Question about the Thumbnail Creation

-- HikaShop version -- : business 2.2.3
-- Joomla version -- : 3.2.2
-- PHP version -- : 5.4.10

Hey there,

i have a question that confuses me.
Read that Hikashop will generate thumbnails as per needed basis.
So I deleted any thumbnails folders inside the upload folder and then refreshed the front-end.
My images sizes settings are set as :
Thumbnail width 200
Thumbnail height 200
Product page image width 480
Product page image height 480
Image width 1400
Image height 1400

However in the upload folder I see the generation of the following thumb folders:
thumbnail_150x146
thumbnail_200x200
thumbnails
-> 480x480

What is generating the 150x146 ? and where it might be used ? Why there is this different folder structuring way for the different dimensions ?
Also, what is the method when setting both dimensions for generating the thumbs ? Cropping ? Especially when uploading images. Is it possible that it will destroy the aspect ratio ?
If I set only the one dimension in the images sizes options and the other set it to auto, it creates even more thumbs folders with various dimensions combinations.
What is the appropriate method for keeping images aspect ration untouched ?

hello Jerome,

I removed and it is being recreated each time, that's why I asked the question, because I don't have anywhere any settings for this thumbs dimensions and while I was experiment with these features it was a bit confusing.
Thanks anyway.