Chapter 1 • Images for Screen

The Mighty Pixel

Images for screens are most commonly taken with digital cameras that record microscopic squares, or pixels (picture elements, Figure 1-1) of red, green, and blue colour information that in turn are displayed on screens.

Planning for Resolution

Readers look at screens on desktop and laptop computers, tablets, eReaders, and smartphones. When preparing documents like web pages and eBooks for screen viewing, it’s important to start by thinking about the reproduction size and required resolution. According to the site Hobo SEO services, 20% of computer users have a screen with a resolution of 1920×1080 or larger. Today one of the smallest cell phones in common use is the 4.7-in.-diagonal iPhone 8 at 750×1338 pixels. iPad tablets at 2048×1536 can show a 1920px-wide image like a desktop computer. A screen resolution of 72 ppi (pixels per inch) or 28 ppc (pixels per centimeter) is optimal. Higher resolution will not necessarily provide sharper or more detailed images and will slow down the download speed.

Text and Photos

A key consideration for photographers who want to reproduce their work for screens is, what is the relative importance of the text and photos? Examples:

• Photo-heavy book. A photographer, who wrote a coffee-table book of beautiful photos that only have short captions, wants to reproduce his work on-screen as an eBook or web site. The priority is to show the photos with maximum impact.
• Text-heavy book. An historical writer, who wrote a book about local history, wants to show photos of historic buildings and people that will be accompanied by lengthy descriptions and long captions. In this case, the photos are important, but the legibility and accessibility of the text must also be considered.