Teefury

Bump. There was a discussion where jimiyo confirmed some settingas for Halftone shading which indicated a Lines Per Inch resolution of 45-65.

Here's an article which describes the difference between DPI and LPI.

When you alter the settings in GIMP using the Newsprint filter, the dialog box gives an interesting display...



SPI is Sample Per Inch (the resolution of your sample image). When you adjust the Cell Size to make the dots smaller, the Output LPI increases. I try to keep the LPI between 45 and 65. For working at around 300dpi, dots with a Cell Size of 5 are at the high end of this, and 6 are at the low end. Illustrator should have a similar way of judging LPI.

Proper halftoning does not need antialiasing: the aim is to reduce the color depth after all... but since the GIMP effect can be used for on-screen special effects, the option is there to smooth the circles. It's useful to apply a little anti-aliasing to simulate ink smearing on paper for an on-screen piece of art... but because this is for someone printing the resulting image, set the antialising to 1 (ie, off) and the ink will 'anti-alias' itself.

I hope the TeeFury staff give an actual answer involving numbers!

Just noticed: the size of the output LPI, multiplied by the cell size, gives your resolution of your image. Flip around that equation... for the 45 to 65 range:

At 72dpi on screen, you could have very small cells. However, if your art is 72dpi and only six colors, it's going to look jagged.

At 200dpi, a Cell Size of 4 gives 50 LPI. Nicely within the range.

At 300dpi, a Cell Size of 4 is 75 DPI (very fine print, too fine for the shirts). '5' gives 60 LPI and '6' gives 50 LPI (both within range). So for shading at 300dpi, use 6 (or 5 at a stretch).



Anything bigger will look like dots instead of shading, but that could be part of your idea all along (see shading in jimiyo's text from a recent shirt of the day)...



DON'T FORGET - the printing process will blur very finely spaced elements together. The ink will spread and touch close-by ink, potentially closing fine gaps. I've made designs that people have said are 'too busy', and they were right. Any design used will be printed on cotton, a medium that looks like Shredded Wheat under a microscope.



Be precise. Just don't be TOO precise!

Exactly! I like being precise but hopefully I'm not too precise. When drawing machines and technology type things I tend to like to include every little screw and cable. So I just one to make sure my stroke width isn't too fine. But I can always simplify if need be! Thanks!