Fish-eye lens imaging theory
The imaging theory of the fisheye lens was based on its special optical structure design. The fisheye lens had a large spherical curvature, similar to the spherical crystal of a fisheye, and the imaging plane was closer to the lens. The visual effect was similar to a fish observing things on the surface of the water. When the fish was close to the surface of the water, the angle of view could reach a wide angle of nearly 180°. This phenomenon was based on the principle of total reflection and optical reversibility. In terms of structure, the front lens of the fish-eye lens protruded from the front in a parabolic shape in order to maximize the camera angle. It was generally believed that lenses with a focal length of 16mm or shorter were fisheye lenses. However, in engineering, lenses with a viewing angle of more than 140 degrees were collectively referred to as fisheye lenses. In fact, there were also lenses with a viewing angle of more than 270 degrees. In terms of imaging mode, the M12 fisheye lens (180°) generally used vertical or horizontal in-cut imaging mode (mode 1 Circular Fisheye, mode 3 Full Horizontal). At the same time, fisheye lens imaging relied on artificially introducing a large number of barrel distortions to obtain a large field of view, so that it could obtain image information with a large field of view. However, except for the shape of the object in the center of the image, the other parts that should be straight lines had a certain degree of distortion. When matching an image sensor with a fisheye lens, a 1:1 or 4:3 image sensor was generally selected to maximize the use of effective pixelation. Read more exciting novels for free
Fish-eye lens is
A fisheye lens was a lens with a focal length of about 6 - 16mm and a viewing angle close to or equal to 180°. It was a type of ultra-wide-angle lens. Its front lens was shaped like a parabola and protruded to the front of the lens, which was similar to the eyes of a fish, hence its name. The concept was proposed and developed in 1906. In the 1920s, it was used for the study of cloud formation in meteorology. Robin Hill was the first person to truly create a fisheye lens and use it for commercial use. Mass production began in the 1960s. It was usually composed of a front group of imaging lenses and a rear group of correction lenses. It was divided into half-frame fisheye lenses and full-frame fisheye lenses. It was first used in photography to create artistic photos with a large field of view and large distortion. It was also widely used in fields that required wide-angle imaging, such as surveillance, dome imaging, aerospace cameras, and other industrial, medical, and scientific research fields. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Distortion correction of fish-eye lens
Fish-eye lens distortion correction aims to reduce or eliminate the image distortion effect caused by fish-eye lenses. When correcting the distortion of the fisheye lens, the core was to solve a "good" remap matrix, which rearranged some of the original image's pixel-points (or intervening points) and "pieced" them into a rectangular image."Good" was linked to the final requirement, and different tasks often used different correction/distortion solutions. For example, in the smart security industry, whether it was a monocular camera or a monocular camera, the images captured would have distortions, which was the same as the distortion correction principle of a fisheye camera. For monocular cameras, in order to obtain the corresponding relationship between the camera's coordinate system and the three-dimensional world coordinate system, the barrel distortion and pillow distortion of the camera needed to be corrected. For binocular cameras, in order to do epipolar line alignment and realize depth estimation, the output of the two cameras needed to be transformed into the same coordinate system. Teacher Zhang Zhengyou's chessboard correction method estimated the internal and external parameters and distortion coefficient of the camera through the position coordinates of the marker, and then calculated the remap matrix. This method had a good correction effect for monocular and binocular cameras. In terms of practical operations, fisheye correction can also be performed using python language (only relying on the opencv-python package and numpy package), and fisheye distortion correction can also be performed from code examples such as PILimport Image. In addition, the distortion correction function based on digital image processing was also applied to the fisheye lens correction. This solution required rearranging the arrangement of the elements, but for the ultra-wide system where the edge image quality itself was a big problem, it might lead to the image quality of the most edge area being worse. Some equipment would use the image field redundant design and the sensor to perform the redundant matching of the elements to reduce the side effects of the digital correction. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Fish-eye lens for piano teaching
Using a fish-eye lens in piano teaching has certain advantages. The fish-eye lens had a large angle of view and could accommodate more scenes. It could adapt to the needs of shooting in a small space. In a piano teaching scene, such as an online piano lesson, the fish-eye lens could be used to let students see more details of the teaching environment, such as the teacher's overall performance posture, the piano's overall appearance, and so on. However, there were some problems with using a fisheye lens. Due to the distortion of the image, the straight lines around the screen would be bent. When shooting piano teaching content, if you need to show some flat music score or the straight arrangement of the keys, there may be distortion. Therefore, when using it, one had to pay attention to the selection of the shooting angle and content. For example, the subject that needed to be highlighted (such as the teacher's hand movements, etc.) could be placed in the center of the lens because the straight line in the center of the lens could maintain its original state. This was also the brightest and clearest part of the photo to reduce the impact of distortion on the teaching content. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
The imaging principle of the car lens
The basic principle of car lens imaging was the projection of a concave lens. The light passed through the lens (equivalent to a concave lens) to form a virtual image, and then the virtual image was transmitted to the imaging module or displayed on the screen. For the vehicle camera, the light reflected from the surface of the object is incident on the LCD/LCD image sensor through the lens. The image sensor transforms the received optical signal into a digital signal and sends it to the image signal processor. The image signal processor performs image filtering and enhancement on the digital signal, and the processed image information is transmitted to the domain controller through the serializer. Finally, the image image is presented. The car panoramic camera synthesized the images provided by the four 180-degree wide-angle cameras installed on the front, back, and side of the vehicle into a bird 's-eye view of the vehicle, which was displayed on the display screen in the car. The process was to first convert the captured image signal into an electrical signal. After the digital conversion, the processor synthesized the image signal again, and finally formed a simulated bird' s-eye view through the vehicle display screen. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
What are the characteristics of fish eye lens in cartoon?
Fish eye lens in cartoons often creates a distorted and wide-angle view. It can make objects appear curved and give a unique perspective that adds a sense of exaggeration or fantasy.
Which software has a fish-eye lens?
The POCO camera had a built-in fish-eye lens. In addition, there was a special fisheye lens app that allowed users to use a fisheye filter to take photos with a fisheye effect. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
A phone app with a fish-eye lens effect
There were two mobile phone applications that had a fisheye lens effect. One was Fisheye Cameras.(English name: Fisheye Plus Pro). It allowed the iPhone to have a digital simulation of a 170-degree wide-angle and an amazing fisheye lens. It also had a real-time fisheye viewfinder, simulated film replacement, lens, and ring flash. It supported five lenses, seven color ring flashes, and 22 effects. It gave a deeper three-dimensional sense and presented a completely different field of view. However, before using it, one had to go to the App Store to review it to fully unlock it. It was easy to flash back when using it. Especially when choosing the mode, color, and filter, the photos imported from the album couldn't be saved directly. Only the photos taken by the camera could be saved with one click. The other was the Fisheye lens app. The user could change the lens they liked during the shooting process. It was simple to operate. With just one click, they could take a funny photo with a big eye effect. It was powerful and had a delay function. It was very convenient to cut, add text or filter when editing photos. There was also a rich material library with many filter effects. When shooting, you could choose beauty effects. The modes were diverse. You could change the lens according to different scenes and needs. You could also adjust the photo parameters online at any time. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
The relationship between lens parameters and imaging
Many parameters of the lens were closely related to the image. ** 1. In terms of resolution ** The resolution restricted the ability of the lens to distinguish the details of the captured scene. The unit was "line pairs/millimeter", and the limiting factor was the phenomenon of light refraction. ** 2. Aperture ** 1. Generally speaking, the size of the aperture affected the amount of light entering. The F value represented the size of the aperture. The smaller the F value, the larger the aperture, and the greater the amount of light entering. For example, in a driving recorder, the aperture size was directly related to the imaging effect at night. When the light was dim, a large aperture (small F value) meant better imaging effect. 2. In the camera lens, different aperture values combined with other camera parameters could meet different shooting needs. For example, a large aperture (small F value) could produce a shallow depth of field effect, making the background blur and highlight the main body. For example, the F1.4 aperture in the SIGMAR fixed-focus lens could give the picture a very good depth of field effect; while a small aperture (large F value) had a large depth of field, which could make the near and far scene relatively clear. ** 3. MTF value (module transfer function)** 1. The MTF value was a comprehensive evaluation of the sharpness, contrast, and resolution of the lens. It was an evaluation of the overall resolution. It was an authoritative and objective technical reference for the quality of the lens. 2. Using Canon's MTF image as an example, the horizontal axis represented the radius of the imaging plane from the center to the edge, and the vertical axis represented the percentage of the imaging quality reaching the physical condition. The black line in the thick line represents the resolution test result at the maximum aperture, the blue line represents the test result at the F8 aperture, the solid line represents the MTF value in the radius, and the dotted line represents the MTF value in the tangency. An MTF value above 0.8 meant that the lens 'performance was in the excellent range, but a lens with an MTF value below 0.6 at the center of the circle was definitely not a good lens. However, it was important to note that MTF charts could not be used to compare lenses with different focal lengths, different frames, fixed focus, and zooming. It was also impossible to compare MTF charts of lenses from different manufacturers under the same focal length because the testing conditions of each manufacturer were different. ** 4. The distance between the two sides of the lens and the inner diameter of the bayonet (affects the compatibility between the lens and the camera and thus indirectly affects the image)** 1. The distance between the two sides was the distance between the bayonet and the plane where the LCD was located. The inner diameter of the bayonet was the diameter of the inner edge of the circular bayonet. The fundamental reason why the lenses of different brands of cameras could not be used in the same way was that the distance between the bayonet and the collar was different. 2. A camera with a short flange-distance could use the lens of a camera with a long flange-distance (the flange-distance could be extended by the transfer ring), but a camera with a long flange-distance could not use the lens of a camera with a short flange-distance. The trend was to use a shorter distance and a larger bayonet diameter, such as Nikon and Canon's new bayonet design. ** 5. Other aspects ** Aspherical lenses and large depth of field were two technical indicators that would also affect the imaging effect of the machine vision lens. In the actual use of the camera, such as the selection of live broadcast equipment, the selection of different lenses (such as the original camera lens and the Vicos fixed-focus lens) would present different imaging texture and depth of field effects. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Wide-angle fish-eye lens relative illumination
The old wide-angle lens has a defect of decreasing illumination at the edge of the field, but the specific information of the relative illumination of the wide-angle fisheye lens was not found. Sorry, according to the information retrieved, I don't know how to answer. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Using a fish-eye lens to take pictures of beautiful women
Using a fish-eye lens to shoot beautiful women was a creative way of photography. Here are some key points: ** 1. Picture composition ** 1. ** Focus on a part ** - You can choose to get close to the model and make a certain part of their body, such as their eyes or hands, look especially big to get an interesting transformation effect. However, he had to make sure that the model was satisfied with the results. 2. ** Combined with the environment ** - It emphasized the architectural or environmental elements around the model. In this way, the model might appear smaller in the picture and be surrounded by the surrounding elements, which could capture more scene content. ** 2. Shooting Points ** 1. ** Using the lens 'characteristics ** - Fisheye lenses would produce barrel distortion. When shooting beautiful women, if you want to highlight the creative effect brought by this distortion, you can place the model in the center of the picture, because the distortion at the edge of the picture will be more serious. 2. ** Avoiding distortion interference (if needed)** - If you don't want the model's body to be overly deformed, you can place the model in the center of the picture as much as possible and maintain an appropriate shooting distance to reduce the degree of distortion to a certain extent. ** 3. In terms of creative effects ** 1. ** Special View ** - You can use the fisheye lens to shoot up or down to create a special visual effect. For example, if there were buildings or trees in the background, it would create a sense of height. 2. ** Capture the atmosphere ** - The super wide angle of view of the fisheye lens could bring more of the environmental elements around the model into the picture, thus capturing the entire environment. For example, in outdoor scenes such as beaches and forests, it could integrate the beauty with the surrounding scenery in a unique way. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>