Every job lists the separations its pages use, each with the screen its profile gave it. While the job is being configured you can change any of them for this job only; the profile stays as it is. Every change is saved at once and the checks run again.
The separations table#
The table lists every separation the preflight found: the process colours first, then the spots in the order the pages use them. Tick the ones to output and set each one's screen and curve.
| Column | What it shows |
|---|---|
| Tick box | Output this separation. Separations with no ink in the file start unticked. |
| Separation | The ink's swatch and name. Under it: the role of a spot ink, "No ink in the file" when the file declares an ink it never paints, and the screen the plate will use (see below). |
| Ink (est.) / Ink | The ink coverage: the 50 dpi preflight's estimate until the job is screened, then the exact coverage of the plates (the highest page). |
| Type | AM, FM or Solid. |
| lpi | The ruling of an AM screen, 50 to 300 lines per inch. |
| Angle | The angle of an AM screen, in degrees. |
| Dot | The dot shape of an AM screen. |
| FM dot (µm) | The dot size of an FM screen, 5 to 100 µm. |
| Curve | Profile curves (the profile's chain), or one curve for this separation (see Plate curves). |
A value the app refuses goes back to the job's value, and the reason shows under the field, such as "Kept 150". A row with an error or warning shows its icon next to the name; the message is in the job's checks.
An unticked spot is still rendered, so it keeps knocking out the inks underneath: the checks warn about it. If the ink shouldn't knock out (a die line, glue, a white underprint), make it technical instead.
Roles of spot inks#
A spot ink has a role you can change in the menu under its name:
- Spot · screened: a screened ink with its own screen, like a process colour.
- Solid ink (varnish, foil…): every tint prints solid.
- Technical · not output (die, glue…): renamed away before rendering, so it neither prints nor knocks out. The row shows "Renamed to None before rendering: neither printed nor knocked out."
Changing the role gives the ink the screen your profile has for that role. Process colours keep their role.
Screen types#
- AM (amplitude modulated): dots on a regular grid, larger for darker tints. Set by ruling, angle and dot shape.
- FM (frequency modulated, stochastic): dots of one size, more of them for darker tints, with no ruling or angle, so FM plates don't make the moiré patterns angled screens can. Each FM plate of a job uses its own pattern.
- Solid: any tint of the ink prints solid; 0 % stays paper.
Screen ruling and angle#
Angles are counter-clockwise from horizontal on the right-reading sheet, whatever the output's mirror setting. They are kept from 0° to 180°: 195° is stored as 15°. The offset built-in profiles use Cyan 15°, Magenta 75°, Yellow 0° and Black 45°; the flexo ones 67.5°, 7.5°, 82.5° and 37.5°.
Resolution and ruling go together: the resolution must be at least 4 times the ruling (at 600 dpi, 150 lpi at most), or the job can't be screened. The line next to the screen shows how many grey levels that ruling gives. Under 150 levels the checks add a note, because long vignettes may show steps.
Round, Euclidean, Square and Diamond dots look the same every 90°. Line and Elliptical dots look the same every 180°.
Dot shapes#
| Dot | What it looks like |
|---|---|
| Round | Circular dots at every tint. Neighbouring dots touch at about 78 %; above that the paper shows as small star-shaped gaps. |
| Euclidean | Round in the highlights, square in the mid-tones, where the corners meet at 50 % (a checkerboard), then round holes in the shadows. The usual offset dot. |
| Elliptical (chain) | Elongated (chain) dots that join along their long axis first and across it later: two smaller tone jumps instead of one at 50 %, for smoother skin tones and vignettes. |
| Square | Square dots at every tint, with their sides along the screen angle. |
| Line | Parallel lines along the screen angle that get thicker as the tint rises. |
| Diamond | Round in the highlights, diamond-shaped in the mid-tones, round holes in the shadows. |
FM dot size#
The size you type is made as a whole number of device pixels, so two nearby sizes can come out the same. The line under the name shows the size the plate will use. The checks warn when that dot is smaller than 20 µm, which most thermal plates and presses don't hold.
The screen the plate uses#
The line under each name shows the ruling, angle and grey levels the plate will use. They can differ slightly from the numbers you typed. An FM size is shown in micrometres and in device pixels. The report and the TIFF description record the same values.