] The term “Z-axis” as used herein may refer to the depth or thickness direction of any object, and in particular, may mean the depth or thickness direction of the photographing object.

[0043]

[0044] hyperspectral optical device

[0045] The present invention relates to a hyperspectral optical device.

[0046] A hyperspectral optical device according to the present invention comprises: (a) a viewfinder photographing unit that divides a photographing target into a plurality of individual regions and then photographs depth-specific images of the photographing target including the individual regions using a view finder;

[0047] (b) A representative depth derivation unit for each area of ​​the photographing subject that calculates the focus for each viewfinder image captured at each depth and then selects the depth corresponding to the viewfinder image with excellent focus as the representative depth for each individual area;

[0048] (c) a hyperspectral image capturing unit that captures individual areas corresponding to the representative depth selected above using a hyperspectral CCD (Charge Coupled Device); and

[0049] (d) an image correction unit that combines hyperspectral images of individual areas corresponding to the representative depth, captured by the hyperspectral CCD, to correct a focus blur phenomenon caused by uneven depth of the subject being captured;

[0050] By performing autofocusing according to the above (a) to (d), the defocus phenomenon of an image captured by a hyperspectral optical system can be prevented.

[0051]

[0052] In the hyperspectral optical system of the present invention, the (a) viewfinder photographing unit divides the photographing target into a plurality of individual regions, and then uses the view finder to capture images of the photographing target including the individual regions at different depths.

[0053]

[0054] Fig. 1a is a schematic diagram showing a viewfinder shooting unit of a hyperspectral optical system for shooting individual areas of a shooting subject using a viewfinder, and Fig. 1b shows viewfinder image data by depth of individual areas shot using the viewfinder.

[0055]

[0056] Referring to FIGS. 1A and 1B, after dividing a photographing target (20) into a plurality of individual regions (21), the photographing target (20) including the plurality of individual regions (21) can be photographed using a viewfinder (10). The depth of each individual region (21) in the photographing target (20) may be different. When photographing a viewfinder image (22) of the photographing target (20) including each individual region (21), the photographing target (20) including the individual regions (21) at each of a plurality of depths can be respectively photographed, thereby obtaining a viewfinder image (22) for each depth of the individual region (21). For example, by dividing the depths into 1 to n, the viewfinder image (22 (n)) captured at the nth depth can be obtained from the viewfinder image (22 (1)) captured at the first depth. From this, data can be obtained by accumulating viewfinder images, which are 1 to n depth-specific viewfinder images (22(1) to 22(n)).

[0057]

[0058] The above viewfinder is a device that allows you to confirm the camera's line of sight, rather than the photographer's. It refers to a camera device that helps you compose a photo and achieve more precise focus on the subject. Typically, a viewfinder can be used to navigate measurement locations (X / Y axes) or to calculate the focus of an image captured at a specific depth (Z axis).

[0059] The above viewfinder is not particularly limited as long as it is one commonly used in the art, and for example, both an optical or electronic viewfinder can be used.

[0060] The optical viewfinder is called an OVF (Optical View Finder), and the electronic viewfinder is called an EVF (Electronic View Finder). The difference between an OVF and an EVF is whether or not they use a lens.

[0061] The optical viewfinder (OVF) uses a prism to reflect light entering the lens, allowing us to see straight ahead. Film SLR cameras allow photographers to preview the captured image through the OVF before pressing the shutter button to take the shot. Because the image generated by light is still transmitted through the OVF, it offers the advantage of delivering a clearer, more accurate image.

[0062] An electronic viewfinder (EVF) reduces the space taken up by the viewfinder compared to an optical viewfinder (OVF), improving the camera's portability. An EVF electronically processes light passing through the lens onto an image sensor, converting that information into data. The processed image is then displayed on a small screen. This image is then viewed through the viewfinder.

[0063]

[0064] In the hyperspectral optical system of the present invention, the representative depth derivation unit for each individual region of the photographing target (b) calculates the focus for each of the photographed viewfinder images for each depth, and then selects the depth corresponding to the viewfinder image with excellent focus as the representative depth for each individual region.

[0065]

[0066] Fig. 2a is a diagram illustrating individual areas divided by depth of a photographing target, and Fig. 2b is a graph for selecting a representative depth for an individual area by using the focus of the viewfinder image for the individual area at a specific depth. At this time, since the representative depth is selected after photographing the photographing target including the individual area at multiple depths, it means a photographing procedure performed for each depth, and the photographing procedure performed for each depth can be referred to as a path. Referring to Fig. 2a, as a preferred embodiment, the individual areas can be divided into 7, and the depths can be divided into 5. For example, in 5 depths including the 1st to 5th depths, the first individual areas can be represented as #1-1, #2-1, #3-1, #4-1, and #5-1, respectively, and the second individual areas can be represented as #1-2, #2-2, #3-2, #4-2, and #5-2. The third to seventh individual areas can also be displayed in the same manner at five depths. Accordingly, the photographing procedures performed at the first to fifth depths can be referred to as the first to fifth passes, respectively.

[0067] The degree of focus for each individual area thus distinguished can be calculated in the viewfinder. For viewfinders commonly used in the art, the degree of focus of the captured image can be calculated. For example, focus can be calculated based on the size of the pixel intensity distribution in an image captured through the viewfinder. If the viewfinder image is clear and black and white are well distinguished, the viewfinder pixel intensity distribution will be large, indicating good focus.

[0068]

[0069] Referring to Fig. 2b, as a preferred embodiment, a graph can be obtained that displays the height (α) of each individual area from the actual shooting target for each individual area (X-axis) and the representative depth (β, Z-axis) selected for each individual area.

[0070] As the representative depth (β) for each individual area is selected, when the representative depth (β) for each individual area is connected, it can be seen that a height shift (γ) along the Z-axis occurs from the out-of-focus state to the representative depth.

[0071] In the hyperspectral optical system of the present invention, the hyperspectral image capturing unit (c) can capture an object including an individual area corresponding to the selected representative depth using a hyperspectral CCD (Charge Coupled Device).

[0072]

[0073] Fig. 3a is a schematic diagram showing a method of photographing a subject including individual areas by path according to a representative depth using a hyperspectral CCD, and Fig. 3b shows a hyperspectral CCD image (scanned image) photographed by path.

[0074] At this time, the shooting using the hyperspectral CCD can be done using line scan. For example, the shooting can be done using line scan for each path according to the representative depth selected for each individual area.

[0075]

[0076] In the hyperspectral optical system of the present invention, the image correction unit (d) can correct a focus blur phenomenon caused by uneven depth of the photographing target by combining hyperspectral CCD images of individual areas corresponding to the representative depth, which are photographed by the hyperspectral CCD.

[0077] Figure 4a shows the process of combining the correction images for each path, and Figure 4b shows the hyperspectral CCD image corrected by combining the correction images for each path.

[0078] The hyperspectral CCD images captured for each path can be combined by an image correction software program to correct for defocusing caused by uneven depth of field of the subject. The image correction software program is not particularly limited as long as it is a program driven by logic that corrects for defocusing of an image by combining multiple images.

[0079]

[0080] Referring to Fig. 4a, the hyperspectral CCD images captured for each path can be combined using an image correction software program.

[0081] First, the entire image can be combined by combining the hyperspectral CCD image captured by 1-path with the images captured by 2-path and 3-path, and then combining the images captured by 4-path and 5-path.

[0082] Referring to Fig. 4b, the images captured along these paths can be combined to obtain a final corrected hyperspectral CCD image.

[0083]

[0084] FIG. 5 shows an image captured by a hyperspectral optical system to which auto-focusing technology is applied according to a preferred embodiment of the present invention, and FIG. 6 shows an image captured by a conventional hyperspectral optical system (Hyper Spectral Camera, Mitutoyo Co.) to which auto-focusing technology is not applied.

[0085] At this time, the shooting subject is not particularly limited, but for example, if the depth of the shooting subject is uneven, the effect of improving the focus blur phenomenon by auto-focusing can be better confirmed.

[0086]

[0087] Fig. 5 was taken by a hyperspectral system with auto-focusing technology applied, and thus, no defocus phenomenon was observed. However, Fig. 6 was taken by a conventional hyperspectral CCD without auto-focusing technology, and thus, a defocus phenomenon was observed.

[0088]

[0089] Autofocusing method using a hyperspectral optical system

[0090] The present invention also relates to an auto-focusing method using the hyperspectral optical system described above.

[0091] (A) A viewfinder shooting step of dividing a shooting target into multiple individual areas and then shooting images of each depth of the individual areas using a view finder;

[0092] (B) A representative depth derivation step for each area of ​​the photographed subject, which calculates the focus for each depth-based image of each individual area photographed above and then selects the depth corresponding to the viewfinder image with excellent focus as the representative depth for each individual area;

[0093] (C) a hyperspectral image capturing step of capturing individual areas corresponding to the representative depth selected above using a hyperspectral CCD (Charge Coupled Device); and

[0094] (D) An image correction step for correcting a focus blur phenomenon caused by depth unevenness of a photographing target by combining hyperspectral images of individual areas corresponding to the representative depth, captured by the hyperspectral CCD.

[0095]

[0096] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0097]

[0098] [Explanation of symbols]

[0099] 10: Viewfinder

[0100] 20: Subject of the photo shoot

[0101] 21: Individual areas

[0102] 22: Viewfinder image

[0103] 22(n): Viewfinder image at the nth depth

Claims

1. (a) A viewfinder shooting unit that divides a shooting subject into a plurality of individual areas and then captures depth-specific images of the shooting subject including the individual areas using a view finder; (b) A representative depth derivation unit for each area of ​​the photographing subject that calculates the focus for each viewfinder image captured at each depth and then selects the depth corresponding to the viewfinder image with excellent focus as the representative depth for each individual area; (c) a hyperspectral image capturing unit that captures individual areas corresponding to the representative depth selected above using a hyperspectral CCD (Charge Coupled Device); and (d) A hyperspectral optical system including an image correction unit that combines hyperspectral images of individual areas corresponding to the representative depth, captured by the hyperspectral CCD, to correct for focus blur caused by depth unevenness of the subject being captured.

2. In paragraph 1, A hyperspectral optical system wherein the above photographing object is divided into 5 to 20 individual areas.

3. In paragraph 1, A hyperspectral optical system that captures 3 to 10 depth-specific images for each individual area.

4. In paragraph 1, A hyperspectral optical system, wherein in the representative depth derivation section for each area of ​​the photographing target (b), the focus is calculated in the viewfinder. 5.(A) A viewfinder shooting step in which the shooting target is divided into multiple individual areas and images of each depth of the individual areas are captured using a view finder; (B) A representative depth derivation step for each area of ​​the photographed subject, which calculates the focus for each depth-based image of each individual area photographed above and then selects the depth corresponding to the viewfinder image with excellent focus as the representative depth for each individual area; (C) a hyperspectral image capturing step of capturing individual areas corresponding to the representative depth selected above using a hyperspectral CCD (Charge Coupled Device); and (D) An auto-focusing method using a hyperspectral optical system, comprising an image correction step of combining hyperspectral images of individual areas corresponding to the representative depth, captured by the hyperspectral CCD, to correct a focus blur phenomenon caused by uneven depth of the subject being captured.

6. In paragraph 5, An autofocusing method using a hyperspectral optical system, wherein the above photographing target is divided into 5 to 20 individual areas.

7. In paragraph 5, An autofocusing method using a hyperspectral optical system, which captures 3 to 10 depth-specific images for each individual area.

8. In paragraph 5, An autofocusing method using a hyperspectral optical system, wherein in the step (B) above, the focus is calculated in the viewfinder.

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