Scanner Information from
Graphic Quality Consultancy
|
||
|
|
Scanner Information fromGraphic Quality Consultancy |
|
| Index Home (Introduction to our colour services) Colour Management & ICC Profiling Theory Colour Management Introduction Printing Specifications (Total Area Coverage, UCR, GCR, etc.) Crosfield & Fuji Scanners & ColourKit Technical Information Crosfield & Fuji Scanner Information (Scanner Colour Management) Crosfield Drum Scanner Background (Explanation & History of model variants) Celsis Scanner Upgrade Info Fuji ColourKit Colour Management Unsharp Masking (USM) Info (part 1) Ranging Images in Celsis Scanners Ranging Images in Fuji ColourKit Editor Links to Other Sites Links to Scanner sites (Links to Scanner sales, spares & engineering companies) Links to Apple Mac sites Site Map Contact Us |
MORE USM INFO - part 3The following applies to Crosfield & Fujifilm Scanners and Fujifilm ColourKit Software in general. Particular software versions will vary. Other high-end scanner software has similar controls. Sharp: This is the amount of "fringing" actually applied. This is the control most often adjusted and witht the greatest effect. Typical values are 4 or 5 in newer software, with more on older scanners. Higher numbers make sharper. If not using "Preset USM" you will need more Sharp at high enlargements and less for reductions. Smooth: The amount of softening or smoothing applied in "grainy" areas. To some degree this will counteract Sharp. Amount of 2 or 3 is typical. Higher numbers reduce grain while also reducing sharpness. Threshold: This is the difference in contrast between the pixel being processed and the surrounding pixels. If the contrast is greater, then the pixel is sharpened. If it is less, then smoothing is applied. The higher the number, the smoother and less sharp the image will be. Threshold is found in USM Variables or "Cal 508". 5 or 6 is typical. Increasing Threshold to about 10 will help reduce "Moire" patterning in pre-printed reflection originals, or paper grain in "wash drawings". Pre-set USM: Found on Celsis only. This will automatically adjust the Sharp setting according to the enlargement ratio. This will increase sharpness for high enlargements and conversely reduce it for reductions. Should normally be ON. It is set to Low, Medium or High. The corresponding values are then set in USM Variables. Set a value for each of High, Medium and Low. The number set is the approximate value you would set Sharp to at about 300% enlargement. Black
Gain:
Varies the sharpness in the Black separation (CMYK only!). ColourKit Software: There is also the image detail MTF to consider. This is more correctly known as the Modulation Transfer Function. This uses very sophisticated algorithms to process the sharpness. This should be set to the type of scanner (i.e. drum or CCD) and type of original (transparency or reflection). For digital cameras use "CCD". The differences can be very pronounced. See ColourKit Job Sheet. There are many other settings. Note that the settings often overlap. You should always test first and view the result in PhotoShop. Ideally at 100% view (actual pixels). Back to Basic USM Information (part 1)Back to Basic USM Information (part 2) |