iOS 7 has several settings that allow those who are visually impaired to improve the readability of the display. This tip looks at zooming the display and increasing the contrast.
In iOS, accessibility settings are found on this path: Settings > General > Accessibility. The ones discussed here are Zoom and Increase Contrast, circled in red below.
1. Zoom. Turning on zoom allows you to magnify whatever is on the display just a bit. (Screen shots don't capture this, so I used an iPad to photograph my iPhone.) A three finger double tap magnifies. Three fingers held on the screen allow you to move around. Another three finger double tap dismisses the magnification.
The disadvantage is that while the screen is magnified, some controls can be temporarily unavailable. You'll have to dismiss the magnification to get to them.
2. Increase Contrast. This setting eliminates the translucency effect and flattens the appearance of the display. Contrast is thereby improved to increase the legibility, according to Apple. A good way to see this effect is to look at the Control Center with the setting on. The gray background is solid instead of letting the background show through in translucency.