Problem with images display

Hi
Few weeks ago, I had problem with the images impossible to upload.
Now I can upload images but the system change the images I am trying to upload. The images appear blurred or even blurred with little modifications as you can see below.
What can I do?
This question of images is really frustrating

Actual image (any upload gives the same result):

Previous image:



Another issue I just noticed maybe related, the component Hikashop is running very slow on the administrator part of my website. It is impossible to access to the configuration. The other parts of the website are working very well.

Hi,

What can be done is import your images via ftp in the desired folders
"media/com_hikashop/upload" for the main images and "media/com_hikashop/upload/thumbnail_100x100" for the thumbnails (100x100 is the default value, you have to replace that with your parameters).
Then in the product edition page, select the image with the "select" button.

I will try to do that, but this is a strange solution when there is a direct option.
That means there is no solution for such problem? Do you know the reason of this modification of images being blurred?

I understand how to proceed regarding the upload category, but I don't know how to proceed with the thumbnails?
As you can see in the screenshot I have several folder, so which one I have to choose and may I have to change the format of the picture?