This wikiHow teaches you how to change the entire display on your iPhone to black and white (greyscale). You can easily switch to a black and white screen view through the accessibility settings.
Step
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Step 1. Open Settings on iPhone
Open Settings by touching the icon
on the home screen.
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Step 2. Touch General under Settings
It's next to the icon
in the Settings menu.
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Step 3. Touch Accessibility under General
Accessibility accommodation will open in a new page.
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Step 4. Touch Display Accommodations in Accessibility
This option is under the " VISION " heading.
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Step 5. Touch Color Filters under Display Accommodations
Color filter options will be opened.
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Step 6. Slide the Color Filters button to
Doing so will activate the color filter on your iPhone, and you can choose one of the provided filters.
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Step 7. Select Grayscale
The device screen display will immediately change to black and white (greyscale).