The advanced method of filtering uses information about your image that is stored in the image file itself (called metadata). To read this metadata AWC must read all or part of the file from disk and decode it. Be wary when using this kind of filtering as the performance hit can be quite large, particularly across a network. The additional time is not generally a problem unless you are filtering very large numbers of files and, of course, the impact is only felt when the file list is being built in Folder Mode: there is no impact to the actual change process itself.
This is a more accurate but slower way of filtering your files by size: in this case by their physical dimensions rather that their file size. So, you can ensure that you only load files that are bigger than 500 x 500 pixels in size and less than 2000 pixels in width for example.
You can also choose to display only those files that are in a particular orientation. If you select landscape then only those files whose width is greater that their height will be selected.
Many people add comments to their files to record information about who is in the picture, what was happening etc. You can filter your images using the contents of these comments by entering words or phrases in the search box. As you would expect you can specify whether some or all of the words need to in the comment. When reading the comments AWC first tries to get the basic file comment for the file and then, if not found, looks for an EXIF ImageDescription Tag. If neither are found the file is not selected for display.
If you want to find all files that have comments in, irrespective of their content, just use the Windows wild card character * (asterisk).