Cutting Out Part Of An Image In Preview

One of the most powerful tools in Preview is the Smart Lasso. You can use that to quickly cut out part of an image to create a new one with a transparent background, or insert an object from one image into another. While Preview lacks a lot of the image editing tools found in more powerful apps, the Smart Lasso is probably easier to use than similar features in expensive apps.

You can also watch this video at YouTube (but with ads).

Video Transcript: Hi, this is Gary with MacMost.com. Let me show you how to use Preview on your Mac to cutout part of one image and insert it into another.
MacMost is brought to thanks to a fantastic group of supporters. Go to MacMost.com/patreon where you can read more about it, join us and get exclusive content.
So the Preview tool on your Mac is great for looking at PDF's and also images. You have a bunch of tools that you can use to manipulate those images. One of those tools is the Smart Lasso which is one of the Selection tools. It allows you to easily cutout part of an image and will actually find the edge of the image for you. Let me show you.
Let's double click on an image to open it up here in Preview. Now we can edit it by using the Markup tools. So I'll click Show Markup toolbar here. I have the Selection tools as the first tool here on the left. There are four different types of selections. You can do a rectangular selection. You can do an elliptical one to select an oval shape. You can do a Smart Lasso where you can define any selection you want. So I can slowly trace along the edge if I want. But it's going to be really hard to get something accurate there. It's going to take a lot of patience to draw it.
Smart Lasso makes this a lot easier. What it will do is instead of actually drawing a specific border for the selection it will give you this red zone where it's going to try to identify the edge. So if I click here and drag you can see it gives me this red zone and I can slowly move along and make sure I get the edge as close to the center of the red zone as possible. So I'll outline everything I want to keep here. So I'll outline me and the backpack. It's going to try and figure out where the edge is based on the pixels inside that red zone. So I'll go all the way down here to the bottom. Then I can just zip across the bottom there and up a little bit and then start on my shoulder, then along the side my face and back up along my cap until I get to the beginning. Notice how it shades in the area that it should select.
Now when I release the mouse or trackpad it's going to try and figure out where the edge is. Sometimes it's going to get it really well, like here. Other times it's not going to be as great. It's going to be a little rough sometimes but sometimes it will be extremely accurate. Now once you have the selection you can Copy it and do various things with it. Like, for instance, I can do File New From Clipboard and it will actually put a new document up there with just the selection. So this is transparent here in the background. I can Save this and this is actually great to use inside of Pages because then this is seen as a transparent area.
But if I want to paste this into an other image, so I'll double click on this one here, I can do Edit and Paste and there that image is on top of this one as a layer. I can position it. I can use the blue dots to resize it and there I go. You can do this with multiple images. So since I never go hiking without my dog, not even if I was going to the moon, I will include my dog here. Cut him out. I'll Copy there. Go back to this image and Paste, resize, and there now my dog is with me because he'll follow me anywhere.
So this could be fun to use and useful. Of course you can do a better job probably with the tools in apps like PhotoShop but Smart Lasso works well enough and it is so quick and easy that I find myself sometimes just using this one tool in Preview even when I'm using a more sophisticated image editing tool for everything else.

Comments: 8 Responses to “Cutting Out Part Of An Image In Preview”

Douglas Brace

5 years ago

Gary, in Preview when using the Smart Lasso tool, is it possible to edit (or adjust) what has been automatically selected?

Gary Rosenzweig

Douglas: Nope. It is frustrating, but reason to go with a slightly better tool if you need it.

Laverne Lachaplle

You have a dog and you take him everywhere with you. You just went up tenfold.

Lorenz Rychner

What version of Preview are you showing? My Macs both run OS 10.14.6, Preview is 10.1 (944.6.16.1), and my Markup Toolbar is different from yours. Far left: (Blue) Aa = Text Selection. 2nd from left: Square in broken lines = Rectangular Selection. No pull-down triangle next to the square. No drop-down with options of elliptical or lasso or smart lasso as you're showing. Ditto under Tools from menu bar on top. How come? Apple Store shows no version of Preview as downloadable.

Lorenz: Are you editing an image? You get a different markup bar when you are editing a PDF. This video is about editing images.

Gary, it works when I use Preview to open .dng, or .jpg, or .tif files - I get the various lasso options. How strange that it doesn't work when I want to excerpt from an image with one of those lasso options if the image is in a .pdf - the file type for which we most commonly use Preview? Anyhow, going back to your video and seeing that the backpack pic was a .jpeg pointed me in the right direction. Thanks!

Gary, please check me on this: To use Gary's suggested method with an image that happens to be in a .pdf, use shift+control+command+4 to copy the image to the Mac's Clipboard, then - still in Preview - go to > File > New from Clipboard, and now you get the lasso options Gary suggested when you click on the Markup icon. And to save that image on its own, use > Save and pick your format (.png is default, not .pdf).

Lorenz: You could do that. Note that when you take a screenshot like that you are grabbing the image usually at a much lower resolution. So it would work is some cases, but not others. Better to open as a PDF in Preview, then use File, Export and choose PNG as the format with a higher resolution. 300 pixels/inch would be good, but ideally using whatever the resolution of the images in the PDF are would be ideal -- if you even know what they are in that case.

Comments Closed.

Cutting Out Part Of An Image In Preview

Comments: 8 Responses to “Cutting Out Part Of An Image In Preview”

Welcome to MacMost

Free Weekly Newsletter

MacMost Online Courses

Keyboard Shortcuts PDF

Connect with MacMost

MacMost Sections

Popular Tutorials

Information