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High raster effect resolution in large document makes effect dissapear

Feb 18, 2013 4:33 AM

Tags: #resolution #effect #dpi #raster

Hello

 

I'm making some graphics to be printed on a car. I have some lines with outer glow on them, but Illustrator won't render these unless I use 72DPI in raster effects reslution. I would like to go higher, but it won't give me anything. Guessing it's to heavy for Illustrator maybe? Is there anything I can do about this? I'm making my graphics in 1:1 scale, but I do it in a lower scale since it's just vector art anyway, however how would that effect my glow? Since it's a raster effect.

 
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  • Currently Being Moderated
    Feb 18, 2013 4:42 AM   in reply to Devoteez

    Yes, Illustrator has a 'maximum pixel size' or somesuch beyond which it will not go. If you design the graphics at a smaller size, then scale them up, you will, of course lose resolution at that point. When we have something like that to do (we make graphics for semis, as well as cars, etc.) we take the design into Photoshop and apply any raster effects there.

     

    --OB

     
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  • Currently Being Moderated
    Feb 18, 2013 4:52 AM   in reply to Devoteez

    The beahviour of Illustrator how effects and resolution is handled is different with Illustrator up to CS4 and from CS5. In the older versions effects changed when the resolution changed from CS5 the effects are as far as possible not changing when the resolution changes.

     
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  • Currently Being Moderated
    Feb 18, 2013 5:21 AM   in reply to Devoteez

    Nope, when you make your graphics in 1:10 all things, also the effects are 1:10.

    The resolultion is inside of you ai file and where you place it. When you have a raster effect with 300 ppi in AI and you place it 10 x so the raster effect has a resolution of 30 ppi.

     

    BTW: Raster resolution is meassured in ppi, not in dpi.

     
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  • Currently Being Moderated
    Feb 18, 2013 5:29 AM   in reply to Devoteez

    Basically, in Illustrator, if it won't let you create the effect at the size/ppi that you want, it won't scale up to that size/resolution sucessfully, either.

     

    Which isn't to say that Photoshop doesn't have it's limitations; it does, just fewer of them where raster effects are concerned.

     

    BTW; I'm using CS6 as well.

     

    Also, just if you're interested, HERE is a good article on viewing distance vs. ppi.

     

    Good luck.

     

    --OB

     
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  • Currently Being Moderated
    Feb 18, 2013 5:49 AM   in reply to Devoteez

    I'm making some graphics to be printed on a car...I have some lines with outer glow on them...making my graphics in 1:1 scale...

    Which means you're printing to a large format viny printer that uses stochastic screening, right? You don't need anything near 300 PPI for that. No one is going to see pixelation in an outer glow effect on that kind of print.

     

    So does that mean that I, using Illustrator CS6, can make my graphics in 1:10 and use 300DPI for raster effects, and the raster effects will still be high when scaled up?

    The change made to Document Raster Effects in version CS5 means that if, while working in Illustrator, you change the resolution of Document Raster Effects, doing so will not change the extent of existing raster effects (i.e.; the dimensions of the generated raster imgaes), as it annoyingly did in earlier versions. In other words, if the 72 PPI drop shadow extended beyond the object about a quarter-inch, it will still extend about that far when you change the PPI to 300. But again; you don't usually need 300 PPI for soft fuzzy raster effects @ 100%, even in offset print.

     

    JET

     
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  • Currently Being Moderated
    Feb 18, 2013 6:40 AM   in reply to Devoteez

    but I asked the printer and he said 300DPI

    Which just goes to show how widely misunderstood overstated rules-of-thumb are in this industry. In estimating appropriate PPI, you want small enough pixels (at print size) to avoid visible pixelation. In other words, you don't want to be able to see the squareness of the pixels. That's a function of the tone screening method resolution. As long as the pixel size is not larger than the screening method size, the screening method is not going to be fine enough to be able to render the squareness of a pixel as a square.

     

    Suppose you've got a pixel that measures 1/75th inch. How many round dots will be required to at least roughly render that square as a square? At least four dots. In other words, you'd have to be printing with a halftone screen of at least 150 LPI for pixelation to be visible. And even at that, the assumption would be a pixel that is perfectly aligned with a halftone cell, and on only one color sep angled at 0°. Stochastic screening is even more forgiving of lower raster resolution, because all the screen dots are the same size anyway. They are randomly patterned and their frequency is altered to suggest different tones.

     

    So vehicle graphics are not going to be printed at anything near a halftone screen resolution of 300 LPI. (Don't be confused by claims of "high resolution" of composite printers like 1440 or 2880 DPI. Those figures are talking about printer spot size, not tone cell size.)

     

    Add to all that the fact that concern over image sharpness doesn't even enter the picture when talking about raster effects that are intenionally fuzzy anyway (shadows, glows, etc., etc.).

     

    Flattening "stitching" artifacts need to be watched for if the soft, fuzzy raster effects overlay text or other vector objects that need to be crisp. But that's usually a matter of correct stacking order (or Illustrator bugs).

     

    75 PPI for raster effects on vehicle graphics is a gracious plenty; probably less. You don't really think billboard photos are sampled at 300 PPI @100%, do you?

     

    JET

     
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