Recently while reviewing a draft of a video project, my client made the observation the store front was in desperate need of a power wash at the time the photo provided me was taken. The deadline was looming and there would not be time to get it washed and then shoot the picture. I mentioned to them I may have a technique to improve the appearance and they agreed to give it a shot. The trick was to not make it look too obvious and retain the textures of the architecture.
There are always different ways to approach it. The building faces were rectangular panels so I chose to cut the panels into new layers and change the blending mode to screen. This significantly lightened the image areas while preserving the underlying textures. I adjusted the transparency of the layers as needed. Adding a mask and using the brush tool the effect could be cancelled in areas where not needed such as the trees in front of the building. The client was very pleased with the results and we lost no time toward the completion of the project.
Final Cut X