Working in large format print for a number of years, the number one thing I see designers struggle with is Large Murals. These projects have a number of opportunities for things to go wrong and it can all stem from your file prep.
The most important factor to keep in mind is resolution; specifically final resolution. What I mean by final resolution is the Dots Per Inch (DPI or sometime called PPI, Pixels Per Inch) for most large format printers, they do not need the same resolution your desktop of offset printer would require. Where the standard is 300-240DPI depending on application. Most large format printers can effectively print a wall mural at about 100 DPI and you wouldn’t notice. This has to do with the dot size on these printers and the “viewing distance” of the artwork.
The number one thing I tell colleagues and students is to design in 10% scale. This is simply for the ease of numbers when scaling down and up and keeps things simple.
This also makes thing easy when it comes time to export a High Resolution Tiff from illustrator. I have found this to be the most efficient way to export large files at scale. Illustrator has the ability to export raster Tiff files. A Tiff file is great format for delivering large files in a tiny package. The beauty is when you enable the checkbox for LZW compression you get a Loss-Less compression, the downside is it can take a lot of space to unpack.
Exporting From Illustrator
Below are some screenshots to guide you through the menus and settings for exporting a 1/10th Scale project from Illustrator.
First go to File > Export > Export As
Click on Export As and a Dialog window will come up. Navigate to where you want your file to be saved and make sure in the drop down to select “Tiff”
When you click save the last dialog box will pop up. This is where you will enter your settings for resolution.
Since we have been designing in 10% scale any images we have imported into the design should be close to 1000 DPI when at their 10% scaled size if not this will not work.
So we will want to enter 1000 for the resolution of our export.
We will most likely want CMYK if we are printing-rare cases it is okay to export RGB if you run into RAM issues
Once Exported you are done. You can either enlarge the Tiff file in Photoshop by changing the resolution in Image Size to 100DPI or the Printer is usually able to do this.
For some projects if they are really big, like My Samaritans Purse Project, you may need to supply the printer with the spliced panels for production so they can handle the files more effectively.
I will show you how that is done in another post.