Images, graphs and tables in publications

Digital images can be divided into two groups: tone images and line art. Tone images include colour images as well as those containing various tones. Tone images may be either photographs or drawings. Line art means, for example, logos and simple drawings which do not contain tones.

The best image formats are TIFF and EPS. High-quality JPEG images can also be used. In the case of printed tone images, the resolution must be 300 dpi and 600 dpi in black-and-white line art.

You can check the resolution in Photoshop from the Image/Image size menu. The default display resolution of the image may be 72 dpi, even if the image is large in size – e.g. 15 Mb (megabytes). In this case, a printable size can be clarified by adjusting the image centimetre dimensions in the view displayed (no check marks in the Resample section). A printable size is one in which the image resolution is approximately 300 dpi. An image on average 1 Mb in size is sufficient only for a printable image about the size of a matchbox: 5 Mb is approximately enough for the standard 10 × 13 cm size.

A lower resolution (72 dpi) is adequate for online versions. Unigrafia looks after the reduction of resolution in connection with making the online version if the file size is otherwise at risk of becoming too large (automatic reduction is not performed).

If you intend to scan images for your publication, it is advisable to save the images in the TIFF format. In scanning the image, take the possible size change into consideration – especially if the size of the image in the printed publication is larger than the original. Note that the resolution of tone images should be at least 300 dpi and line art (e.g. monochrome logos or images that contain text) 600 dpi in the final printed product. Images can always be reduced, but enlarging them does not succeed without reducing their quality.

If you scan text – for example, an image from some text document – it is advisable to save it as a one-bit black-and-white image (line art), the resolution of which is 600 dpi.

Adding a ready image to a Word document can be handled from the Add/Image/from File… menu.

It is recommended that graphs are either rendered with an image processing program or left in the hands of a professional, even if the page layout can otherwise be personally prepared using, e.g. Word. The same applies to tables where there are grey tones or lines.  

Word and Excel are programs that are intended for the production and editing of text content. The page layout properties of these programs are consequently limited. For example, the thickness of a line or quantity of colours or grey tones is limited in these programs, so the quality of the final result does not always match the publisher’s requirements or expectations.

If a graph produced for a Word template is nevertheless prepared in, e.g. Excel, it is advisable to add it to a Word document as an image. In that case, the graph is copied in Excel and exported to the template as an image. The command path varies from one version to another, but is generally in this format: Edit / Paste special… / Image.

In the newest versions of Word, the tables created generally work in printed form. It is nevertheless advisable to use colours and tones with care and discretion. Please note that the thickness of the line may vary when viewed in PDF format.

The same resolution sizes apply to graphs as to images – see the text at the beginning of the guide.

If your publication features graphs that have, for example, bars of various colours, but you want to print your book in black-and-white, change them to grayscale format. If you leave this to the printing house to handle, ALWAYS try the printing of colours in black-and-white on your own printer, for instance, or change them to greyscale in advance. If, in the ready book, all histogram bars are medium-grey, this may essentially hamper reading the book.

Please note that in Unigrafia, colour pages must be treated as an additional task to render them in black-and-white page by page, which is charged separately. If there is colour in the text or image, it will be printed and a draft copy prepared in colour if you have not ordered a correction. The other side of a colour page will also invariably be printed with a colour machine.

Pages printed in black-and-white will be prepared in black-and-white draft copies, also in the PDF draft. In the extra information section to the print job, there should be mention of it if you wish the online version to be in colour and the printed book’s pages to be in black-and-white.

The print results from the printing press always differ from those of a desktop printer, and a line, for example, may be printed more thinly due to the greater resolution. Also in the PDF draft delivered by the press and the electronic PDF version, the thickness and colours of the lines always depend on the precision, scaling ratio and settings of each display. In the display, the line images may even disappear from view when the image is enlarged or reduced in size, especially if the lines have been realised in ‘hairline’ form. This property always applies to PDF files. For this reason, it is indeed advisable to order a printed draft version from the press before having the book printed – especially when the publication has line images, tinted surfaces or colours.

If you doubt the technical or visual quality of the graphs you have prepared or their realisation with basic programs does not succeed, it is a good idea to send the originals in good time before printing to Unigrafia for assessment. At the same time, you can request a price estimate of their realisation by a professional graphic designer who has used the right publication tools. You can also leave the layout as a whole in the hands of a professional. It is recommended that you request a layout tender in good time – preferably already a couple of months prior to the date set for the defence of your doctoral thesis.