Technical questions

Help with the technical apsects of designing and typesetting your book. If you don't find the advice here that you need, please don't hesitate to get in touch and ask.

Here are answers to some questions you may have about book design, production and printing. If you don’t find the answer you want, please feel free to get in touch for help.

What is the best file format for images?

That depends on the type of image and where it’s going to end up. There are two basic types of image — vector and raster (bitmap).

Vector images are made up of lines and fills (which can be solid, tinted or graduated) and are in theory infinitely scalable up and down (the concept of ‘resolution’ is immaterial here). Graphics made up of solid colours such as logos, signs and technical illustrations are best created and supplied in vector format, the most widely usable vector file type being EPS (Encapsulated Post Script), and they can be created using a drawing package such as Illustrator, CorelDraw or Freehand.

Vector image - shows how a vector image is totally scalable without loss of sharpness

Vector image

Raster images (also known as bitmaps) are built up using tiny cells of colour (pixels) and are used for photographic reproduction. Here, resolution and colour mode are of key importance. Resolution, usually measured in pixels per inch (ppi), determines how large and detailed an image will be. As a guide, images for the Web should be 72ppi at 100% size, those for desktop printing and slides (Word, PowerPoint, etc) around 150ppi at 100%, and those for digital or litho printing (for books, brochures and so forth) around 300ppi at 100%. Images for exhibition graphics should be around 72ppi at 100% size (or 300ppi at 25%) unless there is no photographic content (e.g. type only) when vector artwork is best if available. You’ll find more on raster image formats under Image types and uses on the Hints & tips page.

Raster image - shows how the pixels that make up the become larger and the image less sharp as it is enlarged

Raster image

Colour modes are generally either Greyscale (black, white and shades of grey) or RGB colour (red, green, blue) for everything except commercial print work where Greyscale or CMYK Colour (cyan, magenta, yellow, black) are the norm.

RGB colour model - shows how red, green and blue add to each other to make cyan, magenta, yellow and white when overlapped; CMYK process colour model - shows how cyan, magenta and yellow blend with each other to make red, green, blue and black when overlapped

RGB and CMYK colour models

In the case of litho print and screen process, what’s known as ‘Spot Colour’ may also be used — see under Colour reproduction in graphics on the Hints & tips page for more on this and the other colour formats mentioned.

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What is the best way to supply text?

In a rough order of preference, one or more of the following:

In a word-processed document from a software application such as Word, saved as Rich Text Format (.rtf); in a plain text file (.txt); in one of the graphics packages listed in the next question; text written in or pasted into an e-mail; text from a web site you have permission to copy text from — supply the URL (web address) and specify what text you want to use from which pages.

It is also possible to extract text from a printed document — this can be scanned and processed using OCR (optical character recognition) software but beware: copies of copies will produce mostly gobbledegook — the sharper and cleaner the original, the fewer erroneous characters will creep in. Also, simpler paragraph layouts will enable better results — complicated tables are difficult for OCR to decipher. However, no matter how good the original is there will always need to be time spent cleaning up, correcting and checking the resulting text.

If in doubt or you need more information, contact Extrabold.

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I have some artwork I’d like to incorporate into a new project. What formats are usable?

For confirmation it’s best to get in touch, but as a guide InDesign (.indd), Illustrator (.ai), Encapsulated PostScript (.eps) Quark Xpress (.qxd), CorelDraw (.cdr), Publisher (.pub) and Acrobat (.pdf) are all usable depending on the version and the file content. Graphics can often also be extracted from non-graphics applications such as Word.

Results do depend on how the artwork was originated, so there are no guarantees but it can be worth a try! The alternative is to re-create the artwork; this is quite often preferable to be honest, and may be cheaper to do than you think. Again, contact Extrabold for more information.

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What’s the difference between a font and a typeface?

A font is a specific variant of a typeface. For example, within the typeface Helvetica, there are the fonts Helvetica Medium, Helvetica Oblique (Italic), Helvetica Bold, Helvetica Bold Oblique, etc.

Shows the difference between a font and a typeface

Font or typeface?

In the days of metal type (letterpress printing) a font (or originally ‘fount’) was actually the variant of a typeface in a particular size — hence 12 point Helvetica Bold Oblique would have been an individual font. Thankfully, since the advent of computers and digitally-created type, this is no longer the case (no pun intended)!

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