Pictures showing like a negative

Is it just your photos? Maybe you enabled Settings > General > Accessibility > Invert Colors by chance? Did you recently make any changes to your settings?

Perhaps a keyboard shortcut enabled the Accessibility feature, if so the entire screen

would be inverted or negative in OS X Finder for all applications... accidentally by use

of Four keys:

Command - Option - Control - 8 = to Turn the Invert colors setting on or off.

reference:

• Mac keyboard shortcuts for Accessibility features - Apple Support

• Mac keyboard shortcuts - Apple Support

Otherwise, less likely, the issue may have been caused by selecting a view option within an application.🙂

This was posted in the iPhone section, so I assumed this was not an OS X question.

Yes, I see that (now) and understand there may be a difference in the implementation

of this feature formerly part of Universal Access that later became Accessibility.

Both OS X and iOS have an accessibility version; I'd guess the iOS shortcut may be

shorter or not require same keys (not present as such on the iPhone or other iDevice.)

• Use Accessibility features in iOS - Apple Support

Managing Accessibility features using your device

Tap Settings > General > Accessibility to find settings for the following features:

Vision:

• VoiceOver
• Zoom
• Invert Colors
• Grayscale
• Speech: Speak Selection, Speak Screen, Speak Auto-text
• Larger Text
• Bold Text
• Button Shapes
• Increase Contrast
• Reduce Motion
• On/Off Labels

Thanks for pointing out the iPhone as the discussion location area.

I don't browse ASC by area. 😎