Sometimes lighting may lead to a haze like effect in photos. There is an easy method that you should always try first. It often works. All you need is Photoshop. Any version will do.
Step 1 : I have opened this photo in photoshop. I have been asked to remove the haze.
Step 2 : Press CTRL+J. The Background Layer duplicates into Layer 1.
Step 3 : In the Layers pallete click where the red arrow points to, reveal the Blend Mode. Click on Overlay.
You can notice an immediate difference.
Step 4 : Again press CTRL+J. Layer 1 duplicates into Layer 1 copy.
And the Haze has disappeared. Almost.
Step 5 : Press CTRL+J again. A Layer 1 copy to forms.
And, The haze has been removed.
Other Photoshop tutorials are here.
