Apple has built some helpful features into its iDevices to improve accessibility. Most people who need to know are aware of VoiceOver, the screen reader that make the iPod Touch, iPhone and iPad accessible to anyone who is blind or who has extremely limited vision.
There are other lesser known features that also do a great job of supporting vision challenges.
Zoom, Large Text and White on Black are three iOS features that may be helpful for individuals who have difficulty seeing the screen of an iPod Touch, iPhone or iPad. They may be especially valuable on the smaller iPod Touch and iPhone screens.
All accessibility features in iOS are disabled by default, and must be turned on. To turn them on, go to Settings, select General, and then scroll down to select Accessibility.
Once Zoom has been enabled, it enlarges the entire screen, in any app, when the user double-taps with three fingers. By default, the screen is enlarged 200%. Once zoomed, the zoom can be adjusted from 100% to 500% by double-tapping with three fingers and dragging up or down. To move around to see different parts of the screen, drag with three fingers while zoomed.
The video at the conclusion of this post demonstrates exactly how the zoom feature works. The video also contrasts the Zoom feature with the more commonly used, but less powerful, pinch zoom.
Large Text is turned on by selecting the desired font size, as shown below, along with a sample of the largest available font.
White on Black
White on black simply inverts colors on the device screen.