Image extraction system using polarized light

Abstract

The present application relates to a kind of image extraction system using polarized light, it is related to the field of image extraction, system includes: light source, first polarizer, polarizing beam splitter, first photosensitive element, second photosensitive element and processor;The light of the light source is polarized by the first polarizer, and polarized light is obtained;Foreground is arranged between the first polarizer and the polarizing beam splitter;The light not being blocked by the foreground and the light reflected by foreground are split by the polarizing beam splitter, and first beam and second beam are obtained;The first photosensitive element is used to form first photosensitive image according to the first beam;The second photosensitive element is used to form second photosensitive image according to the second beam;The processor is used to obtain foreground image according to the first photosensitive image and the second photosensitive image.The present application can reduce light requirement while ensuring the effect of image extraction.

Description

Technical Field

[0001] This invention relates to the field of image extraction, and in particular to an image extraction system utilizing polarized light. Background Technology

[0002] Image keying (chroma keying) refers to extracting the area of ​​interest from a digital image. Traditional image keying techniques involve placing the subject in front of a flat green (blue) screen and removing the green (blue) areas from the image through post-processing parameters to separate the foreground and background. Disadvantages include the foreground appearing greenish (or bluish) due to the diffuse reflection from the screen, the inability to include green (or blue) elements in the foreground during green (or blue) screen shooting, and high requirements for lighting and distance.

[0003] Natural light, after passing through a polarizer, becomes light with a specific vibration direction. A polarizer only allows light vibrating parallel to the polarization direction to pass through, while filtering out light vibrating perpendicular to that direction. For example, P1 and P2 are two identical polarizers. The first polarizer, P1, is called the "polarizer," and its function is to convert natural light into polarized light. The second polarizer, P2, is called the "analyzer." Rotating P2, when the polarization direction of P2 is parallel to P1, allows polarized light to pass through smoothly. When the polarization direction of P2 is perpendicular to P1, polarized light cannot pass through. A beam splitter (also called a beam splitter) is an optical device that splits an incident beam into two or more beams of the same or different powers. Based on its effect on the polarization state of light, it can be classified as a polarizing mirror, a partial polarizing mirror, or an depolarizing mirror. A waveplate is a transparent sheet with specific birefringence, which can split incident polarized light into two mutually perpendicular polarized beams, o-ray and e-ray, with an optical path difference. When the o-ray and e-ray pass through the polarizer again, they can interfere and exhibit specific colors. Summary of the Invention

[0004] The purpose of this invention is to provide an image extraction system that utilizes polarized light, which can reduce lighting requirements while ensuring keying effects and allowing the foreground to contain arbitrary colors.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] An image extraction system utilizing polarized light includes: a light source, a first polarizer, a polarizing beam splitter, a first photosensitive element, a second photosensitive element, and a processor.

[0007] The light from the light source is polarized by the first polarizer to obtain polarized light; the foreground is positioned between the first polarizer and the polarizing beam splitter; the light emitted by the light source that is not blocked by the foreground and the light reflected by the foreground are split by the polarizing beam splitter to obtain a first beam and a second beam; the first photosensitive element is used to form a first photosensitive image based on the first beam; the second photosensitive element is used to form a second photosensitive image based on the second beam; the processor is used to obtain a foreground image based on the first photosensitive image and the second photosensitive image.

[0008] Optionally, the image extraction system utilizing polarized light further includes a waveplate, a second polarizer, and a third polarizer; the waveplate is disposed between the first polarizer and the polarizing beam splitter; the waveplate is used to split the polarized light into o-light and e-light; the second polarizer is disposed between the polarizing beam splitter and the first photosensitive element; and the third polarizer is disposed between the polarizing beam splitter and the second photosensitive element.

[0009] Optionally, the image extraction system utilizing polarized light further includes a screen; the screen is positioned behind the foreground.

[0010] Optionally, the screen is a metal screen.

[0011] Optionally, the image extraction system utilizing polarized light further includes an optical lens; the optical lens is disposed between the foreground and the polarizing beam splitter.

[0012] Optionally, the image extraction system utilizing polarized light further includes an optical lens; the optical lens is disposed between the polarizing beam splitter and the photosensitive element.

[0013] Optionally, the waveplate is disposed between the first polarizer and the foreground.

[0014] Optionally, the waveplate is disposed between the foreground and the optical lens.

[0015] Optionally, the waveplate is disposed between the optical lens and the polarizing beam splitter.

[0016] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0017] This invention includes: a light source, a first polarizer, a polarizing beam splitter, a first photosensitive element, a second photosensitive element, and a processor. Light from the light source is polarized by the first polarizer to obtain polarized light; a foreground is positioned between the first polarizer and the polarizing beam splitter; light emitted from the light source that is not blocked by the foreground and light reflected from the foreground are split by the polarizing beam splitter to obtain a first beam and a second beam; the first photosensitive element is used to form a first photosensitive image based on the first beam; the second photosensitive element is used to form a second photosensitive image based on the second beam; the processor is used to obtain a foreground image based on the first and second photosensitive images. The first and second photosensitive images have a brightness difference in their backgrounds, enabling image matting. Since the color of natural light does not change after passing through the polarizer to become polarized light, there is no foreground color bleeding problem. This invention uses brightness difference between two images for matting, so the foreground can contain any color without affecting the image extraction effect. The foreground illumination intensity also does not affect the effect, thus reducing the lighting requirements, thereby achieving reduced lighting requirements while ensuring the matting effect. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the image extraction system using polarized light provided by the present invention;

[0020] Figure 2 This is a schematic diagram of the structure of the image extraction system using polarized light with a screen provided by the present invention.

[0021] Symbol explanation:

[0022] 1-Light source, 2-First polarizer, 3-Waveplate, 4-Foreground, 5-Polarizing beam splitter, 6-Second polarizer, 7-First photosensitive element, 8-Third polarizer, 9-Second photosensitive element, 10-Optical lens, 11-Screen. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The purpose of this invention is to provide an image extraction system that utilizes polarized light, which can reduce lighting requirements while ensuring the keying effect.

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] This invention provides an image extraction system utilizing polarized light, comprising: a light source 1, a first polarizer 2, a polarizing beam splitter 5, a first photosensitive element 7, a second photosensitive element 9, and a processor; the light from the light source 1 is polarized by the first polarizer 2 to obtain polarized light; a foreground 4 is disposed between the first polarizer 2 and the polarizing beam splitter 5; the light emitted by the light source 1 that is not blocked by the foreground 4 and the light reflected by the foreground 4 are split by the polarizing beam splitter 5 to obtain a first beam of light and a second beam of light; the first photosensitive element 7 is used to form a first photosensitive image based on the first beam of light; the second photosensitive element 9 is used to form a second photosensitive image based on the second beam of light; and the processor is used to obtain a foreground image based on the first photosensitive image and the second photosensitive image.

[0027] like Figure 1 As shown, the image extraction system using polarized light provided by the present invention further includes a waveplate 3, a second polarizer 6, and a third polarizer 8; the waveplate 3 is disposed between the first polarizer 2 and the polarizing beam splitter 5; the waveplate 3 is used to split the polarized light into o-light and e-light; the second polarizer 6 is disposed between the polarizing beam splitter 5 and the first photosensitive element 7; the third polarizer 8 is disposed between the polarizing beam splitter 5 and the second photosensitive element 9.

[0028] Light source 1 emits unpolarized light, which becomes polarized after passing through the first polarizer 2. The polarized light then passes through waveplate 3 and splits into o-rays and e-rays, which are perpendicular to each other and have an optical path difference. These beams then pass through polarizing beam splitter 5, which divides the incident light into two beams. One beam passes through the second polarizer 6 and enters the first photosensitive element 7 for imaging, while the other beam passes through the third polarizer 8 and enters the second photosensitive element 9 for imaging. When the o-ray and e-ray pass through the polarizers again, they interfere, causing some wavelengths to be enhanced while others are weakened, resulting in different colors. Because the polarization directions of the second polarizer 6 and the third polarizer 8 are different, the wavelengths that are enhanced or weakened by the interference are also different, resulting in different colors of the transmitted light. Therefore, the background colors on the first photosensitive element 7 and the second photosensitive element 9 are also different. Since the light reflected from the person or object in the foreground 4 is natural light, and natural light does not change color after passing through one polarizer, the foreground 4 is the same on both the first and second photosensitive elements. This allows us to simultaneously acquire two images with the same foreground color but different background colors. After the processor removes the parts of the two images that have color differences, the foreground image can be extracted.

[0029] like Figure 2 As shown, the image extraction system utilizing polarized light provided by the present invention also includes a screen 11; the screen 11 is disposed between the foreground 4 and the first polarizer 2. The screen 11 is a metal screen 11. In practical use, due to the size limitation of the light source 1, a screen 11 that does not destroy the polarization characteristics of light, such as a metal screen 11, can be used as a background to reflect the light emitted by the light source 1 and expand the background range.

[0030] In practical applications, the image extraction system using polarized light also includes an optical lens 10; the optical lens 10 is disposed between the foreground 4 and the polarizing beam splitter 5.

[0031] As an alternative implementation, the waveplate 3 is disposed between the first polarizer 2 and the foreground 4.

[0032] As an alternative implementation, the waveplate 3 is disposed between the foreground 4 and the optical lens 10.

[0033] As an alternative implementation, the waveplate 3 is disposed between the optical lens 10 and the polarizing beam splitter 5.

[0034] The position of waveplate 3 is not limited to between the first polarizer and the foreground 4, but can also be located between the foreground 4 and the optical lens 10, or between the optical lens 10 and the polarizer beam splitter 5, etc.

[0035] When the polarizing beam splitter 5 is a polarizing mirror, the second polarizer 6 and the third polarizer 8 are not needed. When the polarizing beam splitter 5 is a depolarizing mirror and a partial polarizing mirror, the second polarizer 6 and the third polarizer 8 are needed.

[0036] When using waveplate 3, the acquired image can be processed using traditional chroma keying techniques, and can be combined with color difference keying techniques to improve the effect. Different parameters of waveplate 3 and different polarizer orientations will cause changes in the background color, which can be adjusted according to the actual situation.

[0037] By removing the third polarizer 8 and the second photosensitive element 9, and replacing the polarizer beam splitter 5 with a liquid crystal grating, an image extraction method based on time information, similar to CN109936709, can be used.

[0038] After removing the polarizer 5, the third polarizer 8, and the second photosensitive element 9, the acquired image can be processed using traditional chroma keying techniques.

[0039] Since the color of natural light does not change after passing through a polarizer to become polarized light, there is no foreground color bleeding problem. This invention uses the difference in background color or brightness between two images for image matting, so the foreground can contain any color without affecting the image extraction effect. The foreground lighting intensity also does not affect the effect, thus reducing the requirements for lighting. Because the image is extracted using the color or brightness difference of the background, the foreground can be any color or brightness. Since the background light source is mixed light and has no color, it will not interfere with the foreground. Because the two images obtained through the polarizing beam splitter are acquired and processed simultaneously, it has advantages over other methods in situations such as live video streaming or high-speed moving objects.

[0040] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0041] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the system and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An image extraction system utilizing polarized light, characterized in that, include: A light source, a first polarizer, a polarizing beam splitter, a first photosensitive element, a second photosensitive element, and a processor; The light from the light source is polarized by the first polarizer to obtain polarized light; the foreground is positioned between the first polarizer and the polarizing beam splitter; the light emitted by the light source that is not blocked by the foreground and the light reflected by the foreground are split by the polarizing beam splitter to obtain a first beam and a second beam; the first photosensitive element is used to form a first photosensitive image based on the first beam; the second photosensitive element is used to form a second photosensitive image based on the second beam; the processor is used to obtain a foreground image based on the first photosensitive image and the second photosensitive image; The image extraction system utilizing polarized light further includes a waveplate, a second polarizer, and a third polarizer. The waveplate is positioned between the first polarizer and the polarizing beam splitter. The waveplate is used to split the polarized light into o-rays and e-rays. The second polarizer is positioned between the polarizing beam splitter and the first photosensitive element. The third polarizer is positioned between the polarizing beam splitter and the second photosensitive element. Unpolarized light emitted from the light source becomes polarized light after passing through the first polarizer. The polarized light is then split into o-rays and e-rays, which are perpendicular to each other and have an optical path difference, after passing through the waveplate. The polarizing beam splitter then splits the incident light into two beams. One beam passes through the second polarizer and enters the first photosensitive element for imaging, while the other beam passes through the third polarizer and enters the second photosensitive element. Image formation: When o-rays and e-rays pass through the polarizer again, they interfere, causing some wavelengths to be enhanced and others to be weakened, resulting in color. Since the polarization directions of the second and third polarizers are different, the enhanced and weakened wavelengths are also different, and the colors of the transmitted light are also different. The background images on the first and second photosensitive elements are also different colors. Since the light reflected from the foreground people or objects is natural light, and natural light does not change color after passing through the polarizer once, the foreground images on the first and second photosensitive elements are the same color. Thus, two images with the same foreground color but different background colors can be acquired simultaneously. After the processor removes the parts with color differences between the two images, the foreground image can be extracted.

2. The image extraction system using polarized light according to claim 1, characterized in that, It also includes a curtain; the curtain is positioned behind the foreground.

3. The image extraction system using polarized light according to claim 2, characterized in that, The screen is a metal screen.

4. The image extraction system using polarized light according to claim 1, characterized in that, It also includes an optical lens; the optical lens is disposed between the foreground and the polarizing beam splitter.

5. The image extraction system using polarized light according to claim 1, characterized in that, The waveplate is positioned between the first polarizer and the foreground.

6. The image extraction system using polarized light according to claim 4, characterized in that, The waveplate is disposed between the foreground and the optical lens.

7. The image extraction system using polarized light according to claim 4, characterized in that, The waveplate is disposed between the optical lens and the polarizing beam splitter.

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