One very popular sharpening approach for digital images is the three pass sharpening technique described by Bruce Frazer and Jeff Schewe in their book Real Word Image Sharpening with Adobe Photoshop, Camera Raw, and Lightroom. Those phases are Capture Sharpening, Creative Sharpening, and Output Sharpening.
Capture Sharpening attempts to correct for the inevitable blurring that occurs in any digital capture. If there is a desire to bring attention to a particular area of the image, Creative Sharpening might be used to achieve it. Every output medium has its own particular requirements for sharpening, be that to a computer screen, or to paper. Output Sharpening optimizes the image for the media requirements and expected viewing distance.
Phase One Capture One allows for that same approach, in its own way. That way differs a bit from Adobe Lightroom and Adobe Camera Raw (ACR), but will achieve much the same results. If I discuss Lightroom’s sharpening, it is for all practical purposed the same as ACR’s.
Phase One determines the optimum capture sharpening for each camera body through internal testing and applies that sharpening by default on import. You see the settings Capture One is using in the Sharpening tool.
If you find the defaults to be unsatisfactory for any given image, you can adjust those settings to suit (more on that in a minute). Perhaps the image is ever so slightly out of focus, or the textures in it need to be emphasized a little more.
Another form of Capture Sharpening offered is diffraction correction, found in the Lens Correction tool. There are no setting for this sharpening; it’s based on a fixed algorithm (deconvolution sharpening) and is simply on or off. The last form of Capture Sharpening is also in the Lens Correction tool, called sharpness falloff, sharpens the outer portions of the image when sharpness declines due to the lens used.
Together, the default sharpening tool settings, diffraction correction, and sharpness falloff make up Capture One’s capture sharpening phase. And each of those, except for diffraction correction, can be adjusted if need be.
Although the available settings for the Sharpening tool are similar to those in Lightroom, they are a bit different: amount, radius, threshold, and halo suppression. Let’s go over the effect of each. But before that, recognize that the numbers used in the settings are not reflective of any absolute measurement, they are only relative. 1 for an amount is just more than 0.4, for example; 0.4 has no direct measurement in the image — such as a number of pixels,
Amount is easy; it’s the strength of the sharpening applied. In other words, how much extra contrast is created around an edge in the image. For those familiar with Lightroom, it is analogous to its amount slider. But 100% in Capture One is not the same as 100% in Lightroom. Each program has its own algorithm.
Radius defines the distance from an edge that the extra contrast will be applied over. Again it is analogous to Lightroom’s radius slider, but using different units.
Threshold is used to tell Capture One what edges to sharpen. It establishes how much difference in contrast must exist on each side of an edge to define the feature as an edge. Low numbers define more edges to be sharpened while larger numbers reduce the number of edges that will be sharpened. Images with many small details need a small threshold while images, such as portraits, will benefit from a higher threshold, for example. It is somewhat like Lightroom’s masking slider.
Halo Suppression helps to reduce the image artifacts sometimes created by high settings for amount and radius. Viewing the image at 100%, or higher, magnification can make these artifacts more apparent and allow this adjustment to be made as needed.
Lightroom has a very helpful feature that allows you to preview sharpening in black and white, making it easier to see its effects. This is especially true for the masking adjustment — holding down the option key shows clearly what will be sharpened and what will not. For an image such as a portrait, it’s easy to be sure the skin will not be sharpened.
The best way that I’ve found to emulate this preview in Capture One is to set the amount to maximum, thereby exaggerating the effect and making it easier to see where it has been applied. When the other settings are right, move the amount slider back down.
Once Capture Sharpening is complete, some images may benefit from Creative Sharpening. Such sharpening can be set globally, using the Sharpening tool, or locally with Local Adjustments layers combined with the brush-in Sharpening tool.
Most of the time, Creating Sharpening will be done with localized masks. And the good news is that the settings for sharpening within a mask are the same ones we’ve already covered as Sharpening Settings (amount, radius, threshold, and halo suppression). So it’s pretty straightforward to mask in the areas that could benefit from a sharpening boost and apply local sharpening settings.
Capture One’s output sharpening controls are part of the Process Recipe tool and are found in the Adjustments tab. The drop-down menu there offers you starting points for No Output Sharpening, Output Sharpening for Screen (with amount, radius and threshold sliders that we already know about), Output Sharpening for Print (which needs more discussion), and Disable All (disables all sharpening — output, global, and local).
Sharpening an image for print is necessary for a number of reasons, mostly related to the intended size of the print, the distance it is expected to be viewed from, and type of paper being used. Capture One allows a viewing distance to be entered and it already “knows” the size of the print from the Basic tab of the Process Recipe tool. From those components, it applies an internal algorithm to estimate the necessary sharpening.
But it doesn’t know the type of paper (glossy, luster, matte, textured, etc.) to be used. For that, there are the familiar amount and threshold settings, which the user must set. That’s a shame because it will take a good bit of trial and error printing tests to establish the right settings for each paper to be used. If this this to be a somewhat weak point in the software.
All of the Output Sharpening we’ve seen so far is for exporting files with process recipes. The print dialog has its own setting, limited to sharpening — which is generally the same as amount. Again, it’s left to trial and error to determine the best setting for the actual print situation. This is a very weak point, in my opinion.
For more information about sharpening with Capture One, here are some online resources:
- The Capture One User Guide
- Printing Fine Art Images Directly from Capture One 9
- Martin Bailey Photography
- Three Stage Sharpening with Proof View (video)
A subject for a future article is noise reduction and its interaction with sharpening. You don’t want to sharpen the noise and noise reduction techniques reduce detail. Finding the right mix of settings can be quite a trick!