Basic tools
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If you have extracted a plot and want data from it, tools like g3data and , WebPlotDigitizer, GraphClick can be very useful (other options discussed here). These allow you to point and click to grab data points and save them as a spreadsheet. For continuous curves, DataThief can nearly automatically recognize the curve in most cases.
For precision when selecting points, you can use a feature called "mouse emulation" to control the mouse by the keyboard. This will allow you to get exactly the right pixel of the plot with ease.
If the paper is more recent, it probably would be a better use of your time to email the authors than to extract the data yourself. This has the added advantage of introducing no transcription errors into the data.
If the paper was part of someone's PhD research, frequently the data will be tabulated in the dissertation. Tracking the dissertation down may also save time and reduce transcription errors.
Creating animated movies and gifs
Webm Movies
sudo apt-get install mjpegtools
sudo apt-get install vpx-tools
png2yuv -I p -f 24 -b 1 -n 1440 -j my_image_%05d.png > my_vid.yuv
Where:
-I p Non-interlaced.
-f 24 24 frames per second.
-b 1 Start with image number 1.
-n 1440 The number of images to process.
-j my_image_%05d.png The file name pattern. %05d is the expanded to 00001, 00002, ..., 01440. %03d would expand to 001, 002, etc.
> my_vid.yuv Send output to a file instead of dumping it to your console screen.
vpxenc --good --cpu-used=0 --auto-alt-ref=1 --lag-in-frames=16 --end-usage=vbr --passes=2 --threads=2 --target-bitrate=3000 -o my_vid.webm my_vid.yuv
Gifs
convert -delay 20 -loop 0 *.png mygif.gif
http://blog.ahfr.org/2008/03/making-animated-gifs-with-free-software.html