Opencv correlation between two images

Opencv correlation between two images. The usual way to represent an Affine Transformation is by using a 2 × 3 matrix. (Use a shear rotate). Lucas-Kanade implementation with OpenCV. I took a look in Sift and Surf feature but it's doesn't work well on 3 days ago · Theory. The side-length of the sliding window used in 2 days ago · Place the kernel anchor on top of a determined pixel, with the rest of the kernel overlaying the corresponding local pixels in the image. i need to compare two image in visual studio according to correlation of two image with open cv c++. Here it seems your images are only translated, so a simple cross correlation-based registration is enough. Jul 14, 2014 · Wow. You may find the cv2 python interface more intuitive to use (automatic conversion between ndarray and CV Image formats). For Step 3: Do Normalized Cross-Correlation and Find Coordinates of Peak. Apply thinning algorithm as described here. matchTemplate () for this purpose. And each group contain 2000 images for cat and dog respectively. My local machine is macOS, and the version of OpenCV is 2. Mask is slid over the image matrix from the left to the right direction. System. This score will be a measure of similarity. Jul 2, 2020 · Pretty robust working solution (I tested) is to check correlation of brightness sign changes between pixels. If these two functions are working can anyone show me an example to find correlation between two images. eps def mutual_information_2d(x, y, sigma=1, normalized=False): """ Computes (normalized) mutual information between two 1D variate Nov 6, 2020 · 1 Answer. When the mask hovers on the image, corresponding elements of mask and image are multiplied and the products are added. My idea is to have image 1 as the original image that will be used to compare the other images with. This will reduce your video stream to an one dimensional signal. But as they are obtained thru an slightly different optical setup, the corresponding spots (physically the same) appear at slightly different positions. To calculate the norm difference the images must have the same size. Template Matching is a method for searching and finding the location of a template image in a larger image. If these two images have the same size, the value returned by this function will be one point (It's up to the module you use. The above implementation is the same as OpenCV "cv. import numpy as np. Bottom), Oct 11, 2021 · This implies a known relationship between the images before going into calculation. Aug 18, 2021 · For each of the noisy methods we can see the similarity results below. We have one original image / photo of the item. what is the common way to measure between two images? May 6, 2015 · The problem that is the contrast and brightness are pretty different. kbarni (Nov 25 '15) edit. py --images images/scottsdale --output output. Photo always taken same angle 90 degree to the item. Jul 20, 2018 · We find the features of both images. I. May 26, 2016 · 1. Beware that even if the images came from the same high resolution source, it is unlikely that they will be bit-identical for the correct rotation. I want to create an image of some sort. There are two types of operators in image processing. If you want to compare for identity - you would need to use a neuronal network with embeddings Mar 10, 2021 · Basically, this seems to me a registration problem (the images need to be registered). 42995582e+00]] Mar 22, 2021 · Figure 5: OpenCV’s “cv2. # import the necessary packages. A lot computer vision, indeed. Here is my current code: import cv2. From the result complex matrix get the phases. To remove the rotation, take pca which gives you the primary axis, and rotate both images so the primary axis is along the x. The filter2D () function finds the correlation between two matrices, but we can also use it to find the convolution. " GitHub is where people build software. ) and the camera angle is rotated as well as the sizes may be different. Something like this: Jan 8, 2013 · To compare two histograms ( H1 and H2 ), first we have to choose a metric ( d(H1,H2)) to express how well both histograms match. More than 100 million people use GitHub to discover, fork, and contribute to over 420 million projects. detectAndCompute(img1, None) kp_b, desc_b = orb Theory. Image-template matching is invariant to changes in brightness and contrast. Mar 14, 2014 · 1 Answer. Sep 20, 2011 · To take a simple example, in one picture 50% of the blue values might be below 110, while in the other 50% are below 130. The comparison is to be done on the basis of Aug 23, 2023 · To compare two images, we use the Mean Square Error (MSE) of the pixel values of the two images. It's better to compute the correlation of feature vectors of these two Mat files instead of on the Mat data directly. matchTemplate function: result = cv2. Here we need to measure the similarity between any two images. double angle = atan2(p1. Pay attention that if both images are in the same size (as you assumed) - you should crop the "pattern" to some smaller size (DON'T SCALE. 7 and the second image is given 0. Cons: Tracking failure is not reported reliably. Jan 4, 2021 · It is used to find corners in the image and then calculate the corners’ motion vector between two consecutive frames. matchTemplate function with three parameters: Jun 28, 2017 · Opencv detect changes between two photos taken by different time. This method is only useful if the two images have the same size and orientation; otherwise, this method is not useful. new PointF(rect. Aug 5, 2014 · Correlation between two image (binary image) I have two binary image like this. . The problem is that normxcorr2 function returns result as an integer value and it doesn't evaluate sub-pixel displacemeent. I got two images showing exaktly the same content: 2D-gaussian-shaped spots. import cv2. Prerequisites: Python OpenCV Suppose we have two data images and a test image. To remove the scale, you then either simply take a bounding box or, if there's a bit of noise in there, take area and scale one until it is equal. Rectangle(Point. The histograms of two images can be compared using cv2. pyr_scale: parameter, specifying the image scale (<1) to build pyramids for each image; pyr_scale=0. TM_CCOEFF_NORMED) Here, you can see that we are providing the cv2. Place the center of the kernel at this (x, y) -coordinate. The question is how now I convert the 2D binary matrix or ones and zeros to a list of the coordinates of only the ones. Time to time we are taking new photos of the item. Drawing. Place the result to the location of the anchor in the input image. Feb 28, 2024 · After normalization, it compares the histograms using the correlation method. Aug 11, 2020 · As described, the images that actually match, are close to being identical. Dec 2, 2022 · OpenCV Python Server Side Programming Programming. signal. This also holds Jun 14, 2023 · To compare two images using OpenCV and Python, you can utilize various image comparison methods provided by OpenCV. add a comment. The values for each noising method corresponds with the intuition gained visually from the image grid above. flow: computed flow image that has the same size as prev and type CV_32FC2. Jan 9, 2016 · If a pixel has a large correlation index between two images, it means that the region of the face where this pixel is located does not change much between the images. Sep 8, 2012 · I believe your code fails because OpenCV is expecting images as uint8 and not float32 format. I see two ways to achieve that: the first would be resizing one of the images to the shape of the other one, the problem is that this can cause distortion in the image. I have to compare two images of the same object taken in different surrounding light (for example one in bright sunlight, other in white light, etc. 5. If you use this method on good-resolution images, you should increase the patch size for more accurate results (d=2 or 3). Nov 23, 2015 · Increment the corresponding element (H1 [A]++). Like phoenixstudio said, first downsample the images to the same size. Here’s an example comparing two images using the Structural Similarity Index (SSIM): Oct 11, 2021 · This implies a known relationship between the images before going into calculation. jpg'. Here is what you can do: find the location of the points with connected components analysis; calculate the shift needed to register the two images. But if you are using a higher version, consider KCF. CV_COMP_INTERSECT Intersection. Threshold source. Feb 10, 2023 · Here is a simple code for doing phase correlation in Python/OpenCV. Let’s first load the image and find out the histogram of images. Sorted by: 1. So we can expect their pixel values to be relatively similar. stream Jan 8, 2013 · second input image of the same size and the same type as prev. The hist1 and hist2 are histograms of the two input images and compare_method is a metric to compute the matching Oct 11, 2021 · This implies a known relationship between the images before going into calculation. I would like to compare them in order to know if it's the same figure or not (especially inside the triangle). jpg") Feb 2, 2024 · The similarity has decreased due to the red color in one image. holger (Jul 3 '18) edit. xfeatures2d. png. levels Jan 4, 2023 · Detecting low contrast images with OpenCV, scikit-image, and Python; Animate image using OpenCV in Python; Drawing a cross on an image with OpenCV; Blur and anonymize faces with OpenCV and Python; Face detection using Cascade Classifier using OpenCV-Python; Real time object color detection using OpenCV; Python - Writing to video with OpenCV Jun 1, 2017 · I met with a very weird problem about OpenCV. 0, this might be the best tracker available to you. OpenCV has the implementation of Pyramid Lucas & Kanade with Shi-Tomasi algorithm improvement to calculate the Optical Flow. The type is the same as image . 3 Feb 4, 2022 · I am using normxcorr2 function from Matlab to compute the displacement and velocity of certain region between two images. , scale and/or rotation invariant) features in the image and comparing them against a set of target Mar 22, 2022 · Here's a working example to compare one image to another. We simply display the MSE and SSIM associated with the two images we are 2 days ago · second input image of the same size and the same type as prev. ) in order to actually generate some correlation. Oct 11, 2021 · This implies a known relationship between the images before going into calculation. It receives as arguments: X, Y: ndarray. y, p1. the second would be padding the smaller image with zeros until the sizes match. 74271490e-01 -5. 5 means a classical pyramid, where each next layer is twice smaller than the previous one. win_size: int or None. The OpenCV version is 2. Then, your goal becomes to find stable points, ie, points that are present in two or more images whatever their location is. Using the compare_ssim method of the measure module of Skimage. 10741683e-02 2. 3 Ways to Compare Histograms Using OpenCV and Python. import argparse. Pearson's R is a common method for finding the correlation coefficient between two variables. The image was taken by a Russian photographer in the early 1900s using one Aug 31, 2020 · We are now ready to apply image alignment and registration using OpenCV! Use the “Downloads” section of this tutorial to download the source code and example images. You take the absolute difference of each value in the array with 5, and index 1 has the smallest difference, so Feb 17, 2022 · The goal of image-template matching is to get the location of the template in an image. We can apply template matching using OpenCV and the cv2. A peak is a indicator of "a big change" in the video Image Alignment (ECC) in OpenCV ( C++ / Python ) Figure 1. png') Oct 22, 2021 · I am using this function to calculate the similarity between two images. MatchTemplate () is what you're looking for. Jul 16, 2014 · However, it uses the trivial method for cross-correlation, which is O(n^4) for a two-dimensional image with side length n. The first image is given a weight of 0. The values returned from doing that are (a tuple of a tuple and a constant), namely: ((Offset_x, Offset_y), phase_corr_score) where the offsets are the shifts in x and y between the two images and the constant is the phase correlation peak value. i e I have obtained a binary image from the filter tat is shown as "pic1", I need to compare this image with the stored images in a folder and if there is a match with the input image then the code/prgm should return true and if there is no match it should return false. The “ Original ” column shows the score after comparing the original image with itself in order to see the ideal score. Feature Detection and Extraction : This method involves detecting "robust" (i. matchTemplate(image, template, cv2. The whole point of this exercise is to determine the relationship (if any) between the two images - or, to restate, the presence (and location) of components of the second (model) image in the first (observed) image. CV_COMP_BHATTACHARYYA Bhattacharyya distance. Also, two very similar images can have very different histograms. On line 19 we load the sift algorithm. Assume image1 is x, and image2 is y. Normalized cross-correlation coefficient is used for image-template matching. All we need to do is: Select an (x, y) -coordinate from the original image. It also offers 4 different metrics to compute the matching: Correlation ( CV_COMP_CORREL ) Jul 14, 2014 · 3 Ways to Compare Histograms Using OpenCV and Python. They all give different outputs that are read differently as shown in Jan 3, 2023 · Save. OpenCV comes with a function cv. 8. 2. The Pearson Correlation Coefficient, or normalized cross correlation coeffcient (NCC) is defined as: The normalization to (n − 1) degrees of freedom in the alternative form of r above is related to a corresponding definition of the sample standard deviation s: sx = √ 1 n − 1 ∑ni = 1(xi − ˉx)2. double confidenceValue = 0; Several methods are used to compare two images. NET wrapper to OpenCV) & C#. images_values[0,:,:] and images_values[1,:,:]? from scipy import ndimage EPS = np. Oct 12, 2014 · My code: i have two images i. The only solution that I found is using imresize function with bicubic interpolation. Does not recover from full occlusion. e. Lines 25-39 handle some simple matplotlib plotting. (All windows are considered the same) If you give matchTemplate two images that are the same size, it will return a single value or score. The data is a 2-d matrix of intensity values. # 2) Check for similarities between the 2 images. If I’m following along, the matches Oct 11, 2021 · This implies a known relationship between the images before going into calculation. I think Image<>. ORB_create() # detect keypoints and descriptors kp_a, desc_a = orb. matchTemplate” function is used for template matching. Importing image data. spatial import distance as dist. The size is not greater than the image size. y - p2. How can I do that? I try estimateRigidTransform and I get a 3x2 matrix like this : [[ 9. addWeighted () applies the following equation to the image: d s t = α ⋅ i m g 1 + β ⋅ i m g 2 + γ. In this case you will use feature distance. Then, i am trying to match them using the following code which is based upon the formula mentioned above. Images of Any dimensionality. pyplot as plt. In this case, the images change radically since you move your camera around. Calculate the correlation. If image is W x H and templ is w x h, then result must be W-w+1 x H-h+1. i have used corr2 in matlab. May 25, 2016 · I have this 2 images : and. We then compute the MSE and SSIM between the two images on Lines 21 and 22. But how can we find this kind of region. absDiff to compute the difference between the frames and cv2. If I’m following along, the matches Aug 31, 2012 · 1 Answer. Importing library. wrapaffine_img Feb 10, 2012 · Image registration using python and cross-correlation. The numerical calculation of the Feb 28, 2017 · In layman terms, correlation determines the linear relationship between two variables/data-sets/etc. compareHist () function accepts three input arguments- hist1, hist2, and compare_method. in this picture you can see how it should look like. 2. A =[a00 a10 a01 a11]2×2B =[b00 b10]2×1. To associate your repository with the normalized-cross-correlation topic, visit your repo's landing page and select "manage topics. (ie sculpture). I call these two 16-bit png-files "left. If you want to compare for occurrence of object - use object detection. import matplotlib. Considering that we want to transform a 2D Oct 13, 2016 · 1. KFC stands for Kernelized Correlation Filters. For this steps you need: dft () phase () matchTemplate () with method = CV_TM_CCORR_NORMED. png". Find contour and approxPolyDP. You can expand it to compare multiple at once. cv. May 10, 2016 · Phase correlation is able to register only translation motion whereas the log-polar transform works in the log-polar domain which essentially converts rotation and scale changes into linear translation. If you want to look if two images are the "same" - use template matching. On lines 20 and 21 we find the keypoints and descriptors of the original image and of the image to compare. imread ('test. The goal is to clearly mark all differences with a strong red color. In practice, with your images it'll take very long. i need a cross correlation function in java openCV through which image similarity can be measured. Use the compareHist() Function of OpenCV to Compare Images. 13 on my server, and the OS is CentOS, compiler is gcc4. # load images. compareHist () function. For a very nice example, look at page 22 in this thesis. I tried these two methods (I tried them on the whole image (globally) and on pairs of the two images (locally)): Gray-Scale method: ImageB= ImageA * (Mean_Of (ImageA)/Mean_Of (ImageB)); Color method: Convert it to HSV then: Jun 28, 2011 · In fact, they can be totally different in every possible way, but just composed of the same colors and in the same proportions. If I’m following along, the matches Jun 20, 2014 · 2 Answers. imread("leftImage. The image on the left is part of a historic collection of photographs called the Prokudin-Gorskii collection. We can use the filter2D () function of OpenCV to find the convolution of two matrices or an image with a kernel. Left, rect. An output image to store the output of the input image convolved with the kernel. result: Result image. So can we perhaps calculate the correlation between the two given signals? But how can this be done efficiently with images? OpenCV has a Template Matching module. x) Do the same for second image and calculate difference in angle. Looking at the Histogram Documentation, there are 4 (5) different comparison methods: CV_COMP_CORREL Correlation. This process repeats for all the pixels of the image. For instance, the noise added by S&P (Salt I have two group images for cat and dog. Look for peaks in this signal and pick keyframes corresponding to these peaks. . jpg Sep 15, 2014 · The mse function takes three arguments: imageA and imageB, which are the two images we are going to compare, and then the title of our figure. img1 = cv. imread ( 'ml. Aug 25, 2008 · This formula is actually the "cosine" of the angle between the matrices (wierd). ) May 19, 2012 · I am having a little trouble in matching two similar images. -1-> highly non linear to each other Oct 24, 2011 · Fourier-Mellin Transform: This method is an extension of Phase Correlation, which can extract the rotation, scale, and translation (RST) transform between two images. from scipy. 6. it shows similarity in correlation coefficient between 1 to -1. 05148056e-02 1. 01445292e+00 -8. The cv2. Apr 26, 2015 · 1 answer. Bonus One-Liner Method 5: Pixel-wise Absolute Difference. Nov 11, 2021 · 4. but. May 17, 2019 · My current approach to make the differences obvious, is to create a mask (difference between the two images), color it red, and then add it to the images. Right : The same image with the channels aligned. It is the spatial relationship between these colors that define what an image looks like. fftconvolve as convolution and correlation are closely related. Let’s find out which data image is more similar to the test image using python and OpenCV library in Python. CV_COMP_HELLINGER Synonym for CV_COMP_BHATTACHARYYA. Here γ is taken as zero. This is a simple approach where you calculate the absolute difference between two images on a pixel-by-pixel basis. finfo(float). The bigger the similarity (lets say Pij=Qij ), C will be 1, and if they're completely different, lets say for every i,j Qij = 1 (avoiding zero-division), Pij = 255, then for size nxn, the bigger n will be, the closer to zero we'll get. From there, open up a terminal, and execute the following command: $ python align_document. Can anyone recommend a library or function that could help me. It simply slides the template image over the input image (as in 2D convolution) and compares the template and patch of input image under the template image. png" and "right. # construct the argument parser and parse the arguments. You need to remove the scale and rotation. Using this Apr 6, 2019 · that's a good one. KCF Tracker. (brightness of pixel 1 from B IS LARGER than brightness of pixel 2 from B) ) {. May 15, 2015 · 9. 4. Calculate the normalized cross-correlation and display it as a surface plot. image = cv2. Empty, modelImage. The peak of the cross-correlation matrix occurs where the subimages are best correlated. Multiply the kernel coefficients by the corresponding image pixel values and sum the result. Jun 5, 2014 · I want to know whether there is any built in functions which can find correlation between two images other than scipy. Feature matching example. (Because cross correlation try to maximize the product (or cross-correlation) of the two aligned images and so the maximum Nov 26, 2020 · Then this I stuck at this step right now where I need to generate 2 correlation bitmap using this 2 image what I got after affine transform: this is the picture show the formula for correlation. This method computes the mean structural similarity index between two images. Size); PointF[] pts = new PointF[] {. The maximal value of C (t) will give you the angle difference t between the images. M = [A B] =[a00 a10 a01 a11 b00 b10]2×3. normxcorr2 only works on grayscale images, so we pass it the red plane of each subimage. and these two is the images I work with: gray_img. metrics import structural_similarity import cv2 #Works well with images of different dimensions def orb_sim(img1, img2): # SIFT is no longer available in cv2 so using ORB orb = cv2. I need to perform two-point correlation function from astroML Python module, my data is originally a jpg image, black and white, and I convert it to binary image using OpenCV image thresholding(not sure that I did it right). Convolution will only give me one pixel image the way it is implemented. Apply some threshold value. 5 days ago · Here I took two images to blend together. With OpenCV, you can do this with the resize function. Only CV_32FC1 images are supported for now. Its a school Jul 3, 2018 · These are neuronal networks explicitly trained to detect similarities between objects (faces for example). Standard similarity matching functions cannot be used for image-template matching. The result of Pearson's R lies between -1 and +1. As for the speed of correlation, you can try using a fast fft implementation (FFTW has a python wrapper : pyfftw). The better too is scipy. Do this for all frames i. If I’m following along, the matches Aug 3, 2016 · This is how I did using EmguCv (. 3. 52325933e+01] [ 1. The relationship maybe positively linear or negatively linear. image1 = cv2. You then will want to convert 110 to 120 in the first image, and 130 to 120 in the second. Left: An image from the Prokudin-Gorskii Collection. there will be some slightly movement up down / left right there will be different length of the same object Nov 26, 2021 · I’m trying to compare two images and return a score based on how similar the second image is to the original. SIFT_create() Apr 22, 2015 · This function does the image correlation which is a common algorithm in image processing. My goal is try to cluster the images by using k-means. To perform the stitching, open up a terminal, navigate to where you downloaded the code + images, and execute the following command: $ python image_stitching_simple. I have a data set with lots of picture like at the bottom but with differents signs. Two test input images with slight differences: May 13, 2009 · I need to be able fill in an image from incomplete data. levels Jul 17, 2019 · The logic to compare the images will be the following one. You'd want to do the same for 25% and 75%; depending on the actual differences you might want to partition the histograms in even This notebook builds on my previous notebook: Cross-correlation of 2 matrices The general process: Load two images and extract their pixel-by-pixel information Normalize and downsample the pixel information Calculate cross-correlation using the processed pixel information Generate visual summaries of cross-correlation, highlighting areas of maximum image overlap Image: Ali Wong Using this b&w Oct 11, 2021 · This implies a known relationship between the images before going into calculation. I OpenCV. So, I watched several videos on how to do this, but nothing seems to return the correct answer because the closer the second image to the first one is, the lower the score gets. Mar 18, 2020 · How can I correctly pass it to the following function to calculate the mutual information between two images ? i. jpg. TM_CCOEFF_NORMED"? and finally How to find correlation between two images using Numpy. Now as the images are of the same object, they should match almost correctly. from skimage. x - p2. The purpose of this module is to find a Aug 24, 2019 · 3. Aug 23, 2015 · Is there a way to compute full cross-correlation (or phase correlation) for two images of same size?-resulting image should be same size as 2 source images. Jan 8, 2013 · Scale operations (linear transformation) you can see that, in essence, an Affine Transformation represents a relation between two images. Aug 27, 2012 · Use cv2. assuming images A and B, loop for significant number of pixels: IF (. sumElems to get the sum of all pixels differences. Repeat the process for all pixels by scanning Feb 12, 2023 · Here are the steps to perform template matching with multiscaling in OpenCV: Load the target image and the template: Use the cv2. This gives the gradient histogram. For example, you can first compute RGB/HSV color histogram (24d vector if use 8-bins for each channel) for each Mat file and then compute correlation of these two histogram vectors. Based on the Template Matching tutorial in opencv doc, After template matching, you need to normalized the result mat between 0 and 1: After normalization, you need to find the maximum value inside the res matrix. correlate2d () and matplotlib xcorr (). So using log-polar matching you can register two images that are scaled rotated and translated copies of each other. Rectangle rect = new System. 13. I thought maybe the opencv reMap method but I can't seem to get that to work. I want to calculate the rotation and translation between the two objects (the long vertical object is noise). Or do I have to compute it by dft and therefore code it manually? Jun 18, 2019 · Or if we can find a shared and unique region in both images, we can use matchTemplate. I use the same codes to calculate the correlation between two histograms, but get different results in two machines. double correlogramMatching(Mat correlogram1, Mat correlogram2) {. sift = cv2. If I’m following along, the matches Apr 8, 2015 · image stitching, as you can implement from opencv's features2d (free or non-free). png --image scans/scan_01. I want to interpolate between the points I have. Now for each consecutive points calculate angle. path1='D:/image/cat1. Then compare rotations of the images. Mat correlogram1 and Mat correlogram2 in which i am storing the values of Correlogram for two images. CV_COMP_CHISQR Chi-Square. It is the equivalent to asking what the index of the closest value to 5 is in the array [1, 4, 9]. The resulting value indicates how similar the color distribution is between the images. Repeat for the second image. OpenCV implements the function cv::compareHist to perform a comparison. (brightness of pixel 1 from A IS LARGER than brightness of pixel 2 from A) AND. Similar images will have less mean square error value. ccorr: Flags to evaluate cross-correlation instead of convolution. We can find the similarity between two images using the compareHist() function of OpenCV. Dec 17, 2018 · Our goal is to stitch these three images into a single panoramic image. sometimes it will return the full size image, then you can use the value at the central point. Then calculate the correlation between the histograms: C (t)=sum (H1 [x] H2 [x+t]). If I’m following along, the matches Jan 8, 2013 · image: Source image. imread () function to load the target image and the template as Add this topic to your repo. In the template matching scenario, you slide a template along multiple places and simply find where the smallest difference occurs. If I’m following along, the matches Nov 25, 2013 · I recommend you the following steps: Transform you images to the frequency domain with DFT (Discrete Fourier Transform). Very common methods are: 1) PSNR values provides a close idea of about the images. templ: Template image. Feb 13, 2017 · If you are using OpenCV 3. Once you get the homography matrix you can get the rotation angle using RotatedRect object. This tracker builds on the ideas presented in the previous two trackers. import glob. Convolution itself is actually very easy. Oct 10, 2023 · Use the filter2D () Function of OpenCV to Find Convolution of Matrices or Images in Python. Jul 25, 2016 · A kernel matrix that we are going to apply to the input image. py --template form_w4. 2) You can apply SSIM of QIUI to compare to two images. iu bm oa qy iv fj eh la rf vj