Whether you are publishing your own manuscript or preparing a manuscript for publication elsewhere, you are usually asked to supply an image or two. Whatever you might feel (and believe me, sometimes there’s a sensitivity about this) images MUST be 300 dpi or higher. Not only do these images look a lot better, often the publishing program will reject those that are not.
So, how to generate 300 dpi images?
First of all, ideally you’ll have thought of this before you start(!). That way you can plan where to get images.
If the images required are just stock photos, then go on over to one of the stock photo sites – make sure you search for hi-resolution, choose colour/ black/white or whatever other things you’re looking for (and, of course, make sure you get copyright clearance).
If you’re generating the photos yourself, check that your camera can produce images of sufficient quality and, if not, then borrow another one that will. If you can scan from documents, postcards or similar, then make sure that the settings are 300 dpi or higher and save as a JPG or TIFF (CMYK). Don’t worry too much about cropping as a good publisher will engage a graphic designer to do this.
So, what if you already have your images and must turn them into 300 dpi? This is a bit of a black art – you really shouldn’t do it, but we all have … The main thing to watch out for here is the overall dimensions of the image file. If it’s too small then no amount of high-tech magic will help.
If the size (height x width) is OK then the simplest way to do this conversion is to use Powerpoint. This might sound a bit weird but how it works is that an image is inserted into a blank slide, then in the Save dialogue you choose to save the current slide as an image, etc. However, Powerpoint does not save by default to 300 dpi. The real magic only occurs (in Windows) when the registry is edited and the default Powerpoint settings are changed. This little trick is worth doing as it will save you a lot of trouble over time and this edit has only to be done once. There are straightforward instructions at Microsoft: https://support.microsoft.com/en-us/help/827745/how-to-change-the-export-resolution-of-a-powerpoint-slide. (There are also a few YouTube videos about how to do this.) The main caveat is to please back up the Registry before you begin just in case anything goes wrong.
The file that is generated by Powerpoint will look just like how the slide is – so it might be worth playing around with colours, sizing the image on the slide, or just cropping the saved image file.