Top 15 Common PDF Errors
In a recent survey about PDF files in the graphic arts industry, 1100 respondents said the top 15 issues they ran into when working with PDF’s from clients were:
Low Image Resolution Low image resolution leads to a loss of sharpness. When the resolution is low images are ‘pixelated’ showing a sawtooth effect. The standard resolution for print is 300 DPI and resolution for images on the internet is 72 DPI. Images downloaded from the internet and added to art for print will print with low resolution and should be avoided.
Use of incorrect or unwanted color spaces When sending a file to print, your printer will request CMYK files as any PDF file containing RGB will be incorrect and unusable for print. RGB is the color profile for screens and monitors, not paper.
Bleed is missing Unless bleed is added to the document a thin white line may appear along the trimmed edge of your finished piece, bleed is used to bring your documents art edge to edge.
Fonts are not embedded in the PDF This can lead to the text being printed with a wrong typeface. When fonts aren’t embedded, the text will change to a default font which can cause the spacing and font size issues.
There are problems with transparency Design applications split up a page into small square areas, called atomic zones. The effect of transparency is then calculated for each separate atomic zone. The stitch between atomic zones can sometimes show up on-screen (and even in output) as thin white lines. A file can also contain transparent objects with different color spaces. For instance, adding a drop shadow to a spot color element that sits on top of a CMYK background (or vice versa) is an example of a design that challenges workflow and creates a problem with transparency.
The PDF file contains an incorrect number of spot colors Printers who ask for pure CMYK files sometimes get PDF files with spot colors in them. When spot colors are expected, the same color might appear multiple times in a document but each time with a different name.
There is an issue with overprint The inappropriate use of overprint is an issue by itself. Issues with overprint can cause page elements to disappear or change color. Small text can become difficult or impossible to read. Overprint is when one color object overlaps another on the printed piece, this is normally used for special effects within the design.
Total ink coverage is too high This can cause issues on press because the ink can’t dry properly. This can lead to set-off where the ink of a still wet area rubs off on whatever is stacked on top of it. Too much ink can also lead to muddy browns in neutral areas.
Incorrect ICC (In Color Management) profiles are used The use of incorrect profiles can lead to printing the incorrect colors of the finished piece.
The dimensions of the PDF do not match the requested size When sending in PDF files to print they should be to size. For instance, if you are printing a 4”x 5” postcard the PDF file should reflect that size plus bleeds. Print ready artwork should always be the size you want to print to avoid errors when printing.
There are issues with flattened transparency Flattening can cause thin white lines to appear, shifts in color or make text appear fat. Flattening can also cause white rectangles to appear in graphic elements such as artwork or images. Flattening divides transparent artwork into vector-based areas and rasterized areas.Colors are not reproduced correctly Most pure blue colors are out of gamut for CMYK printers. In other words, the color cannot be accurately reproduced. The same is true for many RGB colors such a pure bright green. It is a good rule of thumb to check these prior to attempting to print or create a PDF for workflow that requires CMYK printing, to view use the Proof Colors function. You’ll see a rendition of what content will look like in the CMYK color space. This doesn’t mean you export RGB as CMYK, but rather this is what will render when printed.
The output intent is missing or wrong An example of this is the use of US-specific output intent such as SWOP (Specifications for Web Offset Publications) for files printed in Europe. This can lead to incorrect color separations when printing.
The conversion of spot colors to CMYK differs from the expected result When converting any color to CMYK the colors will be slightly off. Especially spot colors which are pre-mixed PMS colors and require the use of one of the press units to be printed in combination with CMYK printing. It is highly advised to avoid converting these colors for printing.
Technical elements are not defined properly A document may need to contain data for die cutting, embossing, spot varnishing or other finishing services. A die line should be defined as a spot color and named ‘dieline’ as well as being set to overprint. If a die line is not in the file and is required, it will need to be add in prepress or a new PDF file must be supplied.
Understanding and knowing about these 15 common errors should make outputting files for print more manageable. For more information on Print ready PDF files contact firstname.lastname@example.org and we would be happy to answer any questions you might have.