The tools of the plate viewer measure the screened plates the way you would measure a printed sheet or a plate: dot percentages, rulings and angles, registration and moiré. Their readings go to the Inspect tab on the right. None of them changes the files.
Choose a tool in the toolbar or with its key. Esc goes back to the Hand.
Loupe#
The Loupe (L) is a round magnifier that follows the pointer: 8 screen pixels per device pixel, with the grid of device pixels and a crosshair at its centre. Rest the pointer for a moment and a 1 mm aperture reading shows under it. The Loupe button next to the zoom keeps the loupe on while you use any other tool. It always shows real device pixels, whatever the zoom of the sheet.
Densitometer#
The Densitometer (D) reads the dot percentage of every shown plate, and the Total ink (the sum, or TAC):
- Click for an aperture reading: a circle of 1, 2 or 3 mm (choose on the Inspect tab), counted exactly from the device pixels, like a densitometer on the plate.
- Drag for the average over an area.
The status bar under the sheet also shows each plate's percentage under the pointer, over a 1 mm square. Readings are of the plates as imaged: misregistration offsets don't change them. On a job that isn't screened yet, the readings come from the 50 dpi preview.
Ruler#
The Ruler (U) measures a distance: drag from one point to another. The length shows on the sheet and on the Inspect tab. At 1:1 and closer, both ends snap to device pixel edges.
Screen analyser#
The Screen analyser (A) measures the screen that was really imaged. Drag over a flat tint of at least 5 × 5 mm; for every shown plate the Inspect tab lists:
- Intended: the ruling and angle the separation asked for;
- Measured: the ruling and angle found in the plate's dots, "FM (stochastic)" for an FM plate, or "No flat tint here" over paper or a solid (below 2 % or above 98 %);
- Ink: the plate's coverage in the area.
A plate whose angle is more than 0.5° off, or whose ruling is more than 1 % off, is flagged with the difference, such as "angle off by 0.80°". Round, Euclidean, Square and Diamond angles repeat every 90°, Line and Elliptical every 180°. The analyser needs screened plates.
Misregistration#
The Misregistration section of the Inspect tab (R opens it) moves plates against each other, as a press out of register would, so you can see whether the traps hold:
- Give any plate an x and y offset in µm, up to ±300 in steps of 10.
- Or use a preset: the first Star button, labelled with the tolerance (such as "Star 50 µm"), moves each plate by the press's registration tolerance in its own direction, by plate order: the first plate right, the second down, the third left, the fourth up, then the diagonals (with the four process plates on the page, Cyan right, Magenta down, Yellow left, Black up). Star 100 µm does the same by 100 µm; Random moves each plate by up to the tolerance; Reset puts them back. The tolerance comes from the job's press, 50 µm when there is none.
Two highlights show the result, in the toolbar or on the Inspect tab:
- Gaps (G) marks in red the paper the offsets expose inside inked areas: where a trap is missing or too thin.
- Overlaps (O) marks in blue where two or more plates are solid at the same spot: the trap itself.
A preset switches Gaps on. The offsets are for viewing only; the files stay in register.
Moiré#
Below 1:1 the viewer averages each plate before combining them, which is right for tone but hides rosettes and moiré. Moiré (M) shows the true composite instead: every shown plate combined at full resolution, then scaled to the screen. It works from 1:1 down to 1:4; further out the button's tooltip says "Zoom in to at least 25% to check moiré". At 1:1 and closer the normal view already is the true composite.
Ink zones#
Zones draws the job's ink zones across the sheet, numbered left to right on the right-reading sheet (see Output settings). The Ink zones section of the Inspect tab shows the coverage of each zone for the plate you choose, as bars; point at a bar for its value. Zone coverage is measured when the plates are screened, so a preview has none. With a press in the job, the zones show when the viewer opens.