Sending mistake free files to the printing house is a sign of a professionalism. Today there is a tool that can help you in this matter. It is a preflight option. It can help you to save time and to avoid the mistakes that can sometimes be devastating for your publication.
Back in the day there was no preflight option in Indesign and Acrobat. All of the files had to be checked by hand before outputting to postscript files. DTP and printing house prepress studios had an application called PitStop which was helpful in spotting the mistakes in print ready files. Today you just have to tick the right check boxes in InDesign and preflight will do the job for you.
Preflight will check all your InDesign layout documents and also the documents that you have placed in the layout, like bitmap images and vector files.
You can let the preflight run in the background all of the time while you work, but it can slow down your computer sometimes. It is best to run it in the end when the layout is finished. But there is a downside to this. For example you miss to check few images and in the end you realize they are in low resolution. Now you will have to get the high resolution ones, or if they are not available you will have to find another one and redo the layout. This is not a good thing especially if you are in the deadline and the time is tight.
Preflight panel will tell you everything you need to know about your document. Green light indicates that everything is OK, red one indicates that there are some things that need your attention. Click on the Error tab and expand the arrow to see the mistakes. Info part below will show you detailed information about the corrections needed.
This article will take you through the preflight setup and explain you what is important and what is not so important. Also I will tell you how to check the files that you receive from others, especially the ads since people tend to send ads with lots of unnecessary elements included, like spot colors.
It is important to say that we will cover the options for traditional 4 color printing process.
- Links: In the links drop-down menu you can tick the “Links missing or modified”. This option will warn you if there are missing or modified links in your document. The name explains itself. Other two check boxes you can leave. If you are producing files for digital output, you can tick the “Inaccessible URL Links” check box.
- Color: Here you can check the “Color Spaces and Modes not Allowed”. This will expand further to the color modes you want to include in the preflight check. Now click on the RBG, Lab and Spot Color check boxes. These options will warn you each time there are these color modes included in your files. Other options you can leave unchecked. Sometimes you can check the “Overprinting Applied in InDesign” which will warn you if you have overprinted some elements in InDesign. But we will cover overprint in some other article since this is the thing that lots of people tend to make mistakes with.
Check also the “Registration Applied”. This is helpful, since sometimes can happen that you accidentally apply Registration color to some elements instead of the black since they are next to each other in Swatches palette and it is easy to make this mistake.
- Images and Objects: First you want to tick the “Image Resolution” checkbox. If you expand it you can add your resolution settings that you want preflight to check. You want to tick all of the check boxes with minimum resolution settings. For traditional offset printing you don’t want to go below 225 dpi for color and grayscale images. For 1-bit images lowest resolution should be 600 dpi.
Also check the “Non-Proportional Scaling of Placed Objects”. This will warn you if there are some images that are non-proportionally scaled.
Image ICC profiles should be unchecked since in my experience it is not good to apply any ICC profiles to your work in InDesign. All of the ICC profiles should be applied to images and vectors in Photoshop and Illustrator.
Check the “Minimum Stroke Weight” option. This will warn you if your line weight is below 0.125 pt by default. Anything below this dimension will be almost impossible to print correctly.
“Bleed/Trim Hazard” option can be handy if you are not supposed to bleed your page elements, like in the newspapers, but in modern magazines, page elements do bleed and this option can be annoying. If you work in newspapers where page elements do not go into the bleed, you should check this option.
- Text: “Overset text” option should always be checked since it will warn you about the text that is oversetting in some text box.
“Font Missing” is another option you want to check. “Non-proportional Type Scaling” is something I do check because I do not like to scale my type non-proportionally since it does not produce nice results in my opinion. Other options you can leave unchecked.
- Document: Here the only important option is “Bleed and Slug” option. Here you can set up your minimum bleed and slug settings, but all of the document settings you have to apply at the beginning of the design process to your document template. When you set up your template correctly you won’t have to worry about all these settings anymore.
Checking the outsourced files
Sometimes you will receive outsourced files from advertisers, freelance illustrators or photographers.
Easiest to check are the photographs. Open them in Photoshop and check if their size and resolution suits your needs. Although InDesign will warn you about any mistakes but it is good to check the images before you place them in the layout since it may happen that they are too small for your intended design.
Vector illustrations can sometimes contain spot colors or be set in RGB mode. These files you can inspect in Illustrator or in the final stages of your work through preflight in InDesign.
PDF files can be inspected in Acrobat’s preflight settings. These settings can be adjusted almost in the same way as in InDesign.
Sometimes you will receive ads from advertisers that are full of the things that are not needed. Like crop marks, registration bars, spot colors and registration colors. I really don’t get it why advertising designers always use these things when they know that the print will be done in CMYK. I especially don’t like it when they include all of those crop marks and registration bars. It is absolutely not needed since you are the one outputting the files to the printing house.
If the file contains spot colors I always return the file to the designer and ask them to remove the spot colors. The thing is that if you send those files to the printing house, these files will be stripped of spot colors in the RIP process and those colors will be converted to CMYK. In this process color shift can occur and after the final output is different than the file they sent, you can be asked those silly questions why this happened. It is not your responsibility, but to avoid those unpleasant situations it is always better to ask for a CMYK ready file.
Image above shows how some spot colors cannot be printed in the traditional CMYK printing process. This means that there will be a color shift and the color will not look as the designer intended. This is why you should warn them about it. In the end they can blame you about it, but it is their responsibility and you should inform them about possible differences in the final result.
So, whenever you receive images or vector files with spot colors, warn the sender of these files and return them asking for a CMYK safe file.
I think we have covered all important stuff around preflighting the documents. If something is not clear or you would like to know more don’t hesitate to ask or comment.