Controls

Shortcuts

Shortcut Description
Ctrl + O Open Spectral image (ENVI file format).
Ctrl + S Save image:
  - as HDR RGB image (exr) if opened image is spectral.
  - as LDR RGB image (png, jpeg …) if opened image is not spectral.
Ctrl + H Show Help.
R Reset view parameters (zoom, rotation, auto tonemapping).
F5 Refresh (reopen current file, doesn’t work with a PNG collection).

Spectrum graph

Spectrum selection

Control Description
Left click Select one wavelength.
Left click + drag Select a range of wavelengths.
Left click (around start or end bar of selection) + drag Move start or end of selection.
Right click Reset selection to fully displayed spectrum.
Mouse wheel up Extend selection on both sides.
Mouse wheel down Shrink selection on both sides.
Middle click + drag OR Ctrl + Left click + drag (inside selection) Move selection.
Left Arrow Move selection to the left.
Right Arrow Move selection to the right.
Mouse move Select nearest point on graph and display its value.

Spectrum X-Axis (Wavelength)

To make this shortcuts work, you need to uncheck the “Auto rescale wavelength” in the “Display” groupbox.

Shortcut Description
Shift + Mouse wheel up Extend wavelength range (x-axis) on both sides.
Shift + Mouse wheel down Shrink wavelength range (x-axis) on both sides.
Shift + Middle click + drag OR Ctrl + Shift + Left click + drag: Move wavelength range (x-axis).
Shift + Left Arrow Move wavelength range (x-axis) to the right.
Shift + Right Arrow Move wavelength range (x-axis) to the left.

Image widget

Control Description
Mouse move Change selected pixel (if not locked).
Left click Select and Lock pixel.
Right click Unlock pixel and select.
Mouse wheel up/down Zoom In/Out.
Middle click + drag OR Ctrl + Left click Move image.
Drag and drop a .hdr file (ENVI format) Open as ENVI file.

Supported file formats

Spectral images

Three types of spectral images are supported:

  • PNG collections.
  • ENVI files.
  • ART raw files.

PNG collection

A png collection can be opened using File -> Open folder. Each PNG image should be a gray image representing a dedicated wavelength. All PNGs must be in the same folder and the folder should not contain any other PNGs.

All PNGs filename must end with _X where X is a positive number indicating in which order the PNGs should be used. The GUI provides a way to specify the mapping between the png number and the wavelengths.

An example of such image collection can be found at: http://www.cs.columbia.edu/CAVE/databases/multispectral/

ENVI file format

The supported ENVI file format is described here: http://www.harrisgeospatial.com/docs/ENVIHeaderFiles.html. It consists of a set of two files: a header (.hdr) and raw data (.raw).

Both files should have the same name (except for the extension) and placed in the same folder.

Some examples can be found here: http://icvl.cs.bgu.ac.il/hyperspectral/

ART Raw file format

Spectral Viewer supports reading of unpolarised spectral ART Raw format. This format is used by ART, The Advanced Rendering Toolkit physically based renderer https://cgg.mff.cuni.cz/ART/.

RGB images

Some HDR and LDR RGB formats are supported: all the formats supported by Qt5, with the addition

  • OpenEXR format.
  • PFM format.
  • Ward’s HDR format.

When a RGB image is opened, the Spectrum graph and Spectrum parameters panels automatically disappear.

User preferences

Some parameters are automatically saved and retrieved when the viewer gets re-opened:

  • Spectrum graph point size
  • Last used folder
  • Spectrum graph/parameters GUI layout
  • Application window size and position
  • Image tools/infos layout