Post processing can be difficult to even start if you do not know where you want to get. I always shoot in RAW format, as should you, since white balance is one of the key components that will most likely need to be corrected. This will be just one way I post process city images, there are many other ways to go about this and I usually follow one of three paths.
The tools (both hardware and software) that I am using in this are a Wacom Intuos5 Touch Small (I love this thing, I was first not sure how much it would help but it has made my workflow easier and faster, especially for portraits), Lightroom 4, Photomatix 32 bit HDR plugin for Lightroom, and Photoshop CS5.
I start by importing my photographs into Lightroom using my default MetaData which has my copyright information on it and some other information I find useful for organizing.
Below is the original base exposure for the photograph we will be working on.
My first step is to crop out the ledge, I decided to leave the corner in because I felt it did not take away from the image and it gave a sense of where I was shooting from. I chose a 16×9 crop which is a favorite of mine for cityscapes because it feels like a panorama without being one. From here I select the exposures I decided to merge to an HDR. With the Photomatix 32 bit HDR merge, all this is done in Lightroom, then you can use the develop module to change the image. After selecting your images (I used 5 after looking at the shadows and highlights needed) left-click on the image, export, Merge to 32-bit HDR. This takes a minute. After it is done, you may not see the image, go back to Library, and click all photographs, the image should be right before the images you used to merged. So for this image, I wanted to keep this low key HDR as I have been trying more and more lately. I first changed everything but the exposure and I got the results below.
I then sent this file to Photoshop (left click, edit-in, edit in Adobe Photoshop CS5). I then took the same file in Lightroom and I know I wanted the front buildings to be brighter, so I upped the exposure to get the results below.
I sent this file to Photoshop as well. I then copied this file and dropped it as a new layer on the first image. You can see below the bottom two layers are the two different exposures (Only the original exposure is visible).
From here, a layer mask is placed on the brighter exposure, and then the areas (sky, some of the background buildings) that I think should be the original exposure is painted in. With the sky, I always am careful not to get the edges of the foreground buildings because halos can happen or unwanted shadows. This is where the tablet really shines making painting layers in so simple and more natural. The results:
In most cases next I adjust either the levels or curves (I use both, this time I felt levels worked better). I wanted to brighten the image up so I raised the midlevel some and then brought back in the darks by raising the shadows up some.
Then I upped the Vibrance a little bit, I never touch the saturation slider, just the vibrancy depending on the image. Next, merge the visible layers, I then sharpen a little bit (especially if used for the web, for print I generally do not do this step). I used smart sharpen this time, but you can do a high-pass filter as well. Layer mask this and paint out the sky since you do not want to sharpen skies since it just introduces noise. (ignore the top two layers, this was done for a black and white version of the image). Here is the final result.
As I said above, this is just one way I post-process images, though this one is one of my most common ways. With Lightroom 4 I also skip the merge to HDR and just process the base image by itself in a similar fashion.
Now get out there and shoot. I know the winter is cold, but the sky is clear and the crowds will be out of your way!!