Density; How To Tune Image Enhancement Settings - Universal Laser Systems VLS2.30 User Manual

The low density parts of the graphic are typically the ascenders and descenders of text or
thin vertical lines in a graphic being printed. Within this area, using too little DEFINITION
may cause thinner parts of the letters or thin vertical lines to appear too thin, faint or even
non-existent when rastering at high speeds. Having too much DEFINITION will cause the
affected areas to appear too thick, bold or over-powered.

Density

DENSITY decreases laser power at the edges of all graphical elements to compensate
for laser lag in turning off at high speeds. If the DENSITY is set too high, then the entire
engraved image may appear too thick, bold or over-powered. Setting the DENSITY too
low may cause the image to appear too thin and thinner parts of characters and thin lines
may disappear altogether. The opposite effect would occur on inverted images such as
white text on a black background.

How to Tune Image Enhancement Settings

These three parameters (CONTRAST, DEFINITION and DENSITY) work together to
compensate for laser response when rastering at higher speeds. For a given material at a
given speed they must be determined by testing. If you use the materials database, these
values are already determined for you. You can look up these settings for a particular
material in the database by selecting that material in the materials database tab and
selecting edit. Keep in mind that these settings are tuned for the particular raster speed
and power level stored in the database and if you need to change the speed or power
significantly for your application, you may need to establish new values by testing. Also
remember that these settings are for high speed engraving on sensitive materials such as
anodized aluminum and acrylic and may not be necessary for your application.
Step 1: Establish the nominal power setting.
The enhancement settings work best when you are not overpowering the material. The
first step is to establish the minimum laser power necessary at the desired processing
speed to mark the material or to engrave the material to the required depth. You should
not use more laser power than necessary. The best way to determine this is to engrave a
4" (101.6 mm) wide by 0.5" (12.7 mm) tall solid black rectangle in the center of the
processing field. Use a scrap piece of material to adjust laser power in a series of 5%
increments at the desired processing speed until you establish the minimum power level
required to produce the desired result. Make sure image enhancements are DISABLED.
Step 2: Use text to set the CONTRAST parameter.
Type in a string of text, using the Times New Roman font, set at 8 or 10 points in size.
Make sure that the text string is at least 6 inches long and that the string includes
punctuation marks, spaces, lower and upper case letters as in the following example:
This is a test to set contrast definition and density for High Speed Engraving
Engrave the sample text with the settings established in step 1 on a scrap piece of
material, but this time ENABLE Image Enhancement and set CONTRAST to 0,
DEFINITION to 0, DENSITY to 100 and the TUNING value to +4. The results may appear
fuzzy, some thinner elements of characters may be missing and overall engraving quality
may not be as good as expected. Keep adjusting the CONTRAST upward in increments
of 5, engraving another sample between each adjustment (you may want to engrave
each sample right beneath the previous one so you can compare them). Note the results
after each trial. The objective is to adjust the CONTRAST just enough to cause thin parts
of the text in the high density areas of the text to be sharp and clear. Ignore the
appearance of the ascenders and descenders that stick out above and below the dense
areas of text as they will be adjusted using the DEFINITION setting. Setting CONTRAST
too high can cause the characters to appear "fat" or "bold" so find the minimum value that
gives good results.
53