Full size image

in
bp-album\includes\templates\album\pictures.php

<div class="picture-thumb-box">

	                <a href="<?php bp_album_picture_url() ?>" class="picture-thumb"><img src='<?php bp_album_picture_thumb_url() ?>' /></a>
	                <a href="<?php bp_album_picture_url() ?>"  class="picture-title"><?php bp_album_picture_title_truncate() ?></a>
				</div>

change
bp_album_picture_thumb_url

to
bp_album_picture_middle_url

then you can adjust the size in css.

.picture-thumb-box a img {

    max-height: 400px;
    max-width: 600px;
}

It depends on what you mean by “full sized image”. BP-Album resizes uploaded images to fit within the maximum image dimensions you set, to save disk space. If we didn’t do this, users could upload huge files (20MB+) and use up all your disk space.

The code above that @deepbevel posted is what most users would be looking for in this situation. Thanks!