How to Edit, Annotate and Highlight a Screenshot on Mac

To edit a screenshot on Mac, click the floating thumbnail right after you take it, or open the file in Preview and click the Markup button. macOS has 3 built-in routes: the thumbnail's Markup view, Preview's Markup toolbar and Markup in Photos (Apple Support). No install needed.

I edit screenshots every day while building a Mac app, mostly to point at one thing and hide another. This guide covers every built-in way to crop, annotate, highlight and cover parts of a screenshot, and where a dedicated app helps. Each section links to a deeper guide when one exists.

Edit right after you take the screenshot

When you take a screenshot, a thumbnail appears in the corner of the screen for a few seconds. Apple says you can click the thumbnail to edit the screenshot. If you wait, it saves to your desktop instead.

The thumbnail opens a Markup view with the same kind of tools found across macOS: sketch, draw, shapes, text, signature, crop and rotate. Apple's Mark up files on Mac page covers them, and notes that the tools vary by file type. Click Done to save the result.

This is the fastest route for a quick arrow or crop. If you need the shortcuts that take the screenshot first, see my guide to Mac screenshot shortcuts.

If the thumbnail never shows up, open the Screenshot app with Shift, Command, 5 and turn on Show Floating Thumbnail in its Options menu.

Edit in Preview with the Markup toolbar

Preview gives you more room and more control. Open the screenshot in Preview, then click the Markup button if the toolbar is not showing. Apple's Annotate an image in Preview page lists 19 tools in that toolbar. I counted them: 4 select part of the image, 1 removes a background, 5 add marks (sketch, draw, shapes, text and signature), 6 change size, colour or style, and 3 rotate, crop or add an image description. None of the 19 is a blur.

The ones I use most on screenshots:

Shapes: rectangles, ovals, lines and arrows. Drag the blue handles to resize. Green handles change the shape, such as the curve of an arrow.
Text: type, then drag the text box where you want it. Text Style changes the font, size and colour.
Highlight: a shape that dims everything except the area you drag it over. It sits in the Shapes menu.
Zoom: a magnifying lens for a small detail. Drag the green handle to change the zoom and the blue handle to change the lens size.
Shape Style, Border Color and Fill Color: line thickness, outline colour and fill colour for any shape.
Crop, Adjust size and Rotate: covered in the crop section below.

One catch from Apple's page: once you save an annotated image, you cannot edit, move or delete the annotations. If you might change them later, keep an untouched copy first.

Add arrows and text labels

In Preview, click Shapes, pick the arrow and drag it so the head sits next to the thing you want to show. Then click Text, type a short label and drag it beside the arrow.

A few habits keep screenshots readable:

Use one colour for all arrows in a screenshot, and pick one that stands out from the app's own colours.
Keep labels to a few words.
For steps, number them 1, 2, 3 with text boxes instead of drawing a web of arrows.

If you are writing up a bug for a developer, my guide on how to explain a bug with a screenshot shows which annotations help most.

Highlight part of a screenshot

You have 3 built-in ways to make one area stand out:

The Highlight shape in Preview's Shapes menu. It keeps the area you choose bright and dims the rest. Best for one button or field.
A rectangle or oval with no fill. Draw an outline around the detail. Best when several things need marking.
The Zoom lens. It enlarges a small detail, such as an icon or a setting, in place.

Avoid covering nearby labels that give the detail its context. On a screenshot, a ring around a button usually beats an arrow pointing from far away.

Hide private details before you share

Preview has no blur tool, so the built-in way to hide a name, email or account number is a filled shape:

Click Shapes and draw a rectangle over the private detail.
Set Fill Color to a solid colour, and check that nothing shows through.
Save or export the image. The shape is then flattened into the picture, as Apple notes that saved annotations can no longer be moved.
Reopen the saved file and zoom in to confirm the detail is gone.

A solid block is safer than blur for text. Blur can leave short text partly readable. Do this on a copy if you want to keep the original.

Crop or resize a screenshot

Apple's crop, resize or rotate page covers this in Preview:

Crop: select the part you want to keep, then click Crop in the Markup toolbar. Edit, Undo Crop reverses it straight away. Later, File, Revert To, Browse All Versions brings back an earlier version.
Resize: click Adjust Size, then enter a new width and height, choose a size from the Fit into menu or switch to percent. Select Scale proportionally so the image does not stretch.
Rotate: click Rotate Left. Hold Option to rotate right.

My full guide on how to crop a screenshot on Mac covers every crop method, including cropping at capture time.

Edit a screenshot in Photos

If your screenshots live in your Photos library, you can mark them up there. Apple's Use Markup in Photos page gives the steps:

Double-click the screenshot, then click Edit.
Click the More button (called Extensions on some versions) and choose Markup.
Use sketch, draw, shapes, text, highlight, zoom and crop, then click Save Changes.

Photos also has its normal editing tools for light and colour. For precise arrows and redaction on a work screenshot, I find Preview easier.

When a dedicated screenshot app helps

The built-in tools are fine for an edit now and then. They get slow when you annotate many screenshots a day, need numbered steps, want a blur-style mask, or want a background and shadow for a slide.

I build Znip, a Mac screenshot and screen recording app, so weigh this with that in mind. Its editor has arrows, text, shapes, freehand drawing, numbered steps, a highlighter, a spotlight and a magnified callout. It can crop, resize, rotate and flip. To hide private details it has solid redaction blocks and pixelation, and its own guidance is to use solid blocks for sensitive text. It can also add a background, padding, rounded corners and a shadow. Znip is in invite-only beta for Apple silicon Macs on macOS 15 or later.

If you want the edited image on the clipboard instead of in a file, see how to copy a screenshot to the clipboard on Mac.

FAQ

How do I edit a screenshot on Mac right after taking it?

Click the thumbnail that appears in the corner of the screen. It opens Markup, where you can draw, add shapes and text, crop and rotate. Click Done to save.

Can I blur part of a screenshot on Mac without an app?

Not with a true blur. Preview's Markup toolbar has no blur tool. Cover the area with a solid filled shape instead, then save and recheck the file.

Can I edit annotations after saving a screenshot in Preview?

No. Apple says annotations on a saved image cannot be edited, moved or deleted. Keep a copy of the original, or convert the image to a PDF if you need to change marks later.

How do I highlight part of a screenshot on Mac?

In Preview, open the Shapes menu and choose Highlight, then drag it over the area. Everything outside it is dimmed. An outlined rectangle or the Zoom lens also work.

What is the best app to edit screenshots on Mac?

For occasional edits, Preview is enough and is free. For daily annotation with numbered steps, pixelation and backgrounds, a dedicated app is faster. I build Znip, so I am biased; try the built-in tools first.

By Siddharth Sharma, who builds Znip.