An image annotation tool for Linux

Linux offers various image manipulation tools to help you edit images. Some of the most popular include GIMP, Pinta, and Krita. However, while these tools offer tons of features and meet the needs of most users, many of them have a steep learning curve, and the added complexity of the features makes them overkill for editing needs and basic image annotation.

For such use cases, you instead need an annotation tool, like Annotator, which simplifies image manipulation and allows you to annotate images with just a few clicks.

Follow the steps for installing and using Annotator on Linux.


What is an annotator?

Annotator is a free and open-source image manipulation tool for Linux that lets you annotate your images with text, images, shapes, and other visual elements. It has a clean interface and is easy to use.

Moreover, you can also use Annotator to crop or resize images and export them to different image formats.

Annotator Features

Annotator comes with a wide range of features. Here is all you can do with it on your machine:

  • Add text, shapes, stickers and other captions to highlight something important in an image
  • Dim the parts containing sensitive information
  • Add magnifying glasses to zoom in on details
  • Change colors, line weights and font properties
  • Export images in several formats: JPEG, PNG, TIFF, BMP, PDF and SVG

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How to Install Annotator on Linux

Annotator is available on all major Linux distributions. Here’s a breakdown of instructions for getting it up and running on your Linux machine.

On Ubuntu and its derivatives, you can install Annotator by running the following commands in the terminal:

sudo add-apt-repository ppa:ubuntuhandbook1/annotator
sudo apt update
sudo apt install com.github.phase1geo.annotator

On Arch Linux, you can download Annotator from Arch User Repository as follows:

sudo yay -S annotator

If you are using another Linux distribution, you can install Annotator via Flatpak. To do this, first ensure that Flatpak is installed on your system by opening the terminal and running:

flatpak 

If this returns a version number, it means you have Flatpak on your system. Otherwise, you don’t, and therefore you have to install it first. See our Flatpak guide on how to install it on your Linux computer.

Once Flatpak is installed, use the following command to install Annotator:

flatpak install com.github.phase1geo.annotator

How to use the annotator

To get started, start by launching the Annotator application on your computer. The easiest way to do this is to open the application menu, search for Annotatorand run it.

Annotator will now present you with a welcome screen with two options: Open image from file and Paste image from clipboard. These two are quite self-explanatory and you can choose one according to your needs.

If you click on the first one, you will need to select an image file from your machine’s local storage on the next screen. On the other hand, clicking on the latter will automatically paste the copied image from your clipboard into Annotator.

Either way, you’ll be taken to an editing window, with all the annotation and editing tools tiled on the taskbar.


We have listed the instructions for using these Annotator tools so that you can get familiar with them.

1. Add an arrow

Most image manipulation tools, including Annotator, allow you to add arrows to your image to help draw the viewer’s attention to something important.

Click on the Arrow (the first toolbar button) to add an arrow to your image. Then click and drag the arrow where you want on the image.

If you want to change its size, press the arrow and drag along its edges inward or outward. Similarly, to change its color, tap on it, click on the shape color (second to last on the toolbar) and choose a color.

2. Add shapes

Similar to adding arrows, you can also use other shapes such as rectangles, circles, lines, stars, etc., to add captions to your images. To use them in Annotator, click the Shapes button (next to the Arrow button) in the toolbar, then tap a shape from the available options.

Once you’ve added the shape, you can change its outline color, just like you did with the arrows. If you used a filled shape, you can also change its color.

Likewise, there is an option to add transparency to the shape as well, which you can do by toggling the Add transparency possibility in the shape color menu—much like a highlighter.

Finally, Annotator also lets you change the border of these callout shapes. To do this, click on the shape border in the toolbar, and from there change the border width and dash pattern as desired.

3. Add text

Adding text is a useful technique for adding important information or missing context to your images. In Annotator, you can add a block of text by clicking on the Text button (with the letter a) to display all text-related options, then type your text in the window.

One cool feature of Annotator is the multiple text formatting options it offers. This allows you to format the text as code block, subscript, superscript, bold, italic, strikethrough, or underline.

Also, if you want to change the font style, click the Font properties button (the last option on the toolbar). Here you can search for your favorite font or click on the listed ones to set the font family.

Likewise, you can use the Cut slider to adjust font size. Either way, Annotator will give you a preview of your changes in the small preview window at the bottom.

4. Zoom in on important details

Annotator also comes with a magnifying glass option, which lets you zoom in on small details of your image, so that you can highlight it for its viewers.

If you want to use the magnifying glass, click on the Magnifying glass icon (with a plus sign). This will place the magnifying glass over your image. Click on the magnifying glass to move it over the detail you wish to enlarge.

Annotator also has a few more options for its magnifying glass – three, to be precise – which are highlighted with tiny squares. Of these, the top one lets you control the amount of zoom, the middle one lets you change the magnification area, and the bottom one helps you change the magnifier size.

5. Blur sensitive details

When you have sensitive information in an image, blurring comes across as a useful option to hide such things.

Click on the fall out in the toolbar to invoke the blur tool. After that, use the extensions along its edges to resize the blur area.

We think Annotator’s blur strength is quite weak and would have liked a blur intensity adjuster on the tool.

6. Crop an image

Cropping is a fairly common editing feature on most image manipulation tools. Annotator’s crop feature allows you to crop out unnecessary elements/parts of an image.

To use it, first click on the Crop the image button to display the crop tool. Next, use the extensions along the edges to select the area you want to crop and press Walk in to crop it.

7. Resize an image

Sometimes you may want images in a particular size. Annotator supports you in such situations, thanks to its built-in image resizer, which allows you to resize images with a custom size.

To use this resizer, click on the Resize image in the toolbar, and it will bring up the resizing window.

Here, enter the desired width and height for the image, then click the Scale proportionality (with the padlock icon) to keep the aspect ratio.

While you’re here, you can also set margins or change the unit from pixels to percentage. Once everything is set, click on the Resize button to resize the image.


8. Export the final image

After modifying your image, you will need to export it and save it locally on your system. Annotator offers a bunch of export options to help you with the same.

To access these options, click the Export Image in the menu bar and select an option from the list.

Annotator will now ask you to name this file and also choose the directory where you want to save it.

Perform these steps and press Export to save the edited image.

All essential annotation features under one roof

If you are someone who needs to edit or annotate a lot of images on your Linux machine, Annotator is probably one of the best image manipulation tools. It is absolutely free to use, offers all the essential features you would need, and is easy to use.

If you’re not a fan of standalone software, you can edit your images using the web browser with these free online image editing tools.


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