February 12, 2006

Resolution Confusion: Is There a Solution?

285ppi divided by the line screen, carry the one -- oh! Hi there! Sorry, you caught me trying to figure out the correct resolution I needed for my file. Resolution you say? Surely Mordy, you must be smoking something good, because we know that vectors are resolution independent and are output at the resolution of the output device. Right?

Well... kinda.

You see, in today's modern world, pixels and vectors live in harmony -- all within Illustrator. And with all the snazzy effects that designers want to use (don't make me say it -- you know which particular effect I'm referring to), one would be foolish to overlook the fact Illustrator artwork today contains many raster-based effects (sometimes even without our knowledge).

The reason why I bring this up is because it requires a change in thought, which is something that doesn't happen easily due to human nature (see, taking that Psychology class I took in college came in handy after all). After all, if you're in Photoshop, you're mind is always on the issue of resolution. Heck, you can't even create a new Photoshop document without first defining a resolution. On the flip side however, those of us who have been using Illustrator for many years have never even thought about resolution. And surely, you wouldn't think to set the resolution of your file in Illustrator when you first create it? Would you? After reading this, you might ask yourself that question again.

Great, so you have come to realization that maybe there is a resolution setting in Illustrator after all. But come on now, do you really think the folks at Adobe would make things so easy for you? Illustrator doesn't have a single resolution control setting -- it has THREE of them. Yeah, grab a beverage, pull up a chair and get comfy -- this one's gonna be a while...

OBJECT RESOLUTION - Actually, this is what it *used* to be called, before Illustrator CS rolled around. Now it's called "Flatness" and can be found in the Paths section of the Graphics panel in the Print dialog box. Back in the old days, you were able to set the object resolution for a file (in the Document Setup dialog), which controlled how smooth a curved line would appear when RIP'ed. In today's "new and improved" Illustrator, this setting has become obsolete and the Flatness, by default, is automatically optimized for your output device. I mention it here, however, because there have been times when I've seen that some legacy files have caused issues with this setting. Jean Claude can tell you of a certain bug that set the Object Resolution to 100 at times, making for files that were not acceptable after printing. If you're using Illustrator CS2 exclusively, then you're in the clear (as far as I know) and don't have to stay up nights worrying about this setting.

FLATTENER RESOLUTION - I love transparency. I really do. I can't imagine living without it. And if you're like me, you know that the flattening process, which must occur in order to properly print transparency effects to a PostScript device, may cause vector objects in your file to become raster. In fact, let me clarify that even more by stating that PARTS of vector objects may even become raster in your final output. Well, if parts of your file are now raster, who determines that resolution those rasters are created at? You do. If you know about your flattener presets, you know you can choose from one of Illustrator's 3 low, medium, and high resolution settings. You may even know that you can create your own presets and set the resolution to whatever value you feel will allow you to sleep at night.

Yet, if you've applied those snazzy effects (did you know that Ted Alspach and I once joked about setting a daily limit on the number of drop shadows you would be able to apply? You'd get a dialog box that said something like "you'd reached your allocated number of drop shadows for today, please try again tomorrow"), you might think that setting your Flattener Preset to the High Resolution setting will get you the results you expect. And sadly, I'm here to tell you that you'd be mistaken. For there's a third resolution setting in Illustrator, and it's probably the most important of all...

DOCUMENT RASTER EFFECTS SETTINGS - You'll find this setting in the Effect menu. This setting controls the resolution that's used for all Effects that are raster-based. This includes Drop Shadow, Feather, Inner Glow, Outer Glow, 3D (when raster or gradient content is mapped to a surface), and anything below the divider line, marked in CS2 as "Photoshop Effects". What makes life "fun" is that the default for this particular setting is 72ppi. If you're a print designer, this setting is blasphemous and is grounds for divorce from Adobe. After all, the only reason why Adobe made the default setting at 72 ppi was to make all of the web designers of the world happy. Well, that's simply isn't true, but it still leaves the print world wanting more. The true reason why the default setting is 72 ppi is because of performance. Go ahead, crank up the Document Raster Effects Settings to 300 ppi. Then apply a Gaussian Blur.

That's ok, I'll wait...

Still waiting....

La la la deee dooo da -- oh, are you back yet? You must have one of those fancy shmancy G5 computers.

Seriously though, the higher the resolution, the slower the performance. Mind you, the performance lags when doing "simple" tasks, like scaling, scrolling, zooming, even just moving objects. And if you have to undo something, that might be a good time to refill that beverage...

OK, so you know that if you're a print designer, you have to set your Document Raster Effects Setting to something higher, and that you're going to have to put up with slower performance. Not much of a choice there. Or is there? I mean, couldn't you dial in a low resolution during the proofing process and change it to high res just before you print? The good news is, you can! But there's a catch. It depends WHICH effects it is that you've used in your file.

You see, the Effects menu is split into two sections: Illustrator effects, and Photoshop effects. Illustrator effects are resolution independent in that you can change the resolution at any time and the effect will look the same. Illustrator does the math for you under the hood and gives you a result you expect. However, when you use Photoshop Effects, those are resolution dependent and such effects look very different depending on what the resolution setting is. For example, the Mezzotint filter offers a very different appears when the resolution is set to 72 ppi than it does with the resolution set to 300 ppi. So you can't just change the resolution right before you print your file, because the apeparance of the effects may change dramatically. (This is why the Print dialog box smartly informs you what the Document Raster Effects Setting is set to, but it doesn't allow you to change it -- as doing so may change the appearance of your file without you knowing it. For this reason alone, if you work in print, it's best to set that resolution setting to 300 ppi at the outset of your design process.

The truth is, there's plenty more to talk about on this topic, but I have to go out and shovel some of that record-breaking snow we just had.

19 comments:

Teri Pettit said...

Here is another fine print detail about Document Raster Effects Resolution:

It only applies to the resolution at which vector objects get rasterized before sending them to the raster effects to run their pixel magic on.

So if you have a particular object that you want to run, say Mosaic Tiles or Pointilize on at an extremely low resolution while allowing your drop shadows to continue to run at a medium resolution, you can apply the Rasterize effect to that object, and pick your specific resolution for that object, and then apply the Photoshop effect. Your object-specific Rasterize resolution can be either higher or lower than the Document Raster Effects setting. The Rasterize effect "isolates" the object from the Document Raster Effects Resolution because by the time the "needs a raster" effect sees it, it is already a raster.

(This fencing off won't work with Drop Shadow, because the shadow that the Gaussian Blur is being run on is generated as a vector and then blurred, rather than blurring the original object.)

John Kallios said...

To stir the pot, and cause more confusion…

It is possible to use 72 dpi raster effect setting AND achieve quality output in many circumstances by maintaining postscript 3 gray levels.

But, it is best for designers (as this thread indicates) to set the effects resolution appropriately before handing off to their printer.

Mordy Golding said...

John, you're correct when dealing with feathers, drops shadows, or glows, as those are continuous tone. However, with the Photoshop effects, especially with things like mezzotint, you'll get pixelated results.

John Kallios said...

I can't argue with you there. : )

Eric Peacock said...

Thanks for writing this up (you've beat me to it).

You can't explain this enough – I see designers suffer from misunderstanding this all the time.

It took me a few years to get a good handle of all of the issues within transparency myself. Illustrator 9 didn't help with it's horrible stability but at least now things work consistently.

Where I work we do large posters or wallpaper and such for retail merchandising in Illustrator, and yes these include drop shadows galore.

I have lots of tricks for getting these done on short timelines, one of which is setting my document raster effects rez to 22 dpi when doing stuff with sizes like 40x60 inch or larger. Just before going to press I set it to our final printer resolution, wait a while for the rendering only once, save and all is well.

Believe me, you can't even work on a large format project using transparency effects at any decent pace without being aware of any of this.

Anonymous said...

Don't forget the 4th resolution setting. Raster images used in illustrator will generally display on your monitor at 72 dpi, and should be manually downsized till they match the printer resolution. You might think that the raster effects setting (or one of the other two) would automatically affect the way that raster images are displayed so that WYSWYG... but no.

finally!!!! said...

i don't know why in the world 72 is the defult raster on ill. effects. what the heck adobe??? i finally found out that i can make it 300 thx to this blog post... (maybe i should read the CS manuel one of these days... since i learned illustrator back in the day of version 7)

Talisha said...

I have a question...wouldn't it be easier to just do what ever effect you need done in Photoshop and then place it in Illustrator? Thus, foregoing this dpi raster nightmare? Or is this too time consuming?

melissa said...

i have read this blog (and numerous other tips) and all the advice is great! however, no matter how many times i change the settings, i still get an error message when i go to save or print stating that my raster settings at at 72 ppi or less. any thoughts?

Rodrigo Violante said...

Great article! has become really helpfull.

I recently -and gladly- switched from Corel Draw to Illustrator after years of fighting my laziness on learning how to use a better software.

Tho, this has left me with too many -bad- tricks and shortcuts no longer available now that im using illustrator. I have no clue why all the pictures (raster bitmaps) i put in seem to be in a different resolution and can't get along with my artwork. I've had to use photoshop to deliver work that has needed photos in it and its not the best idea.

Any tips on how to have photos and vectors work along in Illustrator?

Anonymous said...

Hi, got two questions please let me know if you can help.

1. got a client who needs these setings for printing:

1:1 density/thickness 72- 150 dpi
1:10 density 600-900 dpi

Please can you explain how to get this done correctly in Illustrator?

2. What does this mean and how can I resolve it?

The image was has too low resolution and they said it's not 1:1

Martin said...

Very nice Job!

Linzi R. said...

Thank you so much.
You saved my day... week maybe.

Anonymous said...

very clear explanation and fun to read! thank you

Dzeni said...

Thanks for this! I could not figure out why my drop shadows looked horrible - they are fixed now. Great post.

Anonymous said...

As a printer, we continually receive illustrator files with the Raster Effects set to 72. (CS4) I have found that the effect sometimes changes significantly when we re-set it to a higher setting before processing the job. This leads me to believe that designing at a low setting and upping it for the final save may not be the best policy. Have any of you encountered this?

Anonymous said...

Thank you that was most helpful!

Rebel SEO said...

Thanks for pointing out Document Raster effects settings. I wondered why the effects looked so shitty.

Anonymous said...

Yes you can change these settings:
Effects->Document Raster Effects Settings

Using AI CS6