ImageJCsharp

ImageJCsharp aims to become a C# native replacement for ImageJ on Windows.

The long-term goal is not to build a generic image editor. The goal is to provide an ImageJ-like scientific image analysis application with familiar workflows, familiar menu organization, and a C#/.NET extension model that can grow into its own ecosystem.

Long-Term Vision

ImageJ has been valuable for decades because it combines image viewing, analysis, measurement, batch processing, and extensibility in one practical tool. ImageJCsharp follows that spirit, but uses the C# ecosystem instead of the Java plugin ecosystem.

The long-term target is:

• Replace ImageJ for common scientific image analysis workflows.
• Keep the UI and menu structure close to ImageJ 1.x where practical.
• Implement the most used built-in ImageJ features in C#.
• Provide a stable C# plugin SDK for commands, tools, algorithms, importers, exporters, and analysis modules.
• Reimplement high-value ImageJ/Fiji ecosystem plugins in C# over time.
• Keep the image processing core independent from WinForms so algorithms can be tested, reused, and eventually automated.

See ROADMAP.md for the staged near-term, mid-term, and long-term plan. See docs/near-term-plan.md for the detailed near-term MVP checklist.

Screenshot

Current MVP shell showing a sample grayscale image, rectangle ROI resize handles, the ImageJ-like top-level menu structure, and the measurement results area.

Project Positioning

ImageJCsharp is intended to be:

• A scientific image processing and analysis application.
• A Windows desktop application.
• A C# native platform for future plugins.
• A practical ImageJ replacement for the most common 90% use cases before attempting full feature parity.

ImageJCsharp is not intended to be:

• A Java ImageJ plugin host.
• A Fiji compatibility layer.
• A Photoshop-like image editor.
• A NativeAOT-first application.
• A full clone of every historical ImageJ behavior in the first phase.

Runtime Target

The project targets .NET Framework 4.8.

This is intentional:

• Windows 10 systems commonly support .NET Framework 4.8.
• WinForms support is mature and predictable.
• Dynamic loading, reflection, and future plugin support remain straightforward.
• The deployment model is simpler than NativeAOT for an extensible desktop application.

MVP Goal

The first milestone is a feasible core replacement, not a perfect clone.

The MVP should cover the most common ImageJ workflows:

• Open and save common image formats.
• View, zoom, and pan images.
• Draw basic ROI selections.
• Measure area, mean, min, max, and standard deviation.
• Display and export measurement results.
• View histogram statistics for the full image or active rectangle ROI.
• Adjust simple image data through core processing commands.
• Run thresholding and binary conversion.
• Run basic filters such as invert and edge detection.
• Establish the internal command architecture that future plugins can reuse.

Initial MVP Scope

The first implementation focuses on features that are highly feasible and low risk.

File

• Open PNG, JPEG, BMP, and TIFF.
• Save as PNG, JPEG, BMP, and TIFF.
• Close the current image.

View

• Zoom in.
• Zoom out.
• Actual size.
• Fit to window.
• Pan through scrollbars.

ROI

• Rectangle ROI.
• Rectangle ROI resize handles.
• ROI move support is planned after the rectangle create/resize workflow is stable.
• Oval, line, polygon, and freehand ROI are planned after the rectangle workflow is stable.

Analyze

• Measure current ROI.
• Measure full image when no ROI is selected.
• Results table.
• Pixel-based calibration first.
• Physical unit calibration later.

Process

• Invert.
• Manual threshold.
• Binary image generation.
• Sobel edge detection.
• Blur, sharpen, median filter, morphology, and particle analysis after the first working shell.

Explicitly Deferred

These are important, but they are not part of the first implementation target:

• Java plugin compatibility.
• ImageJ macro language compatibility.
• Fiji plugin compatibility.
• Bio-Formats full format support.
• Complex microscope vendor formats.
• Full stack and hyperstack support.
• 3D Viewer.
• TrackMate-like tracking.
• Stitching and registration workflows.
• GPU acceleration.
• Full undo/redo.
• Complete ImageJ menu parity.

Architecture Direction

The project is split into a testable core library and a desktop shell.

src/
  ImageJCsharp.Core/
    Image model, ROI model, measurements, processing algorithms.

  ImageJCsharp.App/
    WinForms UI, menus, dialogs, image display, command wiring.

tests/
  ImageJCsharp.Core.Tests/
    Unit tests for the core image model and algorithms.

The core library should not depend on WinForms. UI code may depend on the core library.

Plugin Direction

The future plugin model should be C# native.

The planned direction is:

• Every menu action is internally represented as a command.
• Built-in features use the same command model as future plugins.
• External plugins are loaded from .NET assemblies.
• A plugin SDK exposes stable interfaces for image access, commands, tools, and analysis results.
• Algorithm plugins should avoid UI dependencies where possible.
• UI plugins may use WinForms when they need custom dialogs or panels.

Development Principles

• Feasibility comes first.
• Implement stable core workflows before broad menu coverage.
• Prefer tested core behavior over UI-only behavior.
• Keep algorithms in the core library.
• Keep UI code focused on interaction and presentation.
• Prefer fast failure over unclear fallback behavior.
• Avoid promising ImageJ compatibility that is not yet tested.
• Add features incrementally, with clear acceptance criteria.

How to Help

Contributors are welcome.

Good first contribution areas include:

• Documentation improvements.
• Core unit tests.
• Simple image processing filters.
• ROI behavior.
• Measurement features.
• UI polish.
• Manual testing with real ImageJ workflows.
• Sample images for regression and smoke testing.

Please read CONTRIBUTING.md and docs/contributor-guide.md before starting.

Release and Promotion

• Release process: docs/release-process.md
• Promotion plan: docs/promotion-plan.md

Current Status

This project is in the earliest MVP stage.

Implemented or in progress:

• Solution structure.
• .NET Framework 4.8 project targets.
• Core grayscale image model.
• Rectangle ROI model.
• Rectangle ROI resize handles.
• Minimum ImageJ-like top-level menu structure.
• Clean no-image command state for implemented menu commands.
• Status bar reporting for no-image, image size, and zoom state.
• Basic measurement model.
• Measurement results CSV export.
• Histogram calculation and a basic histogram window.
• Threshold, invert, and Sobel edge processing.
• WinForms application shell.
• Focused core and app tests for current MVP behavior.

Name

ImageJCsharp is a working project name. It describes the technical goal clearly: an ImageJ-style application implemented in C#.