pydcmview

PyDCMView

Terminal-based medical image viewer for DICOM, NRRD, and Nifti formats with high-quality graphics rendering.

Installation

pip install pydcmview

Usage

pydcmview <path_to_image_file_or_dicom_directory>

When using over remote SSH, I've only gotten advanced graphics rendering to work with kitty with the following remote SSH command

kitty +kitten ssh <typical_ssh_arguments_here>

e.g., kitty +kitten ssh -p 6000 my_server_address

With other remote SSH connections, it falls back to Unicode block rendering. Adjust the terminal font zoom to increase/decrease rendering resolution. Each character block represents 2 pixels.

Features

• Format Support: DICOM, NRRD, and Nifti formats
• High-Quality Rendering: Uses textual-image with Sixel and Kitty graphics protocols for superior image quality
• 2D Slice Viewing: Navigate through N-dimensional images slice by slice
• Interactive Dimension Selection: Overlay-based dimension selection with axis assignment and flipping
• WASD Scrolling: Pan across images with 5% step size, zoom-aware navigation
• Zoom Controls: Zoom in/out functionality with scroll position preservation (0.01x to 20.0x)
• Crosshair Mode: Interactive crosshair with adjustable opacity and pixel intensity display
• Window/Level Adjustment: Percentage-based contrast and brightness control (1% and 5% increments)
• Colormap Selection: Multiple colormap options for enhanced visualization
• Smart Navigation: Arrow keys and vim motion keys supported throughout
• Comprehensive Status Bar: Real-time display of image info, coordinates, and available commands

Key Bindings

Normal Mode

• q: Quit application
• ↑/↓ or j/k: Navigate through slices
• w/a/s/d: Scroll image (up/left/down/right) - 5% of image size per step
• t: Toggle dimension selection overlay
• c: Enter colormap selection
• h: Enter crosshair mode
• Shift+W: Enter window/level mode
• [/]: Zoom out/in (preserves scroll position)

Dimension Selection Overlay

• ↑/↓ or j/k: Navigate dimensions
• x: Assign dimension to X-axis (swaps if already assigned to Y)
• y: Assign dimension to Y-axis (swaps if already assigned to X)
• f: Toggle flip for selected dimension (marked with *)
• Enter: Confirm and apply changes
• Esc: Cancel and return to normal mode

Crosshair Mode

• ↑/↓/←/→ or h/j/k/l: Move crosshair position
• Shift+↑/↓ or J/K: Adjust crosshair opacity
• Esc: Exit crosshair mode

Window/Level Mode

• ↑/↓ or j/k: Adjust window width (1% of intensity range)
• ←/→ or h/l: Adjust window center/level (1% of intensity range)
• Shift+↑/↓ or J/K: Adjust window width (5% of intensity range)
• Shift+←/→ or H/L: Adjust window center/level (5% of intensity range)
• Esc: Exit window/level mode

Technical Details

Rendering Engine

• Primary: textual-image library with Terminal Graphics Protocol support
• Fallback: Unicode block characters for broader terminal compatibility
• Graphics Protocols: Sixel (xterm, mintty) and Kitty graphics for high-resolution display

Navigation and Zoom

• WASD Scrolling: 5% of image dimensions per step, scaled with zoom level
• Zoom Preservation: Scroll position maintained during zoom operations with bounds checking
• Zoom Range: 0.01x to 20.0x with nearest-neighbor interpolation for medical accuracy
• Smart Constraints: Automatic scroll boundary enforcement to prevent out-of-bounds navigation

Dimension Management

• Dynamic axis assignment for N-dimensional data
• Independent dimension flipping with visual indicators
• Automatic slice axis calculation for 3D+ datasets

Requirements

• Python 3.8+
• textual>=0.70.0
• textual-image>=0.3.0 (replaces rich-pixels for better graphics)
• SimpleITK>=2.3.0
• numpy>=1.21.0
• pydicom>=2.3.0
• Pillow>=8.0.0

Recent Updates

Graphics Engine Upgrade

• Migrated from rich-pixels to textual-image for superior rendering quality
• Added support for Sixel and Kitty terminal graphics protocols
• Maintained backward compatibility with Unicode block rendering

Enhanced Navigation

• WASD Scrolling: Added image panning with percentage-based movement (5% of image size)
• Zoom Position Preservation: Zoom operations now maintain current view position with bounds checking
• Improved Window/Level: Percentage-based adjustments (1% and 5%) relative to image intensity range
• Colormap Integration: Multiple colormap options for enhanced medical image visualization
• Extended Zoom Range: Increased zoom capability from 5.0x to 20.0x maximum

UI/UX Improvements

• Real-time status bar updates with zoom level and opacity display
• Context-sensitive key binding hints
• Smooth overlay transitions with semi-transparent backgrounds
• Improved dimension swapping logic for intuitive axis assignment

Terminal Compatibility

Best Experience:

• Kitty terminal (full graphics protocol support)
• iTerm2 (with graphics support)
• xterm with Sixel support

Good Experience:

• Most modern terminals (Unicode block fallback)
• Windows Terminal
• GNOME Terminal
• Terminal.app (macOS)