The device the colours are stated for
Name the press or the screen the document's colours were chosen for, so they come out as intended.
Summary
A red is not a red. The same red does not look the same on a screen, on glossy paper and on newsprint. The printer reads it — such a reference screen, such a press, such a paper — and knows exactly where it stands. Short of it, the document says nothing about any device, unless it is filed for the long term or prepared for a press: those two call for the statement, and the document then says its colours are those of the ordinary screen.
Technically
Written at the top level of a request, under
"output_intent"
output_intent writes an /OutputIntents entry stating the device the document's colours are stated for: that device's profile in /DestOutputProfile, and the name its condition is known by in /OutputConditionIdentifier — GTS_PDFA1 for an archival file, GTS_PDFX for a print one. A page that fills with four numbers is a page of ink on a press, and the file names the press it was separated for, or the four numbers stand for nothing. Short of a supplied profile, the library writes the sRGB profile it carries. A request stating archive or print carries the entry whether or not it names this key; a request stating neither and naming no key carries none.
Request schema
-
output_intent— object, optional. Absent, the file carries no output intent, unless it statesarchiveorprint, which have the sRGB profile the library carries written for them. -
output_intent.profile— string, optional. The name of the supplied part carrying the ICC profile. Absent, the library writes the sRGB profile it carries. -
output_intent.space— string, optional. The space the profile describes. Three values:gray,rgb,cmyk. Absent, the space is read from the profile, which is what says which it is; writing it has the profile checked against it. -
output_intent.identifier— string, required. The short name the condition is registered or known under:FOGRA39,CGATS TR 001,sRGB. -
output_intent.info— string, optional, empty by default. The sentence a person reads to tell one condition from another.
A whole request that creates a PDF
{
"output_intent": { "identifier": "sRGB", "info": "sRGB IEC61966-2.1" },
"standard_fonts": [{ "name": "sans", "face": "helvetica" }],
"items": [
{
"type": "rect",
"rect": { "llx": 60, "lly": 690, "urx": 240, "ury": 770 },
"fill": [0.85, 0.15, 0.15]
},
{
"type": "text",
"rect": { "llx": 260, "lly": 720, "urx": 535, "ury": 740 },
"content": ["Colours stated for sRGB"],
"font": "sans",
"font_size": 12
}
]
}Colour and how it is shown
Which plate of a separated sheet a page is The device one page's colours are stated for Declaring colour beyond red, green and blue What a page's bare numbers mean A colour sliding into another Opacity, mixing, and what a press asks for A cell repeated to fill a shape The space a page mixes its colours in
Where to go next
Every JSON key of a request, in one page The other forty-one settings of a request