Film output: what goes to the device

Film resolution: 1200 and up

This is not about image quality. It is about whether the halftone has anywhere to stand. A dot at 55 lines is about 0.46 mm across, and at 300 ppi that is roughly five pixels corner to corner. Its edge comes out ragged, and a small highlight dot simply disappears.

At 1200 ppi a pixel is under a tenth of a millimetre, and the dot shape becomes a shape rather than a staircase. There is no reason to go below 1200 even on a coarse screen.

The on screen preview is deliberately coarser. What you see in the bitmap view is a reduced copy; the film is always written at full resolution.

Registration marks and the margin around them

A mark is a ring with a crosshair through it, and it is useful exactly to the extent that it lands in the same place on every film. So it is drawn from the film’s geometry rather than from the artwork: the same four positions, the same margin, the same pixels, whatever a given plate happens to contain.

The marks live in a margin around the artwork, because a mark inside the image is a mark printed onto the garment. The margin is ten millimetres a side: enough for a six millimetre target with room to breathe, and small enough not to force a larger frame.

Which means the film is two centimetres wider and taller than the artwork. That is intended, but worth remembering when you measure a screen.

File names

Each film is named by its print order and then the ink’s name in Latin: 01_White_base.tif, 02_Beige.tif, and so on.

The order comes first because a films folder is read in print order and a file manager sorts by name. Characters Windows forbids are replaced rather than dropped, so two inks cannot collide into one name by losing them.

A small thing that saves phone calls: whoever is at the device sees the order without opening a single file.

What to put in the archive

• TIFF films. One bit, one per ink, at output resolution. This is what goes to the device.
• Combined TIFF. Every plate in one multi page file. Some RIPs want it that way.
• Layered PDF and PSD. For a shop that finishes something by hand before output.
• Preview PNG. To show a customer or to file with the order.
• Palette map. Ink swatches with names and HEX, so mixing is not guesswork.
• Report. Line count, angles, order, profile and every issue, as text.

One bit TIFF is not an arbitrary choice: every imaging device reads it, and there is no tone in it for anybody downstream to interpret their own way. A pixel is either black or clear.

Mirroring does not happen here

Film is output emulsion to emulsion, which means the image on it has to be mirrored. The program does not do that and does not pretend to.

Mirroring stays where it belongs: in the device driver or the RIP, alongside density and linearisation. It is a property of your output setup rather than of the file, and doing it in both places gives you a film the right way round and a ruined run.

Settle it once on your own device and write it into the shop notes. This is a mistake people make exactly once.

FAQ