Expositio theme – Vectorial images blurry and undefined

Hi, I’m working in Expositio Theme (localhost), in the child.
My problem is with the quality of the uploaded images. It’s really bad. I’m trying to add vectorial images (just 2 colors) saved for web (tried png, jpg), and they appears blurry and undefined. I tried to add the following code in functions, but it doesn’t work. How should I do it? The photographies are in good quality, but not the vectorial images.

add_filter(‘jpeg_quality’, function($arg){return 100;});
add_filter( ‘wp_editor_set_quality’, function($arg){return 100;} );

I attach some leaves of the theme, just in case you need it:

Functions.php : http://pastebin.com/8DsX5tGu
Style.css: http://pastebin.com/0wbmNggZ
Conten-page.php : http://pastebin.com/yLHveBzm
Header.php : http://pastebin.com/2tje87ck