grayscale multiplied over a spot colour in a 2 colour job

[NickGross]

G'day,

Wow, first post, before posting this I tried to check to see if anybody else had posted something similar but I couldn't find anything similar, so my apologies if this all sounds boring and If anyone could help me with my problem I would be very grateful.

OK so I'm producing a two colour publication in indesign and on one of the pages I have placed a grayscale tiff over a pantone colour box. I then assigned a multiply blending mode to the tiff so that all the white drops out and the green can be seen 'through' the black.

My question is, can this be offset-printed? will it export OK to PDF? converting the colours to CMYK is obv. not an option because it is a two colour job. I'm a little nervous because when I print it using the desktop from the PDF (uncompressed, high quality) the blending mode doesn't work and it's just a normal BW grayscale,

any help would be greatly appreciated, thanks

 

[carlow]

Hi,

In Indesign you can apply a pantone color to a greyscale image, you don't have to play with the blending mode.

There are two ways:

First create your pantone swatch en be sure that spot is selected as color type

1. Select your image and apply the pantone color.
Now the white of your image are filled with the pantone color.

2. Drag the color swatch over a picture and now the blacks are replaced with the pantone color.

To be able to print as two color job you must be sure that the printing isz done from within Acrobat. If your printer imports the pdfs you made in Quark and prints from there the above mentioned methods won't work;

That your printer does not print as it should be is probably because it isn't postcript.

carlow

 

[apepp]

hi nick,

...the method you have used is ok for output to a highend device, when you have viewed your effort in acrobat it may have looked as though your greyscale image still has a white background, and as you mentioned the blending method hasn't been preserved.

The trouble is with acrobat screen render if exported to a 1.3 pdf. 1.4 and higher will look ok in acrobat because your blending hasn't yet been flattened, pdf 1.4 and higher retain transparency and is meant for rips that can handle flattening. 1.3 is for older rips or problematic artwork.

If your acrobat version allows it, under advanced menu, there is an option named overprint preview. With this enabled the screen will then render correctly for 1.3 pdf, as it would look if ripped through a high end device...

...this all points to the use of transparency flattening on export from indesign, the same occurs to transparent psd files etc...

...rest assured, that your method is ok, multiply acts as overprint so the black will overprint the spot colour. Just discuss it with your print provider as to what version of pdf they can accept...

andrew

 

[NickGross]

Thanks Carlow and Andrew,

That's really helpful information thanks a lot, so as I understand it, things are cool with this method and PDF > press can handle multiply with spot colours?

I was nervous because once I multiplied a spot over a grayscale tiff (the opposite to what I'm doing now) but when the proofs came back the pantone was just a solid colour so I guess I just assumed that pantone + multiply = no.

Also, why is it that the transparency flattening option is [medium resolution] and grayed out when I choose press quality as a PDF preset but [high resolution] if I choose PDF/X? Does this mean that press quality will output at a lower quality than PDF/X? I guess I assumed that the press quality preset would preserve things at the best quality, perhaps I should be using PDF/X...

thanks again people, much appreciated

--N

 

[apepp]

<<<why is it that the transparency flattening option is [medium resolution] and grayed out when I choose press quality as a PDF preset but [high resolution] if I choose PDF/X?>>>

...because they are different versions of pdf, press pdf uses 1.5, so transarency is maintained, a rip cpable of flattening this version is required. The PDF X 1A uses pdf 1.3, therefore flattening takes place as the pdf is created. It isn't a matter of quality it is a matter of whether transparency is flatten now or later. Again, ask your print provider which version their rip can handle...

...from a prepress point of view, with the transparency flattener set to high, it will preserve as much vector areas as possible and rasterize the rest, if problems occur at output, one solution is to set it to its lowest setting...

...the spot over greyscale you mentioned is the same as greyscale over spot, printing ink orders are the defining factor, as a rule, black needs to always overprint a spot colour, unless its a metallic ink. Spot colours are virtually opaque, so a spot on top of black will go some way to covering it up...

andrew

 

[apepp]

...correction, press quality uses 1.4 not 1.5 as i wrote above...

andrew

 

[apepp]

...just to add, if creating 1.3 pdf, the flattener needs to be set to high, if set to low then yes, quality does become an issue in the resulting pdf, with regards to lineart, text, gradients and mesh...

You can set the following options in the Transparency Flattener Preset Options dialog box:

Name Specifies the name of the preset. Depending on the dialog box, you can type a name in the Name text box or accept the default. You can enter the name of an existing preset to edit that preset. However, you can’t edit the default presets.
Raster/Vector balance Specifies the amount of rasterization. The higher the setting, the less rasterization is performed on artwork. Select the highest setting to keep as much artwork as possible as vector data; select the lowest setting to rasterize all the artwork.
Note: The amount of rasterization that occurs depends on the complexity of the page and the types of overlapping objects.
Line Art and Text Resolution Specifies the resolution for vector objects rasterized as a result of flattening. The resolution affects the precision of intersections when flattened.
The Line Art and Text Resolution option should be set at the minimum resolution needed to represent fine elements, such as small fonts or thin strokes, on your output device. Typically, on devices up to 600 dpi, you can use the resolution of the device. For imagesetters, you can use half of the imagesetter’s resolution. For example, a 2540-dpi imagesetter might use a 1270-ppi resolution for line art and text.
Gradient and Mesh Resolution Specifies the resolution for gradients rasterized as a result of flattening, and for drop shadows and feathers when printed or exported. The resolution affects the precision of intersections when flattened.
Gradient and mesh resolution should generally be set between 150 and 300 ppi, because the quality of the gradients, drop shadows, and feathers will not improve with higher resolutions, but printing time and file size will increase.
Convert All Text to Outlines Converts all type objects (point type, area type, and path type) to outlines and discards all type glyph information on spreads with transparency. This option ensures that the width of text stays consistent during flattening. Note that enabling this option causes small fonts to appear slightly thicker when viewed in Acrobat or printed on low-resolution desktop printers. It does not affect the quality of the type when printed on high-resolution printers or imagesetters.
Convert All Strokes to Outlines Converts all strokes to simple filled paths on spreads with transparency. This option ensures that the width of strokes stays consistent during flattening. Note that enabling this option causes thin strokes to appear slightly thicker.
Clip Complex Regions Ensures that the boundaries between vector artwork and rasterized artwork fall along object paths. Selecting this option reduces stitching artifacts that result when part of an object is rasterized while another part of the object remains in vector form. However, selecting this option may result in paths that are too complex for the printer to handle.

andrew

 

[NickGross]

thanks heaps apepp,

that was really helpful, I just got the proofs back and sure enough, everything looks fine which is a relief, for once nothing needed to be changed on the journal; it was a pleasure, no spelling mistakes, no font size problems, no nothing, fantastic!

Just to confirm, if I want spots to multiply over grayscale, I need to tell my printer to print spots after black rather then to overprint black? Will they interact OK with blending set to multiply, or are they kind of unpredictable?
thanks again for your help

Nick

 

[apepp]

hi nick...

...well, as i mentioned above black is a standard overprinting procedure for printing in litho, unless it is a metallic ink being used, in which case a knockout is necessary as black doesn't sit well on top of metallic inks...

...overprinting spot metallics is ok in some cases depending on how much ink coverage is sat underneath...

...i wouldn't advise overprint a spot colour on top of black really, as spot colours are opaque in reality, process cmyk colours are transparent, overprinting an opaque colour on top of a transparent process colour will have an effect on it, even with black, the darker of the four process colours...

...good to hear the proofs had no surprises in store for you...

...reminds me of stroke issues we have with some proofs as proofers have a limit to how thin they print the thinnest line you throw at them, can appear on proofs but not on plates if your not too careful...

...a good tip with really thin strokes, as I so often see, is to keep them above 0.25pt, especially if it is a tinted stroke as these can sometimes disappear due to the screening on plates and the angle of the dots produced. If strokes are solid you might get away with thinner, but 0.25pt is mighty thin in any case...

andrew