There are websites like http://bufferapp.com which can schedule tweets. I'm not sure if Bufferapp can also upload images directly to Twitter (I didn't use it for a while) but you can always upload them to e.g. http://twitpic.com and put the links to tweets that are about to be published.
HootSuite! Yes. Weird how I forgot about that. I think that might actually work even better than TweetDeck. It's a matter of personal preference, I guess.
Twitter will not schedule your tweets and the official OS X client allows. Web allows you to organize tweets, but if you try to add a picture, do not let it. This is a separate issue, but the more you make the more boring Subscription olisi.ongel web can go all fuzzy think would work better, but, but very easy to pull off.
Yes, HootSuite has great image uploader, but you can't schedule tweets with big images like on exact twitter’s posts. The only option is links.
Before tweetdeck my work-around for that was uploading to yFrog or TwitPic and then scheduling a tweet with a link to that photo in HootSuite. The only disadvantage of that method is that both yFrog and TwitPick kind of suck compared to twitter's own photo-posting.