I'm using this tag but it does not support webp format file it does not show image on pdf for webp format. images for other formats it is working fine
<%= wicked_pdf_image_tag(my_img, height: '300') %>
Wicked PDF is a wrapper around wkhtmltopdf. And currents stable version of wkhtmltopdf doesn't support webp: https://github.com/wkhtmltopdf/wkhtmltopdf/issues/3977
If webp support is important for you, you should be looking for other gems. But I think, will be easier to store converted image in png/jpeg format specially for pdf.