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Vjeran_G

Preparing file for offset print in two colours

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Hi,

I have problems with preparing file (book) for offset print in two colours black and P285U.

In five places in the book I used image (like in attach), BW image with colour overlay in spot colour. When I export file in pdf this image convert in cmyk.

Does anyone have any suggestions?

primjer.JPG

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Make sure that you have "Honor spot colors" selected in your export to PDF settings. Also, if you use other than X-4 profile, ensure that you do not embed the color profile, otherwise you end up getting CMYK blacks.

spot_colors.jpg.32368c66fcb03ab022850c40ddd2606c.jpg

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You mention about color overlay... How have you overlayed the PMS color?

I think you should simply just place a PMS object on top of your grayscale image and make it overprint. Your pdf (and .afpub document) shows solid color and without showing through the underlying image unless you have a viewer that allows showing the overprinting in effect (like Adobe Acrobat Pro), but the job prints ok.

 

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Here is a demo Publisher document of using PANTONE spot colors for toning (including a demonstration how the Overlay FX with a spot color results in CMYK rendering).

The screenshots from Adobe Acrobat Pro show the differences.

CMYK colors (CMY exists only in the third image):

pms_tones_cmyk.jpg.a2e752fa59a210d6ee7ef04ad5f0ccf8.jpg

 

K and Spot only (as can be seen, no spot color in third image):

pms_tones_kandspot.jpg.9e91480093d4246b88159c114b4a3258.jpg

Spot color only:

pms_tones_spotonly.jpg.4b168ac83626675d6280a77f1e91eaa7.jpg

K only: as can be seen, the fourth image prints with the spot color only); 

pms_tones_konly.jpg.018d1b1287dff29bfcad4c49487e74a9.jpg

 

Obviously the overprinting technique (image 1) is not useable if there is no reliable way to predict the print result, so the image 2 is likely the best candidate to simulate duotone printing. You can adjust the shades of the gray scale image to determine the effect of black and use tone with the spotcolor to adjust the shade of the color you use. There are certainly other possibilities, too, but I think that most of the FX settings result in image being rendered in RGB (and ultimately in CMYK).

 

 

PMS Toning without duotones.afpub

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@Lagarto

Thanks for that. 

It shouldn't be such a mystery for users to produce duotones. The software should make it dead simple for designers and layout artists. Moreover, there should be a Studio Panel within the Affinity software that accurately previews color separation plates.

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2 hours ago, Mark Oehlschlager said:

BTW, can you please explain how to assign a spot color to a Grayscale image?

If you mean image 4 (bottom right), please open the attached .afpub file and in the Swatches palette, select from the list of palettese the topmost "Document" palette: you can see that it has "PANTONE 7460C" highlighted, when you select the 4th image. (Note that this swatch has "Overprint" setting turned on, but it does not have in practice any effect on other than the first image.)

The "duotone" effect (2nd image) can be achieved by placing the PMS color below  a grayscale image, and then using "Multiply" blending mode on the Layers palette for the image. The grayscale image can further be manipulated with e.g. Curves, and the underlying spotcolor can be made lighter with a tint value.

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@Lagarto

I see now. If you place a Greyscale image, and you have the "K Only" contextual button selected, you can apply a spot color to the grey values in the image.

I suppose one could place a positive and a negative version of an image in greyscale (perfectly aligned), and then apply a different spot color to each version of the image to manufacture a duotone effect between any two spot colors.

Pretty kludgy though. 

Would be better if Photo handled spot color channels and allowed users to produce duotone, tritone and quad tone images for placement in Publisher.

Screen Shot 2019-10-10 at 8.07.27 PM.png

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1 hour ago, Mark Oehlschlager said:

I suppose one could place a positive and a negative version of an image in greyscale (perfectly aligned), and then apply a different spot color to each version of the image to manufacture a duotone effect between any two spot colors.

Yes, duo(tri/quad)tones are basically just superimposed toned grayscale images. The benefit of having a built-in feature is mostly in having the curve tools (along with ink overprinting control) readily at hand, and being able to save useful workflows. I also use duotone features to get richer "black-and-white" photos and handle areas of images that cannot be accessed easily with single curves, and then use the results as standard RGB/CMYK for production, so the "original purpose" of this technique (using spotcolors and go to print with them) is not necessarily used at all.

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3 hours ago, Mark Oehlschlager said:

"K Only" contextual button selected

I am not sure what you mean by this but the Acrobat screenshots were just for demonstration of how different tone settings are composed in terms of color production (CMYK and spot color, or more specifically, just K and spot; CMY was included only to show that use of FX tools in Affinity apps results in RGB/CMYK).

So when you apply any of these settings, you do not need to do any further tweaks, and do not depend on any extrenal tools (other than if you apply the kind of overprinted effect that is done in image 1, as seeing its effect requires a feature that allow simulating the effect of overprinting). Having a tool like Acrobat Pro is useful, though, for checking color output. You could do that also by opening the pdf in Affinity Publisher but you should note that it fails to keep an imported color's overprint status (even if it keeps its spotcolor status).

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@Lagarto

Place a greyscale image in Publisher. You'll see the "K Only" contextual button in the toolbar. I believe this must be toggled on in order to apply a spot color. No?

I was interested to learn from you that Serif's layer effects including the very useful gradient map automatically converts everything to CMYK equivalents. Unfortunate that spots are not honored there.

I also tried experimenting with the Blend Options in the Layers panel to see if I could make use of the curves there for a duotone effect. Unfortunately this approach also converts everything to CMYK equivalents.

Not the end of the world, but gets in the way of creative two-color jobs, and other special effects in an otherwise standard CMYK job.

 

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58 minutes ago, Mark Oehlschlager said:

Place a greyscale image in Publisher. You'll see the "K Only" contextual button in the toolbar. I believe this must be toggled on in order to apply a spot color. No?

Oh, I had not noticed that! That was very useful information, I'd not have imagined that it needed something like this in order to NOT convert an inherently gray scale image to a color image! I think it really should not do these kinds of things, but rather do it conversely: if color conversion is wanted, it should be separately performed. On the other hand, this would allow you to use any image as a grayscale image to use if for these kinds of effects, so it has its benefits.

 

58 minutes ago, Mark Oehlschlager said:

I also tried experimenting with the Blend Options in the Layers panel to see if I could make use of the curves there for a duotone effect. Unfortunately this approach also converts everything to CMYK equivalents.

It seems to behave a bit vaguely. I have managed to adjust the image levels by using the Curves and Levels adjustments for Gray channel only, and the image stays in K only (also an RGB image that has K only setting on), and I think that I managed to also use Blend curves with K channel for the same image, but I am not sure. But levels and curves definitely.

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