Hey all: So, yes, it appears we're hard coding these sizes. That's fine for compact album sizes since those have always been fixed in size, but not for extended albums.
Changing the CSS for extended albums to the size you want won't resolve this, because the underlying thumbnail is still the same size, which means that you're thumbnail is one size, the CSS is another, and the thumb will be pixelated.
As @rakupa pointed out, the only quick fix for this to go to this file:
You'll need to look for these lines (around line 153ish) and change the thumbnail dimensions to what you are looking for:
// legacy templates expect these dimensions
$image_gen_params = array(
'width' => 91,
'height' => 68,
'crop' => TRUE
I will add an issue for this for the developers. We'll need to re-add the logic for this, and think about the best way to do it.
I'll make this relatively high priority, though I will want to be sure we get through issues that are having more dramatic impacts on people's sites or basic gallery functionality first.
Again, apologies for being slow on the uptake here. If you have other thoughts or questions, let me know. (Erick)