Radial distortion opencv. In OpenCV, the function calibrateCamera() estimates the camera parameters using a set of 3D-2D point correspondences. For the radial factor one uses the following formula: So for an old pixel point at coordinates in the input image, its position on the corrected output image will be . This leads to barrel distortion (where straight lines curve Two major distortions are radial distortion and tangential distortion. 2 function cameraCalibration() and I noticed a flag CV_CALIB_RATIONAL_MODEL that enables a new radial distortion model supposed to work better with wide-angle len 0. The distortion added in the images is mostly due to the camera used to capture the image. In my application I do not need to calculate the orientation of the calibration target (chessboard Feb 4, 2013 · For the distortion OpenCV takes into account the radial and tangential factors. The reverse process is the backward mapping or inverse mapping (Fig. In the functions below the coefficients are passed or Dec 18, 2009 · 8 I am looking for ways to create fisheye lens effect, looked at documentations for openCV, it looks like it contains Camera Calibration functions for radial distortions like fisheye. Is this because my image isn’t a fisheye but wide angle instead? And in either case how do I reduce the perspective distortion? FYI I have lost the specs on this lens but got its intrinsics from a calibration routine. Jan 8, 2013 · Goal In this section, We will learn about distortions in camera, intrinsic and extrinsic parameters of camera etc. learn about distortions in camera, intrinsic and extrinsic parameters of camera etc. Radial distortion becomes larger the farther points are from the center of the image. May 5, 2021 · lens distortion matrix lens distortion coefficients are a list of numbers. Is it possible to simulate fisheye distortion by openCV? If it is possible to do it by openCV, comparing to openGL, which one will generate better results? Thanks. In the functions below the coefficients are passed or returned as vector. Oct 25, 2025 · Radial distortion can be represented as follows: x d i s t o r t e d = x (1 + k 1 r 2 + k 2 r 4 + k 3 r 6) y d i s t o r t e d = y (1 + k 1 r 2 + k 2 r 4 + k 3 r 6) Similarly, tangential distortion occurs because the image-taking lense is not aligned perfectly parallel to the imaging plane. How to undistort an image with these co-efficients? I know about the Aug 6, 2016 · * MY QUESTION * Anyway, my problem is that I'm using OpenCV solvePnP so I need to find out the distortion camera matrix. These range from a simple 4-parameter model with two radial and two tangential distortion coefficients to a more complex models, with up to 14 parameters. Jan 8, 2013 · Goal In this section, we will learn about types of distortion caused by cameras how to find the intrinsic and extrinsic properties of a camera how to undistort images based off these properties Basics Some pinhole cameras introduce significant distortion to images. g. May 5, 2017 · OpenCV takes into account both the radial and tangential factors. a) result of undistort of perspective camera model (all possible 2 days ago · The presence of the radial distortion manifests in form of the "barrel" or "fish-eye" effect. Mar 15, 2017 · I have a distorted picture, where without distortion the point A, B C and D form a square of 1 cm * 1 cm. Distortion Coefficients and Correction There are three coefficients needed to correct for radial distortion : k1 , k2 , and k3 . . These values are the distortion coefficients from the OpenCV fisheye camera model. Oct 10, 2017 · OpenCV's distortion coefficient vector is composed of MATLAB's two tangential distortion coefficients followed by the two radial distortion coefficients. There are up to 6 parameters for radial distortion (k1-k6) and two parameters for tangential distortion (p1-p2). 10. calibrateCamera method supports various distortion models. In addition, extrinsic parameters (pitch, yaw, and roll) can also be measured for stereo camera pair alignment or to calibrate a camera’s angular orientation. Jul 5, 2025 · SIMPLE_RADIAL, RADIAL: This should be the camera model of choice, if the intrinsics are unknown and every image has a different camera calibration, e. In the following equations, (x, y) (x,y) is a point in a distorted image. I managed to "draw" the radial distortions which gives me this : From what I understand, everything in the green area Jan 21, 2013 · The OpenCV implementation, however, differs significantly from the method proposed in the paper and is not actually an undistortion model, but simply an extension of the radial distortion model with extra terms k_4 to k_6 in the denominator, with the idea that lenses with more extreme distortions (wide angle, fisheye) can be better modeled with The model includes intrinsic and extrinsic parameters, as well as distortion coefficients that account for radial and tangential distortions caused by the camera lens. It explains the concept of distortion and its types, such as radial and tangential distortion Apr 20, 2023 · Using the software, you can determine the intrinsic parameters (radial and tangential distortion coefficients, principal point, focal length) crucial for distortion removal. Computer Vision lecture. This model uses the following parameters: K1, K2, K3 = Radial distortion parameters. They should match. Due to radial distortion straight lines in real world appear to be curved in the image. So, the above model is extended as: , , are radial distortion coefficients, , are tangential distortion coefficients. Aug 11, 2022 · [openCV]Camera Calibration 相機校正 鏡頭變形是攝影中常見的現象，在使用廣角的時候更可以看的出來，失真主要有以下兩種: radial distortion tangential … Oct 22, 2024 · Camera Calibration using OpenCV Camera calibration is the process of computing the intrinsic parameters of the camera i. Jan 8, 2013 · The function transforms an image to compensate radial and tangential lens distortion. These radial distortions can usually be classified as either barrel distortions or pincushion distortions. I have the following image below, and using the undistort function have the result. Mapping from the undistorted space to the distorted space is the forward mapping (Fig. Imagine subtle manufacturing flaws where the optical elements not aligned with the imaging plane. Here is my frame : From this frame (and many others), I calculated the camera matrix and the distortion coefficients using the function cv::calibrateCamera. Undistort Images Using OpenCV While capturing images with cameras, some images get distorted. In the functions below the coefficients are passed or returned as Real lenses usually have some distortion, mostly radial distortion and slight tangential distortion. the matrix is a projection matrix. The function is simply a combination of fisheye::initUndistortRectifyMap (with unity R ) and remap (with bilinear interpolation). Introduction For correcting radial and/or perspective distortion, we need to know a model to map between distorted space and undistorted space. OpenCV enables us to remove this distortion and rectify the image using the estimated camera parameters. I try to project a 2D depth map on a 3D point cloud. Edit: I found a related link here that explains the camera distortion model. Similarly, another distortion is the radial distortion. input image Apr 10, 2015 · In the opencv guide there's the explanation of the formulas behind the process of calibration where radial distortion coefficients are multiplied for "r", the distance between the point and the center, is that distance in pixels or mm? I just had this problem today and asked myself the same question. Basics Today's cheap pinhole cameras introduces a lot of distortion to images. In the functions below the coefficients are passed or Sep 9, 2014 · Hello, I would like to calculate image distortion (radial and tangential) using only one image. OpenCV will give you K4, K5 or K6 only if you explicitly ask for it with CALIB_RATIONAL_MODEL. Summary This text provides a tutorial on how to calibrate a camera using OpenCV and Python, focusing on three methods: chessboard, ArUco boards, and ChArUco. Radial distortion causes straight lines to appear SIMPLE_RADIAL, RADIAL: This should be the camera model of choice, if the intrinsics are unknown and every image has a different camera calibration, e. Each tri Feb 15, 2014 · The function makes the assumption that the radial distortion is monotonous (from your distortion coeffecients), that you either have constant outwards or inwards warping in your images. There are four kinds of combination of sign of K1 and K2: A K1: positive K2: positiv The tangential distortion corrects for tilts of the image plane after radial distortion. Radial distortion is always monotonic for real lenses, and if the estimator produces a non-monotonic result, this should be considered a calibration failure. 2. Due to radial distortion, straight lines will appear curved. The presence of radial distortion is manifested as a barrel or fisheye effect. Camera radial and tangential distortion coefficients, returned as a five-element vector in the form [k1 k2 p1 p2 k3]. Even though there is undistort function, there is no distort function. Two major kinds of distortion are radial distortion and tangential distortion. Extrinsic Parameters キャリブレーションをすれば，画像中からレンズ歪みの影響を取り除くことができます．OpenCvは歪み補正のために二つの関数を用意しています．それぞれの関数を紹介する前に， cv2. Learn camera calibration techniques, including Zhang's method, radial distortion, and undistortion using OpenCV and Matlab. 04. Kannala-Brandt model [1] — 4-element vector of the form [k1 k2 k3 k4]. The function transforms an image to compensate radial and tangential lens distortion. For example this function would give me a distortion of up to 5% at the full relative field height of 1. The tomato crosses are the undistorted points from my code and the teal circles are results from cv2. and are tangential distortion coefficients. Sep 13, 2025 · Overview Camera calibration is the process of estimating the parameters of a camera model, including: Intrinsic parameters: Focal length, principal point, skew, and distortion coefficients. Tangential distortion occurs because the image taking lenses are not perfectly parallel to the imaging plane. 12 Detailed description Hi, folks! It's a little bit surpring that the simplest Radial distortion model (inside point Sep 4, 2023 · Currently doing camera calibration with OpenCV checkerboard and encountered this issue. SIMPLE_RADIAL, RADIAL: This should be the camera model of choice, if the intrinsics are unknown and every image has a different camera calibration, e. The last one is optional. See the former function for details of the transformation being performed. This model relies on transforming the radius with even polynomial powers in the coefficients k 1, k 2, k 3. The presence of the radial distortion manifests in form of the “barrel” or “fish-eye” effect. find the equations for radial distortion in the OpenCV documentation. Two major distortions are radial distortion and tangential distortion. Common types include radial distortion (which makes straight lines appear curved) and tangential distortion (which can tilt the image). Now, let’s try to determine the necessary coefficients to detect and remove image distortion using OpenCV for a particular sensor. Both models are simplified versions of the OPENCV model only modeling radial distortion effects with one and two parameters, respectively. Aug 30, 2013 · Hi! I'm porting to opencv a little script for lens distortion correction. 1. When the lens distorts inwards, this is termed barrel distortion. Its effect is more as we move away from the Nov 24, 2017 · Thanks in advance. Dec 20, 2024 · Distortion Model The OpenCV cv2. Although I can't get OpenCV to generate similar coefficients to what the Meshroom calibration utility generates. Distortion Models OpenCV offers two types of distortion models: radial distortion and tangential distortion. The most common distortion model is the Brown’s distortion model. I presume a different algorithm is at play to calculate radial distortion. I think you need to reverse that statement to two radial coeffs followed by two tangential coeffs. I need to be able to distort the images to create the "barrel distortion" / "radial distortion" effect. Its effect is more as we move away from the center of image. But you can see that The function transforms an image to compensate radial and tangential lens distortion. Mar 4, 2020 · And the result is what I get, and it is wrong. In the most recent builds (after ASP 3. In case that the camera model was SFM_DISTORTION_MODEL_DIVISION, it's only needed to provide _polynomial_k1 and _polynomial_k2 which will be assigned as division distortion parameters. For example, one image is shown below, where two edges of a chess board are marked with red lines. Although distortion can be irregular or follow many patterns, the most commonly encountered distortions are radially symmetric, or approximately so, arising from the symmetry of a photographic lens. Jul 15, 2025 · We need to consider both internal parameters like focal length, optical center, and radial distortion coefficients of the lens etc. The values of k1, k2, and k3 describe the radial distortion and p1 and p2 describe the tangential distortion, specified in OpenCV. Jul 23, 2025 · Usually, two types of distortion happen in an image. Jan 8, 2013 · In case that the camera model was SFM_DISTORTION_MODEL_DIVISION, it's only needed to provide _polynomial_k1 and _polynomial_k2 which will be assigned as division distortion parameters. Distortion Correction Camera lenses often introduce distortion in the captured images, deviating from the ideal pinhole camera model. Extrinsic parameters: Rotation and translation vectors relating the camera to the world coordinate system. Distortion models: Radial, tangential, and fisheye distortions. Oct 5, 2020 · Radial distortion: This type of distortion usually occur due unequal bending of light. More over, openCV already has built in source code examples of how to calibrate the camera. Nov 21, 2024 · Radial distortion occurs when light rays passing through the edges of the lens are bent more than those passing through the center. Here is one way to produce barrel or pincushion distortion in Python/OpenCV by creating the X and Y distortion maps and then using cv. -5. While the distortion coefficients are the same regardless of the camera resolutions used, these should be scaled along with the current resolution from the calibrated resolution. 7. Tangential Distortion: Misalignment of the lens and image sensor that causes additional distortion. The first matrix after the '=' is the camera matrix. But I'm stuck with the distortion effect due to the lens. Abstract The article discusses the importance of camera calibration in computer vision systems to correct distortions caused by the camera lens. Mar 3, 2022 · I download the opencv source code,but i dou’t see the source code about how to solve the distortion coefficients. You don't need distCoeffs or just pass it as distCoeffs=None. Oct 1, 2021 · I am experimenting with undistorting images. Rotation vector and translation vector: Oct 19, 2025 · Radial distortion can be represented as follows: x d i s t o r t e d = x (1 + k 1 r 2 + k 2 r 4 + k 3 r 6) y d i s t o r t e d = y (1 + k 1 r 2 + k 2 r 4 + k 3 r 6) Similarly, tangential distortion occurs because the image-taking lense is not aligned perfectly parallel to the imaging plane. Real lenses usually have some distortion, mostly radial distortion and slight tangential distortion. I read the documentation of the "Camera Calibration and 3D Reconstruction" and recognized that theoretically at least two images are required and for better results more than 10 images are recommended. This program is doing the undistortion with the Brown normalization, and it uses some parameters that gets out of a (close source) software for camera calibration that has values in the so called photogrammetric representation. So, a pixel value at fractional coordinates needs to be retrieved. Matlab version Another version is from the matlab tutorial, which is contrary to the opencv version, but looks correct x distorted = x (1 + k 1 r 2 + k 2 r 4 + k 3 r 6) Radial Distortion y distorted = y (1 + k 1 3 days ago · Is assumed that modern cameras have their principal point in the image center. remap () to do the warping. P1, P2 = Tangential distortion parameters. Jul 5, 2015 · The distortion you are experiencing is called "barrel distortion". Jul 14, 2016 · The equations you mention are used to calculate the pixel position after the removal of the radial distortion (first set of equations) and the tangential distortion (second set of equations). This matrix factors in radial distortion and slight tangential distortion. See below the results of undistortImage. Methods for correcting distortions 2. [1] Barrel distortion In barrel distortion, image magnification decreases with distance Oct 29, 2019 · Unfortunately, so far, I was unable to succeed: the same distortion coefficients used in HALCON and OpenCV generate very different undistorted images! I guess, the problem is the way HALCON and OpenCV are interpreting the distortion coefficients, or even the way they perform undistortion. Higher-order coefficients are not considered in OpenCV. 3 LTS Python version: 3. The fisheye module doesn’t work. Apr 16, 2017 · Given a set of sparse correspondences between two images, is there an easy way to estimate a homography including radial distortion parameters in OpenCV? The values of k1, k2, …, k6 describe the radial distortion and p1 and p2 describe the tangential distortion, specified in OpenCV. OpenCV provides robust algorithms Today’s cheap pinhole cameras introduces a lot of distortion to images. To measure distortion of an optical systems it is possible to use photos of real world object with well-known shape. In radial distortion, the straight lines in an image Nov 16, 2017 · Good evening, I would like to remap a trapezoid ROI to a rectangular ROI after correcting a barrel distortion on a frame. e. Basics ¶ Today’s cheap pinhole cameras introduces a lot of distortion to images. The rays bend more near the edges of the lens than the rays near the centre of the lens. Estimation of lens parameters using OpenCV For unwarping images OpenCV takes the radial and the tangential distortion factors into account. [x y z] = R [X Y Z] + t Apr 12, 2023 · We make the distinction between forward and inverse models, clarify terms, and explain how we apply distortion models in-house. Typically, we recommend using OpenCV when removing distortion Apr 17, 2018 · It can also be calculated when calibrating the camera with a chessboard. 1 Forward mapping Nov 15, 2018 · Radial Distortion Effects One group of lens distortion effects have radial symmetry, meaning that at a given distance from the principle point, the amount of distortion is constant. Jul 11, 2017 · I am trying to use K1 and K2 to correct radial distortion in camera calibration using functions from OpenCV. Here is an example below of a type of radial distortion known as barrel distortion. Mar 31, 2021 · How to apply distortion on an image using OpenCV or any other library? Asked 4 years, 6 months ago Modified 1 year, 8 months ago Viewed 20k times 20. More generally, radial distortion must be monotonic and the distortion function must be bijective. , and external parameters like rotation and translation of the camera with respect to some real world coordinate system. a) result of undistort of perspective camera model (all possible 2 days ago · This means that f x, f y can be either an affine or perspective transformation, or radial lens distortion correction, and so on. Just google it and you will find documentations in openCV wiki. In contrast, when it disorts outwards, it is called pincushion distortion. getOptimalNewCameraMatrix () 関数を使ってカメラ行列 (内部パラメータ)を改善し Although distortion can be irregular or follow many patterns, the most commonly encountered distortions are radially symmetric, or approximately so, arising from the symmetry of a photographic lens. Camera Matrix and the Distortion coefficients. Distortion Coefficients 在相机的 成像矩阵 中，沒有包含 lens distortion，这是因为一个理想的 Pinhole Camera 是不需要 透镜 (lens) 的；但在实际的相机中，Camera model 则包含了 radial lens distortion 以及 tangential lens distortion。 Radial Distortion Jun 13, 2022 · After doing some digging, it turns out OpenCV actually supports 6 radial distortion coefficients, not just 3. Feb 9, 2019 · How to perform camera calibration and deal with Image distortion using OpenCV and Python. For this, I want to found the inverse of the radial and tangential distortion formula. 1). The values seem to be scaled somehow and I'm having a hard time figuring out how to convert them to a useful number. 72 Operating System / Platform: Ubuntu 22. For example, one image is shown below in which two edges of a chess board are marked with red lines. To undistort these points, OpenCV calculates r , which is the known distance between a Sep 22, 2025 · 这篇文章主要讲解桶形畸变矫正，首先介绍一下相关背景。 Radial Distortion 尽管畸变可能是没有规律或遵循某种模式的，但一般情况下我们遇到的最多的情况是畸变呈放射状且是对称的，其主要产生于相机镜头的畸变。这种呈放射状的、对称的畸变，即radial distortion主要可以分为两种，barrel distortion Feb 27, 2012 · I was looking into the OpenCV 2. Jun 5, 2021 · My understanding is that OpenCV uses a variant of the Brown-Conrady lens distortion to model radial and tangential distortion. Sep 27, 2019 · I want to apply radial and tangential distortion coefficients to my image that I got from opencv. To correct the appearance of radially distorted points in an image, one can use a correction formula. Due to radial distortion, straight lines will appear curved. 2. The radial displacement, however, is not just an even-order polynomial as in Brown-Conrady but a variant where a low-order polynomial coefficients (k_1,k_2,k_3) are related to the same even-order polynomial but with higher order coefficients (k_4,k_5,k_6) in a fraction 3 days ago · The presence of the radial distortion manifests in form of the "barrel" or "fish-eye" effect. So, some areas in the image may look nearer than expected. Radial distortion occurs when straight lines appear curved. Tsai ¶ A common distortion model [Tsai87]. I've ran multiple camera calibration trials, each with the same camera BUT different sets of images. Its Feb 2, 2024 · This tutorial will discuss undistorting an image using the undistort() function of OpenCV. 2 days ago · Radial distortion causes straight lines to appear curved. Tangential distortion occurs when the camera lens is not exactly aligned parallel to the camera sensor. The distortion present in an image can be radial or tangential. Basically, You need to May 26, 2023 · Simply theory introduction: For distortion, Opencv considers radial and tangential distortion. 2). , in the case of Internet photos. First radial distortion, causes straight lines to look slightly twisted or bent when a camera photographs them. If you look after these equations you will notice an equation that is composed by 3 matrices. A technical name is "combination of radial distortion and tangential distortions" The solution for your problem is openCV camera calibration module. 먼저 distortion을 고려하지 않는 경우 다음과 같다. Feb 8, 2019 · Given the distortion co-efficients D = k1,k2,p1,p2,k3 of a pinhole model which is defined by radial and tangential distortion. These parameters are crucial in transforming 3D points in the world to 2D points on the image plane. So, the above model is extended as: , , , , , are radial distortion coefficients, , are tangential distortion coefficients. Radial distortion is pretty much what leads to the barrel or fisheye effect described above. So, if you want no tangential distortion factors and only two radial distortion factors, you can supply flags=CALIB_FIX_K3 + CALIB_ZERO_TANGENT_DIST. Look at the images in the link. Mar 8, 2025 · Radial Distortion: How much the lens distorts the image, generally modeled as a polynomial function. Homography: This refers to the transformation between two Real lenses usually have some distortion, mostly radial distortion and slight tangential distortion. Barrel distortion Pincushion distortion Mustache distortion May 19, 2020 · But the distortion values don't work correctly: k1, k2, and k3 values I get from camera calibration in OpenCV overcompensate the distortion by a large margin. In CameraTransform, we only consider the radial part of the model, as this covers all common cases and the merit of tangential components is disputed. undistortPoints. Jun 20, 2019 · 이때 일반적으로 distortion은 radial distortion과 tangential distortion을 고려한다. So, the above model is extended as: , , , , , and are radial distortion coefficients. Basically, k1, k2, k3, k4, k5, and k6 are radial distortion coefficients; p1 and p2 are tangential distortion coefficients; and s1, s2, s3, and s4, are the thin prism distortion coefficients. I tried to use homography to correct it, but it distort the line AD and BC, as you can see Jul 12, 2016 · To correct for lens distortions in the camera images I made use of OpenCV's camera calibration tool. 0) this was made to agree precisely with the OpenCV radial-tangential lens distortion model. With its use of constructive statistical geometry and a spline model of radial distortion, the new calibration method outperforms standard solutions—such as OpenCV—in accuracy. Dec 27, 2023 · System Information OpenCV python version: 4. a) result of undistort of perspective camera model (all possible Nov 10, 2022 · OpenCV can calculate up to six distortion coefficients for radial distortion and up to two coefficients for tangential distortion. Notice the bulging in the image that is making straight lines (in the real world) appear curved. And more important, about zhang’s method ,he only think of radial distortion,then I can learn how to solve radial distortion,but i don’t konw the theory about how to solve the tangential distortion,can you give me some suggestion,thank you all at first. Mar 10, 2020 · I'm making a custom virtual reality headset with code in python / opencv. k1-k6, p1-p2 don't have units. 3. 7843597214487474e-001</data></distortion_coefficients> @endcode Add these values as constants to your program, call the @ref cv::initUndistortRectifyMap and the @ref cv::remap function to remove distortion and enjoy distortion free inputs for cheap and low quality cameras. learn to find these parameters, undistort images etc. We will learn to find these parameters, undistort images etc. Camera Calibration with OpenCV: A Step-by-Step Guide Real lenses usually have some distortion, mostly radial distortion and slight tangential distortion. 0. Fig. Both of these things are a … Oct 15, 2021 · I've a radial distortion function which gives me relative distortion from 0 (image center) to the relative full image field (field height 1) in percent. 3mn2 cumc kkfw20ie b7omm plh yl 3kg07s tkdo gxfc7l clybua