How can I invert colors of photos on Mac?

You'll need a 3rd party app that can invert the image:

Some Image Editors That Support layers and can invert images:

Photoshop Elements 11 for Mac - $79

GraphicConverter - $40
Imagerie - $38
Acorn - $50

Pixelmator - $60

Seashore - Free

GIMP for Mac - Free

You will have to export the original image file out of Photos to the Desktop and do the inversion there. Then import back into Photos as a new image file. Note: Option-dragging the image thumbnail to the Desktop will give you the original file.

Photos does not have a curves adjustment, that will let you turn the photo into a colour negative.

Use a different application.

An easy way to invert the colors of any photo you can select in the Finder is an Automator workflow like this.

• Launch Automator and create a new workflow.
• Add a "Get selected Finder items" action from the Actions library to the workflow in the right panel.
• Ad a "Apply Quartz Composition Filter" to the work flow. Set the filter to "Color Invert" and check "Luminance".

Now select your photo in the Finder an press the "Run" button. It will turn into a negative.

Forgot about the Automator solution 😟

But otherwise a great list! 🙂 A pity, that Automator does not have Photos actions.

There are some 3rd party Automator actions for Photos: Photos and Automator

They will give you these actions:

That is great! I wonder how robust the "Get the Selection" action is.

I've only used the Import action so don't know.

You're welcome 🙂

I can no longer test in Leopard so I cannot check if the "Luminance" option is supposed to be there.