How can I achieve the dramatic sky as seen in these sample images?

Question

Below are some samples. Is this effect made with an optical filter or is it edited during post processing? In either case, what it is called?

• http://jpgmag.com/photos/3181099
• http://jpgmag.com/photos/3202143

Answer

In considering the second image I found an example out of my own collection as an example image to illustrate my point.

Before adjustments: After adjustments:

I think what you are looking at may have been achieved with HDR, as I did with my example images. I used Photomatix Pro with 3 source RAW files to achieve this. Outside of Photomatix, I did not process any further. The images that you provided look to have quite a bit of grain, so you could add that in. My original images did not have any filters applied to them.

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