This documentation targets SikuliX version 2.0.5 and later.
Docs for previous versions you can find here

Automate what you see on a computer monitor

SikuliX is a WYSIWYS-Tool: What You See Is What You Script.

When to use SikuliX?#

  • You want to automate repetitive tasks in daily usage of applications or web pages
  • While playing games you want to automate some aspects
  • In IT administration you want to automate admin tasks
  • Developing an application you want to do visual testing

... and you do not have the adequate tools at hand.

What is a visual workflow?#

Something like that we do every day sitting in front of our PC:

  • we want to achieve something
  • we use an application for that (e.g. the browser to access web content)
  • the following steps might be repeated several times
    • we click some buttons, links or other visuals
    • we wait for the app to react and show the expected result on the screen
    • we fill in some text somewhere and press some keys like TAB or ENTER
    • we might have to click some button to go on
    • we wait some more for some expected reaction or result

This is a visual workflow.

Visual Automation#

So again taking the above workflow, now using SikuliX commands:

openApp(someApp) # we use an application someApp
click(imageButton.png) # we click some button
wait(imageExpected.png) # we wait for the app to react and show the expected result on the screen
type(“some text”); type(Key.ENTER) # we fill in some text and press ENTER
wait(imageExpected1) # again we wait for some expected reaction or result
click(…) # we click …

Using the SikuliX IDE, you can setup and maintain your visual workflows including capturing and organizing the needed images. Besides SikuliX's basic commands, you do not need any programming or scripting knowledge. Only when you would like to optimize, repeat a more than basic linear workflow, you have to dive deeper into the scripting language of your choice (currently supported in the IDE: Python, and Ruby).

Visual Testing#

In software testing sooner or later testers want to check some visual content against their expectation. This might be the presentation of GUI elements on the screen or the visual content of some part of the screen.

SikuliX can be integrated in various ways into such testing environments, either on the scripting level or using the Java based API (where the SikuliX features are implemented). Prominent examples for this approach are RobotFramework or Cucumber.

A combination of GUI aware tools and SikuliX already exists (e.g. together with Selenium for web apps).

  • SikuliX needs a real screen running the application under test
  • or at least some equivalent virtual solution
  • SikuliX is only available on PCs/Workstations running Windows, Mac or Linux
  • and needs a Java version 8+

How SikuliX handles images#

To use images with the features of SikuliX like click(someImage), you need to store these images as image files preferably in the PNG format someImage.png somewhere on the file system or the net.

An image in this sense is some rectangular pixel area taken from the screen. With SikuliX we use the phrase capture or make a screenshot as the process of getting the image from the screen and saving it in an image file for later use in the image search process.

Capturing is supported by the IDE or programmatically via the respective SikuliX features. You might use any capture tool instead to get your images (as mentioned preferably in PNG format).

How SikuliX loads images at runtime:

  • bundle path: the images are stored together with the script file (.py for Python, .rb for Ruby) in a folder named someScript.sikuli or someScript, where the scriptfile must be named the same as the folder (e.g. This all is automatically assured, when working with the SikuliX IDE.
  • image path: additionally SikuliX supports a list of places as an image path. Possible places are folders in the file system, folders in a jar-file and folders somewhere in the net. The bundle path always is the first entry. There are functions available to manage your own image path. When an image has to be loaded (exception: the absolute path is given), the places are sequentially checked for the existence of the image. The first matching place wins.
naming scheme

It is strongly recommended, to have a naming scheme for the image files and to not rely on the basic timestamped image file naming of the SikuliX IDE, which is basically for new users with little programming experience.

Finding images on the screen#

SikuliX uses the OpenCV package for finding an image on the screen.

The SikuliX feature is based on OpenCV’s method matchTemplate(), which is rather good explained on their example page. If you are not familiar with how it works, you should just have a look there and then come back to here and read further.

A basic feature in Sikulix is to wait for an image to appear in a given region:

# some top left part of the screen
aRegion = Region(0, 0, 500, 500)
# a png image file on the file system
# this is the image we want to look for in the given Region
aImage = “someImage.png”
# search and get the result
aMatch = aRegion.find(aImage)

The matchTemplate() expects an even sized or larger image (base), where the given image (target) should be searched. To prepare that, we internally make a screenshot (using Java Robot class) of the screen area defined by the given aRegion. This now is the base image and held in memory. The target image is also created as in memory image read form the image file. Both images then are converted to the needed OpenCV objects (CVMat).

Now we run the matchTemplate() function and get a matrix in the size of the base image, that contains for each pixel a similarity score for the target image compared pixel by pixel with it’s top left corner at this pixel location.

Sikulix implements a still-there-feature: before searching in the search region, it is first checked, whether the image is still in the same place as at the time of the last search (if the search region contains this last match). On success, this preflight operation usually takes some milliseconds, which speeds up workflows if they contain repetitive tasks with the same images.

Images showing up multiple times#

Not knowing the magic behind SikuliX’s search feature and the matchTemplate()function, people always wonder, why images showing up multiple times on the screen, are not found in some regular order (e.g. top left to bottom right). That this is not the case is caused by the implementation of the matchTemplate() function as some statistical numeric matrix calculations. So never expect SikuliX to return the top left appearance of a visual being more than once on the screen at time of search. The result is not predictable in this sense.

If you want to find a specific item of these multiple occurrences, you have to restrict the search region, so that only the one you are looking for is found.

For cases where this is not suitable or if you want to cycle through all appearances, we have the findAll() method, that returns a list of matches in decreasing result score order. You might work through this list according to their position on the screen by using their (x,y) top left corner coordinates. findAll internally evaluates the search result matrix, by repetitively looking for the next max value after having “switched off” some area around the last max.


In this list you can find words and phrases together with a short explanation, that are used in the context of SikuliX.

capture get a rectengular area of pixels from a monitor/screen, that can be stored as an image file