I will use the Seagram Building (architect: Ludwig Mies Van der Rohe) as an example for this tutorial. While walking around Manhattan with my professor and classmates we passed by the Seagram building located on Park Avenue and I had just enough time to take only a couple of photographs.
Here are some steps to take to clean up the photograph:
Step 1: Transform
a. Lens Correction: Go to Filter>Distort>Lens Correction
b. Use the Vertical and Horizontal Perspective sliders to adjust and align edges with the grid. Not everything may not align so there is another option to use after the Lens Correction tool
c. Free Transform: Hold CTRL A to select the whole photograph, the hold CTRL T to enter Free Transform, then right click and select skew
d. You can set up guides by going to view>Rulers and click and drag off of the ruler to bring down guide lines.
e. Adjust the image as needed and then hit enter
Step 2: Levels
a. Go to Image>adjustments>Levels
b. Slide the black tab right, and the white tab left until you see desired results in brightness and contrast.
Step 3: Sharpen
a. Unsharp Mask: Go to filter>Sharpen>Unsharp Mask
b. A good setting to use is to have it around 30% or 40% amount and a radius of 3.0. I would not increase these values too much; the photo will start to lose its quality.
Step 4: Color
Vibrance, Hue/Saturation, Channel Mixer, and Selective Color.
Step 5: Desaturate Top Layer
a. Under the layers tab select the background layer, right click and select duplicate layer
b. On this new layer I will de-saturate the photograph.
Step 6: Reveal Orange
a. One way I can do this is to use the rectangular marquee tool, select a window and use this to delete the selection from the b&w layer.
b. To make the process go faster, set up guides to lock the selections to, and after making the first selection, hold the CTRL key to add to that selection.