Image Processing
Animations and surface stabilisations in PIPP
Animations and surface stabilisations in PIPP.
Build a sequence of shots to create a video of your favourite astronomical target
We’re taking another look at the freeware astro video processing program PIPP (https://sites.google.com/
site/astropipp), the key features of which we covered in our August and October 2017 issues. In our previous instalments, we discussed some of its basic editing functions; this month, we’re looking at how to combine your stills together into an animation and stabilise surface features on videos of the Sun and the Moon.
PIPP is able to convert video between a number of formats and readily split videos into individual frames. Conversion the other way around – that is, taking frames and stitching them together to make an animation – is just as easy. You might want to do this to show the
evolution of a solar prominence, the rotation of a planet or the movement of its moons.
The first step in making an animation is to add your set of frames to the list in the Source Files tab using the Add
Image Files button. When you select multiple frames, the Join function dialog box will pop up. Click Ok to link all the frames together. If the files aren’t in the correct order for the animation, you can shuffle them by clicking on the column headers – name, date and so on. Alternatively, you can select individual frames in the list and move them around using the up/down buttons. The next step is to go to the Output
Options tab and decide if you want to have a GIF or AVI animation. In most
cases GIF is most appropriate, as they allow you to set the animation to repeat indefinitely by ticking Loop Frames
Repeatedly. On this tab you can also set the GIF’s quality and the desired frame rate. Incidentally, the frame rate option can be used for any video, allowing for slower or faster playback speed than the original recording – a useful function, especially for creating timelapses.
Options and adjustments
Other animation related options are available on the Animation Options tab, and these include the option to introduce pauses at start or end of the sequence, and to determine forward and reverse playing. Once you have set all the options use the >
> Start button in Do Processing tab to then create your animation.
Another valuable PIPP feature allows you to adjust the gain (brightness) and gamma (contrast) of all the frames of your recorded video. This is great for bringing out details in footage such as all-sky camera timelapses or overly dark lunar drift videos. The gain and gamma controls are found in the top-left of the Processing
Options tab. To preview their effect on a frame, use the Test Options button at the upper-right corner of PIPP.
PIPP is adept at successfully aligning and stabilising lunar and solar videos so that difficult and jumpy videos can then work successfully in stacking programs such as AutoStakkert! and RegiStax. It will cope well with sudden positional changes due to pauses in the recording or sudden wind buffeting that might cause issues for the stacking programs without editing. To align a solar or lunar video, click on
Surface Features in the Processing Options tab and select Surface Feature Tracking and Surface Stabilisation. An ‘anchor feature box’ (AFB) will automatically appear in the preview image which will be the first frame of the video. You should drag the middle of the AFB onto a high-contrast feature such as a crater or sunspot and resize it by dragging the corners of the AFB until it fits the outline of the chosen feature.
Smoothing out wrinkles
A nice refinement for lunar and solar videos is that you can also set an ‘area of interest’ (AOI) for the video by clicking on the AOI box. This produces a box that every frame must contain, or else the frame is rejected. The use of an AOI prevents issues where the final stack might become a patchwork of dissimilar areas around the edge, each where different numbers of frames have contributed to them. The different regions require different amounts of processing and this can create annoying artefacts at their junctions.
You can position and resize the AOI box just like the AFB box, with the handles or via numerical entry. Do be aware that if the box is made too large you might find there are hardly any frames left which have not been rejected for not containing the AOI.
A final feature that may be useful is PIPP’s ability to perform lossless compression using the ULRG codec available on the
Output Options tab. This can be used for archiving purposes and reduces file sizes by about 30 per cent. Don’t worry, ULRG files can still be read by RegiStax and AutoStakkert!, should you want to reprocess them at a later date. S