DICOM 2D Viewer

The default viewer, and the way into the others

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. It can also overlay a PET or SPECT series on a CT/MR base — see Image Fusion.

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.

In a layout with several views, rolling the wheel over any view scrolls that view’s series straight away: the view under the pointer becomes the selected one, so it no longer has to be clicked first since v4.6.4.

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. The same button carries the Viewport Layout submenu since v4.8.0, which splits the selected viewport into a grid of tiles — see Viewport layouts.
• 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

Viewport layouts

The viewing area is a grid of viewports. A viewport normally holds one image that you scroll through; it can also be split into a grid of tiles showing consecutive images of the same series at once since v4.8.0 — the arrangement the DICOM standard calls a tiled image box in a hanging protocol. It is the usual way to read a long series at a glance: a whole stack of slices on one screen instead of one slice at a time.

Each viewport is in one of two modes:

• Stack — one image, scrolled through as usual. This is the default and the behavior of earlier versions.
• Tiled n×m — the viewport is divided into columns × rows cells filled with consecutive images of the series. Scrolling advances the whole set, so the tiles keep their order and always show a contiguous run of images.

The available grids are 1×2, 2×1, 2×2, 2×3, 3×2, 3×3 and 4×4.

The mode is changed from the Viewport Layout submenu, reachable from three places:

• the layout button in the main toolbar;
• the viewer’s own menu;
• the right-click context menu on a view.

It applies to the selected viewport only, so a scrolling stack and a mosaic can sit side by side in the same layout. Switching modes carries the displayed series with it — to the first tile when you go tiled, and back to the single image when you return to Stack — so nothing has to be reopened.

Synchronization inside a viewport

When the selected view is one tile of a viewport, the synchronization drop-down replaces Apply to all views with Apply to all tiled views since v4.8.0. Window/level, zoom, pan and the other synchronized actions are then propagated to every tile of that viewport rather than to the other viewports of the layout. A tiled viewport is kept out of the synchronization between viewports altogether: its tiles never follow another view sharing the same Frame of Reference, and the master Synchronize checkbox is grayed out while a tile is selected. See View Synchronization for the rest of the synchronization model.

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 until v4.7 — hide identifying information only inside the views. Replaced by Identity masking since v4.8.0, which masks the whole application and the pictures it produces.
• Scale — display the rulers on the left and bottom of the image K.
• Lookup Table — display the LUT on the image L.
• Fusion Color Scale — display the color scale of the fusion overlay, next to the LUT bar when both are shown.
• 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.

Graphics

Check / uncheck to show or hide the graphic objects (see Draw & Measure), one check box per layer since v4.8.0: Measurements, Drawings, Annotations, DICOM PR and DICOM SR.

Image Tools D

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

Each section below can be collapsed or expanded by clicking its header since v4.7.1. The expanded/collapsed state of every section is remembered and restored the next time you open Weasis.

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.

Fusion

Overlay a PET or SPECT series on the displayed CT / MR base, with adjustable color LUT and base/overlay opacity since v4.7.1. Collapsed by default and enabled only when the study contains a compatible overlay. See Image Fusion for the full workflow, SUV statistics, and MPR inheritance.

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.