Canon EOS-1 V. SHARPENING METHODS IN POST-PROCESSING

V. SHARPENING METHODSIN POST-PROCESSING 30
Adobe Photoshop’s
Unsharp MaskFilter
Iflittle or no in-camera sharpening has been applied prior to viewing an EOS-1 class
DigitalSLR image at 100% magnification, especially with the EOS-1D Mark II, most
photographerswill agree that the image looks soft, even if it has been properly focused
and exposed. Thisis mostly due to the detail-softening effect of the camera’s
anti-aliasing (AA) filter, which ispermanently mounted in front of the image sensor. The
AA filter playsan important role in reducing or eliminating false colors and moiré, but
the trade-offis that images must be sharpened either in the camera or in the computer
prior to finalusage.
There are dozensof sharpening techniques, but the Unsharp Mask filter in Adobe®
Photoshop®isone of the best-known methods. Some photographers prefer to sharpen
onlyonce prior to printing. Others apply Unsharp Mask twice: once to eliminate the
softening effectof the camera's AA filter prior to editing for contrast and color balance,
and again to compensate for the softening effectsof various output methods prior to
printing.
Also, manyskilled photographersdon’t sharpen the entire image in post-processing.
Rather, theyapply sharpness only to appropriate areas. For example, they might
sharpen the foreground in a landscape photograph and notsharpen the sky. This
selective sharpening technique iseasily accomplished with layers or masks.
Unsharp Maskoffers 3 settings: Amount, Radius and Threshold. Radius and Threshold
determine which pixelsand which areas around them are affected by the Amount
adjustment. AsAdobe says, “The effects of the Unsharp Mask filter are more
pronounced on-screen than in high-resolution output. Ifyour final destination is print,
experimentto determine which settings work best for your image.” The difference is
attributed to the screen’sresolution being different from the printer’s resolution.
Ifyou haven’t worked with Unsharp Mask, try the following settings as a very rough
guideline for high qualityinkjet printed output at A4 or Letter size:
Amount: 300%
Radius: 0.3 pixels
Threshold: 0 pixels
You’llfind that small adjustments to Radius and Threshold have a much stronger effect
than smalladjustments to Amount. Also, sharpness preferences vary according to
subjectmatter (human subjects often look better with less sharpening, whereas
V. SHARPENING METHODS IN
POST-PROCESSING