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Profil impression Offset pour bichromie

Forum|Forum|5 years ago
March 11, 2021
3 replies
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Bonjour

j'ai un livre à imprimer en offset en bichromie noir + PANTONE Warm Gray 2 C

savez vous quel profil de sortie je dois utiliser dans l'export du fichier (impression) sous Indesign

pour de la quadri j'utilise le Coated Fogra 39 mais y a t il un profil pour la bichromie ?

Merci

Import and export

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rob day

Community Expert

Hi Nicolas, the Photoshop duotones are noisey, which is more obvious if I zoom in—here’s 300%:

The noise is getting exaggerated a bit on the export to PDF because of the default PDF/X Compression settings. The image in the page layout has been scaled down to 43%, so the effective output resolution is 560ppi. The default Compression setting downsamples any resolution over 450ppi to 300ppi, so the downsample plus the JPEG compression is exaggerating the noise. I’m not sure you will actually see that in the print, but you can see it at high magnifications.

Here’s a comparison of the default compression you used (top) vs. downsampling and compression turned off (bottom):

Also, I don’t think it will affect output, but .PSD is probably a better format than .EPS for any image file.

PSD gives you more resolution and color info in the InDesign Link Info panel:

N

Nicolas5C5EAuthor

Participating Frequently

Hello

j'ai donc mis la photo au format final impression et enregistrée en .PSD voila le PDF produit avec en haut la premier photo en .eps et en bas la nouvelle redimensionnée en .PSD

rob day

Community Expert

Yes, there are always the 4 CMYK inks plus any document spot colors. Your duotone colors are set to Black and PANTONE Warm Gray 2 in Photoshop and the Black ink maps to InDesign’s process black plate—the [Black] swatch. If you give the Black Ink a different name it will show up in InDesign as a new spot color, but you would still have the 4 CMYK inks + the 2 spot colors.

Using process Black for the 2nd duotone color is probably the best choice—with a PANTONE spot black there would be two black plates in the document and it would be easy to confuse them.

A Photoshop Duotone with no curves applied and the first ink set to Black (InDesign’s process black)

InDesign’s Separation Preview shows the same output values:

Export to the default PDF/X-4 preset

N

Nicolas5C5EAuthor

Participating Frequently

Thank you very much

N

Nicolas5C5EAuthor

Participating Frequently

Hello Rob

J'ai une autre question

quand je produis mon fichier PDF pour l'impression selon les normes prècédentes, et lorque j'ouvre ce PDF je constate que les photos en bichromie sont légèrement différentes que sur photoshop ou Indesign : un peu plus sombre et dense et pour certaines plus de grains (voir photos ci dessous)

Est ce normal ?

Quel est le fichier référence , Le PDf pour l'impression ou les fichiers sources photoshop ?

Merci

détail grain photoshop

Détail grain du PDF

Photoshop

PDF

rob day

Community Expert

If you are using Process Black for the black channel of the duotones (the black ink is named Black in Photoshop) then you have to set the Export>Output> Destination profile to Document CMYK or set Color Conversion to No Color Conversion, otherwise the process black channel will get converted to 4-color CMYK. Either Document CMYK or No Color Conversion will export the duotone values unchanged:

If you are using a Pantone spot black —i.e. PANTONE Black 6C—for the black channel, the CMYK profile has no affect on the soft proof preview or the export numbers. The duotones will export with their Photoshop output values unchanged—the 1: & 2: values you see in the Info panel with the eyedropper set to Actual Color.