Free Python Lecture (Usage 6) - Image Processing (OpenCV)

Learning through diverse and fun projects
Image processing lecture using Python !

We meet every day in our daily lives
Image processing

Until recently, you had to scan a QR code to enter a restaurant, cafe, or other location. If you've ever tried QR check-in , you've already experienced image processing. If you hold the QR code displayed on your smartphone screen up to the device installed at the store entrance at an appropriate distance, it will automatically find the area and recognize the QR code.

(Source: https://www.emkat.com/products/emkat-temperature-screening-kiosk/)

You've probably tried measuring your body temperature at least once. By placing a tablet at a person's height and placing your face against it, it automatically detects the facial area, measures your body temperature, and reports whether it's normal.

Thus, image processing (computer vision) refers to the process of manipulating and analyzing images to extract useful information from them . It's used in a wide range of fields, beyond automatically detecting QR codes or human faces in images captured by cameras.

Face filters , everyone has tried something like this at least once, right?

(Source: https://play.google.com/store/apps/details?id=com.campmobile.snow&hl=ko)

Let me think of a few more:
For example, in an interview video to be broadcast on the news , you can find people's faces and mosaic only that part .
When I try to upload a video from a car black box , it automatically finds the license plate number of another car and mosaics it.
Oh, if it's a license plate, it's automatically recognized when entering and exiting a paid parking lot, right?

Recommending clothes that suit the user ,
Automatically putting clothes on body parts virtually ,
There is also fun content to check if someone is handsome or ugly... such as celebrities who look like them,
Recognize hand gestures to create something like the swoosh swoosh from Minority Report,
Automatically recognizes prohibited items when passing through security checkpoints, etc.

OpenCV

Image processing is done with the help of OpenCV .
OpenCV is an open source library for real-time image processing , and it's just the best 😊😊

In this lecture, we will learn one by one what can be done using OpenCV through various examples .

Example #1

We'll transform the original image in various ways.

Original image

swing

incision

Reduce size

Black and white effect

Blur

Does it look too easy? 😀
Let's delve a little deeper.

Example #2

I'm trying to get all the text parts in the book.

Original image

There is a picture of me reading a book.

grayscale conversion

First, to simplify the image, we convert it to grayscale. Black and white is much simpler than color, right?

threshold function

To get the text in the red area, you can use OpenCV's threshold function. However, the desired area isn't clearly visible. This is due to the coexistence of bright and dark areas caused by sunlight shadows. This is because the entire image is being applied as a reference.

Apply adaptive threshold

In such cases, how about applying something called adaptive thresholding? Isn't that much better? By dividing the image into smaller areas and processing them, you can clearly identify text in the book even when there are shading differences due to sunlight (or other lighting)!

After studying this far, you'll probably have all sorts of creative ideas floating around in your head, eager to put them into practice right away. Of course, you'll be able to implement them easily, too. You'll even be able to create playful programs like a mischievous child ✨

All of this would take about 5 hours and 40 minutes .

Well then, shall we start right now?

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