Handling tracking pixel for GDPR purpose

Summary:

Hi All for GDPR purpose we need to identify the current setup we have in Eloqua for using tracking pixel. We know we are using tracking pixel to track mail opening from the recipients but we are not sure about the type of these tracking pixels. Are these unique tracking pixels for all emails sent or are they unique, for each mail, Contact or campaign? Our IT department is asking for this information.

To handle the legal requirement we would need to ask the single Contact to give his consent to let us use the tracking pixel. What should be the best approach to handle this? Use a custom development to trace the contact consent when acquiring his data?