I am creating a web service for my online shop and need to generate invoices, i know how to generate invoice and pdf invoice but what i want to know is how to generate image invoices like jpg or png for example.
You could try using: https://github.com/xvilo/invoice-generator or https://github.com/Invoiced/invoice-generator-api
Google has many options when searching for "PHP invoice generator".
I hope this helped.