./var/www/projects/.../0401b0ca555959f391752bb1b0ea9ba1.jpg
The '.' before that means that it will be looking in current directory for a folder called var.
You will need to remove this . in order to begin at the root. Which is correct.
This is how it should look '/var/www/projects/.../0401b0ca555959f391752bb1b0ea9ba1.jpg'
It looks like you are trying to use cURL to get the image, so i suggest you should try and change the image to be a URL such as http://URL of project folder/../0401b0ca555959f391752bb1b0ea9ba1.jpg
Other than that suggestion its hard to know what is happeneing but i suspect the TCPDF is not playing nicely.