Now that the tonal and color corrections are finished, the next step is sharpening. A question that often comes up is, "When should sharpening be carried out?" The answer actually depends on what type of sharpening is being performed. A two step sharpening approach was used with this image. One sharpening layer was created after the tonal and color corrections were completed. Another sharpening layer was created just before the image was printed. The first sharpening step was designed to sharpen for the image content. This sharpening step was fairly mild and produced a gentle sharpening. This first sharpening step should be performed after all global, tonal and color corrections (major corrections that affect the entire image) have been completed but before any local, tonal and color corrections (i.e., fine tuning of tone and color that is restricted to specific areas of the image). There is a reason for this. Sharpening is actually an increase in local contrast (i.e., the contrast along edges). Changes in tonality modify contrast (changes in color can also alter tonality and thus contrast). Therefore, large changes in tone can alter the contrast that defines the sharpening. Thus, the sharpening can be affected (usually degraded) by large tonal and color edits. One the other hand, performing a mild sharpening after the major edits creates a clearer image that helps the photographer make better, final, local editing decisions than if the image is soft. The second sharpening step was designed to sharpen the image for the specific output device (in this case an inkjet printer). This sharpening should be performed as the last step just before printing.
This image is a bit unique. All of the tonal and color editing affected such large areas of the image that it was decided to treat all of the edits as if they were global. Thus, the first sharpening step was not performed until all of the tonal and color editing was completed. Then, the image was interpolated and the second sharpening step was carried out.
The goal of the first sharpening step was to sharpen only the major detail. The finer detail had to be left alone. Thus, an edge mask was used. The edge mask identifies the edges of the major detail in the image and will only allow the sharpening to be applied to those edges. The less significant detail will be masked. To create an edge mask, the three channels had to be examined to determine which ones had the best detail. Figures 1 -- 3 show the channels for this image. An examination of these channels indicates that the red channel has the best detail in the grass, and the blue channel has the best detail in the mountain reflections. This information will be used in creating the edge mask.
It was now necessary to turn the Mono layer into a black and white layer with the most detail possible. The best tool for this was the Channel Mixer. The Channel Mixer allowed the photographer to choose how much detail was pulled out of each channel. This allowed the photographer to fine tune the Mono layer to contain the maximum amount of detail.
With the Mono layer selected, the Channel Mixer was launched (choose Image/Adjustments/Channel Mixer). The Channel Mixer is shown in Figure 5. Since a black and white layer was to be created, the Monochromatic option was checked. Now, the goal in this image was to pull out as much detail as possible in the grass. Since it was not desired to sharpen the water (since that would have given the water and the reflection an unnatural look), it was not important how much detail was created in the water. Since the red channel had the most detail in the grass, it was used the heaviest in the channel mixer (140%). It was found that adding a small amount of the blue channel (26%) enhanced the contrast and, therefore, the detail in the grass. The green channel was actually decreased (-50%). Clicking OK converted the Mono layer to black and white. Figure 6 shows the Mono layer after the Channel Mixer was used. Figure 7 shows a close up of the grass.
It was now time to turn the Mono layer into a selection and then an edge mask. The Channels palette was selected. Within the Channels palette, the RGB channel was selected. The Load Channel as Selection icon at the bottom of the palette was clicked. This turned the Mono Layer into a selection.
Moving back to the Layers palette, the Sharpen Content layer was selected and the eye icon was clicked to unhide the layer. Figure 21 shows the image with the selection.
There was one problem with this selection, as can be seen in Figure 21, parts of the water were selected. This was not acceptable, as the water was not to be sharpened. To solve this problem, the image was moved into Quick Mask Mode (choose Edit in Quick Mask Mode on the Tools palette). The Brush Tool was selected from the Tools palette and the water was painted over with a black brush. However, care was taken not to brush over the grass that was floating in the water as that grass needed to be sharpened. Figure 22 shows the image in Quick Mask Mode after the editing.
It was now time to apply a mild sharpening to the Sharpen Content layer. With the monitor set to 100%, the Sharpen Content layer was selected, and Smart Sharpen was launched (choose Filter/Sharpen/Smart Sharpen). On the dialog box, Remove was set to Lens Blur, and the more accurate option was checked (see Figure 26).
When sharpening, perhaps the most important key to getting the sharpening right is to find the correct Radius. Too large of a Radius will destroy detail, and too small of a Radius will sharpen unwanted detail (e.g. noise). Thus, the Radius was set first. At this point, it was not desired to actually sharpen the image. Rather, the intention was to find the correct Radius. To start off, the amount was set at a fairly high value (300%). The high amount produced a greatly exaggerated sharpening. This was okay for now because it made it easy to see what impact different Radius settings had on the image detail. The Radius slider was moved around while the image was observed. The Radius was moved to the point where the image detail began to degrade; then, the Radius setting was backed down a bit. This resulted in a Radius of 1.6. This is a fairly small Radius, but it was necessary due to the fine detail in the grass.
With the Sharpen Content layer still selected, the Sharpen Content selection was loaded (choose Selection/load Selection and New Selection). The selection was then turned into a mask (choose Layer/Layer Mask/Reveal Selection). The Opacity was set to 50%. This was done so that the sharpening could be adjusted either up or down, at a later time, if so desired. The Layers palette is shown in Figure 29. Last, the monitor was set to 50% view.