How to Make and Read From QR Codes with Python! OpenCV and PyQRCode Tutorial

what's up you guys welcome back to the channel in today's video I'm going to show you how to generate and read from QR codes using the pi QR code and CV2 modules in Python [Music] all right so QR codes obviously incredibly common incredibly versatile they're essentially just two-dimensional barcodes but they can tell you basically any string of text because they're they can vary in size based on how many characters you need in the string and obviously they're all over the place right now particularly because every restaurant and every other place in the world start using a QR code instead of a menu in the last two three years because of covid but they're just all around something that's kind of here to stay for scanning technology and it can be really useful to know how to create those in Python and also how to read those in Python so we're going to do both in this video and we're going to start with creating them and to do that we're going to use a module called import Pi QR code and to get this if you don't have it already you just need to do pip install Pi QR code in your terminal window mine's already installed but just know that you should run this if you need to okay so I'll leave it there in case you need to come back to that in the video and also some of you may find that your computer does not already know how to save something as a PNG file that might not be intrinsic to it so you may need to add this line of code you may need to do pip install Pi PNG and then you may need um import PNG just like this my computer does not require this so I could have it in my code it's just not going to add anything but I will say if you're getting an error message that like PNG is not a recognized format or anything in a in a minute when we get to it know that you might need to come back and add these lines of code okay but so now let's go ahead and do the important parts which is what data do we want to save as the QR code and initially I'm just going to make this a plain text string okay so literally no URLs no fancy anything it's not pointing you anywhere particularly particular on the Internet it's just a string of text because at its root level that is all a QR code really needs so then we're going to save that string of text as a QR code using the pi QR code module and then dot create and then in here we're just going to put the data that we want it to turn in into a QR code and then we're going to create and save QR code AS image files okay and first we'll do it as a PNG so we're going to take that URL and do dot PNG and then give it a name and I'm just going to do my qr1.png that's going to be the name of this image that I want to create and then this scale variable because by default Pi QR code is going to kind of give you the smallest possible QR code it could generate so you can just use this scale variable to make it a little bigger of an image that can make it a little bit easier to read a little bit easier to detect on mobile I like scale equals six but that's something you can just play around with as you want and this is actually all the code we need to create our first QR code so if I run this and I open this up then if you were to pause this video right now and look at this QR code with your phone or hopefully you're coding along and you've done the same thing hover over this and your phone is going to scan and detect this barcode as this QR code as plain text string or at least it better okay but now let's do something a little more fun let's say you found a a cool image online that you want to share with people so you just wanted to leave kind of a URL link to that online image and I promise if you scan this image it's not going to take you to anything nefarious or bad this is a very harmless image that it's going to take you to but now I'm not even going to rename it I'm just going to overwrite this QR code with a new QR code so like if I were to run this again now it's going to run and this QR code just got changed to the new one and you can kind of see immediately how this simple uh like three lines of code really is all you need to take you all the way to a URL on the internet anywhere that you choose now let's take a look at kind of the flip side of this which is what if I have an image that has a QR code in it and I want my python code to figure out what that QR code's text is to do that we need another module which is going to be called CV2 and if you don't have CV2 then you need to run pip install and then this module is called opencv Dash python when you install it using pip but then it's just CV2 when you import it but this is going to be kind of the computer vision module that is going to take an image recognize a QR code and pull the text out of it and so to do that we're going to create a few new variables we're going to create one that's going to be just what image are we reading it out of and so now let's say my QR and let's do a new one for this let's say my qr2.png and let's grab a new link let's just grab this one okay and so let's say we've got a new length and we're going to create a new image my qr2.png and then in this image equals CV2 and then uh it's at I'm sorry it's got to be I am read and then we put the address of the file in quotes like this okay so now we're saying image is equal to our CV2 module dot IM read image read and then just the text file and you can see like or the image file and you can see we don't even have this image yet but our code is going to create it when we run it again and then this CV2 code is going to go into the image and figure out what that QR code actually means so it may seem a little silly because obviously what that QR code's text is going to correspond to is this link that we're going to pass into it um but this is a really just useful way of showing how we detect QR codes and images using the CV2 module so let's set up a detector variable that I'll call DET and it's just going to be QR code detector like that and you don't need to put anything in those parentheses and then by default when we detect and decode an image it's going to pass three things back the actual value uh the points where it detected it at and then some state code information you just need to be prepared to receive these three arguments because that's the standard that the module passes back but for now really all that we need is uh we want to see what the value is just to verify that this is working okay and so to do that we're just going to print out the vowel that we get back and so in our terminal window when we run this we should see a couple things we should get myqr2.png because we're creating it right here and then we should also get down in our uh terminal window as an output the text of the link that we had right there okay so let's go ahead and run it and you can see we get my qr2 but then we also get down in here we get this URL and if you're a little skeptical right now and you say like oh big deal the URL is right here well let's just change this to my qr1.png where now the text is nowhere to be found right that image of a cool cat which if you didn't look at qr1 you should go back and look at qr1 but now if I run this again you'll see it's able to pick apart that image even though we don't have that text stored anywhere in this program anymore so it's just reading this QR code and it's able to turn it back into text okay so this is obviously the uh this is obviously some pretty simple code and a very basic and efficient way to both create QR codes and read QR codes back and one thing I'll add is that you can use URL dot to save it as a few different file types probably the next most common if you don't want to save it as a PNG would be saving it as an SVG file which essentially isn't going to have a background that's really the biggest difference but it still has that scale variable it still runs the exact same way and so if I were to run that now you'll just see I also get a my qr2.svg and that's just it's got some um extra like code behind it and it doesn't have a background so that's just the kind of difference between those two but I hope you found this useful if you have any questions about how to use this application and go a little bit further be sure to let me know about in the code in the comments below I've got code on the brain um but I hope you found this useful be sure to scan this barcode figure out what to do once you get there and I really hope you guys enjoyed this video Happy New Year to everybody happy 2023 hope it's an awesome year we're all going to learn tons of new stuff and thank you guys so much for watching good luck with your code thanks bye