Camera notes

Pi Settings

Increase the memory available to the GPU from 128 to 256 on the pi configuration>>performance [memory]

Tip: If you want a continuous camera preview it is unfortunately not exitable. To exit camera preview use Ctrl+Alt+t to get a new active terminal (hidden behind the preview, which you can then blindly type pkill python3 or similar to kill the preview)

Pi Camera CLI

grab a preview without recording, also configure the different effects modes and exposure modes

raspistill --imxfx colourswap -t 60000 --rotation 270
raspistill --imxfx none --exposure nightpreview -t 60000 --rotation 270

Grab a still

raspistill -o Desktop/image.jpg

Grab a raw video

raspivid -o Desktop/video.h264

Python PiCamera package

docs https://picamera.readthedocs.io/en/release-1.13/

• Set resolution max (2592x1944) https://projects.raspberrypi.org/en/projects/getting-started-with-picamera/8 . Note framerate of 15 caveat...

• Consistent exposure image sequence (esp. for timeseries) https://picamera.readthedocs.io/en/release-1.13/recipes1.html#capturing-consistent-images

• Low lighting settings (needs tweaking) https://picamera.readthedocs.io/en/release-1.13/recipes1.html#capturing-in-low-light

• Various methods for image series capture

  • https://picamera.readthedocs.io/en/release-1.13/recipes1.html#capturing-timelapse-sequences
  • https://projects.raspberrypi.org/en/projects/cress-egg-heads

Using avconv for timelapse sequence video collation

https://projects.raspberrypi.org/en/projects/cress-egg-heads/10

avconv -r 10 -i image%04d.jpg -r 10 -vcodec libx264 -crf 20 -g 15 timelapse.mp4

this uses zero prefix padded numbers.

To create a timelapse with non-zero prefix padded numbered files i.e. 1,2,3...300 rather than 0001,0002,...300.respectively image%00d.jpg rather than obased image%03d.jpg)

avconv -r 10 -i cat-spy_%00d.jpg -r 10 -vcodec libx264 -crf 20 -g 15 timelapse.mp4

Composite Image generation

Using Python PIL (pillow) package to generate a Composite Image https://pythontic.com/image-processing/pillow/alpha-composite.

PIL Image class provides two options here (see above link) blend() and alpha_composite() see here:

Using ImageMagick

• Composite Func https://imagemagick.org/script/composite.php
• Blend Func https://imagemagick.org/script/command-line-options.php#blend

Playback (raw video .h256)

raw video format player playing on pi3 .h256 raw video (on pi4 the vlc works but not pi3) see https://www.raspberrypi.org/documentation/usage/video/ using omxplayer

omxplayer video.h256

convert to mpg

ffmpeg -r 30 -i video.h264 -c:v copy video.mp4