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OCR-powered screen-capture tool to capture information instead of images

Project description


OCR powered screen-capture tool to capture information instead of images.

Build passing License: GPLv3 Code style: black Coverage Status

Links: Releases | Changelog | Roadmap | Repo

Content: Introduction | Installation | Usage | Contribute | Credits


Basic usage:

  1. Launch normcap
  2. Select region on screen
  3. Retrieve recognized text in clipboard

normcap screencast


On Linux

1. Install dependencies:

## on Ubuntu/Debian:
sudo apt-get install tesseract-ocr xclip python3-tk python3-pil.imagetk

# on Arch:
sudo pacman -S tesseract tesseract-data-eng xclip tk python-pillow  

# on Fedora
sudo dnf install tesseract xclip python3-tkinter

2. Install normcap:

## on Ubuntu/Debian:
pip3 install normcap

# on Arch:
pip install normcap

(OR download and extract binary package from the latest release)

3. Execute ./normcap

On Windows (recommended method)

1. Download and extract binary package from the latest release (no installation required)

2. Execute normcap.exe

On Windows (alternative method)

1. Install "Tesseract", e.g. by using the installer provided by UB Mannheim

2. Set the environment variable TESSDATA_PREFIX to Tesseract's data folder, e.g.:

setx TESSDATA_PREFIX "C:\Program Files\Tesseract-OCR\tessdata"

3. Install tesserocr, e.g. by using the Windows specific wheel:

pip install

4. Run

pip install normcap

5. Execute normcap

On Mac

Attention! On Mac not everything works. Help needed!

1. Install dependencies:

brew install tesseract tesseract-lang

2. Install normcap:

pip install normcap

(OR download and extract binary package from the latest release)

3. Execute



  • After launching normcap press <esc> to abort and quit.

  • Before letting go the mouse button, press <space>-key to switch mode, as indicated by a symbol:

    • ☰ (raw): Copy detected text line by line, without further modification
    • ☶ (parse): Try to auto-detect type of text using magics and format the text accordingly, then copy
  • To download additional languages for Mac and Linux, check the official repository of your distribution for tesseract-languages. Packages names might vary.

  • The Windows release of normcap supports English and German out of the box. If you need additional languages, download the appropriate files from the tesseract repo and place them into the /normcap/tessdata/ folder.

  • normcap is intended to be executed on demand via keybinding or desktop shortcut. Therefore it doesn't occupy resources by running in the background, but it's startup is a bit slower.

  • By default normcap is "stateless": it copies recognized text to the systems clipboard, but doesn't save images or text on the disk. However, you can use the --path switch to store the images in any folder.

Command line options

normcap has no settings, just a set of command line arguments:

(normcap)dynobo@cioran:~$ normcap --help
usage: normcap [-h] [-v] [-m MODE] [-l LANG] [-c COLOR] [-p PATH]

OCR-powered screen-capture tool to capture information instead of images.

optional arguments:
  -h, --help               show this help message and exit
  -v, --verbose            print debug information to console (default: False)
  -m MODE, --mode MODE     startup mode [raw,parse] (default: parse)
  -l LANG, --lang LANG     languages for ocr, e.g. eng+deu (default: eng)
  -c COLOR, --color COLOR  set primary color for UI (default: #FF0000)
  -p PATH, --path PATH     set a path for storing images (default: None)


"Magics" are like addons providing automated functionality to intelligently detect and format the captured input.

First, every "magic" calculates a "score" to determine the likelihood of the magic being responsible for this type of text. Second, the "magic" which achieved the highest "score" take the necessary actions to "transform" the input text according to its type.

Currently implemented Magics:

Magic Score Transform
Single line Only single line is detected Trim unnecessary whitespace
Multi line Multi lines, but single Paragraph Separated by line break and trim each lined
Paragraph Multiple blocks of lines or multiple paragraphs Join every paragraph into single line, separate different paragraphs by empty line
E-Mail Number of chars in email addresses vs. overall chars Transform to comma separated list of email addresses
URL Number of chars in URLs vs. overall chars Transform to line-break separated URLs

Why "normcap"?



Setup Environment

Prerequisites are Python, Tesseract (incl. language data) and on Linux also XClip.

# Clone repository
git clone

# Change into project directory
cd normcap

# Install pipenv (if not already installed)
pip install pipenv

# Install project development incl. dependencies
pipenv install --dev

# Register pre-commit hook
pipenv run pre-commit install -t pre-commit

# Run normcap in pipenv environment
pipenv run python -m normcap

Design Principles

  • Multi-Platform
    Should work on on Linux, Mac & Windows.
  • Don't run as service
    As normcap is (hopefully) not used too often, it shouldn't consume resources in the background, even if it leads to a slower start-up time.
  • No network connection
    Everything should run locally without any network communication.
  • Avoid text in UI
    This just avoids translations ;-) And I think it is feasible in such an simple application.
  • Avoid configuration file or settings UI
    Focus on simplicity and core functionality.
  • Dependencies
    The less dependencies, the better. Of course I have to compromise, but I'm always open to suggestions on how to further reduce dependencies.
  • Chain of Responsibility as main design pattern
    See description on
  • Multi-Monitors
    Supports setups with two or more display.


This projected uses the following non-standard libraries:

And it depends on external software

Thanks to the maintainers of those nice libraries!



Project details

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