The blob cache is meant to save database access, because binary files (like images) will be stored on the webfrontend server. Sometimes you will run into problems like I did a couple of days ago.
So I had to flush my cache with this little script:
$webApp = Get-SPWebApplication 'WEBAPP'
[Microsoft.SharePoint.Publishing.PublishingCache]::FlushBlobCache($webApp) An you're done. Pretty easy.