DICOM 2D Viewer

Displaying DICOM images

The 2D viewer is the default viewer for any DICOM series that contains images — CT, MR, US, CR / DX, mammography, color photographs, and so on. It handles both single images and stacks (volumetric series), and is the entry point for the more specialized viewers such as MPR, the 3D Volume Renderer, and the MIP projection.

Open the 2D viewer

The viewer can be opened with in the toolbar, or by double-clicking a thumbnail (or right-clicking it and choosing 2D Viewer > Open) in the DICOM Explorer.

The rulers K display a real-world size whenever Weasis can derive one from the DICOM file. When a small label M is shown above the calibration, it indicates how that calibration was obtained:

• At detector: projection radiography calibration taken at the detector plane.
• Magnified: projection radiography calibration corrected by the magnification factor (e.g. mammography, as in the screenshot above).
• Used fiducials: calibration derived from fiducials (e.g. a manually placed ruler in the image).
• At scanner: calibration taken from a digitized medium (e.g. film digitizer).

Toolbars A

Viewer Main Bar

Choose the action assigned to each of the three mouse buttons and the mouse wheel. Defaults are:

• Left button — Window / Level. Can also be changed from the context menu F or the keyboard shortcuts.
• Right button — Context Menu.
• Wheel — Series Scroll.
• Middle button — Pan.

Available actions:

• Pan — move the image position. T key to select. Alt + Arrows to pan while another action is selected.
• Window / Level — change image contrast. W key to select.
• Series Scroll — navigate through the images of the current series. S key to select.
• Zoom — zoom in / out. Z key to select.
• Rotation — rotate the image by a free angle. R key to select.
• Measure — draw a graphic to measure something. M key to select.
• Draw — draw a graphic to annotate. G key to select.
• Context Menu — open the context menu. Q key to select.
• Crosshair — 3D cursor. H key to select. Ctrl + click or Ctrl + Shift + click adjusts Window / Level without leaving crosshair mode.
• No Action — do nothing. N key to select.

• Default layout — change the layout of the view. DICOM Information and Histogram are special layouts that update automatically as you scroll through the series.
• Synchronize — apply the same settings (window/level, scroll, zoom, …) to multiple views simultaneously. Two modes are available: Default Stack (the default — couples series sharing the same Frame of Reference UID) and Default Tile (mosaic display of a single series). A master Synchronize checkbox at the top of the drop-down turns synchronization on or off globally without changing the active mode. Each 2D view also exposes its own auto-sync and manual-sync overlay buttons in its bottom-right corner. See View Synchronization for the full mechanics, the per-view controls, and the FoR color-chip system.
• Reset — restore the default image rendering (see Reset). Escape key to select.

Toolbars available in the DICOM 2D viewer

• DICOM Import
• DICOM Export
• Screenshot
• Viewer Main Bar (see above)
• Measurement
• Zoom
• Rotation — rotate the image by 90° clockwise or flip it horizontally. Not visible by default.
• DICOM Header
• Lookup Table
• Basic 3D — MPR and MIP (disabled when the series has fewer than 5 images).
• 3D Viewer (disabled when the series has fewer than 5 images).
• Cine
• Key Object Selection

Viewer tools

The right-side panel groups all the tools tied to the 2D viewer.

The mini-tool is always visible; the other panels open by clicking the corresponding vertical button. The normalize button docks a panel into the main layout — otherwise it opens as a pop-up that can be kept in front with the pin button (not recommended, as a pinned pop-up hides other panels).

Mini-tool B

By default the mini-tool scrolls through the images of the selected series (the one surrounded by the orange focus border). The combobox at the top can switch it to control zoom or rotation instead.

Display C

Controls how the image and graphic objects are displayed in the view.

The Apply to all views option propagates the chosen display settings to every view in the selected tab. When unchecked, settings apply only to the focused view (orange border).

Image

Display options for the image itself. Unchecking Image hides the image and leaves only the annotations and graphic objects visible. The other options expose DICOM-specific behavior:

• DICOM Image Overlay — apply the DICOM overlays when checked. The overlay color is configurable.
• Shutter — apply the DICOM shutters when checked.
• Pixel Padding — apply the DICOM pixel padding when checked.

DICOM Annotations

Display transformation values and DICOM information directly on the image.

• Annotations — DICOM information shown in the image corners:
  • G Top left — patient information.
  • H Top right — study information.
  • I Bottom right — series information (depends on the modality).
  • J Bottom left — image information and the position of the image in the series.
• Minimal Annotations — reduce the number of annotations shown. Press Space or I to cycle through the three states (minimal, none, all).
• Anonymize — hide identifying information only inside the views (not in other parts of the GUI such as the tab title). Combine with the screenshot tool when exporting an image.
• Scale — display the rulers on the left and bottom of the image K.
• Lookup Table — display the LUT on the image L.
• Orientation — display the orientation of the image N.
• Window / Level — display the window and level values J.
• Zoom — display the zoom value J.
• Rotation — display the rotation value J.
• Frame Value — display the frame number J.
• Pixel (Value / Position) — display the pixel value and the cursor position J.

Drawings

Check / uncheck to show or hide the graphic objects (see Draw & Measure).

Image Tools D

Image Tools groups every control that affects how the image is rendered.

Windowing and Rendering

Transform

Zoom, rotate, and flip the image. Zoom and rotation can also be driven from the mini-tool or the mouse actions.

Cine

The Cine start button plays the series at a fixed speed (frames per second). The default speed is taken from the DICOM file when present. Cine options are also accessible from the context menu.

• Click Cine stop to end the animation.
• Click the Loop / Sweep toggle to switch between looping and sweeping playback.

Reset

Returns the image to its default rendering, either for every parameter or for a specific one. Also available from the toolbar button and from the context menu.

Draw & Measure E

Other specific tools

• DICOM RT tools — for radiotherapy studies (RTSTRUCT, RTPLAN, RTDOSE).
• DICOM Segmentation — for pixel-based SEG overlays (binary, fractional, label-map).

Preferences

From the menu File > Preferences > Viewer > 2D Viewer.

Mouse Action Sensitivity

Adjust how strongly a mouse drag translates into action for: Window, Level, Zoom, Rotation, and Series Scroll.

Zoom

Zoom interpolation controls how new pixels are computed when the image is zoomed in or out:

• Nearest neighbor — the simplest method: extends the nearest pixel value as-is.
• Bilinear — averages the four neighboring pixels. Slightly sharper than nearest neighbor, slightly slower.
• Bicubic — uses a 16-point kernel. Sharper than bilinear, but the slowest of the four.
• Lanczos — uses a sinc kernel; produces the sharpest results, with performance between bilinear and bicubic.

The default is Bilinear. Nearest neighbor is the fastest option but produces aliasing artifacts.

Other

• Apply Window / Level on color images — when checked, the window / level is applied to the RGB channels. Unchecked, window / level has no effect on color images.
• Inverse level direction — when checked, the level direction with mouse drag is inverted (dragging down increases brightness), matching the Basic Image Review profile. Unchecked, dragging down decreases brightness.
• Apply by default the most recent Presentation State — when checked, the most recent Presentation State object is applied automatically. Otherwise it has to be selected manually via .
• Overlay color — color and opacity of the DICOM overlay. The default is white; the opacity is the transparency / alpha slider of the color picker.