The exportation of files for print is an interesting topic. I create signs, and the digital aspect of that operating parameter is governed by that manufacturing requirement. What that means is that I'm constantly thinking about the Big D, (destination) and that means color model, resolution, file transfer method, file format and my sanity.
I take files from clients, so I work in all applications. With that said, I’ve worked with files that have been from 130' wide to 1” wide. I work in full scale, res and scale my proofs down from transmitting to the client via publish to PDF. When my work is approved, it's done. That means I use the CorelDRAW Graphics Suite a great deal due to the compatibility of the application to my working environment.
My experience for exportation is quite diverse. Not all file formats support the proper size, and some have size and or resolution limitations with which we need to work around. I tend to set one rule -- talk to the output provider. If the output provider is me, it's business as usual because I talk to myself all the time.
Image resolution for large- and grand-format printing ranges from 200 DPI for art prints and 150 DPI for high-quality, closely viewed trade show graphics. A resolution of 100 DPI for cloth printing, usually dye sublimation, like table spreads and 50 DPI for billboards. I do very little billboard work and I have heard of users working at 25 DPI. The great aspect of working in a program designed for producing signs is that you can build at full scale and set the effects resolution to what you need it to be for output so you can save system resources.
For outside service providers, the first question is what color model. For digital prints it is simple. For the RGB or CMYK color models, embed the file’s ICC profiles with the file and send it along. Color handled.
On the printing press, create your file only in the CMYK color model, with images at a resolution twice the plate screen ruling. Then send the profile along with your file. A PDF will work fine. For all PDF exportation, if you want 100 percent guaranteed file compatibility, flatten all transparency in your file and publish the PDF at high resolution.
If you're working in spot color, use only one spot color palette, i.e., don't use the same color (i.e., PMS 286) in the C and U palette. Use one or the other because you'll get extra plates you don't need or a file repair bill.
Do not send Illustrator editable files. If you’re using Illustrator, turn off Illustrator editing compatibility in your exported PDF because when left on, this feature causes issues for a lot of RIP applications. Unfortunately, now many Illustrator users only save as PDF and confuse the process. Smart users use the AI file format for saving to their server or local machine and send PDF files without Illustrator editing capabilities for export. If you want to send an AI file for editing, make sure you turn off compression because this will help when importing to other applications. Fonts to outlines also help.
There some file format considerations. For output over 200 inches, forget about using PDF. We need to consider other options.
Is the file going to be viewed up close, like a trade show graphic? If so, then we will need as high of a resolution as possible for images. Vectors should not be an issue; that means EPS for exportation. You will need to communicate the color profiles used because EPS does not support embedded profiles. Illustrator EPS files maintain Illustrator editing capabilities. And like Illustrator PDF exportation, that can be an issue for other pre-press applications.
If the file is viewed from a distance, like 20 or 30 feet, we can consider these facts. Print for viewing at distances shouldn't have small print, and the resolution of the files can be 100 DPI or even lower. For billboard-sized prints, sometimes as low as 50 or 25 dpi. The best solution I've found for these exports is a flattened TIF file, which means no layers.
The TIF file format has limitations. Beware that Photoshop will reduce the physical dimensions of files being rasterized to fit within that parameter. I use PhotoZoom Pro to increase the resolution of original-quality images. A version ships with CorelDRAW X7.
I'm in many print and sign shops on a regular basis, and I can tell you that more times than you can imagine a PDF file -- especially ones from InDesign -- are simply rasterized in Photoshop and output as a TIF file. I know of several shops where that is the standard procedure. They don't even try to output the PDF; they rasterize the file, send a JPG proof, and output the full-sized high-resolution TIF file.
The problem with large- and grand-format printing is that the files are very large and the transmission of these files can take some time. Many people use an online service for file transfer. I will only use one if required because I have an FTP client loaded on my systems and prefer this method, most likely because I'm old school.
I use PDF for proofing. In my mock ups I send all outlines to scale to the drawing. I then scale everything down to an 8? x 11 proof sheet and publish to PDF, reducing the resolution to 96 at the proof size. Then I email away and hope for the best.
My last article detailed PS and PDF exportation, so with that being done let's concentrate on image exportation.
Accompanying this story are some dialog captures from Photoshop, Corel Photo-PAINT and PhotoZoom Pro, which operates as a plugin for Corel Photo-PAINT and is distributed free with CorelDRAW as is Photo-PAINT, with some explanations on how I use them.
The TIF file format has some limitations for 32 bit systems, 4 GB in general. I suggest that you ignore big TIF, even though it does exist because most RIPs -- even though they run on 64 bit systems -- are still 32 bit software.
The first thing to discuss is the nomenclature. Size can be the byte count and the physical dimensions. With an image, the total byte count is the maximum limit, as the pixel count per inch is reduced, the physical dimension can be increased.
For example, the physical dimension of a maximum size TIF as defined by byte count at 300 PPI can be increased 300 percent if the PPI is reduced to 100 PPI. This is fine as long as the resulting PPI at the output size is sufficient for the print device. This is where software like PhotoZoom Pro comes in.
Big warning: Test a small piece of the output.
As long as the image is of good quality using a program like PhotoZOOM Pro, you can in many cases go 300 percent to 600 percent increases in physical dimension.
When exporting as a TIF from any application, you may or may not be made aware of the size limitation. In Acrobat you get an error if the size is too large; in Photoshop when you import a PDF, the physical size limitations appear in the import dialog. It simply won't let the image’s physical size be too large for the resolution. Be sure to set the resolution first, then manually enter the physical size.
A new CMYK Photoshop document at about 101” x 101” at 300 DPI is very near the 4 GB limit; however, we need to understand something first. Photoshop is just one element in the process. Most RIPs are still 32 bit and therefore they have a 4 GB limit, making it impossible to RIP maximum TIF limit files. The true 64 bit RIP applications are just getting started, so we need to mind the fact that 1GB TIF files are tough to process.
Remember that in your pricing, also. If you're bringing in these large files, just transferring the file can take a few minutes, edits on these files can take several minutes for each edit and RIPing can take 5 to 10 minutes or more per file.
Recently I was working on a large Photoshop document with smart objects from Illustrator. Each little edit took 9 minutes and the client wanted 15 different changes. Try that in the middle of a busy day with a client and sales staff who not only don't have any understanding of the technology, but don't want to understand it.
This brings up one of the most serious issues with the graphics environment today, management’s lack of understanding of the technology as well of the client’s lack of respect for what we do. I've heard this so many times it unbelievable: “You're only doing it on a computer.”