Add a warm, antique feeling to your photos using the 'Sepia' filter effect. This is done by setting the effect parameter to sepia (e_sepia in URLs). You can also customize the strength of the Sepia effect.

Here's an original example image:

And here's the same image after applying the sepia effect:

In order to customize the effect's strength you add a colon and the strength of the effect. While the default value is 80, you can specify the strength between 1 and 100. For example:

You can add any further transformations, for example - changing the strength to a higher value, resizing, cropping to a circle, and adding a watermark: