Smarter Sharpening: Sharpening For the Image at Hand - Part II
The image below was made back in July of 2007 during a workshop at Olympic National Park. This is the Sol Duc River as it plummets over Sol Duc Falls. I took the photo from the footbridge that spans the falls. Heavy rains had paused briefly and the air above the falls was soaked with mist.
After performing basic post-processing and resizing for desired output (i.e. 720px long for this website) I've reached the time to perform some image sharpening. What is clear to me immediately is the need to bring out some details in the forested area. What I do not want to disturb is the silky smooth water of the Sol Duc River. Though, looking closely, the water might benefit from a slight boost in contrast, giving it a little more punch and visual depth. I probably should have performed contrast enhancements earlier on in my workflow, but I believe that it can be accomplished while sharpening.
I'll start by duplicating the background layer, naming the new layer "High Pass Sharpening". Next, I'll isolate the forested area, leaving the water alone. Since the river is pretty contiguous, I'll use the "Magic Wand Tool" to quickly select the flowing water. I'll then invert my selection, thus excluding the river entirely. I could have set up a mask here, but since selection was so easy, I'm not going to waste the time. I'm now ready to sharpen the forested area. Before I proceed, let's review the steps taken up to this point.
Step 1: Duplicate the background layer.
Step 2: Use the lasso tool to quickly select the river.
Step 3: Invert the current selection (Shift+Ctrl+I).
To sharpen up the forested area, revealing more detail, I'll apply a high pass filter to the current selection. For this image, a pixel radius of 0.8 seems to look about right. Use the preview box to judge the effect of the filter while moving the slider left or right. When using the high pass filter, you should see what looks like a bass relief of the original image. Focus on getting the right amount of detail within the high pass filter preview window. Somewhere between 0.5 and 2.0 pixel radius is often optimal.
After applying a high pass filter, I'll change the blending mode of our High Pass Sharpening layer to Soft Light. This will show me my sharpened image. This blending mode also affords me a bit of contrast in the running water.
Reviewing the previous two steps:
Step 4: Filter -> Other -> High Pass
Step 5: Blending Options -> Soft Light
In the case of this image, applying a selective high pass filter to our sharpening layer brought out good detail in the forested area while sparing the smooth flowing water. By setting the blending mode of that layer to Soft Light, the river water received a nice, punchy contrast boost.
Not bad!
Jamie, JFP
Questions? Comments? Errors, typos, screwups, doh's, etc? Use the contact form.
|
|
