Archive for May 22nd, 2013
Which is the best file format for output?
Wednesday, May 22nd, 2013
The most commonly used formats are AI/In-design, TIF, JPEG, EPS, PS and PDF. Nowadays, the technicians working in the output center have little knowledge with different file formats except PDF. Most of their works involves receiving files and sending them straight to the output machines. If they encounter problems with other file formats, they will have very little clue on how to fix those files. PDF does have a few automated tools for pre-flight checking. Thus, a lot of mistakes can be caught at earlier stage. As a result, output centers don’t like people submitting files in AI/In-Design format. On the other hand, end users do like submitting files in those formats because they can let the output center to amend any mistake in the output file.
AI/In-Design – The procedure to send the files to the output machine is more troublesome because these file formats need matching fonts and link with correct photos. It is very common that files are submitted with missing and/or low resolution photos. Matching fonts can caused problem with different spacing and even missing some words. It is because there are cases even the fonts have the same name, they are different in certain character spacing even though the rest looks consistent. Experienced designers will outline the fonts before sending them to output center. However, there are cases that some wordings cannot be outlined. For example, page numbering in In-Design files.
JPEG – It is the worst output format but it is most well-known format by users. It has two unique disadvantages, limited bit depth at 8 bit and lossy compression. Users need to know how to tune the compression ratio with optimum size/quality balance. Any people know how to convert a work to JPEG format. However, not many know the 300dpi minimum resolution requirement for 4C 175lpi printing and 1200dpi for B/W line art. Even fewer people know JPEG’s have to be submitted in CYMK color space in order to match with offset printing colors.
TIFF – It is the same as JPEG as a raster file format. But it has the advantage of using different compression algorithms, such as a few non-lossy ones (zip, lzw or no compression). It also has more color bit depth, such as 16 bit or 24 bit. Thus, it can retain a lot more information than JPEG and it is the preferred format for photos. However, it is still a raster format and needs a lot of information even for a few simple straight lines and words.
EPS – it is a preferred file format in the pass. It is vector based, cross platform and minimum data loss. However, it lacks a few recent technologies, such as layer and spot color. Nowadays, not many data center knows how to handle EPS files so that it is not recommended as an output format anymore.
PS – Most people, especially the designers with lesser experience, knows about PDF but not PS. Postscript is a very old format but it is as good as PDF. For some old program such as Freehand, they cannot export to PDF directly but they can print to PS for output. It is also a very reliable file format, which is cross platform, vector based and compatible with raster graphics, and having all the features of PDF format. The only disadvantage is that this format can only be previewed by very specific design software, such as Adobe’s Illustrator. Sometimes, when a file exporting to PDF has problem, exporting to PS may actually work.
PDF – it is the most well known file format for any kind of work. Office documents, Internet forms and articles, files submission to output center are all using PDF file formats. Most output center welcomes PDF over any other file format. PDF files also have automated tools to check for the most common mistakes (pre-flight), such as using spot colors, RGB graphics, white graphics/wordings with over-print, not embedding fonts and so on. Whenever possible, submit PDF files to output center.