Hi,

You can either use img tag in report to add the image to report pdf.

<img src='/module_name/static/src/img/name of image file' style="your custom style"/>

Or 

You can span the field containing the image in the report pdf.

<span t-field="line.image" t-options='{"widget": "image"}'/>

Or 

Add the image source dynamically.

<img t-if="company.logo" t-att-src="image_data_uri(company.logo)" class="float-left" alt="Logo"/>

View similar forum post before

https://www.odoo.com/forum/help-1/question/display-image-in-qweb-report-76746" target="_blank">https://www.odoo.com/forum/help-1/question/display-image-in-qweb-report-76746

Hope it helps