Is it possible to set a different thumbnail size for different pages?
For example, I want the thumbnails on my category, archive and tag view to be bigger than on my home.php.
Right now I have the following code in my function.php:
add_theme_support( 'post-thumbnails' );
set_post_thumbnail_size( 250, 165, true );
Do I have to modify my function.php or is it also possible to modify the thumbnail size in the home.php where I want the size to be different from index.php?
In your functions file you need to add image sizes:
http://codex.wordpress.org/Function_Reference/add_image_size
Here is the one you need:
http://codex.wordpress.org/Function_Reference/wp_get_attachment_image
And some examples of how to use it:
That way, It will return an 300 width and 200 height image. But yeah, @Alex makes a right point here. Use add_image_size is easier.