Managing Generated Images
Jekyll Picture Tag creates resized versions of your images when you build the site. It uses a caching system to speed up site compilation, and re-uses images as much as possible. Filenames take the following format:
(original name without extension)-(width)-(id-string).(filetype)
Try to use a base image that is larger than the largest resized image you need. Jekyll Picture Tag will warn you if a base image is too small, and won't upscale images.
By specifying a
source directory that is ignored by Jekyll you can prevent huge base images from being copied to the compiled site. For example,
source: assets/images/_fullsize and
output: generated will result in a compiled site that contains resized images but not the originals. Note that this will break source image linking, if you wish to enable it. (Can't link to images that aren't public!)
output directory is never deleted by Jekyll. You may want to empty it once in awhile, to clear out unused images.