Bridge minimalist (pb picture gallery : landscape -portrait On my page )

Hello everybody ,
Sorry for my English .
so my question is : I have bridge minimalist template in picture gallery : portrait-landscape problem

I 'm putting in place the picture gallery on my page, the problem is : when I used my pictures in portrait and landscape , they are not not the same format , the pictures have to be the same space (for example rectangle) tI would like to have the same high , same width no resize in order to see the same pictures (original), to avoid to seeing the resize pictures and go to the top or the bottom so please I just need to have a picture gallery who I can mix portrait landscape square or other size without problem to see the pictures

Best regards