PDF is good!
But it is very easy to create a bad PDF... After all these years, some people still don’t like PDF. Probably ‘because something happened’, probably ‘some time ago’. However, PDF has evolved, and PDF-tools have also evolved, making PDF the best option for creating a reliable file for output. Industry experts overwhelmingly admit that It is much more reliable than PostScript. And it is much more compact and flexible than TIFF-IT. But there is one down side: it is very easy to create a bad PDF... That’s why you need to ensure the quality of your PDF, by using the right settings to make it. You need to check it before you send it to a printing company, before you send it to a proofer or a RIP. This checking is called preflighting. It is a technical analyses of the file, based on settings you define upfront. Don’t run away! You can download those settings, assembled by the ‘best and brightest’ within our industry, for 13 specific market segments, FOR FREE! From the website of the Ghent PDF Workgroup, a worldwide association of industry experts. Go www.GWG.org.
How To Guide
Try the following with the PDF test file Step 1
Open the test file in Adobe Acrobat or Adobe Reader. Do you see any errors that will become a problem in print? Now send this file to your proofer or your RIP. Please note: an ordinary desktop printer is not a proofer! Files are handled differently and can come out differently. If you have another PDF viewer on your system, other than Acrobat or Reader (e.g. Foxit Reader, or Mac OSX Preview), use that one too and check if both viewers show the same information.
If you have a tool to convert any PDF to a PDF/X-1a compliant file (which is a more restricted version of PDF, specific for the printing industry), convert the file and save it. If you don’t have an application that does that and you have Acrobat 8, do the following: ‘Advanced’ > ‘Preflight’ > select ‘PDF/X compliance’ > select ‘Convert to PDF/X-1a (Coated FOGRA27). Look at the report! After that, send your file to your proofer, your RIP.
Now check the PDF/X-1a compliant file (Step 2) with a GWG compliant preflight application and with a Sheetfed offset CMYK profile (e.g. in Adobe Acrobat under ‘prepress’. And see what errors are still in this file... Even after conversion to PDF/X-1a. That’s why you need preflight, why you need GWG!
What’s wrong with this PDF file?
The 9 - not 5 ! - issues #1 Image resolution
The image consists of 4 different quadrants, all with a different resolution. • Top left: 200 ppi, which is good • Top right:149 ppi, which is good for some applications (newspaper), but not for others (high quality books) • Bottom left: 72 ppi, which is not good for print jobs • Bottom right: 150 ppi, which is good for most applications, but we’ve used a 125% scaling factor, which means that the scaled image is not good enough for e.g. high quality books. Always look at resolution in combination with scaling factor (and don’t scale over 30%, both upscaling and downscaling).
#2 Unintended RGB The image is in RGB. Could you detect that, without a special tool?
#3 Spot colors
The purple part of the logo contains 5 different variations of the same Pantone color... One of them is a CMYK simulation, the other four will end up as seperate plates. Unless you detect and fix it.
#4 Font issues
The text at the top will probably look different on your screen, proofer, RIP. That’s because the font is not embedded in the PDF. The text at the middle is probably too small to print, it’s only 4 points high. The text at the bottom is bigger, but the color used is 100% C, 100% M, 100% Y. Try to print that one without showing registation errors!
#5 White text
The intention was to have a white text onto a solid black. But it has disappaered... That’s because we set it to ‘overprint’. Which means that we will place that ink on top of the other ink. But there is no white ink... This should ‘knock out’. Also you need to set your PDF viewer to show this overprint!
There is a text set to 0% opacity, which equals to 100% transparency. If your proofer, your RIP doesn’t support transparency, this text will appear.
The PDF also contained a hidden layer. If your proofer, your RIP doesn’t support layers, all layers will be placed on top of each other. To be sure that this layer would appear on your proofer, or on your RIP, we set Layers to ‘always print’.
The picture of the flower has been placed just up to the trim marks, which is not good: during cutting the paper can shift a little bit and then a white line will appear on the finished paper. Therefor we need to place the image a bit outside the finished page. That is called ‘bleed’.
#9 Rich black
The black rectangle is composed of 100% C, 100% M, 100% Y, 100% K. That’s something printers don’t like: too much ink. This can cause web breaks on a web press and it looks ‘smudgy’. A very deep black can be obtained with 40% C and 100% K. That’s all you need!
Now, are you convinced that you need preflighting?
Yes? Then go www.gwg.org and check out the complete list of all GWG compliant applications. And download the settings for your line of work.
This is valuable knowledge, all available to you for free...