DanK's tutorial on the use of Zerene stacker and LR has inspired me to do a little demo on what the LR Adjustment Brush can do. Please note that this is based on a RAW file.
I'll start with the BEFORE image - one I very nearly discarded. The BG was messy, and in harsh direct daylight. I used my diffuser for the flower but the sun was 90 degrees to the axis of the lens, resulting in some terrible highlights. Since the BG really couldn't be salvaged, I decided to make it black.
When I zoomed in, I noticed the blemishes near the top of the flower.
The first thing I did was to set LR4.4 to the 2012 process with the camera profile set to Camera Faithful - I prefer this as it tends to give me more detail in petals.
Then I set the WB to Daylight, and selected Auto for exposure, etc. At this point, it's wise to hold down the Alt key, and click the mouse on Highlights and Whites to check for blown out areas; these can often be salvaged with a negative correction (to the left).
Next step is to remove the blemish with the touch-up brush (not the adjustment brush). I use the CLONE setting rather than the HEAL setting as it allows me to select where the "patch" is coming from. The keyboard command for this is "Q". Zoom in by three (3.0).
Then I selected the Adjustment Brush (keyboard K), and used the following settings:
Exposure = minus 4.00
Contrast, Highlights, Clarity, and Shadows settings don't matter with Exposure at minus 4.00.
With the brush set with Auto Mask checked (on), I traced around the edges of the flower. To obtain a very clean BG with no noise beyond the edges of the flower, I un-check Auto Mask when doing the main area that will be black (don't go over the flower or you'll have to UNDO).
The upper left still had some bright areas, so I selected another Adjustment Brush with the same settings and repeated the masking procedure. This resulted in a completely black BG. A new feature in LR5 (just issued) is that a brush can be duplicated - a real time saver with a complex flower.
One more step (optional):
One more Adjustment Brush, but with values thus:
A little bit of positive clarity and contrast with the Density set rather low, and brush over the parts that are in relatively good focus and that have some interesting lines/features. This can be used to bring out the details.
I also used the HSL sliders, with the Red and Orange Hue sliders at +12 and +16 respectively (some would call this cheating, I refer to it as creativity).
That's it. It took me about 15 minutes to save it.
Glenn