We always have a choice about how to perceive things. We can be positive or negative. Attitude begins inside us. Choose to be influenced by information all around you or learn to step back and see it for what it is. Realize that anything you hear about in "news" is simply someone's opinion about what is important at a give time. Images are shaped based on what newscasters wish you to see and feel.
Ask yourself why news broadcasting agencies often have different daily and even hourly headlines. Networks compete based on which station can offer a story about the most shocking incident or tragedy. Shock value often builds audiences and thus boosts ratings. As you learn to see through such systems, you may learn not to permit it to affect you in the same way. Did you ever see the film, Broadcast News? That is an example of how editing behind the scenes can include an enormous amount of manipulation. What people think is emotional also sells advertising time or sponsorship dollars.
Once you realize that people use news to try to manipulate your emotions, you can learn to desensitize yourself from media images. This doesn't mean you ignore world conflicts or crises entirely, but you can obtain information from varied sources which would enable you to be more objective and less negative overall. I would encourage you to learn to decide what you consider is worth your time and attention. Your priorities evolve based on how you understand images are manipulated to manipulate your perception and values. I think its especially interesting to consider why you think an image is sad or beautiful.
If you're interested in manipulated images, take a look:
Dove