- the name of the images (it looks for words that often are used for previews like “folder”, “freebie”, “preview” etc)
- the closeness to the download link it thinks is a freebie.
If your images have names like “740692.png” etc, the system has no clue what that means and it is more likely to choose an image that has a more meaningful name.
- Remember that the only images the system can “see” are those that are shown in the blog feed, NOT the blog post. So you need to check your image is shown in there.
- If you have only one image in the blog feed entry, then that image is assumed to be the preview.
- The best thing to do it to just make sure that the links to your freebies are “wrapped around” the preview image, i.e. that you have [A LINK TO FREEBIE…][PREVIEW IMG…][/LINK] which looks something like this in HTML: <a href=”http://draft.blogger.com/myfreebie.zip”><img src=”freebie-preview.jpg” /></a>.
- If your entry has multiple images, the system will either choose one that has indicative phrases in it (like “free”, “folder” and “preview”), or otherwise it will select the closest image to the freebie download link, or the last image since often people put the freebie last.
Remember that there may be images in your post that the blog host puts there, like “Email This” types of buttons. Quite frequently the names of previews are some random number, so a system doesn’t have a lot of information to work with and just makes the best guess it can. Sometimes Feedburner etc will corrupt the image links too which causes problems. I apologise for those cases where the system gets it wrong, but in the vast majority of cases it is correct or close enough and I think it is helpful for people to see previews here rather than no images. Sometimes this can go very wrong though, and I correct the really bad ones when I can. But mostly I don’t because there are just too many to go through.
Why are images sometimes blank?
Sometimes images are blank if the reference to an image which is selected from the feed is actually invalid. This happens sometimes in blog feeds but unfortunately there isn’t a way for a system to identify this automatically. Try naming images carefully as above.