Usage

Getting LeanHRPT

You can get the latest version of LeanHRPT from the releases tab.

Linux releases are packaged as AppImages and can be run on most distributions by simply running the file. Windows releases come as a zip archive which can be extracted and then run like any other executable.

Opening a file

The first step of using LeanHRPT-Decode is loading some data. This is done by clicking "Open" in the "File" menu. LeanHRPT-Decode supports a large amount of file types, including:

• Raw binary data (from either LeanHRPT-Demod or the GNURadio Flowcharts DEPRECATED)
• VCDUs (from LeanHRPT-Demod)
• CADUs (from SatDump/etc)
• raw16
• HRP

NOTE: While you can load files from other software such as SatDump, the length of the images may be shorter in comparison to using the full LeanHRPT workflow.

After a supported file has been opened, LeanHRPT will begin decoding. The time required will vary depending on the file type and hardware, although normally takes under 5 seconds on a decent computer.

The viewport

Scrolling and zooming

Once a file has been opened, a preview of the first channel will show. You can scroll by dragging it with the mouse, using the scroll wheel or with the arrow keys.

• The level of zoom can be changed using the selector in the "Zoom" combo box (or Ctrl++/-).
• The preview can be rotated by 180° by selecting "Flip" in the "Options" tab (or Ctrl+F), used for northbound passes.

Equalization

By default, no equalization is applied to the image, but can be easily selected.

The equalization type being applied can be changed in the "Equalization" box, located in the bottom-left corner of the GUI, above the "Zoom" selector. There are three types of equalization currently available;

• None - The image is displayed as is.
• Stretch - The dynamic range of the image is "stretched" to the full 16 bit dynamic range of the output.
• Histogram - Histogram equalization, flattens the histogram of the image (read more on Wikipedia)

Compositing

Creates a color image by directly mapping the satellite's channels to the RGB channels of the image. Some common mappings include:

• rgb221
• rgb321
• rgb124

Presets

Presets are used for advanced compositing of channels, LeanHRPT-Decode includes a default set of presets that should cover most use cases. You can read more about the default presets on the Presets page and Custom presets to learn how to create your own.

Saving the image

LeanHRPT-Decode can save in 5 formats: PNG, JPEG, WebP, TIFF and GeoTIFF (if GDAL is installed)

• Save current image saves the image currently being displayed.
• Save current image (corrected) saves the image currently being displayed but corrected for earth curvature.
• Save all channels saves each channel as an individual file into a folder unequalized.
• Save GCP File saves a file of ground control points for later georeferencing