DPI vs LPI

J
Posted By
JasonSmith
Apr 9, 2004
Views
276
Replies
3
Status
Closed
No, I’m not talking about file resolution, I’m talking about image setters.

Basically we have some wide format Roland HiFi’s that have a max resolution of 1440x1440dpi.

Feasibly what’s the highest LPI AM screening that I could expect with this resolution? What’s the typical DPI/LPI relationship?

While we have some fantastic FM screening, I’m in experimental mode right now and am playing around with AM screening.
Related Tags
dpi vs

How to Master Sharpening in Photoshop

Give your photos a professional finish with sharpening in Photoshop. Learn to enhance details, create contrast, and prepare your images for print, web, and social media.

RW
Rene_Walling
Apr 9, 2004
printer dpi and lpi relationship can be calculated as follows:

No. of shades of grey = (printer resolution in dpi / line screen in lpi) squared + 1

So a 600 dpi printer outputing a 60 lpi screen will allow you 101 shades of grey

Your Roland outputing the same would give you 577 shades of gray

Now the optimum lpi/dpi relationship is one where you have the finest linescreen while not loosing any of the 256 shades of grey in a PS document.

Thus we have

linescreen = printer resolution / sq.root of (256-1)

in the Roland’s case we have: 1440/16 = 90 lpi (rounding off the square root of 255 to 16)
J
JasonSmith
Apr 9, 2004
Wow. Thanks, very interesting.

Ironically I just tried a 95LPI setting and looks pretty darn good (for 95lpi).

The rosettes seem to get lost around 135LPI. I realize this isnt the type of machine needed for that type of output.

I just remembered – the Rolands use variable dot technology, so the ‘inferred’ output of the device may be higher.
RW
Rene_Walling
Apr 9, 2004
I forgot to mention that the above formula is for "traditional" screened outputs, stochastic screens, variable dot technology, and other such niceties surely change it, but I don’t know how.

Guess I could try to figure it out, but it would take way too much time and energy.

MacBook Pro 16” Mockups 🔥

– in 4 materials (clay versions included)

– 12 scenes

– 48 MacBook Pro 16″ mockups

– 6000 x 4500 px

Related Discussion Topics

Nice and short text about related topics in discussion sections