Labels:text | screenshot | font | number | paper OCR: Unsharp masking Threshold: This determines what level of contrast to sharpen. At a setting of 0 the Digital sharpening works by creating a trompe d'œil (that is, a fooling of the eye) by program looks at everything; it looks at less as this number is increased. This number selectively adding contrast to edges and thereby making the picture appear sharper. becomes critical with flesh tones - unless you'd like to see every pore, keep it over 6. This sleight of hand can be controlled by programs such as Photoshop that provide the following settings when using unsharp masking: A recommended base setting for images for print is an Amount of 125, a Radius of 1.5 and a Threshold of 3. Amount: When the unsharp masking algorithm considers the pixels of an image, it notes areas of contrast. Then it adds density along the dark edge and subtracts density Sharpening tips along the light edge. "Amount" refers to how much these edges differ in darkness or · Sharpening should be the last operation you do; it's best to wait until the image is lightness from the original (increasing the amount makes dark areas darker and light ready for output before determining sharpness. areas lighter). · Flesh tones can look very bad if oversharpened. We recommend you increase the default setting (which is 50), bringing it closer to 100, to begin experimentation. . Sharpening is a subjective decision and should be based on tests of images you actually output - files onscreen almost always look oversharpened. Radius: This looks at the size of the area that will be affected by the sharpening. The larg er this number, the greater the area to be taken into account. If your image includes lots · Expect the grain to increase when you sharpen. of detail, keep this number low. Also worth noting We recommend you increase this number as file size increases. For a standard onscreen · One of the most effective ways to sharpen your image is to convert it into CIELAB resolution, a Radius setting of .5 works well; for a standard printing resolution, increase color. In this format the L, or luminance, channel has no color information, and this number to about 1.5. Images with low tonal differences and without fine detail can sharpening it creates very smooth results and avoids the color fringing common on be improved by increasing the setting to about 3. saturated images. 22 23
