Hello.
First, please post your qustions about DirectResize 0.8 in
this topic, not here.
$resize_method manages only method to calculate the height and width of the thumbnails. If only width is set on the source image, $resize_method automaticaly sets to 1. So this parameter does not affect the result in your case.
Whether or not the image is processed by plugin depends on the parameters $lightbox_mode and $allow_from (read the manual). If you are using default config file, all
supported images in "assets/images" folder must be processed by the plugin, if it was correctly installed.
BUT, as readme said "Support for JPG and PNG files (
GIF is not currently supported)"