Many of our books contains images and graphics. These serve a variety of purposes (maps, photographs, charts). Very often, the images provided by the authors during the initial submission cannot be used. This blog post will shed light on some of the common issues we encounter when dealing with images.
We can only include graphics for which the book authors have the distribution rights. This is the case if
- the author created the work
- the creator of the work is known and has given it a so-called “free license”
- the creator of the work died more than 70 years ago
- the work was created by the US government
If you do not know who the creator is (e.g. you found the graphic on the Internet) WE CANNOT USE THE IMAGE.
If you wish to reuse a graphic from another publication, you have to ask the original publisher for permission (in most cases). Note that the permission must include “licensed under Creative Commons Attribution license (CC-BY).”
Images come in two types, raster and vector. Raster images are for instance the well-known jpg and png image formats. These images can be seen as a grid (raster) of width x and height y, where x and y indicate the number of pixels. When zooming in, these pixels can be discerned. In distinction, vector images describe shapes and path, e.g “a circle of diameter 2cm; a straight horizontal line cutting the circle in two halves; a dot of size 3mm at 2/3 of the length of the horizontal line”. Vector images never reveal pixels when zooming in. See the images below for an idea of the difference between vector (above) and raster (below)
The problem with pixelated images is that they appear blurry when printed on paper even if they look fine on the screen. In general, raster images should only be used at a resolution of over 300 pixels per inch.
Depending on the type of information which should be represented, one type or the other might be better suited. We will discuss frequent types below:
Use jpg. Make sure the resolution is at least 300 pixel per inch when printed.
Photographs in png format are generally not printable.
Screenshots of programs or websites:
Use png. Do not use jpg, as this will create so-called artefacts. Maximize the window you want to screenshot, using all space you have on your monitors. The size of the window on the screen should be 4 times larger than it will appear on paper. A standard image in our books will have a width of 10cm, so on your screen, the window should be 40 cm wide. If you can manage more, the better.
Screenshots in jpeg format are generally not printable due to artifacts. See screeshots from the wikipedia logo below in png, with clean surfaces, and in jpeg, with blurry surfaces and artefacts.
Note that both images above, regardless of artifacts, would have too low a resolution for being printed.
Plots and charts:
If you create plots with R, export them as svg. If you create plots within a spreadsheet, try to export them as svg, eps, pdf, in that order of preference. Do not screenshot your spreadsheet. See below the difference between a graph created as png and a graph created as vector.
If the data come from a simple table, you can also send us the data and we will create native LaTeX vector plots from the data.
Diagrams, lines; vector (or raw data)
Same as plots
Export as svg or pdf.
Use vector maps. DO NOT SCREENSHOT GOOGLEMAPS. Do not use any maps you find on the Internet, with the exception of OpenStreetMaps. If you send us the coordinates of the map and the features it should have, we can try to produce a vector map over here. See below the difference between a “screenshotted” map and a vector map.
From praat, export as eps. It might be OK to export as png as well. Do not use screenshots.
If you are unsure how to proceed, please use the following flow chart: