So you’ve found a good image library or two and you’re ready to choose images. How do you know which ones will work best on your site?
Image ratios: landscape, portrait, square or panoramic
Whether you need a landscape, portrait, square or panoramic image depends on the design of your website, but as a general rule you’ll be looking for landscape ones most often at all. You often end up using an image in more than one size on your site, e.g. a full sized version on your article, but a small square thumbnail where the article headline appears on your homepage. If you’re using a decent content management system (CMS, e.g. WordPress), it will automatically create your thumbnails for you, so you just need to worry about choosing the larger version.
Since the majority of people view websites on landscape screens, landscape photos tend to fit the best. Panoramic photos can be very effective as banners at the top of pages, but it can be hard to find photos that work well when cropped that way, unless they’re abstract images.
The better stock image libraries (e.g. Dreamstime) will let you filter the kind of images you’re searching, so choose the right ratio before you search. But make sure you know which ratio will work best before you download anything, especially if you’re paying.
Size (width and height)
Some libraries will only give you one size of image to download, and some will allow you to choose the size without affecting the price. In the latter case, download the largest version they offer you and keep it safe; you can always resize it downwards, or your content management system (CMS) may do this for you.
Other libraries charge different prices depending on the size of the image you need. In that case, make sure you know the size of your website layout and how the image will be used. If you’re looking for fullscreen background images, then you’ll probably want something 1920 pixels wide x 1080 pixels high or larger. If you only need to use a small or thumbnail photo, you can survive with something much smaller (maybe 600 x 400). It’s always OK to get something too big; you want to avoid having an image that’s too small, and stretching it. Bear in mind also that your website may change in future – you may want to make the overall layout larger, as average screen size or resolution changes.
Once you’ve downloaded the image, it may need resizing or cropping before you add it to your website. In most cases this won’t be necessary; with a CMS like WordPress you just upload the largest version you have and it does all the resizing work for you.
If you only intend to use the photo onscreen (i.e. on your website), then you only need a photo that is 72dpi in resolution. If you also want to use it for print, you will need a higher resolution e.g. 150dpi or 300dpi. Make sure you know what your printing requirements are before purchasing any particular resolution.
While your content management system may compress images for you to keep filesize down, you will still make your site slow if you force it to load several huge images on the same page. The content of the photos matters too: a photo that uses thousands of different colours and detailed imagery will take up far more filesize than one that isn’t “busy”, e.g. an abstract background image.
If you’re using fullscreen background images, choose simpler ones to keep the filesize down. If you want to layer text over imagery, then again choose something with less detail, and perhaps large areas of flat, darker colours so you can easily read light text over the top.
If you’re displaying thumbnail versions of your photos (e.g. in a list of news items on your homepage, or on social media), then steer clear of white/light backgrounds or line illustrations; colour photos, where the colours fill the edges of the image, tend to work better.
If you’re going to be using black & white photos on your website, then buy or download the colour versions and keep them safe. You can turn them grayscale using a graphics tool or even some simple coding, but you can’t turn a grayscale photo into a colour one. So prepare yourself for future changes by keeping the colour originals to hand.
Royalty-free vs rights-managed
On most paid-for image galleries, you’ll be offered the choice of royalty-free or rights-managed images when searching. Generally, you want to limit your search to royalty-free images. This means that multiple people can buy and use the same image, but once you’ve paid for the image, you can use it forever under the terms of its license.
Rights-managed images tend to be much more expensive and may only allow you to use the image for a set period of time before you have to pay again. However you may be able to acquire exclusive use of the image, so that nobody else can buy the same one.
How to search
When you search for images in a library, be as specific as you can. If you search for city you’ll get thousands of results; London city skyline will give you far fewer, more targeted results. Images in libraries have keywords in their title but also many more attached as metadata, so feel free to describe the exact elements you’re looking for.
If the image library has an advanced search filter, go through its options and use any of them you can to filter your results: choose the right size, colour, licensing, and features to give yourself better results.