Hello to make them losslessly compressed there are few tools you can use if you dont have root right to the webhost.
PNGOptimizer - Converts into PNG other lossless image formats (BMP, GIF, TGA).
Platform: Windows
At a tiny 146KB download, PNGOptimizer is the smallest program here, so it's no real surprise that the interface is a little basic. Or that it concentrates on PNG files.
http://psydk.org/PngOptimizer
FileOptimizer
Not only can it compress JPG, GIF and PNG images, but it can also work with executable files, archives, Microsoft Office documents, PDF files, and the list goes on.
http://nikkhokkho.sourceforge.net/static.php?page=FileOptimizer
Other Way is to check your phpinfo
1) Open notepad
2) Write
<?php phpinfo(); ?>
Save as info.php upload to server and see if you have mod_deflate & GZIP on
then upload to your .htaccess file
<IfModule mod_deflate.c>
# html, xml, css, and js:
AddOutputFilterByType DEFLATE text/html text/plain text/xml text/css application/x-javascript text/javascript application/javascript application/json
# webfonts and svg:
<FilesMatch "\.(ttf|otf|eot|svg)$" >SetOutputFilter DEFLATE</FilesMatch>
</IfModule>
don't forget to add above the image type i am sure that png can be done only jpegs are already compressed.
Have a great day
From: Shomron David
Hawk-Tech