How To Install Nomacs on Debian 13

Nomacs stands out as one of the most versatile image viewers available for Linux systems. This free, open-source application brings professional-grade image viewing capabilities to Debian 13, combining speed with an impressive feature set that rivals many commercial alternatives. Whether you’re a photographer managing RAW files, a designer reviewing mockups, or simply someone who appreciates a powerful image viewer, installing Nomacs on Debian 13 opens up a world of possibilities.

This comprehensive guide walks through everything needed to successfully install Nomacs on Debian 13 (Trixie). Multiple installation methods are covered, from the straightforward APT package manager approach to advanced source compilation. Troubleshooting solutions, configuration tips, and usage guidance ensure a smooth experience from installation to daily operation.

Understanding Nomacs Image Viewer

Nomacs represents a lightweight yet powerful approach to image viewing across multiple platforms. Developed as a free and open-source project, this Qt-based application delivers functionality that professionals demand while remaining accessible to casual users. The viewer handles everything from standard JPEG files to professional RAW formats and even Adobe PSD documents.

What distinguishes Nomacs from alternatives like Gwenview or Eye of GNOME is its unique synchronization feature. Multiple Nomacs instances can display different images while synchronizing pan and zoom operations—invaluable for comparing similar photographs or design iterations. The application runs seamlessly on Windows, Linux, macOS, and FreeBSD, making it an excellent choice for users working across different operating systems.

The development community actively maintains Nomacs with regular updates. Recent versions have added AVIF image support and enhanced cropping features, demonstrating ongoing commitment to modern image format compatibility.

Core Features Worth Knowing

Nomacs packs impressive functionality into a relatively small footprint. The image viewer supports an extensive range of formats including RAW files from major camera manufacturers, making it particularly attractive to photographers. Basic editing tools cover brightness, contrast, saturation, hue, gamma correction, and exposure adjustments—sufficient for quick image tweaks without launching a full photo editor.

The frameless viewing mode maximizes screen real estate by hiding window decorations, ideal for presentations or detailed image examination. Thumbnail previews appear in a customizable panel, allowing rapid navigation through image collections. EXIF metadata display reveals camera settings, timestamps, and other embedded information directly within the interface.

Advanced features include batch processing for applying operations to multiple images, pseudo color functions for scientific or technical imaging, and side-by-side comparison tools. The histogram panel provides immediate feedback on tonal distribution, while the synchronization feature mentioned earlier enables sophisticated multi-image workflows.

System Requirements for Debian 13

Debian 13 (Trixie) serves as an excellent foundation for running Nomacs. Minimum hardware requirements remain modest: a modern dual-core processor, 2GB of RAM, and approximately 50MB of disk space for the application and its dependencies. These specifications ensure smooth operation even on older hardware.

The software stack requires Qt6 libraries, libraw for RAW image support, OpenCV for advanced image processing, and Exiv2 for metadata handling. Debian’s package manager handles these dependencies automatically during installation. Both 64-bit and 32-bit architectures receive support, though 64-bit installations are recommended for optimal performance with large image files.

Nomacs integrates with all major desktop environments including GNOME, KDE Plasma, XFCE, and LXQt. The Qt-based interface adapts to system themes, maintaining visual consistency regardless of desktop choice.

Preparing Your System

Proper preparation prevents installation headaches. Start by updating the system package database to ensure access to the latest software versions. This step proves crucial for Debian 13, as Trixie continues active development.

Open a terminal and execute:

sudo apt update

Verify that APT sources include the necessary Debian repositories. Debian 13 requires properly configured main, contrib, and non-free-firmware repositories for complete package access. Check the sources file at /etc/apt/sources.list to confirm entries for both the main repository and security updates.

Administrative privileges are essential for system-wide installation. Most commands require sudo prefix or root access. Creating a system backup before installing new software represents best practice, particularly on production systems.

Terminal familiarity helps, though the instructions provided work even for beginners. Each command includes clear explanations of its purpose and expected outcomes.

Method 1: APT Installation from Official Repository

The simplest installation path leverages Debian’s APT package manager. This method provides automatic dependency resolution, seamless system integration, and straightforward updates through the standard system upgrade process.

Installing the Package

Begin with a fresh package list update:

sudo apt update

This command contacts Debian repositories and downloads current package information. Output displays the number of packages that can be upgraded and any repository connection status.

Install Nomacs with a single command:

sudo apt install nomacs

APT automatically identifies and installs required dependencies including Qt libraries, image format handlers, and supporting utilities. The package manager prompts for confirmation, displaying the total download size and disk space requirements. Press ‘Y’ to proceed.

Installation typically completes within 2-3 minutes depending on internet speed and system performance. Progress indicators show download and unpacking status for each package component.

Adding Language Support

Nomacs includes internationalization support for numerous languages. Install translation packages separately if needed:

sudo apt install nomacs-l10n

This optional package adds localized interface strings for non-English users. The installation remains lightweight, adding only a few megabytes for complete multilingual support.

Verification Steps

Confirm successful installation by checking the installed version:

nomacs --version

This command returns the Nomacs version number and build information. Query detailed package information using:

apt show nomacs

Output includes version, repository source, dependencies, package size, and description. This verification ensures proper installation before first use.

Method 2: Flatpak Installation

Flatpak offers an alternative installation approach with distinct advantages. Containerized applications run in isolated environments with bundled dependencies, eliminating potential conflicts with system libraries. This method suits users who prefer sandboxed applications or need newer versions than official repositories provide.

Setting Up Flatpak

Install Flatpak on Debian 13 if not already present:

sudo apt install flatpak

Add the Flathub repository, the primary source for Flatpak applications:

flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo

System restart or logout may be necessary for complete Flatpak integration with desktop environments.

Installing Nomacs via Flathub

Search available versions:

flatpak search nomacs

Install Nomacs from Flathub:

flatpak install flathub org.nomacs.ImageLounge

Flatpak downloads the application and required runtime libraries. First-time Flatpak installations appear larger as base runtimes are downloaded, though subsequent Flatpak applications share these components.

Launching Flatpak Version

Run the Flatpak version using:

flatpak run org.nomacs.ImageLounge

Desktop launchers typically appear automatically, allowing GUI-based launching like traditionally installed applications. Flatpak sandboxing restricts filesystem access by default. Grant additional permissions using Flatseal or flatpak permission commands if Nomacs needs access to specific directories.

Method 3: Building from Source

Compiling from source provides access to the absolute latest features and allows custom compilation flags for optimized performance. This advanced method suits experienced users comfortable with build systems and troubleshooting compilation issues.

Installing Build Dependencies

Source compilation requires development tools and libraries:

sudo apt install git cmake g++ qtbase6-dev qt6-tools-dev qt6-tools-dev-tools libqt6svg6-dev libexiv2-dev libraw-dev libopencv-dev libtiff-dev quazip-qt6-dev

This comprehensive command installs the complete build toolchain including CMake build system, C++ compiler, Qt6 development headers, and image processing libraries. Installation may require several hundred megabytes for complete development environments.

Obtaining Source Code

Clone the official GitHub repository:

git clone https://github.com/nomacs/nomacs.git
cd nomacs

Alternatively, download release tarballs from the GitHub releases page for specific stable versions. The repository includes complete source code, build scripts, and documentation.

Configuring the Build

Create a separate build directory to keep source trees clean:

mkdir build
cd build
cmake ../ImageLounge

CMake analyzes the system, locates dependencies, and generates build files. Configuration output lists found libraries and enabled features. Address any missing dependency errors by installing additional development packages as indicated.

Custom configuration options modify behavior:

cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr/local ../ImageLounge

Release builds enable optimizations for better performance. The install prefix determines where files are placed during installation.

Compiling the Application

Initiate compilation with:

make -j$(nproc)

The -j flag enables parallel compilation using all CPU cores, significantly reducing build time. Compilation typically requires 5-15 minutes depending on hardware capabilities. Monitor output for errors, though most issues stem from missing dependencies caught during configuration.

System Installation

Install the compiled binary:

sudo make install

This copies executables, libraries, and resources to the specified prefix location. Refresh library cache if needed:

sudo ldconfig

Local user installations avoid system modifications by setting a different prefix during configuration, though this requires updating PATH and environment variables manually.

Launching and Initial Configuration

Nomacs appears in application menus under Graphics or Viewers categories after installation. The exact location depends on desktop environment and menu organization. Search functionality in modern launchers quickly locates “Nomacs” by name.

Command-line launching offers more control:

nomacs

Open specific images directly:

nomacs /path/to/image.jpg

Multiple files can be specified, creating a browsable collection. Command-line options modify behavior—explore available parameters with:

nomacs --help

First launch presents the default interface with panels and toolbar visible. The layout proves intuitive with clear icons and logical organization. Spend time exploring preferences under the Settings menu to customize behavior, keyboard shortcuts, and interface appearance to personal preferences.

Configuring for Optimal Use

Customize Nomacs extensively through the preferences dialog. Panel visibility toggles via View menu, allowing minimalist single-image displays or information-rich layouts with thumbnails, metadata, and histograms visible.

Set Nomacs as the default image viewer through Debian’s system settings or using:

xdg-mime default nomacs.desktop image/jpeg image/png image/gif

This command associates common image formats with Nomacs for double-click opening.

Essential keyboard shortcuts include:

• F11: Toggle fullscreen
• Ctrl+Shift+T: Show/hide thumbnail panel
• Ctrl+I: Display metadata panel
• Ctrl+H: Open histogram
• F: Fit image to window
• Alt+Shift+M: Toggle frameless mode

The synchronization feature requires multiple instances. Launch additional Nomacs windows and enable synchronization from the Sync menu. Instances mirror pan and zoom operations while displaying different images.

Troubleshooting Common Issues

Installation rarely proceeds without occasional hiccups. The most frequent issue involves repository configuration where apt install nomacs returns “package has no installation candidate” errors. This indicates APT cannot locate the package in configured repositories.

Resolve by verifying /etc/apt/sources.list includes Debian 13 repositories and running sudo apt update to refresh package lists. Ensure main and contrib repositories are enabled, as Nomacs may reside in contrib depending on packaging decisions.

Dependency conflicts occasionally arise, particularly on systems with mixed packages from different sources. APT typically resolves these automatically, but persistent conflicts benefit from aptitude’s more sophisticated conflict resolution:

sudo apt install aptitude
sudo aptitude install nomacs

Aptitude presents resolution options when conflicts occur, allowing informed choices about package versions.

Launch failures with cryptic error messages often trace to missing libraries. Execute Nomacs from terminal to capture error output:

nomacs

Missing library errors specify exact packages needed. Install missing components and retry. Graphics rendering problems may stem from OpenGL driver issues. Verify driver installation and try software rendering as fallback by setting environment variables before launching.

Configuration corruption rarely occurs but can prevent proper operation. Reset settings by removing the configuration directory:

rm -rf ~/.config/nomacs

Nomacs recreates default configuration on next launch.

Keeping Nomacs Updated

Regular updates ensure access to bug fixes, security patches, and new features. APT installations update through normal system maintenance:

sudo apt update
sudo apt upgrade

This command updates all installed packages, including Nomacs. Check for Nomacs-specific updates with:

apt list --upgradable | grep nomacs

Flatpak versions update separately:

flatpak update

Source-compiled installations require manual updates. Pull latest changes from Git repository and rebuild:

cd nomacs
git pull
cd build
make clean
cmake ../ImageLounge
make -j$(nproc)
sudo make install

Subscribe to the Nomacs GitHub repository for release notifications or monitor the project website for announcements.

Removing Nomacs

Removal proves straightforward regardless of installation method. APT installations uninstall with:

sudo apt remove nomacs

This removes the application while preserving configuration files. Complete removal including settings uses:

sudo apt purge nomacs
sudo apt autoremove

The autoremove command cleans orphaned dependencies no longer needed by any package.

Flatpak removal executes with:

flatpak uninstall org.nomacs.ImageLounge

Remove unused runtimes to reclaim space:

flatpak uninstall --unused

Source-compiled installations require manual deletion. Remove installed files based on installation prefix:

sudo rm -rf /usr/local/bin/nomacs /usr/local/lib/libnomacs* /usr/local/share/nomacs

Delete build directories to free disk space occupied by compiled objects and source code.

Congratulations! You have successfully installed Nomacs. Thanks for using this tutorial to install the latest version of Nomacs open-source image viewer on Debian 13 “Trixie” system. For additional help or useful information, we recommend you check the official Nomacs website.