Desktop app reference¶

Every control of valerian-gui, with its range and default. The desktop app describes the window and the tutorial walks through a session. Command line: valerian-gui [FILE] opens FILE; -V and --version print the version and exit.

Top bar¶

Start screen¶

Shown in the middle of the window while no image is open (and the Export step has nothing to export). It tells you how to start and lists what you worked on lately. See Tutorial: sort a folder of frames, and pick a session up again.

Sorting dropped frames¶

Drop a folder (or several files) on the window, or press Ctrl+Shift+O and choose a folder. Valerian reads the headers of every FITS file (.fit, .fits, .fts) under it, down to 6 folders deep and up to 50 000 files, skipping hidden folders, links to folders and its own valerian-sorted folder, and shows a review. One dropped FITS file is opened as an image instead. Dropping while a step runs is refused with a message; Esc cancels a scan in progress.

How each frame is classified, in this order:

1. The header card IMAGETYP (else FRAMETYP, then FRAME). Case, spaces, underscores and a trailing "Frame" or "Field" do not matter.
2. The file name (Light_M31_001.fit).
3. The name of the folder it is in (.../DARKFLAT/...).
4. Otherwise it is Unsorted and left out until you assign it.

The group is then settled from the whole set, and every automatic change is explained in the frame's note:

The review¶

On accept, a group that is all of one folder is used as that folder, and a group that is one file (a master) as that file. A group that is only part of a folder, or comes from several folders, is gathered into valerian-sorted/<kind>/ beside the dropped folder as links (hard links, or copies when the disk differs); the files are not moved or changed, and names that clash get their folder name in front. Gathering again replaces the links of the earlier gathering. With calibration frames the Calibrate output is calibrated beside the lights, Register reads it and writes registered, and Stack reads that and writes stack.fits; with lights only, Register and Stack read the lights.

Rail¶

One button per step: Calibrate, Register, Stack, Process, Export. Status: Optional, Ready, Running, Waiting or Done (with a tick). Below 900 px wide only the numbers show.

View¶

Zoom is in screen pixels per pixel of the open image: 100 % is one for one (1:1), 400 % is four screen pixels to an image pixel. The range is 2 % to 3200 %. Fitted, the picture is never enlarged above 100 %.

Cancelling a step¶

Full-resolution tiles¶

The picture is drawn from a reduced copy (1600 pixels on the long side) and, where the zoom goes beyond what that holds, from the real pixels. The open image gets a pyramid of levels (each half the size of the one before, averaging the finite pixels, down to one 512 pixel tile) built on a worker thread, announced above the picture while it runs (images of 1600 pixels or less are prepared at once, with no message). The level is chosen from the zoom (floor(log2(1/zoom)), level 0 from 100 %), and the tiles of it that the window shows (512 by 512, smaller at the right and bottom edges) are stretched with the current stretch, tinted when night vision is on and drawn over the reduced copy. A least-recently-used cache keeps at most 256 MiB of tile textures; a change of stretch or palette discards them. A frame spends about 12 ms on tiles and asks for another frame when more are needed. The extra levels hold about a third of the image's pixels again. Tiles are drawn for the stretched open image (the Stretch, Plate solve and Export tools, and Colour before it is calibrated); the star-removal layers, the colour-calibrated view and the pictures of the folder steps are drawn from reduced copies. See the zoom tutorial.

Pixel readout¶

With the pointer over the picture a box at the bottom left shows the pixel under it:

From 400 % the pixel is outlined. The readout does not change the picture and cannot be switched off; it is drawn only while the pointer is over the picture.

Calibrate¶

Register¶

Stack¶

Drizzle¶

Science¶

Measures a folder of frames and shows the per-frame plots in the viewer. How each number is measured, and the files the report holds, are in How subframe analysis works; the walk-through is tutorial 12.

Changing a limit judges the frames again at once and discards hand changes to the list. Measuring again replaces the table.

Process¶

Image box, Browse..., Open: the working image. Chips: Stretch, Star removal, Plate solve, Colour.

Stretch¶

Star removal¶

Plate solve¶

Optics¶

What the stars of the open image say about the telescope. How each plot is made is in How the optics plots work; the walk-through is tutorial 13.

Astrometry¶

The plate solution drawn on the open image, its residuals and their map, the colour fit, the zero point of each colour and the limiting magnitude. How each is made is in How the astrometry and photometry outputs work; the walk-through is tutorial 15 and, for the magnitudes, tutorial 20.

Colour¶

Export¶

GPU¶

Keyboard shortcuts¶

F1 or ? shows this list over the window (Esc or the same key closes it). Function keys and chords work everywhere; plain keys (N, ?, +, -, 0, 1, Enter) are left to a text box that has the keyboard. Every action says what it did in the notice above the picture; while a step runs, the words appear beside its progress and the step's own message stays.

Ctrl is Command on a Mac. Keys that need Shift on your keyboard (+, ?) work as typed; = also zooms in. The picture keys act on the open image; with none open they say "Open an image to zoom it."

Settings file¶

$VALERIAN_GUI_CONFIG, else %APPDATA%\valerian\gui.conf on Windows, else $XDG_CONFIG_HOME/valerian/gui.conf, else ~/.config/valerian/gui.conf. Plain key=value: window=WxH, night=1, up to eight recent= paths (images) and up to eight session= lines (folders: lights, darks, flats, dark flats and bias, separated by tabs, empty when not used). A damaged or relative line is skipped. Clear recent sessions and images on the start screen empties both lists.