Photoshop will save out your images in a huge variety of formats. It can seem very complicated, but the fact of the matter is that you will only ever need a small handful of these formats - and you can forget the rest! They can be divided up into two main camps - file formats for print and file formats for Internet and multimedia. In this tutorial I will just be covering the file formats used for print.
I will describe the Internet and multimedia file formats in detail in another post, but you should be aware that you SHOULD NOT USE GIF or PNG file formats for print - these are designed for use only in multimedia type situations and will generally cause you a-lot of hassle with printers and may severely reduce the quality of your final output. JPEGs should also be avoided in most cases, only use it if you are having trouble sending a file electronically due to file size - your only option is a high quality CMYK colour JPEG, but be aware that there will still be a loss in quality as this file format degrades image quality to compress the file - so ensure you put that quality level nice and high! Also some printers are not happy with handling JPEGs and may need to resave them, with a possible charge incurred, so be careful with this one - it is not really recommended!
Finally, if your file is destined for print you will almost always want it to be in CMYK colour (which all the below formats support) and setup at the correct resolution and dpi.
A final word of advice - if you are supplying digital files for print to a commercial printer, you should get in-touch with them to discuss exactly how they would like the files supplied. I always advise that you obtain a colour matched proof from the printers that has been produced using their RIP so so you can highlight any potential problems and rectify them - it may cost you a bit of money, but it might ultimately save you the cost of a reprint, which is going to be a-lot more hassle and more expensive!
Photoshop File (.psd)
This is the native file format of Photoshop, which has now been adopted by a number of other design applications.
A PSD will save all your transparency data, editable layers, masks, adjustment layers, layer effects, special colour channels and all other editable features of a layered Photoshop file. This is the only file format you need to use to save layered work in progress.
If you are using InDesign, you can import layered PSD files directly onto your page with no reformatting or resaving. InDesign fully supports the transparency in PSD files too - meaning you can have feathered soft edges on cutout images rather than a solid harsh cutout - so if you are using InDesign you dont have to use the EPS file format (see below) for this anymore! Although InDesign supports multi-layered PSD images, I often merge all my layers onto a transparent background to speed up printing. Using PSD files in any other application apart from InDesign is not advised and can cause printing problems, even if you manage to get the image onto your page!
TIFF (.tif)
TIFF stands for Tagged Image File Format. The TIFF file format is your meat and two veg of image file formats - nothing too clever but it does the job well! If you are preparing images that are not cutout and dont have special colour channels, this is the file format to use in almost every situation.
It also offers ‘lossless’ file compression, called ‘LZW compression’ - which will reduce the size of the file with no loss in quality. There used to be an issue with printers accepting LZW compressed files, but this has now been addressed by all but the most antiquated print houses. You are advised not to use any of the other compression options apart from LZW. Also you should avoid the layered TIFF file format - it creates very large files that take ages to save and open - for layered files you should only be using the PSD file format.
You also get the option to save the file with IBM PC or Macintosh encoding - this doesnt actually make a great deal of difference, Photoshop on either platform will open files encoded in either way - but it is a good idea to save the files with the appropriate encoding for the platform you (or your printers) are working on.
Although you can embed and use a vector clipping path in a TIFF, you should be using an EPS when you want a cutout image for DTP applications like Quark XPress (see below).
TIFF is also a good format to save pictures in for archiving and if you are at-all unsure about how to supply a flattened image file to someone for print, you cant go wrong with TIFF!
Photoshop EPS (.eps)
EPS stands for Encapsulated PostScript. It is important to realise that you can have pure vector EPS files that are saved out of applications like Illustrator and Freehand (with no images in) and vector/bitmap EPS files saved from Photoshop. This is the file format to use if you want an image cutout for print layout applications like Quark Xpress. You can embed a vector clipping path into a Photoshop EPS that also contains bitmap image data.
An EPS generally has a low resolution screen preview image embedded in it (depending on the file saving options you select) that you are shown when the file is inserted into another application. Dont be put off by the quality of this, it will look pretty rough. When you send the file to print high resolution data is sent down to the output device and it should print perfectly. Note that non-postscript printers usually cant handle these files and may print out using the low resolution preview. There are a number of ways to get around this, the most common one is to turn the layout into a PDF and print from this - it usually works!
EPS files are very large, but like a TIFF are ‘lossless’, meaning their quality doesnt degrade if you open, alter and resave the file. So, if you have an image for your print layout with no cutout area, you dont need to save it as an EPS, just use a TIFF!
DCS2 EPS (.eps)
The DCS stands for Desktop Colour Separations. This is a special kind of EPS bitmap file that can contain spot colour channels for special printing processes. You will only ever need to use this file format if you are preparing images that will use these spot colour channels as opposed to either a single colour greyscale image or standard CMYK colour image.
There you go then, I told you that you only ever need a very small handful of the file formats available for presenting image files for print! So, the bottom line is that you should use TIFF for almost all images for print, and either PSD (if you are using InDesign, where you can utilise variable soft edged transparency) or EPS (if you are using any other DTP software) for files that have cutout or transparent areas - and if you need to use a DCS2 EPS you must already vaguely know what you are doing!
I didnt mention PDF, which is a viable option too and will save you vector data - but PDF production is a whole other can of worms that you can either avoid if you are just presenting images, and you are advised to avoid if you are inserting your saved images into a layout in another application!
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