WAYS TO SHARPEN IMAGES USING ADOBE PRODUCTS

Introduction: Everything that we do in Adobe results in some loss of sharpness. There are several ways to restore most of the sharpness before we make a print.

“The Truth About Sharpening” by Tim Grey

“Sharpening is just an optical illusion designed to fool our eyes into thinking that the image is sharper. It does this by increasing the contrast of pixels where there is an ‘edge’ or natural difference in contrast, brightness or color.”

For making small prints: In Elements 2 and 3 when you click on “Filters” > “Sharpen” you find the following options: “Sharpen”, Sharpen More”, “Sharpen Edges” and “Unsharp Mask”. Only use “Sharpen Edges” - - - never any of the other options. Only use it once!

For making “Exhibition” prints: Here we use the “Unsharp Mask” found under “Filters” > “Sharpen”. When you open this filter you will see three “sliders”:

AMOUNT: This determines how much sharpness you apply. It increases contrast along the edges of elements in the image. Using too high a percent here will “over sharpen” and result in a harsh image with white rings around the edges. When in doubt use less.

RADIUS: This determines how much of an edge change is used in the sharpening effect. Usually one uses less than 3 pixels. Using too large a radius results in over sharpening with “ringing”. Decimals such as 1.4 or 0.6 may be used. Use smaller numbers for files less than 10 MB and larger numbers for larger files. When in doubt, use less!

THRESHOLD: Sharpening does not affect the entire image only those parts having edges. Threshold tells the software at what contrast to look for to do its sharpening. This may be the most important setting when you sharpen. Low settings give the most sharpening effect. A low setting may increase the grain and “noise” in the image. When in doubt, use a larger setting! Higher number settings usually result in a need to increase the “amount” setting.

Images with different amounts of contrast require different settings. RECOMMENDED STARTING POINTS:

AMOUNT RADIUS THRESHOLD

HIGH DETAIL IMAGE 200-300% 0.6 0 TO 4

AVERAGE DETAIL IMAGE 100-150% 1.5 4

LOW DETAIL IMAGE 75-125% 2.5 8

`All of these settings involve making some judgments. You may prefer more sharp images while others may prefer softer looking images. It’s your choice. Remember you must start with a sharp image. You cannot make an un-sharp image sharp. You may, if you like, select part of an image and sharpen it. Then you can select another part or the rest of the image and sharpen it using different settings.

Most important: As a general rule we only sharpen an image once. I have formed the habit of sharpening just before I print to avoid this problem.

If this seems to be too complicated, just use the “Sharpen Edges” option. In most cases it works just fine.

Bill Popejoy, Jan. 2005 wpopejoy@aol.com