Should I match the DPI of a raster image to LPI in Engrave settings?

[GrooveStranger]

I’m having a blast playing with 3d engraves. I just realized that the default Proofgrade setting for a 3d engrave is 340 LPI.

When I create a raster image, should I match the DPI to the Glowforge LPI? Is there an optimum ratio?

Seems like the LPI exceeding the DPI is, at best, useless.

[jbmanning5]

DPI = LPI * 2

or

LPI = DPI / 2

[GrooveStranger]

Cool, thanks!

[loren]

So the answer is no? Guessing from the answer above, it would make sense to raster at 2x the planned LPI?

[jamesdhatch]

@loren

it would make sense to raster at 2x the planned LPI?

That’s a good rule of thumb.

Keep in mind that the higher levels of LPI can be overkill for many projects as the lines are closer than the width of the laser beam so you end up double or triple burning. For most materials 270 LPI is about as high as you need to go.

Aluminum is an exception - very high LPIs make for incredibly smooth engraves/markings.

[jbmanning5]

Preparing a Photo for Raster Engraving (NOT NECESSARY FOR GLOWFORGE)

It’s commonly stated DPI = LPI * 2, or DPI / 2 = LPI. What’s not stated is that those formulas are for suggested resolution of an image. What it really should say is that the suggested resolution for printing is Target LPI * 2 = DPI of your image. And that’s not even accurate… it should be PPI rather than DPI, though the two terms are really used interchangeably anymore: PPI is input. DPI is output. For example, the wide-format canon printer I have here has a max print resolution of 2400 X 12…