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Category: tutorial

How to easily image search with python

image search with python

This is the second time that I’m writing on how to do image search with python. The first blog post. That I wrote about the subject got a lot of interest and even today I regularly get people commenting on it or coming to the github repo asking for help. So I figured it was time for a refresher.

Python imagesearch is now a pip-eable package

I have put a bit of work to put the library as a package. In order to allow you to just pip the library. This is a much better solution than me saying nonsense like “copy the file in your project”. Now it is as easy as doing :

pip3 install python-imageseach-drov0

The above will probably fail or you won’t be able to use the library as you need extra packages depending on your os :

Linux

sudo pip3 install python3-xlib
sudo apt-get install -y scrot -y
sudo apt-get install -y python3-tk
sudo apt-get install -y python3-dev
sudo apt-get install -y python3-opencv


MacOs

brew install opencv
pip3 install -U pyobjc-core
pip3 install -U pyobjc

Windows

No extra installation steps needed 🙂

Quick start

The simplest example to do image search with python is this:

from python_imagesearch.imagesearch import imagesearch

pos = imagesearch("./github.png")
if pos[0] != -1:
print("position : ", pos[0], pos[1])
else:
print("image not found")

Simply search for one occurrence of the image “github.png” on the screen and print its x/y position

Other functions

imagesearcharea

Performs an image search on a specific rectangle of the screen, it’s very useful to speed up searches as there will be less screen space to search.
It’s also useful to focus the search only on a specific part of the screen to reduce the chances of having a false positive.

pos = imagesearcharea("./github.png", 0, 0, 800, 600)
if pos[0] != -1:
    print("position : ", pos[0], pos[1])
else:
    print("image not found")

Input:
image : path to the image file (see opencv imread for supported types)
precision : the higher, the lesser tolerant and fewer false positives are found default is 0.8
im : a PIL image, usefull if you intend to search the same unchanging region for several elements

Output:
the top left corner coordinates of the element if found as an array [x,y] or [-1,-1] if not

region_grabber

Very useful to optimize imagesearcharea or imagesearch calls, by getting an already processed image you can perform multiple searches on it with great speed gains. Here’s an example

# non -optimized way :
time1 = time.clock()
for i in range(10):
    imagesearcharea("./github.png", 0, 0, 800, 600)
    imagesearcharea("./panda.png", 0, 0, 800, 600)
print(str(time.clock() - time1) + " seconds (non optimized)")

# optimized way :

time1 = time.clock()
im = region_grabber((0, 0, 800, 600))
for i in range(10):
    imagesearcharea("./github.png", 0, 0, 800, 600, 0.8, im)
    imagesearcharea("./panda.png", 0, 0, 800, 600, 0.8, im)
print(str(time.clock() - time1) + " seconds (optimized)")

# sample output :

# 1.6233619831305721 seconds (non optimized)
# 0.4075934110084374 seconds (optimized)

Input: a tuple containing the 4 coordinates of the region to capture tuple should contain coordinates of : topx, topy, bottomx, bottomy

Output: a PIL image of the area selected.

imagesearch_loop

Searches for an image on screen continuously until it’s found, useful to make a waiting script until x image appears. For instance waiting for the end of a loading screen.

from python_imagesearch.imagesearch import imagesearch_loop

pos = imagesearch_loop("./github.png", 1)
print("position : ", pos[0], pos[1])

Input:
image : path to the image file (see opencv imread for supported types)
time : Waiting time after failing to find the image (seconds)
precision : the higher, the lesser tolerant and fewer false positives are found default is 0.8

Output:
the top left corner coordinates of the element if found as an array [x,y]

imagesearch_numLoop

Searches for an image on screen continuously until it’s found or max number of samples reached.

from python_imagesearch.imagesearch import imagesearch_numLoop

pos = imagesearch_numLoop("./github.png", 1, 50)
if pos[0] != -1:
print("position : ", pos[0], pos[1])
else:
print("image not found")

Input:
image : path to the image file (see opencv imread for supported types)
time : Waiting time after failing to find the image
maxSamples: maximum number of samples before function times out.
precision : the higher, the lesser tolerant and fewer false positives are found default is 0.8

Output: the top left corner coordinates of the element if found as an array [x,y]

imagesearch_region_loop

Very similar to imagesearch_loop except it works with regions

from python_imagesearch.imagesearch import imagesearch_region_loop

pos = imagesearch_region_loop("./github.png", 1, 0, 0, 800, 600)
print("position : ", pos[0], pos[1])

Input:
image : path to the image file (see opencv imread for supported types)
time : Waiting time after failing to find the image
x1 : top left x value
y1 : top left y value
x2 : bottom right x value
y2 : bottom right y value
precision : the higher, the lesser tolerant and fewer false positives are found default is 0.8


Output:
the top left corner coordinates of the element as an array [x,y]

imagesearch_count

Counts how many occurrences there are of the image there are on the screen.

from python_imagesearch.imagesearch import imagesearch_count

count = imagesearch_count("./github.png")
print(count)

Input:
image : path to the target image file (see opencv imread for supported types)
precision : the higher, the lesser tolerant and fewer false positives are found default is 0.9

Output:
the number of times a given image appears on the screen.
optionally an output image with all the occurances boxed with a red outline.

imagesearch_from_folder

Performs an imagesearch on all the images in a folder. This function was done by kadusalles

from python_imagesearch.imagesearch import imagesearch_count

results = str(imagesearch_from_folder('./', 0.8))
print(results)

Input:
path: to the folder containing the images (supported image types are jpg, gif, png and jpeg)
precision : the higher, the lesser tolerant and fewer false positives are found default is 0.9

Output:
A dictionnary with all the images where the key is the image path and the value is it’s position

Conclusion

And that’s about it ! Now you should be able to easily perform Image search with python. If you are interested in the actual code or want to contribute feel free to head on over to the github repository : https://github.com/drov0/python-imagesearch and if you liked my article, come to see more at https://brokencode.io

How to use local go modules with golang with examples

Image result for golang modules"

When coding I like to put everything inside of folders depending on what they do. I almost always got specific directories for utils, parser, etc. So here’s a complete guide on how to use local go modules with golang

When I started using go modules I was migrating a project from dep which followed this architecture. I had an utils directory, and another directory which handled all parsing for my data input into structs. But then I ended up needing functions from the utils directory. I was stuck and couldn’t find how to make directories importable everywhere in the project (like dep used to). Because relative imports are a nightmare with go modules (removing the gopath has a toll after all).

So after quite a bit of fuming and searching all of the web for a solution that is elegant and not something like some crazy relative imports, I found this solution and since I struggled so much to find the solution I figured that I would share it with you all.

The example project

Here’s our example project directory structure :
├── go.mod
├── hello
│   ├── go.mod
│   └── hello.go
├── main.go
├── README.md
└── utils
├── go.mod
└── multigreet.go

You can also see the example code on my github repository here : https://github.com/drov0/GolangLocalModulesExample

The code is relatively straightforward : I have two directories, hello and utils that I want to import from the main.go file. And when things get a little tricky is that I want to import the hello directory inside of the utils directory.

The code for the hello.go file that we want to import is this super complicated function :

package hello

func Hello(name string) string {
   return "hello " + name
}

The code for the addAndGreet.go file is a bit more complex :

package utils

import (
"example.org/hello"
"strconv"
)

func AddAndGreet(name string, a, b int) string {
return hello.Hello(name) + " " + strconv.Itoa(a + b)
}

Notice how we are importing "example.org/hello".

Finally here’s the main.go file :

package main

import (
"example.org/hello"
"example.org/utils"
"fmt"
)

func main() {
fmt.Println(hello.Hello("martin"))
fmt.Println(utils.AddAndGreet("martin", 2, 3))
}

Obviously the modules example.org/hello or example.org/utils do not exist so these imports make zero sense to our compiler so let’s help him out a bit

Importing local modules in main.go

So first we simply have to convert all of our directories into go modules. For that we need to add a go.mod at the root of every directories.
Then inside of that go.mod give them whatever name that we want as module name. but bear in mind that it has to be an url. In my example I put this:

module example.org/hello in the go.mod for the hello directory
module example.org/utils in the go.mod for the utils directory

The import makes a bit more sense now huh ? but we are not done yet.

The replace keyword

This is where the magic happens, go.mod files have a few keywords that can be very useful, one of them is replace what replace does is that it takes a module path (eg : example.org/hello) and replaces it with a direct or relative path.

here’s the syntax for the replace keyword :

replace url.com/of/the/module => /direct/path/to/files

Note that replace also works with relative paths.

The main go.mod

module example.com/localmodexample

go 1.13

require (
example.org/hello v0.0.0
example.org/utils v0.0.0

)

replace (
example.org/hello => ./hello
example.org/utils => ./utils
)

Usuall go module dependencies work with versions, so to use local go modules with golang you have to set v0.0.0

Finally after the require, I just tell the compiler that those urls are local and can be found in the same directory under ./hello and ./utils. The great thing about this main go.mod file is that now even the utils module will know where to find the hello module because the url have been replaced.

Conclusion

And that’s all you need to know to use local go modules with golang. Hopefully this will save you all the hours I put into it. Keep in mind that you can find the complete code on my github : https://github.com/drov0/GolangLocalModulesExample

I know it’s been a while since my last post but I got quite busy. But now I should be able to make posts more often on this blog.