How to set size/rotate image in jekyll?

Jekyll seems to accept attribute lists. You can set the size of an image as follows:

![steam-fish-1](/assets/steam-fish-1.jpeg){: width="250" }

(or use height="250"). The property value is in pixels, and should (according to the HTML spec) not have explicit units.

Markdown doesn't have built in support for image-sizes, so the only real solution is to use a little HTML inside your markdown. Given that, my jekyll-image-size plugin can do the resizing you need without any CSS.

Example:

<!-- template -->
{{ /assets/steam-fish-1.jpeg:img?width=250 alt='steam-fish-1' }}

<!-- output -->
<a href="/assets/steam-fish-1.jpeg" width='250' height='YYY' alt='steam-fish-1'>

(Where YYY is the actual, proportionally scaled height of your image.)

If you need the absolute_url filter:

<!-- template -->
<a 
  href={{ "/assets/steam-fish-1.jpeg" | absolute_url }} 
  {{ /assets/steam-fish-1.jpeg:props?width=250 }} 
  alt='steam-fish-1'
>

<!-- output -->
<a href="http://test.com/assets/steam-fish-1.jpeg" width='250' height='YYY' alt='steam-fish-1'>

For rotating your images, would it make sense to just rotate the image file itself?

If there is no way to include a size/rotation attribute to a Jekyll generated HTML code (as illustrated here, see the comments)... there is always the CSS route.

See "Resize image proportionally with CSS?": you could add a CSS stylesheet to set the size of your picture. Or even rotate it.

With jekyll-image-size, should use

<!-- template -->
{% imagesize /assets/steam-fish-1.jpeg:img?width=250 alt='steam-fish-1' %}

<!-- output -->
<a href="assets/steam-fish-1.jpeg" width='250' height='YYY' alt='steam-fish-1'>