How To Remove a Photo Background With Preview

Hi, this is Gary with MacMost.com. Let me show you how to remove the background from a photo using Preview on your Mac.

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Now in my last two tutorials I showed you how to use Pixelmator Pro and Affinity Photo to remove the background from a picture. Now you can use the Preview App that comes with your Mac to do this as well. But the tools it has aren't as well suited for this as the professional apps. But let's look at how to use Preview to do this anyway because sometimes it's better to be able to do this even imperfectly rather than not being able to do it at all.

So I've opened up the first image here in Preview and this should be the easiest one to handle because it's a very solid blue background. I'm going to use the Markup Tools here and I only have two options here for selections. The second one is Instant Alpha which seems to be exactly what we want. In most cases it wouldn't work because the background is too complex. But here, with a solid background, it might work well enough. So let's try it. I'm going to select the tool and then click and drag and as I drag more and more of the background is going to be included. I can actually get to a point where I've selected all of the background and it has left the subject there. So I'm going to now hit Delete to delete the background. Now because I'm working in a jpeg image it's going to ask to convert this to a png, something it can actually edit. So I'm going to say okay. Now you can see it worked really well. I still have the blue here behind the glasses. Let me zoom in here. I'm just using my trackpad to do that. You can use these buttons here. I'm going to do the same thing here and get it to just the right point where it's good enough. Delete that section and delete this section as well. You could get a little more detailed if you want, like that. 

Now I've got the background removed and I have a transparent image with a subject on it.

But here's an example where it won't really work that well at all. So I've got this more complex background. If I try to use that same tool it's going to grab some of it but you could see before I even get close to grabbing all of it it's grabbing part of the subject. So that's not going to be an option. So I'm going to, instead, use one of these tools. Now the two tools that will work are Lasso Selection and Smart Lasso. Lasso means I need to zoom in really closely and then carefully trace the outline here. It's almost impossible to do. Since you could only make one selection at a time in Preview you can't just keep adding to it or anything like that. So that's not going to work. Instead let's try Smart Lasso. Smart Lasso gives you this red outline here and you could outline close to the edge like that and then say grab a section like this and it kind of works. But you could see here it doesn't do a good job around some corners and things. Now the more you zoom in the better it works. So let's zoom in part of the way and let's just try to do it now. So a little zoomed in makes a big difference. You could see that's a lot better. Still not perfect but it's a little bit better and I can't do multiple selections so if I wanted to keep going I need to delete this section here. It's going to ask to convert to a png like before. Now I can go to do the next section. So section by section I can do that. You can see I can grab another piece there and continue to remove. You can see here that you've really got to be careful. If you just mess up a little bit that it takes out too big of a piece you can Undo and try that section again which is why it's important to do it in small sections so that you could easily Undo.

Let's try this image here. I'm going to use that same Smart Lasso tool. Let's start here at the bottom right and just draw around here. I find it works if you go to a point like that. Then you move off to the edge and you bring it back to the starting point. Then it works pretty easily. So I'm going to get rid of that piece. Scroll down and do another section here. (Continuing to delete sections). You end up with something like this. Now I could go to the regular Lasso Selection and much more easily remove the extra pieces here. Go all the way out to the edges of the image like that and take larger chunks. Eventually I get to something pretty decent like this. Let's say I wanted to alter the original image. Now I can select All and Copy. I could go back to the original image here and what I could do is go to these Adjustment Tools here. Let's adjust Exposure. Maybe Desaturate like that the entire image. If I Paste, I paste the subject on top and I just need to very careful align the subject up and now effectively change the background of the image. Or if I choose another image I could past it into this and I can move the subject there and resize. 

So you can accomplish the basic task of removing the background or taking the subject out and putting the subject into another image. But you're just not going to have the fine control that you do in an app like Pixelmator Pro or Affinity Photo. Hope you found this useful. Thanks for watching.