I need to go to design school

May 28, 2009 9:45 PM

Large-format printing filter: Help me figure out a workflow for getting my very large photographs into a 60" x 90" Adobe Illustrator file. Difficulty: need the job done tonight!

I need to build some camera-ready PDFs that will be printed 60" by 90". CMYK, 1 inch bleed, one large 300 ppi photograph plus some small text elements per file.

My problem is that we're talking about HUGE file sizes here. Am I doing something wrong? I exported the files from Lightroom as 30", 300 ppi, and they come out as 200 MB monsters. This is one thing, but then I took them into photoshop to get them up to the 60" dimension I need. Unfortunately, when I save the PSDs, they're 2 freaking gigabytes! These things take forever to work with and even longer to save. I must be doing something wrong.

What workflow should I be using so that I can keep the file sizes down and still achieve decent print quality? I have access to Adobe CS3, and I need to finish this project tonight. I haven't done any large-format design work before. Help me hivemind!

posted by hamandcheese to media & arts (12 comments total)

Are you upsampling them in Photoshop? Just place them in Illustrator and scale them up while keeping an eye on the res.
posted by nathan_teske at 10:26 PM on May 28

Your "very large photographs," are they at least 18300x27300 native pixels? By which, it would probably mean that you stitched together several digital photos together to get to that high of a resolution or scanned a large-format piece of film?

If not, you have to make up the pixels for such a specification (61x91x300ppi).

Making these pixels can be done in Photoshop using the interpolation in the Image Size command, but it will make the pixels soft, since it's using a form of averaging.

There are various plug-ins that will attempt to add realistic detail (Genuine Fractals is one), but let's also keep in mind the viewing distance of the output, shall we?

If you were to see a billboard-sized photo, you'd be surprised at how big the pixels actually are. They usually use a technique called stochastic screening so you can't see the blockiness.

Yes, a photograph scaled to those pixel dimensions is going to be big, so you can either:

1- Scale it yourself, using something like Photoshop's Image Size, a plugin like Genuine Fractals, or a combination of Image Size plus gaussian noise, which will approximate a stochastic screen on printers whose rips don't do stochastic screening
2- Let the output device scale it to the paper. This is only a good option if the device offers stochastic screening. Otherwise you will see the pixels.

BTW, there's no need to bring Illustrator into this scenario. Yes, PDF is now Illustrator's native format, but Photoshop will output PDFs just fine. PDF, in this case, is just a wrapper to a raster (or bitmap). Where PDF really shines is when you have both vector and raster in the same file, which I don't think you will.
posted by tomierna at 10:29 PM on May 28

Yes I am upsampling them. Should I not be? Will scaling in Illustrator be good enough? What do you mean keeping an eye on the res?
posted by hamandcheese at 10:29 PM on May 28

Sorry, I need to clarify: I require Illustrator in order to include vector text elements.

The photos are only large because I thought I needed to upsample them to the actual dimensions they will print at. They were standard 15 MB files to begin with. I'm just concerned that if I just place them in Illustrator and scale them to 60" wide, they will print pixelated.

I do a lot of graphic design projects at smaller sizes, but as for this scale, I don't know what the hell I'm doing!
posted by hamandcheese at 10:33 PM on May 28

I would resample the bitmap portion in Photoshop to your output size and add something like 1-2% Gaussian noise. Then save that and place it in Illustrator.

Then, place your vector graphics and resave as PDF.

You can, and should, be using PDF's compression settings to optimize the bitmaps in the output file.

Again, your output device and output viewing distance are key here - if you know your audience is going to be viewing these prints at 5-10 feet, you don't have to worry as much about the bitmaps being crisp, or showing the pixels. If they require up-close scrutiny, you may need to ensure that the output device is using stochastic screening rather than a regular photo screen, or that you've scaled the bitmap with a plugin or with some technique (like adding noise) that will mask the pixel boundaries.

Also consider that your source bitmap, if 15MB, when scaled, will end up with printed "pixels" of about 10x10 device pixels. Not huge - 30ppi.
posted by tomierna at 10:46 PM on May 28 [1 favorite]

Thank you. It sounds like I'm mostly up against hardware boundaries then. That sounds pretty close to my intended workflow. I just can't believe how frustratingly slow it is to work with these files.
posted by hamandcheese at 10:55 PM on May 28

You could place a low-res proxy in Illustrator and scale it to your Canvas size, work with the Vector aspects of it, and then as a last step, place the full-size bitmap and save.

Good luck!
posted by tomierna at 11:00 PM on May 28

Yes indeed, that's what I've been doing. Thanks again for your help.
posted by hamandcheese at 11:05 PM on May 28

a somewhat reliable formula to get a reasonable resolution is R = 290/d, where R is the resolution in ppi and d is the distance in feet your print is supposed to be looked at.
I can show my work if required
posted by _dario at 11:11 PM on May 28 [1 favorite]

OK, it's late, so my brain may not be up to snuff, but here's a few random thoughts. (And I see on preview that you've already gotten some good answers.)

If you can use 200 ppi for the full-sized photo, it will make a big difference in file size with no noticeable difference in print quality. I print large banners with photos all the time and I wouldn't dream of going 300 ppi, even for the sizes I do, which are "only" about 36 x 70.

Keep in mind that every increase in ppi adds tons more pixels to the file size. Example: a 1 inch square image at 100 ppi is 10,000 total pixels. At 300 ppi, that same image is 90,000 pixels! We always consider 300 ppi to the magic number for photo quality, but as the print size gets bigger, lower ppi is not only acceptable, but often necessary.

Yes, a native PSD file in those dimensions will be huge. After resizing, can you save it as a maximum quality JPG, or a PDF, or a PNG, then import that into Illustrator to add your text and other elements? Don't be afraid of a maximum quality JPG. Also, if you are making a montage or combining elements in the PSD file, either flatten the file or link and merge the layers. That will help file size as well.

Once all the elements are in Illustrator, you are creating a PDF, correct? Just make sure the PDF settings are high quality and you shouldn't get any compression artifacts.

Hope this helps...
posted by The Deej at 11:17 PM on May 28

Just a quick follow up for posterity. The Deej was on the money on all counts, although I ended up having to take the final elements into InDesign because Illustrator was having a heck of a time rendering Gaussian blurs at that size.

I got the files off a little behind deadline but it all worked out and apparently the print shop had never seen files prepared so well for print. Thanks MeFites!
posted by hamandcheese at 5:58 PM on July 15

Awesome! Thanks for the followup!
posted by The Deej at 7:10 PM on July 15