Topic: Image preview and upload


I have some questions regarding the upload of images in my web app. My idea was to upload an image, generate thumbnails and store them in a blob column in the database.
How can I implement this? I found some gems like Carrierwave and Paperclip, but from what I understand pictures are uploaded to filesystem and not to database, am I right?
How can I implement an image upload, thumbnail generation, and save to blob quick and dirty?

Many thanks in advance!