Planet Engine Manual

From frame / To frame Free

The part of the video to use. Leave out clouds, bumps of the mount, or the end of a long video in which a planet has rotated too much.

Analyse selection / Analyse all / Use suggested Free

Analyse selection and Analyse all, at the top of the first column under Load a video or an image, score every frame and draw the chart. The suggestion starts from the "knee" of the sorted quality curve, the point after which frames get clearly worse, and multiplies it by 2.5: more frames lower the noise more than they soften. It is always between 20% and 60%. Good as a starting point; then try a little more or less and compare. In the chart, drag the orange line to change Frames to stack and the two cyan bars to change the range. Analyse selection reads only the frames of the range, so on a long capture you can set it roughly and analyse just that part; Analyse all reads the whole capture, to look for the best stretch on the curve (the parts not analysed stay grey). Under the sliders Planet Engine shows how long the range lasts (from the time stamp of every frame in SER files) and, for Jupiter, Saturn and Mars, how many pixels the rotation of the planet moves a detail at the centre of the disk: above 2 px the line turns orange and a shorter range is better.

Target default: Automatic Free Pro: Sun

Planet: a disk on a black sky; it is found in every frame; tick Crop around the subject to crop the work area around it. Surface (Moon, Sun): a close-up that fills the field; the whole frame is used and its drift is followed. Automatic decides from the first frame; force it if it gets it wrong (for example a crescent Moon with a lot of black sky). Sun stacks like a surface and then opens the solar tools of the Sun mode; in the Free edition it shows Sun (Pro), and a solar video is stacked and finished as a surface.

Frames to stack default: 50% Free

The share of the best frames, within the range, that goes into the stack: the same thing as the orange line in the quality chart. More frames = less noise but more blurred frames. Planet Engine’s advanced stacking tolerates more frames than a classic stack. Measured at equal grain on two Jupiter videos and one Saturn video, 50–70% of the frames gave 8–12% more structure than 35% (the previous default); Saturn gained nothing beyond 50%. Stacking takes about 40% longer than at 35%. With poor seeing try less and compare. The reference is taken from the best frames in the middle third of the range, so that the planet’s rotation smears the detail less.

Reference (best frames) default: 3% Free

The share of the very best frames stacked to make the first reference, the image the frames are stacked against (at least 20 frames). Raise it with noisy videos, lower it if only a few frames are really sharp.

Quality default: Normal Free

Normal, High, Maximum or Extreme: higher quality gives more detail and takes more time. Normal is a good balance; try High or Maximum on your best videos, and compare. It is saved with the parameters.

Stack upscaling default: 1.0x Free

1.5x or 2x: the frames are accumulated on a finer grid, so their sub-pixel offsets add real resolution (like a drizzle or the resample of other stackers). The result goes back to the original scale before sharpening, so the image keeps its size. Useful for undersampled videos (a small planet on few pixels); slower and with more memory.

Multistack default: off Pro

Several stacks of the same video with different percentages of frames, all with the same settings, to see which works best. Tick the box under Stack upscaling, tick the percentages (10 to 90%; 20, 40, 60 and 80% to start with) and press Start stacking: at the end the toolbar has one button per percentage. With few frames the fine detail is at its best but the grain shows more; going up the grain drops, but the detail softens and the halo around the planet grows. The right point depends on that night’s seeing. It all runs in one go: it takes about as long as the stack of the highest percentage, and the results are the same as stacks made one by one (on a Saturn, 30, 50 and 70% in 79 s instead of 178 s). Save image… and Save stack… save the chosen one, with the number of frames in the name; Save all…, after the percentage buttons, saves the stack and the processed image of the percentages you choose, in a folder.

Local selection default: automatic Free

More detail on Jupiter and Mars, with a little more grain; on smooth Saturn it only adds noise. Automatic turns it off when the subject has rings and keeps it on otherwise (Moon and Sun included); On and Off force it. The Result box says what was used.

Crop around the subject default: off Free Pro: moons one by one

Off, Planet Engine works on the whole frame, as captured. On, it crops the work area around the planet, moons included: faster. In the Pro edition the moons in the field are aligned one by one.

Align RGB channels default: on Free

Corrects the shift between red, green and blue caused by atmospheric dispersion, which gives coloured fringes at the top and bottom of a low planet. Turn it off only if you used an ADC that already removed it. (The Align RGB channels button for an image that is already stacked is a Pro feature: see First steps.)

White balance default: on Free

Removes the colour of the sky background and makes the planet neutral on average. Then refine with the R, G and B curves. Turn it off for objects that are not neutral, or if you want to balance the colour yourself. With the Sun target it is turned off by itself, and put back as it was when you choose another target.

Derotation default: off, experimental Pro

Compensates the rotation of Jupiter and Saturn, so that the detail of a long video does not smear. It uses the times in the SER (or the frame rate of an AVI) and recognises the planet from the name of the file or of its folder; when it does not help, it stays off. The Result box says whether it was used, and if not, why.

Defaults Free

At the bottom of the column: puts back only the stacking settings to the starting values. The From/To range is kept.

Result: resolution and signal Free

After every stacking the Result box, at the bottom right, shows the measured resolution in pixels and signal to … px: down to which size there is real detail rather than noise. A smaller number means finer real detail; use it to compare settings on the same video. The same values are written to NAME_info.json (resolution_px, signal_limit_px) and printed by the command-line tool.

Deconvolution: radius default: off Pro

Richardson-Lucy deconvolution: it "undoes" a blur of the given radius (in pixels). Typical values 0.8–1.5 px. Too large and dark or bright rings appear around edges and the noise grows. It works best on stacks with many frames.

Deconvolution: iterations default: 30 Pro

How strong the deconvolution is. More iterations = more detail, but also more noise and ringing. 30–80 is a good range; with many frames and a clean signal you can go up to 200 to see how far the image holds.

Wiener: diameter and strength default: 5 px, strength 0 (off) Pro

A one-pass Wiener deconvolution: a quick sharpening with just two sliders. Diameter (0–8 px) is the size of the blur to remove, Strength (0–1) how much of it to remove; at strength 0 it is off. It boosts the detail only as far as the stack has real signal and leaves the finer noise as it is, so it stops by itself where the stack runs out of detail.

Two ways to use it. On its own, strong (for example 5.7 / 0.9, plus a little Soften): on a Jupiter test it gave 85–90% of the detail of a carefully tuned wavelet + deconvolution + unsharp mask recipe, with less grain and three settings instead of eight. As a base, light (for example 3 / 0.3), under the detail sliders. At the same grain, well-tuned wavelets still give a little more fine detail: Wiener is the quick road, not a replacement.

Detail scale default: 0.7 px Free

Not a strength but a size: the size in pixels of the finest wavelet layer (0.7 px by default, from 0.5 to 2 px). The other layers follow at twice, four and eight times that size: with 0.7 they work at about 0.7, 1.4, 2.8 and 5.6 px. So it moves all the detail sliders together: at 1.5 they work at 1.5, 3, 6 and 12 px; at the maximum of 2, at 2, 4, 8 and 16 px. Raise it for oversampled videos (long focal ratio) or soft stacks, so that Fine detail sharpens real detail and not noise; keep it low for sharp, well sampled videos. First choose the scale (the size you work at), then the detail sliders (how much each layer is pushed).

Fine detail / Medium-fine / Medium detail / Large-scale contrast / Structures default: 10 / 0 / 10 / 1.25 / 5 Free

How much each wavelet layer is strengthened. 0 leaves that layer as it is. Fine detail sharpens the smallest features but also the noise; Medium detail is the most useful for festoons, spots and the Cassini division; Structures brings out belts and zones; Large-scale contrast acts on the whole disk, a little goes a long way. Medium-fine gives an extra boost to the finer half of the medium layer, between fine and medium detail (about 1 px at the default detail scale of 0.7 px): it adds structure with less grain than pushing Fine detail; at 0 nothing changes. All of them go from 0 to 100; for Structures, at the end of the group, the scale is five times finer, because beyond that it ruins the image. With the mouse the slider is finer at the low end, so small values stay precise; the arrow keys move it by 0.1, with Shift by 1.

To work finer than Fine detail, lower Detail scale (down to 0.5 px) and raise Fine detail: there is no separate slider.

Unsharp mask: radius and amount default: 1.5 px, amount 0 (off) Free

A classic unsharp mask, applied after the other filters, for those used to it from other programs. Radius goes from 0.5 to 10 px, Amount from 0 to 100, with the slider finer at the low end. With the amount at 0 it is off and the radius slider is faded.

Noise reduction default: 13 Free

In the Noise group. Cleans every wavelet layer of the variations smaller than the noise level measured in that layer, before strengthening it. It is a soft threshold judged on the neighbouring pixels and on the three channels together, so it works the same on bright and dark areas: no isolated or coloured dots left in bright clouds or rings. It goes from 0 to 200; 0 = off. With the arrow keys it moves in steps of 1. Raise it if the sky or the disk become grainy. Too much flattens faint details: if fine detail disappears, lower it. Settings files and presets from older versions are converted automatically (the old 0.4 reads as 13).

Noise reduction scale default: 2 Free

Up to which detail size the noise reduction acts, shown as ≤ N px. It goes from 0.5 to 4 in steps of 0.1: for example 1.5 cleans the finest layer fully and the next one by half. The default 2 reaches ≤ 1.4 px at a detail scale of 0.7 px.

Soften default: 0 (off) Free

In the Noise group, up to 1.5 px: a light blur after the unsharp mask that removes the finest grain. It is the last step of a common recipe: fine detail and a fine unsharp mask, then a minimal blur (like Photoshop’s Blur).

Luminance only default: off Free

When on, deconvolution and wavelets work on the brightness, and the colour comes from the stack: no coloured edges and no colour noise. Turn it on if colour fringes or colour noise appear; when off, each channel is sharpened separately.

Protect the limb default: off Free

When on, the edge of the planet stays almost as sharp as without protection, but with no bright rim and no dark ring. On the sky, the glow of the limb is darkened down to the sky background, so no grey veil is left around the planet. Turn it on if a bright rim or a dark ring shows on the limb after sharpening. Moons and stars in the field are not treated as sky: they stay as bright as without protection. Not used on lunar and solar surfaces. For the saw-tooth that strong filters leave along the edge, see Smooth limb.

Reset to zero Free

At the bottom of the column: sets only this column to zero (detail, deconvolution, noise reduction and unsharp mask). The other columns are not touched.

Normalise default: off Free

When on, the black goes to zero and the brightest point to the chosen percentage (50–100%); this also applies to Save stack…. When off, the stack keeps the brightness of the capture.

Saturation default: 1.2 Free

Colour intensity: 1 leaves it as stacked, 0 is black and white.

Midtones (gamma) default: 1.0 Free

Above 1 brightens the midtones (shows more on a dark limb or on the rings), below 1 darkens them and increases the contrast. Colours are not changed.

Contrast default: 0 Free

The overall contrast, from −100 (flat) through 0 (as it is) to +100 (strong). It is an S curve around the middle grey of the subject (the median of the light above 10%, so the black sky does not count and a bright solar disk is not flattened): black, middle grey and white stay in place, the curve gets steeper or flatter around the middle. It does not burn the highlights or close the shadows, and the whole pixel is scaled, so the hue stays.

Blur colour default: 0 (off) Free

Blurs only the colour (a and b of Lab), up to 6 px: luminance and detail stay. It removes the colour noise, like a blurred layer in colour blend mode in Photoshop, and works in both RGB and Lab mode.

Reset to zero Free

At the bottom of the column: only this column goes back to neutral: saturation 1, midtones 1, normalisation and colour blur off. The curves have their own reset buttons (below).

Curves: RGB Free

A curve maps the brightness you see (left, black to white) to the brightness you get (bottom to top). The histogram of the channel is drawn behind it. Drag the two end points to set the black and white point; double-click to add a point in between and bend the curve, right-click a point to remove it. Light changes the brightness without shifting the colours; R, G and B act on each channel, to correct the colour of an object that is not neutral, like Mars. Settings files from older versions with Red and Blue are turned into R and B curves automatically.

Curves: Lab Free

As in the Lab mode of Photoshop: L is only the light, a and b only the colour (green–magenta and blue–yellow). Curve L to change the contrast without touching the colours; make a and b steeper to strengthen the colour. The Blur colour slider above softens the colour channels only: the colour noise goes away and not a single detail of the light is lost. The R, G and B curves, also shown in Lab mode, apply in both modes, so switching mode never changes the colour; the points of both modes are kept.

Reset channel / Reset curves Free

Puts the shown channel, or all the curves, back to a straight line.

Histogram and colour cast Free

The R, G and B histograms of the image as shown, with the letter of each channel over its peak. The scale is taken on the planet, not on the sky: the sky peak is clipped at the top, so the disk fills the height. Below, the average R G B of the sky with neutral or the colour cast, and the R/G and B/G ratios of the disk.

Tint default: 0° Pro

Rotates all the colours around grey, from −180° to +180°: positive towards yellow and green, negative towards magenta. The brightness stays, only the hue turns. Next to the value Planet Engine writes, in words, the hue that the average colour of the subject takes with that rotation, so you can read it without judging the colour by eye.

Sharpness default: 0 (off) Pro

Sharpness (general sharpening, in the colour column): a quick final touch of the fine detail over the whole image, from 0 to 200, after colour, tint and contrast and independent of the sharpening column (and of the zones of the Sun mode). It is a small-radius unsharp mask (1 px) on the brightness only: every pixel is scaled like its brightness, so no colour fringes are born. It never goes beyond the darkest and the brightest of the neighbouring pixels (within 2 px), so there are no bright rims, no dark halos and the white does not rise.

Smooth limb default: 0 (off) Pro

Strong filters turn the edge of the disk into a saw-tooth (the Sun, but also Jupiter against the sky). Smooth limb, from 0 to 100, smooths it while the limb stays sharp; disk, sky and prominences do not change. It is the very last step, after Sharpness; it does nothing on the Surface target (the Moon).

Filament threshold default: 3, from 1 to 8

How much darker than the surrounding disk the filaments must be. Used by Adjust: Filaments and by their colour.

Spot threshold default: 6, from 2 to 15

How much darker than the surrounding disk the spots must be (umbra and penumbra, compact parts).

Plage threshold default: 3, from 1 to 8

How much brighter than the surrounding disk the plage must be (extended bright zones).

Show the zones default: off

Draws the zones over the finished image, to see whether they match while you move the thresholds. Zone opacity (0 = invisible, 100 = solid, 50 by default) sets how much the marks cover the image, and a check box for each zone chooses which to show. Every zone has a colour and a mark, written next to its name, so they can be told apart without seeing the colours: Sky · dots, Disc · dashed outline, Prominences · oblique lines, Filaments · solid, Spots · double outline, Plage · horizontal lines. Sky and disk are off at the start. On screen only: the zones never go into the saved images or the parameters.

Adjust: Disc / Prominences / Filaments / Plage / Spots

At the top of the sharpening column, under the presets. The sharpening sliders below (Wiener, deconvolution, detail, unsharp mask, noise and soften) apply to the chosen zone; switch zone and the sliders show that zone’s values, while the values of the zone you left are kept, its switched-off sliders too. A zone you never touch uses the same filters as the disk. The settings blend at the zone borders. The sharpening works on the linear stack, before the solar tools: on the faint prominences you can push the detail harder than on the bright disk, or calm the noise of the sky without softening the granulation.

Disc halo default: 0 (off)

Many telescopes add a halo of scattered light around the disk, often stronger on one side. Planet Engine estimates it sector by sector (72 sectors of 5°) in a band just outside the limb, ignoring the prominences, and removes it from the stack before everything else: 0 = off, 100 = all the estimated halo removed, up to 200 = twice the estimated halo. Inside the disk, where it cannot be measured, it is extended moderately, so the veil near the edge goes without inventing a disk profile that cannot be seen.

Flatten sky background default: 0 (off) Pro

From 0 to 100: looks at the whole sky background, outside the disk and the prominences, and removes glow, gradients and haze at the frame edges, leaving the sky even (100 = an even sky); it never takes the sky below its own level.

Show sky imperfections default: off Pro

Instead of the image, shows the sky stretched very strongly, after the chosen flattening, with the disk in black: the glow, gradients and patches that are left stand out at once. On screen only.

Invert default: Off

Negative: channel by channel, the colour is inverted too. Brightness negative: only the brightness, the colour of the filter stays. Negative on the disc only: the disk in negative, the prominences outside the edge stay positive. With Colour by zone you can then give the sky (white in a negative) any colour, black included, without touching the prominences.

False colour default: None and Colour strength default: 100

Puts the brightness on a black → colour → white ramp, as with the filter: H-alpha, Calcium K or White light. For mono captures, or to change the colour. It is applied after the negative, so a negative can be coloured too. Colour strength goes from 0 (grey) to 100 (the whole ramp).

Disc brightness default: 0, from −3 to +3

The exposure of the disk, in stops: +1 doubles the light, −1 halves it.

Prominence brightness default: 0, from −2 to +6

The exposure of what lies outside the edge, in stops. The gain applies to the faint light and decreases smoothly to nothing at the light of the limb, so the faint prominences rise and join the limb without turning its edge into a burnt ring. With the disk brightness it works like two exposures of the same image.

Limb darkening default: 0 (off)

Compensates the darkening towards the edge of the disk, estimated from its average profile: 0 = off, 100 = a uniform disk. It is corrected on the linear light, before the brightness sliders.

Disc evenness default: 0 (off) Pro

Corrects the brighter or darker patches that an etalon leaves on the disk, while the limb darkening stays intact: 0 = off, 100 = even light.

Even out contrast default: 0 (off) Pro

Brings the contrast of the fine texture (fibrils, granulation) to the same level over the whole disk, where an etalon leaves it uneven; plage and filaments stay as they are: 0 = off, 100 = even contrast.

Zone Disc / Prominences / Filaments / Sky / Plage / Spots

The zone that the colour, hue, saturation and brightness below apply to. Each zone keeps its own values. The colour is applied on the final look, after negative and false colour: the sky colour changes only the sky, the prominences stay as they are, in the negative too.

Colour default: Original

Original: the colour that is there (false colour included), with adjustable saturation and brightness. Chosen tint: the hue below, with the light of the zone. Solid colour: the whole zone in one colour, for the sky; it works like a mask over the disk and the prominences: they stay untouched, like a layer on top, and the colour goes only on the sky, and it looks the same at every hue, in positive and in negative. A prominence fainter than the chosen colour stays as it is, so it can look darker than the background; to make it stand out, choose a darker sky or raise Prominence brightness. Black and white: no colour. Black, White: the zone filled. Under the menu, a row of ready colours, each with its name written on it (Black, White, Grey, H-alpha red, Orange, Yellow, Gold, Calcium violet, Blue, Light blue, Green): one click gives the chosen zone that colour as a preset tint: every pixel takes its hue and keeps its own brightness and saturation, so the colour is uniform and the prominences take the same tint as the disk.

Hue, Saturation, Brightness

Hue of the chosen tint, in degrees (0 red, 60 yellow, 120 green, 180 cyan, 240 blue, 300 magenta), shown with a small swatch and the name of the hue in words. Saturation of the zone, 0 to 200%: 100% = as it is (or the full tint), 0 = grey. Brightness of the zone, −100 to +100: −100 black, 0 as it is, +100 white. With the white sky of a negative, −100 brings it back to black.

Language and Interface colour Free

The language of the whole program and the accent colour; see First steps and Tips.

At start-up default: Defaults Free Pro: a preset

The settings the program starts with: Defaults, Filters at zero, or (Pro) one of your presets. Parameters saved with a video always take precedence.

Sensor pixel (µm) and Aperture (mm) default: 0 (not set) Free

The data of your telescope. With them, the Result box adds the focal length and focal ratio and the sampling in pixels per λ/D, with a judgement (undersampled, a bit low, right, oversampled) that takes into account whether the camera is colour or mono. The pixel size is used only when the camera is not written in the SER: for ZWO, QHY, Player One, ToupTek and SVBony cameras and Sony IMX sensors it is read from the file. For Jupiter, Saturn and Mars the box always shows the scale in arcseconds per pixel, from the measured size of the disk and the distance of the planet on the night of the video (from the SER time stamps, the file name or the file date), and the measured resolution in arcseconds and in λ/D.

Computing default: Automatic Free: processor Pro: graphics card

Where the heavy part of stacking runs. Automatic uses the graphics card if there is a suitable one (NVIDIA with CUDA, or Intel and AMD with OpenCL), otherwise the processor; Graphics card and Processor force the choice. In the Free edition the menu stays on Processor; your choice is kept for when Pro is active. On Windows 7 graphics card computing is not guaranteed. The result is the same, within a few hundredths of a percent; the Result box says which was used (for example GeForce RTX 3050 Ti Laptop GPU (Cuda)). If the card fails, stacking is redone on the processor by itself; the log says which card and why, and the full detail goes to %AppData%\Planet Engine\errore-scheda.txt, to send with the report. Measured: a 3-minute Jupiter video, 51 s on a Ryzen 9 9950X and 22 s with an RTX 4080; an 8000-frame Jupiter video on the whole frame, 357 s on a laptop Ryzen 7 5700U and 135 s with its RTX 3050 Ti. The frame analysis and the reading of the video still run on the processor: keep the videos on a fast internal disk, since a slow external disk can take as long as the stacking.

Keyboard shortcuts… Free

The list of commands with their key: open a video (Ctrl+O), undo (Ctrl+Z), redo (Ctrl+Y), remove the preview box (Esc), switch the last touched slider off or on (W). Click a command’s key, then press the new one (Ctrl, Shift or Alt allowed); Del removes it. If the key belonged to another command, that one is left without and the window says so. Defaults brings back the original keys.

License…

Opens the Planet Engine license window: the edition in use, Pro activation and the 7-day trial. See Licence.

About Planet Engine

Version, credits and the people who support Planet Engine.

Activate Pro Pro

Type the e-mail address you bought Pro with and press Activate Pro (or Enter). Planet Engine asks the licence server for the licence linked to that address and installs it at once: Pro version active: every feature is unlocked. After a purchase, Renato enables your e-mail on the server; then you type it here. If the computer has no connection, you can paste a licence text into the same box instead of the e-mail. If the address has no licence, the window says so: check the spelling, or use the address you bought Pro with. The purchase of Pro will be available soon (Coming soon).

Try Pro free for 15 days Pro trial

The button Try Pro for 15 days: every feature, free, for 15 days on this computer. No e-mail is needed: the server only receives an anonymous code of the computer. The days left are shown in the window. When the trial ends Planet Engine goes back to Free by itself and says so in the log; the trial can be used once per computer, and the button is offered only if you have no licence and have not used it there yet.

Use Free Free

Analysis, advanced stacking, sharpening, noise, colour, curves and caption: free, with no expiry. Every saved image (PNG, JPG, TIFF) carries the Planet Engine logo, also without a caption; a FITS never does. The Pro features stay in view with the padlock. The first time, closing the window without choosing (Later (Free)) also means Free. The choice is kept with new versions too.