Python Opencv Copy Image

Detecting multiple bright spots in an image with Python and OpenCV Detecting multiple bright spots in an image with Python and OpenCV Normally when I do code-based tutorials on the PyImageSearch blog I follow a pretty standard template of: Explaining what the problem is and how we are going to solve it. Image Pyramids are one of the most beautiful concept of image processing. SIFT KeyPoints Matching using OpenCV-Python: To match keypoints, first we need to find keypoints in the image and template. You will also build, train, and test your own custom image. NOTE: Are you interested in machine learning? You can get a copy of my TensorFlow machine learning book on Amazon by clicking HERE In my previous tutorial, Color Detection in Python with OpenCV, I discussed how you could filter out parts of an image by color. destroyAllWindows() to destroy all windows, cv2. OpenCV and Python versions: This example will run on Python 2. Luckily for us, we can now easily compute the differences and visualize the results with this handy script made with Python, OpenCV, and scikit-image. I started working on SURF feature detector based Tracking algorithm using OpenCV python bindings and SimpleCV. dll', and 'opencv_ffmpegXXX_64. OpenCV Python – Resize image Syntax of cv2. What are the exact steps to follow to compile a cmake enabled project for Raspberry Pi, with host as an Ubuntu machine? Note: I am going to use OpenCV in a python project, and not C++. This is much like what a green screen does, only here we wont actually need the green screen. Learn about the data and image types unique to OpenCV, and find out how to manipulate pixels and images. I found the GetSubRect() function to copy or isolate part of the image but it does not appear to be available in python. ~60,000 images in total. It doesnot have to be shorter as long as its much better. GitHub Gist: instantly share code, notes, and snippets. OpenCV to handle computer vision and image processing. Find contours in the binary image, then for each contour, create a mask image of that shape. Later the HSV (Hue Saturation Value) and HSL (Hue Saturation Lightness) are developed and found to be more…. In this post on OpenCV Python Tutorial For Beginners, I am going to show How to Read, Write, Show Images in OpenCV. Extracting a ROI (Region of Interest) using OpenCV and Python is not so hard as it could may sound. Digital Image Processing using OpenCV (Python & C++) Highlights: In this post, we will learn about why the Fourier transform is so important. OpenCV is a library full of great easy-to-use algorithms that can be used in 3D modeling, advanced image & video editing, tracking an identifying objects in videos, classifying people who are doing a certain action in videos, finding similar images from a dataset of images, and much more. The relevant OpenCV functions are as follows: Find contours in a binary image. Access image properties; Setting Region of Image (ROI) Splitting and Merging images; Almost all the operations in this section is mainly related to Numpy rather than OpenCV. Copy the two files ' opencv_ffmpegXXX. imwrite(‘lena_copy. I'm running Windows Vista if that helps any. This example shows the Python code for reading an image in one format − showing it in a window and writing the same image in other format. com/8rtv5z/022rl. You'll need to install it first, follow the instructions [1] and then you should be able to import the module. The module also provides a number of factory functions, including functions to load images from files, and to create new images. Extracting a particular object from image using OpenCV can be done very easily. OpenCV on Wheels. Open a file and name it fpt. Because it's a very popular computer vision package, and is capable of performing basic image processing to relatively complex image processing, OpenCV is often used together with more advanced packages like, TensorFlow or PyTorch for deep learning. OpenCV is a library of cross platform programming functions aimed at real time Computer Vision. It’s very cool. resize(img, (h/8, w/8)) h1, w1 = resized_image. Python Image Processing on Azure Databricks - Part 1, OpenCV Image Compare By Jonathan Scholtes on June 6, 2018 • ( 1) I have been working with Azure Databricks the past few months and am having more fun than I probably should admit online. Click right on project name > new > Python file > Set Name file with tes-opencv > write this code. Let's move into some code to see how finding the distance from your camera to an object or marker is done using Python, OpenCV, and image processing and computer vision techniques. I read a couple of books about opencv at the library, I did not understand a single thing. pyd) and paste it in the folder C:\Python27\Lib\site-packages\ 5) Now open your "Python IDLE" ( from Start > All Programmes > Python 2. __version__) 9. You can easily do it by following Life2Coding’s tutorial on YouTube: Linking OpenCV with Python 3. Then, I converted the copied image img_copy to grayscale,. OpenCV is a library full of great easy-to-use algorithms that can be used in 3D modeling, advanced image & video editing, tracking an identifying objects in videos, classifying people who are doing a certain action in videos, finding similar images from a dataset of images, and much more. We create a 'final' variable and keep the duplicate/copy of the main image. It is based on the original Mean Shift algorithm. 4 with python 3 Tutorial 31 by Sergio Canu May 14, 2018 Beginners Opencv , Tutorials 6. Home » Python » How to crop an image in OpenCV using Python. In my last post, I was able to create a disparity map from a stereo image. Alright, so my post Getting Webcam Images with Python and OpenCV 2 was wrong! I did not fully understand how to read the OpenCV API documentation and instead of demonstrating how to capture an image with OpenCV 2, I just demonstrated a way to capture an image with OpenCV 1. Next we convert the image to gray scale. (OpenCV only has the Hough transform for straight lines, you can write your own one for detecting curves. 4) Now copy everything in the folder C:\opencv\build\python\x86\2. opencv python fails to load image. Opening and Saving images in OpenCV. Then crop out the face and save it. 04, blender 2. __version__) 9. Often there would be a need to read images and display them if required. There is also no support for the OpenCV classes like Rect, Point etc. NOTE: Are you interested in machine learning? You can get a copy of my TensorFlow machine learning book on Amazon by clicking HERE In my previous tutorial, Color Detection in Python with OpenCV, I discussed how you could filter out parts of an image by color. To this pool of nodes include: Image Sampler, Image Viewer, ROI, Custom Input, Custom I / O, Stethoscope, TypeConvert. One problem that naturally arises is how to handle the boundaries. By becoming familiar with these characteristics of using Python and OpenCV, you will be able to jump around to different concepts more easily. OpenCV 3 image and video processing with Python OpenCV 3 with Python Image - OpenCV BGR : Matplotlib RGB Basic image operations - pixel access iPython - Signal Processing with NumPy Signal Processing with NumPy I - FFT and DFT for sine, square waves, unitpulse, and random signal Signal Processing with NumPy II - Image Fourier Transform : FFT & DFT. In this post on OpenCV Python Tutorial For Beginners, I am going to show How to Read, Write, Show Images in OpenCV. Copy the image to the Desktop/workshops/image-processing/03-opencv-images directory. Organizing information (eg, indexing databases of images and image sequences) 3. It contains a large collection of image processing functions. One of the many brilliant features of OpenCV is that you can visualize images with very little effort. Use Otsu threshold cv2. Have you ever had to loop over an image pixel-by-pixel using Python and OpenCV? If so, you know that it’s a painfully slow operation even though images are internally represented by NumPy arrays. This is in the opencv-python tutorial below is the link. It is increasingly being adopted in Python for developing applications to process visual data such as. The guide is based on the official OpenCV Installation Guide on Debian and Ubuntu. Find and Draw Contours using OpenCV | Python Contours are defined as the line joining all the points along the boundary of an image that are having the same intensity. shape[:2] Then put the resized one into the original image. Since GPU modules are not yet supported by OpenCV-Python, you can completely avoid it to save time (But if you work with them, keep it there). Video Analysis using OpenCV-Python. You can easily do it by following Life2Coding’s tutorial on YouTube: Linking OpenCV with Python 3. I recommend that you visit Adrian’s “PyImageSearch - Be awesome at learning OpenCV, Python, and computer vision” website for more information. imread('lena. 0 and Python 2. matchTemplate() for this purpose. 비디오 입력 출력 3. Flip Image OpenCV Python October 7, 2016 Admin 2 Comments OpenCV provides the flip() function which allows for flipping an image or video frame horizontally, vertically, or both. NOTE: Are you interested in machine learning? You can get a copy of my TensorFlow machine learning book on Amazon by clicking HERE In my previous tutorial, Color Detection in Python with OpenCV, I discussed how you could filter out parts of an image by color. OpenCV on Wheels. OpenCV-Python Tutorials. Satya Mallick is raising funds for AI Courses by OpenCV. import cv2 import numpy as np import pprint image = cv2. Перевод статьи «OpenCV-Python Cheat Sheet: From Importing Images to Face Detection». OpenCV is an image processing library. OpenCV-Python Tutorials Documentation, Release 1 10. I have a small script running on a raspberry Pi (Stretch) using the picamera with python and openCV (read the video frames, copy them in a np. I'm new to windows, open-cv, python, and cameras, and I see that you decided not to use opencv/python/windows for your purpose. imwrite() function − This is the function for writing an image. I need you to use OpenCV 3. copy — Shallow and deep copy operations¶. I want to make a rectangle in the middle of a video stream I was able to do it with a static image using the PIL library CODE: from PIL import Image, ImageDr…. If just using Matplotlib,. pyd in the folder "C:\opencv\build\python\2. We use OpenCV’s imread method to read the image file and then we create a copy of it to prevent us from accidentally modifying the original image. Python Project Examples for Gender and Age Detection. This article talks about a couple of methods that you can use with Python and OpenCV to explore We use OpenCV's imread method to read the image file and then we create a copy of it to prevent. OpenCV Wrapper is a simpler wrapper for the opencv-python package. We will also explain some fundamental properties of Fourier transform. This tutorial explains Seamless Cloning using OpenCV by showing an image and video example. resize and get hands-on with examples provided for most of the scenarios encountered in regular usage. watermark image in python using openCV. This way, the convolution can be performed over the needed pixels without problems (the extra padding is cut after the operation is done). PhD, Author, Entrepreneur. Image processing is done in software by applying numerical operations on the image data. Installation and Usage. OpenCV comes with a function cv2. Extracting a ROI (Region of Interest) using OpenCV and Python is not so hard as it could may sound. You then need to detect the left mouse button down using the cv2. Are you interested in computer vision and image processing, but don't know where to start? My new 2nd edition of Practical Python and OpenCV + Case Studies is your guaranteed quick start guide to. So why is this? Why are individual pixel accesses in NumPy so slow? You see, NumPy operations are. copy an object from one image, and paste. Here, the tx and ty values are the X and Y translation values, that is, the image will be moved by X units towards the right, and by Y units downwards. Also how come the person know the exact position to copy the image of a ball inside of an image as for that you would have to be very accurate down to the pixel. we will se how to use cv2. first step we need understand whenever program start we should import opencv to python libary so that we use so. I have been working on SIFT based keypoint tracking algorithm and something happened on Reddit. In this sense, image moments are useful to describe some properties of the detected contours (for example, the center of mass of the object, or the area of the object, among others). Move into the tutorial bin directory and copy and paste this code into a file called test_vision_node. Here we will learn all about showing images in OpenCV. jpg', -1) to read and image, cv2. Find and Draw Contours using OpenCV | Python Contours are defined as the line joining all the points along the boundary of an image that are having the same intensity. Before starting. We will share code in both C++ and Python. That was back then. py or you can directly open fpt. 6; How to copy a image region using opencv in python? cv2. OpenCV is a library of cross platform programming functions aimed at real time Computer Vision. import cv2 import numpy as np import pprint image = cv2. We'll then devise a computer vision and image processing algorithm that can:. Posted by: admin November 25, copy region of interest. Copy-Move Detection on Digital Image using Python. We will also explain some fundamental properties of Fourier transform. Anyone have a good spot for a newbie to start. The Image module provides a class with the same name which is used to represent a PIL image. Python Project Examples for Gender and Age Detection. I am surprised how fast the detection is given the limited capacity of the Raspberry Pi (about 3 to 4 fps). So why is this? Why are individual pixel accesses in NumPy so slow? You see, NumPy operations are. So additions of the image is adding the numbers of two matrices. The code runs, but I get no image (only a grey window). Image processing is done in software by applying numerical operations on the image data. Most of the time, developers just need to use one kind of programming languages to read, write and process images with hundreds. first step we need understand whenever program start we should import opencv to python libary so that we use so. Note that I started reading the 3rd edition of the. Then crop out the face and save it. It was all C++ code and it was a little bit too hard for me. Images and OpenCV. It's used to process images, videos, and even live streams, but in this tutorial, we will process images only as a first step. Ask Question Make a shallow copy of the original image as follows: Browse other questions tagged python opencv or ask your own. I remember, my first time I installed OpenCV was trivial and complicated. What is Python, NumPy and OpenCV? Python is a programming language well suited for scientific computing. In this beginner-friendly course you will understand about computer vision, and will learn about its various applications across many industries. To resize an image, OpenCV provides cv2. py which compares two images and returns the percentage of similarity. We create a 'final' variable and keep the duplicate/copy of the main image. by Kardi Teknomo. How to watermark a video with image using opencv and c++. In my last post, I was able to create a disparity map from a stereo image. Python & Programming Projects for $30 - $250. I started reading it and then got busy with other things. copyTo() function binding is missing in Python but it is available in Java. imgcodecs provides methods to read and write images. I have a contour mask image and would like to copy only the contour object which is possible with the copyTo() function. Have you ever had to loop over an image pixel-by-pixel using Python and OpenCV? If so, you know that it’s a painfully slow operation even though images are internally represented by NumPy arrays. you must understand that OpenCv video and image frames are just numpy arrays that contain the values of all the pixels in. If I add two images, it will change color. I found the GetSubRect() function to copy or isolate part of the image but it does not appear to be available in python. OpenCV is a library of cross platform programming functions aimed at real time Computer Vision. __version__) 9. imwrite() function − This is the function for writing an image. How to copy frames read by videoCapture. Python Project Examples for Gender and Age Detection. I figured it. 7 Copy file cv2. OpenCV-Python Tutorials. You start by drawing a rectangle around the foreground image. 4) Now copy everything in the folder C:\opencv\build\python\x86\2. Image Classification in Python with Visual Bag of Words (VBoW) Part 1. shape: Height is at index 0, Width is at index 1; and number of channels at index 2. Image coordinates can be best examples by looking at the reference image below taken from the Practical Python and OpenCV tutorial book. py by downloading the source code: #import all the necessary packages import numpy as np import cv2 def order. Home › AI › Python Image Processing on Azure Databricks - Part 1, OpenCV Image Compare. x in a way different from the example I…. OpenCV provides a function called resize to achieve image scaling. If you have previous/other manually installed (= not installed via pip) version of OpenCV installed (e. Video Analysis using OpenCV-Python. As part of this course you will utilize Python, Watson AI, and OpenCV to process images and interact with image classification models. Now, we simply loop through all the pixels in the output image, addressing. I write about #DeepLearning, #ComputerVision, and #Python over at https://t. Consider the steps shown below −. The relevant OpenCV functions are as follows: Find contours in a binary image. It was developed by Fredrik Lundh and several other contributors. jpg', -1) to read and image, cv2. This book will help you design and develop production-grade Computer Vision projects tackling real. Detecting multiple bright spots in an image with Python and OpenCV Detecting multiple bright spots in an image with Python and OpenCV Normally when I do code-based tutorials on the PyImageSearch blog I follow a pretty standard template of: Explaining what the problem is and how we are going to solve it. Ask Question Make a shallow copy of the original image as follows: Browse other questions tagged python opencv or ask your own. OpenCV is a library of cross platform programming functions aimed at real time Computer Vision. I have openCV installed with python but all the tutorials I am finding expect you to know a bunch of prior knowledge. Gwyddion A data visualization and processing tool for scanning probe microscopy (SPM, i. Posted by: admin November 25, copy region of interest. We can reduce noises, control the brightness and color contrast. OpenCV officially provides both C++ and Python APIs for developers. image, imread, imshow, imwrite, Move, opencv, python, resize, 그리기, 이미지 이미지 입력 출력 도형 그리기는 빈 공간에 무엇인가를 새로 그리고 보여주는 기능이지만 이미지 입출력은 기존에 존재하는 이미지 파일을 작업하는 부분이라 간단하게 테스트 할 수 있습니다. If we do the same enlargement using cubic interpolation, we can see. It helps developers build complete projects in relation to image processing, motion detection, or image segmentation, among many others. How to Make a Copy of an Image in Python using the Numpy Module In this article, we show how to make a copy of an image in Python using the numpy module. In this blog post, you will learn how to extract email and phone number from a business card and save the output in a JSON file. There are two kinds of Image Pyramids. This post is to explain how fast array manipulation can be done in Numpy. NumPy is a Python library that simplifies doing numerical operations on. This video shows you how to open images, view them using the built-in Python and OpenCV tools, and then save the images back to a disk. EVENT_MOUSEMOVE event and at last you need to detect the left mouse button released. Then crop out the face and save it. This is a short tutorial about using Tkinter, the default Python GUI library, with OpenCV. Copy files from PC to Rpi When I used opencv on the Pi I just ran sudo apt-get install opencv-python and did a whole host of. Satya Mallick is raising funds for AI Courses by OpenCV. The code runs, but I get no image (only a grey window). However, if you want to use OpenCV Python APIs with an extended C/C++ library, it will be tricky to pass the data. Create a Python script to control Webcam. This tutorial explains Seamless Cloning using OpenCV by showing an image and video example. It was developed by Fredrik Lundh and several other contributors. How cool would it be to have your computer recognize the emotion on your face?. This way, the convolution can be performed over the needed pixels without problems (the extra padding is cut after the operation is done). OpenCV is a highly optimized library with focus on real-time applications. OpenCV Tutorial: A Guide to Learn OpenCV. Not all paintings are of people. 0 & Python – Drawing shapes and text on images; The following examples are all run on Raspberry Pi 3 Model B. I'm new to windows, open-cv, python, and cameras, and I see that you decided not to use opencv/python/windows for your purpose. (Thanks @HKoshdel point it out) Use Hough Transformation to find the curve lines in your image. jpg’, -1) to read and image, cv2. I started reading it and then got busy with other things. Opencv Python image processing based tutorial, to turn from the network, the main Python for image enhancement, transformation, matching, contour, video processing, segmentation, tracking, projection and so on Key Technologies of the primary tutorial. One of the basic operations of OpenCV is the ability to draw over the image. However, if you want to use OpenCV Python APIs with an extended C/C++ library, it will be tricky to pass the data. The first step in any image processing stuff is to load and read the image for further prepossessing. Here are the examples − How to read copy and paste an image using Java (read/write). imread() Store all the images into a list. EVENT_LBUTTONDOWN event, then continuously locate the position of the mouse using the cv2. Is there an up-to-date documentation of the python interface to opencv?. Ask Question Make a shallow copy of the original image as follows: Browse other questions tagged python opencv or ask your own. But the quality of the resulting image will be higher. Flip Image OpenCV Python October 7, 2016 Admin 2 Comments OpenCV provides the flip() function which allows for flipping an image or video frame horizontally, vertically, or both. The guide is based on the official OpenCV Installation Guide on Debian and Ubuntu. each sample consists of a grayscale image of size 28×28. Using Python and OpenCV, we can detect faces in paintings. imread(‘lena. We will learn about three basic functions in OpenCV imread, imshow and imwrite. Recognize text from image with Python + OpenCV + OCR Get link; Extract opencv to a folder Install Python 2. OpenCV is a library of cross platform programming functions aimed at real time Computer Vision. But what if we want to process the image files without using any external library like OpenCV. Along with "numpy" and "matplot" OpenCV provides easy and strong facilities for image processing. It's fairly common to want to mark detected objects in some way, so we the humans can easily see if our programs are working as we might hope. An image moment can be seen as a weighted average of image pixel intensities, or a function of such moments, encoding some interesting properties. Python opencv can't read in default images. Posted by: admin November 25, copy region of interest. This course offers Python developers a detailed introduction to OpenCV 3, starting with installing and configuring your Mac, Windows, or Linux development environment along with Python 3. If I add two images, it will change color. 0 & Python – Drawing shapes and text on images; The following examples are all run on Raspberry Pi 3 Model B. copy file cv2. imshow(‘image’, img) to show an image in a window, cv2. Because it's a very popular computer vision package, and is capable of performing basic image processing to relatively complex image processing, OpenCV is often used together with more advanced packages like, TensorFlow or PyTorch for deep learning. OpenCV is a library full of great easy-to-use algorithms that can be used in 3D modeling, advanced image & video editing, tracking an identifying objects in videos, classifying people who are doing a certain action in videos, finding similar images from a dataset of images, and much more. But Matplotlib displays in RGB mode. In this section we will perform simple operations on images using OpenCV like opening images, drawing simple shapes on images and interacting with images through callbacks. cl How to Make a. NOTE: Are you interested in machine learning? You can get a copy of my TensorFlow machine learning book on Amazon by clicking HERE In my previous tutorial, Color Detection in Python with OpenCV, I discussed how you could filter out parts of an image by color. We know OpenCV is widely used to operate on images and has a wide spectrum of functions to do so. Let's start. My professor adsistance has give an assignment to me, about programming in Image Processing fields. One problem that naturally arises is how to handle the boundaries. copy an object from one image, and paste. In opencv using python - How can I create a new image that is simply a copy of an roi from another image? Surely there is something along the lines of Mat roi = img( Rect(x,y,w,h) ); for python. Providing code to solve the project. Using Python and OpenCV, we can detect faces in paintings. 이미지를 복제할 때, dst=src로 사용할 경우, 원본에도 영향을 미칩니다. OpenCV image to Matplotlib. ' To execute a valid command, run the below command but with your image's path. OpenCV-Python Tutorials. In this blog post, you will learn how to extract email and phone number from a business card and save the output in a JSON file. ui Design Form with The PushButton. Along with "numpy" and "matplot" OpenCV provides easy and strong facilities for image processing. You'll need to install it first, follow the instructions [1] and then you should be able to import the module. Once we scale down and if we rescale it to. 7\ ( most probably, there will be only one file cv2. ie, if first ball is cosidered, the region of that ball in mask image will be white, while all other shapes and backgrounds are blacked out. Let's see how can we do this. So for every shapes. You can easily do it by following Life2Coding's tutorial on YouTube: Linking OpenCV with Python 3. import cv2 print (cv2. Assignment statements in Python do not copy objects, they create bindings between a target and an object. Understanding image Histograms using OpenCV Python - python_opencv_histograms. Get savvy with OpenCV and actualize cool computer vision applications. Simple wrapper for opencv-python. threshold(img, 0, 255, cv2. We'll then devise a computer vision and image processing algorithm that can:. copy() is not necessary-but performance (speed) may benefit from. destroyAllWindows() to destroy all windows, cv2. In this part of the tutorial, we are going to focus on how to write the necessary code implementation for recording and training the face recognition program using OpenCV's LBPH Face recognizer. 1Node OpenCV Laboratory is a series of preinstalled Python libraries and the Blender extension kit. so file to site-packages on my Pi and it would work? I highly doubt it. How to copy frames read by videoCapture. How can we convolve them if the evaluated points are at the edge of the image? What most of OpenCV functions do is to copy a given image onto another slightly larger image and then automatically pads the boundary (by any of the methods explained in the sample code just below). / output nodes. Because it's a very popular computer vision package, and is capable of performing basic image processing to relatively complex image processing, OpenCV is often used together with more advanced packages like, TensorFlow or PyTorch for deep learning. It is free software and provides a rich API in C, C++, Java and Python. If you need to use parts of opencv that don't rely on these components, copy the following libraries from your container host into the container's \System32 folder (assuming 64-bit usage here, adjust accordingly). OpenCV Tutorial: A Guide to Learn OpenCV. In this blog, we will do a small project using OpenCV-Python where we will be creating video from image sequences. Once we scale down and if we rescale it to. Integrating Vision Toolkit (IVT), a fast and easy-to-use C++ library with an optional interface to OpenCV. Organizing information (eg, indexing databases of images and image sequences) 3. waitKey(0) to wait for a key event, cv2. Hello everyone I have a problem regarding python and openCV. It would be very good if you implemented this in node-opencv, this would make node-opencv almost a full-featured g. THRESH_BINARY_INV|cv2. (Thanks @HKoshdel point it out) Use Hough Transformation to find the curve lines in your image. If at any point you're stuck/lost/whatever, feel free to ask questions on the video and. OpenCV uses machine learning algorithms to search for faces within a picture. Face detection using OpenCV and Python: A beginner's guide. copy() to avoid unexpected results if using OpenCV. Most common image processing techniques have a solid mathematical background. Extracting a particular object from image using OpenCV can be done very easily. shape: Height is at index 0, Width is at index 1; and number of channels at index 2. You can click on image to enlarge: I have placed an image named “ironman. Or actually not madness, but OpenCV and Python. The guide is based on the official OpenCV Installation Guide on Debian and Ubuntu. A practical, project-based tutorial for Python developers and hobbyists who want to get started with computer vision with OpenCV and Python. Open a terminal session and make starting the virtual environment where you installed OpenCV 3. 4+ Python 3. To learn detailed image processing fundamentals, visit this video. py or you can directly open fpt. Consider the steps shown below −. Source image: So, we begin to import our modules and the source image: import cv2 import numpy as np #import image image = cv2. OpenCV Python Computer Vision. Using OpenCV, you can read an image and store it in a matrix. The fact-checkers, whose work is more and more important for those who prefer facts over lies, police the line between fact and falsehood on a day-to-day basis, and do a great job. Today, my small contribution is to pass along a very good overview that reflects on one of Trump’s favorite overarching falsehoods. Namely: Trump describes an America in which everything was going down the tubes under  Obama, which is why we needed Trump to make America great again. And he claims that this project has come to fruition, with America setting records for prosperity under his leadership and guidance. “Obama bad; Trump good” is pretty much his analysis in all areas and measurement of U.S. activity, especially economically. Even if this were true, it would reflect poorly on Trump’s character, but it has the added problem of being false, a big lie made up of many small ones. Personally, I don’t assume that all economic measurements directly reflect the leadership of whoever occupies the Oval Office, nor am I smart enough to figure out what causes what in the economy. But the idea that presidents get the credit or the blame for the economy during their tenure is a political fact of life. Trump, in his adorable, immodest mendacity, not only claims credit for everything good that happens in the economy, but tells people, literally and specifically, that they have to vote for him even if they hate him, because without his guidance, their 401(k) accounts “will go down the tubes.” That would be offensive even if it were true, but it is utterly false. The stock market has been on a 10-year run of steady gains that began in 2009, the year Barack Obama was inaugurated. But why would anyone care about that? It’s only an unarguable, stubborn fact. Still, speaking of facts, there are so many measurements and indicators of how the economy is doing, that those not committed to an honest investigation can find evidence for whatever they want to believe. Trump and his most committed followers want to believe that everything was terrible under Barack Obama and great under Trump. That’s baloney. Anyone who believes that believes something false. And a series of charts and graphs published Monday in the Washington Post and explained by Economics Correspondent Heather Long provides the data that tells the tale. The details are complicated. Click through to the link above and you’ll learn much. But the overview is pretty simply this: The U.S. economy had a major meltdown in the last year of the George W. Bush presidency. Again, I’m not smart enough to know how much of this was Bush’s “fault.” But he had been in office for six years when the trouble started. So, if it’s ever reasonable to hold a president accountable for the performance of the economy, the timeline is bad for Bush. GDP growth went negative. Job growth fell sharply and then went negative. Median household income shrank. The Dow Jones Industrial Average dropped by more than 5,000 points! U.S. manufacturing output plunged, as did average home values, as did average hourly wages, as did measures of consumer confidence and most other indicators of economic health. (Backup for that is contained in the Post piece I linked to above.) Barack Obama inherited that mess of falling numbers, which continued during his first year in office, 2009, as he put in place policies designed to turn it around. By 2010, Obama’s second year, pretty much all of the negative numbers had turned positive. By the time Obama was up for reelection in 2012, all of them were headed in the right direction, which is certainly among the reasons voters gave him a second term by a solid (not landslide) margin. Basically, all of those good numbers continued throughout the second Obama term. The U.S. GDP, probably the single best measure of how the economy is doing, grew by 2.9 percent in 2015, which was Obama’s seventh year in office and was the best GDP growth number since before the crash of the late Bush years. GDP growth slowed to 1.6 percent in 2016, which may have been among the indicators that supported Trump’s campaign-year argument that everything was going to hell and only he could fix it. During the first year of Trump, GDP growth grew to 2.4 percent, which is decent but not great and anyway, a reasonable person would acknowledge that — to the degree that economic performance is to the credit or blame of the president — the performance in the first year of a new president is a mixture of the old and new policies. In Trump’s second year, 2018, the GDP grew 2.9 percent, equaling Obama’s best year, and so far in 2019, the growth rate has fallen to 2.1 percent, a mediocre number and a decline for which Trump presumably accepts no responsibility and blames either Nancy Pelosi, Ilhan Omar or, if he can swing it, Barack Obama. I suppose it’s natural for a president to want to take credit for everything good that happens on his (or someday her) watch, but not the blame for anything bad. Trump is more blatant about this than most. If we judge by his bad but remarkably steady approval ratings (today, according to the average maintained by 538.com, it’s 41.9 approval/ 53.7 disapproval) the pretty-good economy is not winning him new supporters, nor is his constant exaggeration of his accomplishments costing him many old ones). I already offered it above, but the full Washington Post workup of these numbers, and commentary/explanation by economics correspondent Heather Long, are here. On a related matter, if you care about what used to be called fiscal conservatism, which is the belief that federal debt and deficit matter, here’s a New York Times analysis, based on Congressional Budget Office data, suggesting that the annual budget deficit (that’s the amount the government borrows every year reflecting that amount by which federal spending exceeds revenues) which fell steadily during the Obama years, from a peak of $1.4 trillion at the beginning of the Obama administration, to $585 billion in 2016 (Obama’s last year in office), will be back up to $960 billion this fiscal year, and back over $1 trillion in 2020. (Here’s the New York Times piece detailing those numbers.) Trump is currently floating various tax cuts for the rich and the poor that will presumably worsen those projections, if passed. As the Times piece reported: