Pinterest uses thumbnails instead full with images

Hi,

First, thanks for this great plugin !
It works fine, but I’ve a little problem with the Pinterest button.

All the pictures on my posts are displayed with the basic wordpress gallery tag.

When I click the Piterest button, it use the thumbnails (50px x 50px) instead the full width image.
The only image with the full width is the featured image of the post.

Any way to force Pinteres to use full width for all the images from the post gallery ?

Many thanks

Fonfon13

https://www.ads-software.com/extend/plugins/simple-share-buttons-adder/