Cv2 imwrite black image. , in OCR, face detection, or object .

Cv2 imwrite black image Whether you’re a beginner or an experienced developer, we’ll cover everything from file paths to data types, ensuring you can reliably save images with OpenCV. Intelligent Recommendation the opencv cv2. In this article, we will give you a detailed explanation of the syntax and features of cv2. The behavior is a bit random, and I am not sure what is causing this issue. This comprehensive guide covers various methods, including saving in different formats and adjusting image quality. Since your input image already contains an alpha channel, the solution is simple -- just reuse the alpha channel. threshold(). imwrite () function is: cv2. imwrite("filename. Dec 11, 2021 · Thank you for the suggestion. imwrite operation returns a black image. Mar 30, 2024 · Inverting an image involves swapping the values of each pixel’s color channels, resulting in a reversed color scheme. def detect_colors(image): color_red = np. I recently updated my OpenCv version to 3. imwrite('color_img. 04 I load an image image = cv2. We display and Jan 15, 2018 · When I decode a base64 encoded cropped face image, it goes black and the data corrupts. Jul 26, 2024 · OpenCV-Python is a library of Python bindings designed to solve computer vision problems. COLOR_BGR2GRAY, and then saves the resulting grayscale image back to disk. To perform image inversion using OpenCV in Python 3, we need to follow a few steps. The images are displayed. then i have 14 First, let me mention that if you display an image with alpha transparency using cv2. imwrite (), find the pixel values of the two images are not equal, there is a slight difference, looking as if nothing Jan 30, 2024 · When working with images, some of the most basic operations that are essential to get a grip on include reading the images from disk, displaying them, accessing their pixel values, and converting them from one color space to another. The resized image looks good while displaying using cv2. bmp', img2): raise Exception("Could not write image") Note: the read works fine because "escaped" uppercase letters have no particular meaning in python 2 (\U and \N have a meaning in python 3 so it wouldn't have worked) And if there's an error, the program now complains loudly. You have to pass an image composed of values in the range [0, 255]. imwrite() function cannot. imwrite () in Python and cv::imwrite () in C++. It allows you to isolate specific parts of an image. There are more than 150 color-space conversion methods available in OpenCV. destroyAllWindows() This doesn't work, presumably because the data type of b isn't correct, but after substantial searching, I can't figure out how to change it to the correct one. numpy () # Assuming single class segmentation for simplicity, adjust as needed mask = masks [0] # For multi-class, iterate over masks # Save the mask cv2. jpeg Steps : First, we will import OpenCV. imshow, but show a b Jan 15, 2023 · Using OpenCV in Python, how can I create a new RGB image? I don't want to load the image from a file, just create an empty image ready to work with. imwrite() Aug 12, 2020 · I am trying to . It was instrumental in the development the first self driving car. In this This code uses cv2. l have black and white images pixels are either 0 or 255 only. selectROI in OpenCV: Correctly Save Cropped Images OpenCV (Open Source Computer Vision Library) is a cornerstone tool for image processing and computer vision tasks. imread('dumb. here is my code: We often use cv2. Any help why is this issue occuring and how to resolve it? Appreciate it! python opencv asked Apr 8, 2022 at 13:25 Pressing_Keys_24_7 1,86321536 Jan 8, 2013 · The function imwrite saves the image to the specified file. The cv2. png, etc, image: (required) The image is basically a NumPy array. Mar 28, 2017 · Hello! I am processing a 16-bit 3D CT Scan image formatted as . 1 day ago · How to Fix cv2. cvtColor (src, code [, dst [, dstCn]]) Parameters: src: Image code: It is the color space Jan 16, 2023 · Add a third black channel. imshow() function but while saving using cv2. # Load the model model = Feb 16, 2025 · img = cv2. In this article, we will convert a BGR image to RGB with python and OpenCV. This tutorial explains these basic operations, starting first with a description of how a digital image […] The answer by @Jaime works. putText() is: putText(img, text, org, fontFace, fontScale, color[, thickness[, lineType[, bottomLeftOrigin]]]) -> None The second argument of cv2. Introduction In this tutorial we will learn how to convert an image to black and white, using Python and OpenCV. destroyAllWindows Apr 12, 2018 · I have one image and one co-ordinate (X, Y). I tried with io. But, cv2. Oct 8, 2024 · Can you please provide the image you are working with? It would really help in testing your code and troubleshooting the black image issue. 06 step # Run It Mar 11, 2024 · The output is a grayscale image file ‘gray_image. Apr 8, 2022 · The cv2. Method 2: Using imread’s Second Argument Another method involves the use of imread function’s second Nov 10, 2019 · I have a 2D numpy array which it's values are float between [-4, 3]. dst is the thresholded result image In your code thresh is a float not a Mat. OpenCV imwrite non-destructive saving image and the method to solve the black screen of saved image, Programmer Sought, the best programmer technical posts sharing site. When writing TIFF images, we can control aspects such as compression quality and color depth. imwrite() to save images. waitKey () Sometimes I would get the lovely picture of the original butterfly image, but sometimes I would get a small black window. The process is simple and requires just a few lines of code. Solution about the picture saved by cv2. imshow shows this array as a BGR Image, but when I saved it with cv2. imwrite () The syntax for the cv2. img = cv2. imread, cv2. The window automatically fits the image size. jpg", blank_image). The format depends on the Python OpenCV cv2. This simple yet powerful concept is at the heart of image thresholding — a fundamental technique in image processing. OpenCV can be used with Python, C++, Java. Mar 15, 2025 · Learn how to automate image processing tasks using OpenCV and Python scripts. imwrite("img_inv. This is the piece of code: def create_learn_msg(db_name, person_name, last_location, images, labels): Jul 26, 2024 · OpenCV-Python is a library of Python bindings designed to solve computer vision problems. Among its many functionalities, it offers essential methods to read, display, and write images, making it a crucial library for various image-processing applications. 14 First, let me mention that if you display an image with alpha transparency using cv2. imread('mandrill. imwrite one of the MNIST test images with openCV but it shows just a black square. Why is this happening? Both the numpy arrays are equal, so I should get the same output right? Apr 19, 2021 · I am trying to use a bit mask to cut out an object from a JPG image to a 4 channel PNG image that has transparent background. For example, a white pixel becomes black, and a black pixel becomes white. imread accepts a flag after the filename ( cv2. However, after decoding this image the colors have been changed slightly. The function imwrite saves the image to the specified file. Apr 28, 2014 · I am trying to read images directly as black and white. putText() - Add text to resized image Now, lets get to the meat of the post - adding text to the image. 0-dev, and the code that I used before does not work anymore. g. waitKey(0) cv2. The filename must include image format like . Jan 11, 2017 · The solution provided by ebeneditos works perfectly. balanced_img = whitepatch_balancing(image, 60, 70, 60, 70) cv2. 255. Here's how you do it: Jul 23, 2025 · Saving an Image The cv2. We take these two images to blend : gfg. cvtColor method cv2. Normalization to 0-255 is changing the output, although it manages to give the same output for imshow and imwrite. type () and depth_mat. Converting an image to black and white with OpenCV can be done with a simple binary thresholding operation. We welcome everyone from Feb 27, 2024 · The simplest way to access or modify the value of a single pixel in an image using OpenCV is by specifying its position with x and y coordinates. jpg gives a complete black image. It shows correctly when I show the result with cv2. imread () and cv2. Convert a color image to Apr 21, 2025 · Image masking is a powerful technique in computer vision. You need NumPy and OpenCV installed. So just unpack the (x,y,w,h) coordinates directly and use Numpy slicing to extract the ROI. imwrite Saving Black Rectangle When Using cv2. To save image to local storage using Python, use cv2. 2 OpenCV and Image I/O OpenCV provides a set of functions for reading and writing various image formats, including TIFF. imread ('butterfly. convertScaleAbs(img, img, 1, brightness) return img img = cv2. masks. Nov 13, 2025 · This blog post dives deep into the most common reasons behind this silent failure and provides step-by-step solutions to fix it. We start with a gray scale image and we define a threshold value. In my code, the imshow function shows the correct image, but the imwrite function saves a completely black image. The image format is chosen based on the filename extension (see imread () for the list of extensions). How to save the created images to image format files, such as PNG or JPG file formats. Images are read as NumPy array ndarray. Here's a minimum working example to extract and save a ROI: Input image -> Program to Dec 20, 2023 · OpenCV(Open Source Computer Vision Library) is an open source, platform independent library for image processing and computer vision. Apr 29, 2022 · Hence when you save such images they are perceived as a black image. Each row/columns contains a number ranging from o-255 for single channel Apr 23, 2025 · Image thresholding is the process of converting a grayscale image into a binary image using cv2. Sometimes, when we try to save an image using the OpenCV 'imwrite' function, when ended up with a blank (black) image in our working directory. imshow ("White Blank", blank_image2) cv2. g. Use cv2. imread() function is used to read in the image, after which a pixel’s value can be accessed or modified by passing its coordinates to the image array. inRange(image,color_red,def_color) green_mask Nov 16, 2021 · I am trying to use OpenCV to convert the results of the model I trained into a png image. Simpler models: Less input data reduces complexity and speeds up training. I still gives a black image! Jun 10, 2025 · In the vast landscape of computer vision and image processing, OpenCV stands as a beacon for Python developers. I want to save the images to disk but the original array has float values ranging around -5 to 5, which gives black images when using imwrite. imwrite to make a picture archive, but we sometimes find that the program runs, the picture folder is empty, it is very pit, so we need to understand its working status. Importance of grayscaling Fewer dimensions: RGB images have three channels, while grayscale images have only one. Grayscale images simplify data by reducing it from three color channels (red, green, blue) to a single channel, making computations faster, reducing storage needs, and often improving the performance of machine learning models (e. With its simple yet efficient functions- imread (), imshow (), and imwrite () -users can seamlessly load images Sep 21, 2023 · Your balanced_image has been scaled between 0 and 1, so you will need to rescale it back between 0, 255 before saving it. I suppose I have to convert it from a 3 color + alpha channel to a 3 channel image, but no idea how. So, imread () will internally convert from rgb to bgr and imwrite () will do the opposite, all under the hood. An example is this image, i would like it to be cropped such that all the unnececairy white space is removed. If you could define a certain value where all pixels above that value become white and all below become black, it would make your task easier. zeros (shape= [512, 512, 3], dtype=np. Jun 26, 2015 · cv2. invert() Method in Python OpenCV or Open Source Computer Vision Library is a real-time computer vision library used for image processing and machine learning. normalize() function: Oct 8, 2013 · pyplot. putText to overlay text on an image. You may transform this matrix by using some algorithms. imwrite() in several sections of a large code snippet and you want to change the path where the images get saved, you will have to change the path at every occurrence of cv2. rectangle(mask,rect1,rect2, 255, -1) The rect1 and rect2 represents the upper-left and bottom-right coordinates and they should be updated accordingly since the image ins resized as 0. shape I get (48 if not cv2. the documentation: >0 returns a 3 channel The following would load an image, create a proof of the image with the embedded ICC profile, then output that proof to a . So l need white pixel padding. jpg, . im Here, you will learn how to read an image, how to display it and how to save it back You will learn these functions : cv2. imwrite () function on OpenCV library. Use cv::imdecode and cv::imencode to read and write an image from/to memory rather than a file. I’ve got the code working but am experiencing some weird behavior I do not understand. 7) and bindings for OpenCV 2. imwrite(path, image) path: (required) The complete path where the file needs to be saved on the disk. imwrite('test. jpg" image is black. Read Apr 22, 2021 · I’m using the CUDA functions to calculate optical flow. 3, and the proposed solution no longer seems to work. tiff',cv2. imread(img) # Checking if the image is empty or not if image is None: result = "Image is empty!!" else: result = "Image is not empty!!" return result # driver node img = "Gfg. The operation is not done inplace, so you can still use maskimg for indexing etc. 6 days ago · In the world of image processing and computer vision, converting RGB images to grayscale is a fundamental preprocessing step. Usage Methods 4. imwrite() method is used to save an image to any storage device. imread opencv use of () to read an image, then save the image function cv2. Chances are, random_shape in your code does not store "valid" characters. imwrite () method # Saving the image cv2. png', maskimg * 255) So this converts it implicitly to integer, which gives 0 for False and 1 for True, and multiplies it by 255 to make a (bit-)mask before writing it. It is written in C/C++ and is available for many programming languages such as C++, Python, and Java. The image format is chosen based on the filename extension (see cv::imread for the list of extensions). imwrite () which i am obtaining after gabor filter . imwrite, I got total black or gray noise in the image. imwrite () saved the same image as black Asked 12 years, 1 month ago Modified 2 years, 10 months ago Viewed 55k times Jan 31, 2023 · Detailed description The following piece of code returns a black image on my raspi. imshow () method is used to display an image in a window. Now as long as you operate within OpenCV, you should face no issues and you can treat the image as is - i. Basic operations with images Accessing pixel intensity values C++ Java Python In order to get pixel intensity value, you have to know the type of an image and the number of channels. In OpenCV you can convert your image to int data type and scaling the pixel intensities between the expected [0 - 255] using cv2. the image is of type float32. Mar 4, 2019 · import cv2 import numpy as np # black blank image blank_image = np. May 30, 2023 · In digital images, Transparency is the functionality that supports transparent areas in an image or image layer. Mar 11, 2025 · Learn how to save images using OpenCV's imwrite() function in Python. This article describes the following contents. This video shows why this happend and what should we Feb 11, 2019 · I just would like to know if it's possible to save gray 1 channel images with opencv starting from rgb images. png', mask. 04, python 3. imshow() on the new numpy array, I get only a black screen. Then, for Jul 23, 2025 · Prerequisites: OpenCV OpenCV is a huge open-source library for computer vision, machine learning, and image processing. 4. Sep 6, 2024 · Imagine you’re sifting through a pile of photos and want to separate the black-and-white images from the color ones. It helps in object detection and analysis. I have developed a workaround to achieve this, but this is non-ideal because (a) it makes the image unnecessarily 2x as large as it needs to be, and (b), its an 'obtuse' way to solve the problem: import cv2 import numpy as np img = cv2. However, for Jun 17, 2021 · Convert image to heatmap. But sometimes the image will vary so I think of edge detection first to detect the area I want to crop and then crop the image. Among its myriad functions, cv2. 7. I'm tr Cv2. imwrite ('segmented_mask. Converting the datatype to uint8 using pic = pic. How can I overlay a transparent PNG onto another image without losing it's transparency using openCV in python? Learn how to transform a color image into a pure black and white format using Python and OpenCV, with step-by-step guidance and code examples. imsave. png",image) This is because the "tilde" operator (also known as unary operator) works doing a complement dependent on the type of object for example for integers, its formula is: x + (~x) = -1 but in this case, opencv use an "uint8 numpy array object" for its images so its range is from 0 to 255 so if we apply this Dec 19, 2017 · So, I want to create a 500x500 white image using python Numpy library, though I can easily do it in photoshop. This will save the image according to the specified format in current working directory. channels () wont return AttributeError: ‘numpy. 4. However, there are many features of the cv2 imwrite function that are not known to many people. 25 times big. INTER_LINEAR) Notice how that it is width in the first place and height in the second. Executing the following code: import cv2 import numpy as np import matplotlib. IMREAD_COLOR) cv2. imshow (img), but the image displayed is all black instead of what it was originally. imread('image. Pls see the attached photo below. Then you should be able to view it. ones (shape= [512, 512, 3], dtype=np. jpg’, image) In this Topic, we’ll learn to: 1. imread in OpenCV. pyplot as plt img = cv2. Dec 18, 2017 · When I call cv2. IMREAD_GRAYS Apr 13, 2019 · In this tutorial we will learn how to convert an image to black and white, using Python and OpenCV. Grayscale images are useful for simplifying image processing tasks and reducing computational complexity, making them an essential tool in computer vision and image analysis. Declare a path and pass it as a string into cv2. May 24, 2020 · If I imwrite a binarized image, it only creates a grayscale image file not an indexed=2 file. Additionally, rectangles are drawn on the original image to visualize the patches using cv2. jpg', fast_brightness Jul 15, 2023 · OpenCv is an advance library used for image detection and manipulation . So you are passing values to cv2 Oct 8, 2024 · onePic. boundingRect(). Is there a way so OpenCV can process the image correctly? Also,I need to be able to convert the image to Oct 5, 2022 · 05 step # Saving an Image # To a Filename # Using cv2. Step 2: Read the Image: Use cv2. imread will convert a 16 bit, three channel image in a. imwrite(filename, image) Drawing Shapes and Text on Images OpenCV provides the following drawing functions to draw geometric shapes on images. imread() for input. If you can offer any pointers, it would be greatly appreciated! This is my code, all i want to do is filter the each color and see the image but the output is just black image all of them. This behavior is not seen using pn This is actually what I want saved on my file system, but for some reason whenever I try to write the image using cv2. @Zindarod. This code loads a color image from disk, converts it to grayscale using the cvtColor function with the color space conversion code cv2. OpenCV uses BGR Feb 4, 2015 · First, you can just save an image using cv2. imwrite(filename, blank_img) True An image must have been saved inside /DATA folder. array([0,0,0]) red_mask = cv2. imread (), then convert it to grayscale, and save it to the local file system using cv2. But if you have cv2. jpg', b) cv2. 0. There are two ways: one is to use OpenCV function cv2. imwrite () In our previous tutorial - cv2 imread (), we learned to read an image into a matrix. We have a while loop that runs while the choice is 1. The return value True means that Oct 3, 2017 · I am trying to read and display an image in Python OpenCV. I have run the following script: import cv2 img = cv2. imwrite (). How to create a new image with the desired background color and dimensions in Python and OpenCV. Then, this image is encoded as a jpg file with opencv. Sep 16, 2015 · import cv2 def fast_brightness(input_image, brightness): ''' input_image: color or grayscale image brightness: -255 (all black) to +255 (all white) returns image of same type as input_image but with brightness adjusted''' img = input_image. imwrite () method is used to save an image to any storage device. Enter an alpha value. imshow then the transparent areas are going to be black. astype ('uint8') * 255) on Mar 15, 2024 coder-glitche on Mar cv2. In this tutorial we would explore some of the building block of image manipulation using the python OpenCv library. imwrite() individually. In this tutorial, we will learn how to save an array as image in file system. It saved the image but with a lossy conversion du Oct 15, 2022 · In Python and OpenCV, you can read (load) and write (save) image files with cv2. argv[1], cm. imread ("test_image_with . tif to 8 bit as shown in the question. jpg How do you convert a grayscale OpenCV image to black and white? I see a similar question has already been asked, but I'm using OpenCV 2. How to display the created images in Python and OpenCV. imwrite() function I get this: In some cases the image that is saved is completely blank (all pixels are white). RGB, CMYK, HSV, etc. This is all as expected. First, you read a method using cv2. threshold returns 2 parameters: retval is used when thresholding using the OTSU method (returning the optimal threshold value) otherwise it returns the same threshold value you passed to the function, 128. jpg gives the correct segmented image but onePic2. In this OpenCV tutorial, we will learn how to save an image object to a file in Python using imwrite() function. rectangle (x, (0, 0), (50, 50), (0, 0, 255), -1) cv2. putText() It takes in parameters for the positioning and customization of the text (font, format, color, size) in the image. I don't get why!! import keras import numpy as np import mnist import tensorflow as tf from tensor May 30, 2022 · For more information about Python CV2 image quality compression, please search the previous articles of script home or continue to browse the relevant articles below. imwrite (filename, image) Parameters:filename: A string representing the file name. png with the sRGB profile embedded in it. GitHub Gist: instantly share code, notes, and snippets. threshold(), and the other is to process ndarray with a bas Jul 23, 2025 · Let's understand steps to edit and modify pixel values using OpenCV: Step 1: Import Necessary Libraries: OpenCV (cv2) is the primary library for handling images. waitKey (0) cv2. Jan 13, 2019 · While the function cv2. Jul 30, 2022 · Hello there, I’m trying to crop white from images generated in vpython. We read the two images that we want to blend. imwrite () function after the read image, whose pixel values are not equal problem Cv2. copy() cv2. I wish to create a 2-channel png image - 1 channel would be grayscale and 1 channel would be alpha (the bit depth doesn't concern me). imwrite is black, Programmer Sought, the best programmer technical posts sharing site. I wanted to post the result here but since im new I can only post one image Jul 15, 2025 · The most optimal way to convert any input image into grayscale is using the OpenCV library’s cv2. ndarray , then i converted like this: depth_mat = cv2. The path must include an image format like . imread("img. We discuss OpenCV functions, their syntax and options. Computer Vision is the scientific subfield of AI concerned with developing algorithms to extract meaningful information from raw images, videos, and sensor data. How do I save the correct image as it was displayed? Aug 29, 2024 · OpenCV (Open Source Computer Vision Library) is a powerful open-source computer vision and machine learning software library. array([0, 0, 255]) def_color = np. This guide covers syntax, examples, and common use cases for beginners. I am always getting a black image of around 4KBs. Any help is appreciated Apr 12, 2025 · Image segmentation divides an image into parts. image: It is the image that is to be displayed. imwrite but it saved black images. jet) It does fine, but the "colorized. png apple. imwrite('output. Syntax: cv2. Aug 22, 2019 · 3. imshow() can handle images stored with float values in the range [0, 1] the cv2. COLOR_GRAY2RGB) So i guess the change should happen here or directly to the np array. imshow ("Black Blank", blank_image) # white blank image blank_image2 = 255 * np. The docstring for cv2. uint16 images with 16 bit depth). most of my characters in images are written in black. astype ('uint8') did not help. OpenCV is quite tolerant and writes int64 images with 8 bit depth (but e. . I applied it in 2 different data sets, in first it worked as expected but in second when I tried to save images it only saved full black images. As Soltius stated, here is a better way. OpenCV supports a wide variety of programming languages like Python, C++, Java, etc. This community is home to the academics and engineers both advancing and applying this interdisciplinary field, with backgrounds in computer science, machine learning, robotics, mathematics, and more. Mar 6, 2021 · import cv2 image = cv2. It provides a wide range of functions and algorithms that can be used to process and manipulate images and videos. Images with a floating-point type expect values between 0 and 1. array([255,0,0]) color_green = np. threshold (). imread () method loads an image from the specified file. float32) print (x. Python makes it easy with libraries like PIL and OpenCV. But when I call cv2. How to draw a point with this co-ordinate on the image. to shades of gray. jpg’ saved on the disk. and mask = cv2. imwrite () function returns a boolean value: True or False. putText, "text", is a string. I can see correct image in MuJoCo main window->rending->select the view to my camera. It can process images and videos to identify objects, faces, or even the handwriting of a human. Then it may be required to save this matrix as an image. I tried with cv2. This can again be simply added using the function cv2. Each pixel is represented as an element in the array. What options do I need on the imwrite to accomplish this? I would also like LZW compression if possible Feb 25, 2025 · 3. Apr 23, 2021 · I have a float32 signed image that displays when I use imshow() but gives a black output when using imwrite(), which I suspect is because the float 32 array has values between around -6 to 6, which result in the output having pixel values 6 in the 0-255 range. uint8) # print (blank_image. png") image = ~image cv2. Mar 4, 2024 · Saving Images # Simply use ‘imwrite’ specificing the file name and the image to be saved cv2. Apr 17, 2025 · When I use cv2. One important constraint is that PIL is not present. tif image in OpenCV Python. imshow (window_name, image) Parameters: window_name: A string representing the name of the window in which image to be displayed. png', balanced_img*255) Jul 12, 2025 · OpenCV-Python is a Python library used to solve computer vision tasks. Unfortunatley the image crop is produced wrong. imwrite () function of OpenCV is a very common function to save images into files. something curious is that depth_mat. jpg') I then check the shape of the image array print image. If you convert an image to grayscale, it transforms a color image into a single-channel image where each pixel represents a shade of gray In this image, you need to flood fill in several regions, since all the background green color is not connected. array([0, 255, 0]) color_blue = np. I load the image using cv2. Nov 1, 2014 · cv2. Mar 4, 2025 · OpenCV is an open-source computer vision library that provides a robust set of tools for handling images and videos. I want to use Python OpenCV. this function is saving a whole black image in the directory. imwrite('mask. Feb 14, 2021 · I am trying to save image after calculating local entropy of the image. Perfect for developers and enthusiasts alike. 6 on Ubuntu 12. My guess is that the saved black rectangle is due to rounding issues when converting the bounding box coordinates to an int type. imshow or cv2. May 24, 2009 · I have a matrix in the type of a Numpy array. This guide covers basic Dec 2, 2018 · I am working on a game project about image neutral-style models. Then I found that I ha i am trying to save an image using cv2. imwrite the image would be written to disk with the colors in normal (RGB) order. if you use cv2. Is there a way to save the image shown in the imshow() call correctly ? Apr 21, 2022 · I have the following image of a lego board with some bricks on it Now I am trying to detect the thick black lines (connecting the white squares) with OpenCV. jpg') cv2. The reason is that I want to get the specific area from the image below. shape) cv2. Jun 10, 2015 · The problem in your code is that you're misusing the return values of cv2. Feb 2, 2024 · Inverting Images Invert Images Using bitwise_not() Method in Python Invert Images Using numpy. Step 3: Access Pixel Values: Use NumPy indexing to access the pixel values. ndarray’ object has no attribute 'type’ and i am running them after running the Dec 3, 2020 · The function image_resize_add_padding() works fine and is doing what I am trying to do. We go through an example of applying transformations to an image object, and saving the image. For image processing/image editing, background removing is allowing us to highlight the subject of the photo and create a transparent background to place the subject into various new designs and destinations. imread(r"path\to\image") cv2. resize(img, new_size, interpolation=cv2. imread() to load the image into a NumPy array. imshow("image", image) cv2. waitKey(0) Note about imshow This function should be followed by a call to cv::waitKey or cv::pollKey to perform GUI housekeeping tasks that are necessary to actually show the given image and make the window respond to mouse and keyboard events. This will save the image according to the specified format in the current working directory. imwrite(r'C:\Users\Niladri\Desktop\tropical_image_sig5. imwrite("colorized. uint8) cv2. Change Apr 21, 2025 · Converting color images to black and white is a common task in image processing. 0 in your case. jpg', cv2. cvtColor () method. Nov 23, 2024 · How can I efficiently invert an image in Python using OpenCV? In the quest to manipulate images using Python, one common requirement is to load a color image, convert it to grayscale, and then invert the pixel data. jpg", colorized) if __name__ == "__main__": import sys colorize(sys. Loading it in openCV and saving it now won't change the rendering of it - but the colors aren't the original ones, they just LOOK like the original image LOOKED. May 23, 2021 · Learn how to Read, Display and Write an Image using OpenCV. Jul 18, 2019 · 9 I want to load and display a . imwrite ('x. mat(depth), cv2. Python makes it easy with powerful libraries. Jul 23, 2025 · # Importing OpenCV library import cv2 # user define function # that return None or def check_empty_img(img): # Reading Image # You can give path to the # image as first argument image = cv2. imread ('1_00001. 1 Installing OpenCV Before we start working with OpenCV to write TIFF images, we Sep 18, 2013 · I am using Python (2. imwrite (‘output. imshow() on the original numpy array, it prints the image. Your rgb values are <1 for all channels which is basically black. Here is an example for a single channel grey scale image This is due to legacy reasons during the original development of the library. The code below is valid and the image is white (because I saved the image using cv2. Images are just numpy array with which has a given row and columns . Master the differences between IMREAD_UNCHANGED, IMREAD_COLOR, and other flags for efficient image processing. Attached is a usb webcam. imshow displays the image correctly. This guide covers basic masking methods in Python. imread(filename[, flags]) ) which specifies the colour type of the loaded image cf. Jul 23, 2025 · In this article, we will discuss how to remove the black background and make it transparent in Python OpenCV. imshow ('ImageWindow', img) cv2. What is Image Normalization? Image normalization is the process of adjusting the pixel intensity values of an image to a predefined range. my image for testing is This Please help me thanks. , in OCR, face detection, or object Jun 10, 2021 · Syntax – cv2. Return Jul 23, 2025 · In this article, we will explore how to normalize images using OpenCV in Python. ImWrite () Save Image is black (suscontient), Programmer Sought, the best programmer technical posts sharing site. This range is typically between 0 and 255 for images with 8-bit depth, where 0 represents black and 255 represents white. If the image cannot be read because of missing file, improper permissions or an unsupported/invalid format then it returns an empty matrix. imshow('Color image', b) cv2. imwrite () along with examples. One common task in image processing is converting an image to black and white, also known as grayscale. In this article, we will explore how to convert an Feb 26, 2024 · When working with images, a common task is to remove a solid black background and replace it with transparency to isolate objects or improve aesthetics. With practical examples and clear explanations, you'll master image saving in no time. I have already experimented a lot with Jan 3, 2023 · Alpha blending is the process of overlaying a foreground image on a background image. Oct 25, 2013 · import cv2 image = cv2. Is it possible to write the image I originally viewed through imshow (the float Jul 12, 2020 · I am trying out cv2 on ubuntu 20. Oct 26, 2024 · Learn how to properly load images in OpenCV using imread() flags. It varies between complete black and complete white. imwrite() I have written some code to create a black image, and then draw a red square in the top-left corner: import cv2 import numpy as np x = np. mhd/. png" # Calling and printing Jan 17, 2024 · Introduction cv2. 4 days ago · The function imwrite saves the image to the specified file. rectangle () in both implementations. Mar 24, 2020 · I am trying to write a program that finds center of black objects and cuts around that area. addWeighted () to add the weighted images. data. The result is a binary image with 0 = black, and 1-255 = white. The image on input (as a png) is in RGB order but the image in memory (as a cv::Mat) is in BGR order. imwrite() function is the primary method for writing images in OpenCV. Algorithm-ready: Some methods, such Mar 26, 2025 · The cropped patches are saved separately in a “patches” folder using cv2. 4 days ago · Note Format of the file is determined by its extension. raw Opening the file and taking a 2D slice using Fiji/ImageJ gives me a regular grayscale image, but when I import it into OpenCV (python), and also get a 2D slice, both imshow and imwrite do not give me a good image. png', x) This saves the following image: And it prints out the shape of x to be (100, 100, 3). cvtColor () method is used to convert an image from one color space to another. This is achieved by selecting a threshold value and assigning pixel values accordingly. imwrite() function it seems to be a fully black image. cvtColor(np. My output has 4 channels, and I am not sure how to convert these 4 channels to png. In the mean time I managed to also solve the problem using cv2. tif') and then I display it using plt. However l have also some images where the characters are in white so l need black pixel padding. In your case, you are passing values that are all close to zero and "far" away from 255. By default cv2. Feb 2, 2016 · I am trying to save a JPEG image onto the disk using imwrite, seems that I am missing something. In Python, generally, OpenCV is used Oct 9, 2020 · This article describes how to binarize an image into black and white with a threshold. Discover efficient workflows, coding tips, and real-world applications. imshow () , cv2. It was developed by Oct 13, 2020 · I create and view a random image. zeros ( [100, 100, 3], dtype=np. imsave () saves image correctly but cv2. If you’re looking to achieve this task leveragely with OpenCV while ensuring your solution remains elegant and efficient, we’ve got you covered! Below are several methods you Sep 23, 2025 · Grayscaling is the process of converting an image from other color spaces e. I tried MINMAX normalisation, but this results in the black parts of the image flashing white when I iterate through the frames. How would I write it to disk it as an image? Any format works (png, jpeg, bmp). selectROI returns the (x,y,w,h) values of a rectangle similar to cv2. imread (), cv2. imwrite it was completely black. imread(f, cv2. OpenCV does not recognize an image with only 2 channels. Jul 19, 2019 · The reason is that uint8 images expect values from 0. e. cv2. imwrite () Optionally, you will learn how to display images with Matplotlib Jan 15, 2025 · Learn how to use Python OpenCV cv2. Jun 21, 2021 · The image is coming as a numpy. This problem involves taking an input image with a solid black background and outputting the image with the black areas replaced by transparency, preserving only the non-black content. l'm wandering if there is a trick in open cv to detect that then add white or black pixel padding Apr 9, 2025 · In this article, we will learn how to convert an image to grayscale using Python and OpenCV. The Mar 11, 2024 · # Loop through the results for result in results: # Access the masks masks = result. What am I doing wrong here? Image I see seems fine Dec 8, 2023 · How to create a new image with a black background and with desired dimensions in Python and OpenCV. If you have a floating-point image with values above 1, they're all assumed to be 1. uidw erjj ysmpl cwiwqrlf obcd pja eldxmpii szm stntv otzzn vjev byktz zybq dkgfga jjxuxo