Crop, Resize and Export an Image With Preview

Learn how you can use the macOS built-in app Preview to crop, resize and export an image in another format. You can use this to shrink images to smaller files for sending or storing.

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Video Transcript: Hi, this is Gary with MacMost.com. Let me show you how to Crop, Resize, and Export an image using Preview. 
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If you need to change an image by Cropping it, Resizing it, and then Exporting it in some different format you can do that all in the Preview Tool that comes with your Mac. You don't need a third party app for that. 
So I'm going to double click on a JPEG image here in the Finder. It's going to open it up in Preview by default. Now the first thing I may want to do is crop an image. After all if you want to get something to a smaller size the first thing they want to do is crop out unnecessary parts of the image. There is a crop tool but it is usually grayed out. What's happening here is you need to select something first. So when you're working with an image you should have a crosshair cursor here and you can just click and drag to where you want and then grab any of the edges or corners. Figure out what part of the image you want. I'll just crop out some of the edges here. Then you can use the Crop Tool. You can always go to the Markup Tools here and then click on the selection tool to make sure that you get the selection rectangle there and then can go ahead and use Crop or just Command K. 
So now I've trimmed a lot here. The file is already going to be smaller if I Export it. Next let's resize the image. Often when an image is too big it's because it is a high resolution image and you may not need a high resolution image in your current situation. So, you can go to Tools and then Adjust Size. Now you get this pretty complex little dialogue box here and you could resize using this. You just need to take the time to learn how this tool works. You've got Fit Into and you can select a certain number of pixels. Or you can choose your own here. Now, by default it is going to be set to percent. So if I wanted to say resize everything by 50% I can easily just type 50 there and it is going to resize everything and you'll see the resulting size here and the resulting file size as well. Now you could change this to pixels and then you could actually see the real pixels here. Say if I want something to be 800 pixels wide it will automatically do the height to match the width and I can distort the image by changing one dimension but not the other. In general you want to have these locked. Set the width or the height. 
Resolution really doesn't matter. Unless you're doing special print work a pixel is a pixel. Having 300 pixels per inch or 72 pixels per inch doesn't really matter. These checkboxes here, this one Scale proportionally maps to this same function. Then you want to have Resample Image turned On otherwise you can't change the number of pixels. It is just going to change the resolution. Again, that's probably not what you want to do. So you get the resulting size here and you can click OK. 
So now you've got a much smaller image there. Let's zoom in a bit and we can see it is still a pretty decent quality but obviously it is going to be a much smaller file. It has been saving the changes this whole time as that is how Preview works. If I get information on the file here now it will be much smaller than it was before. So at this point I could just Close and leave Preview and I'm set. I don't need to Export. 
But exporting will help you convert it to another file format or a different quality level. Let's go to File and then Export and here this allows me to Export using various formats.  HEIC is the new modern format that will highly compress an image but still keep the quality. But it is not compatible with older computers. Then you could choose JPEG or some other standards here as well. When you choose HEIC or JPEG you do get to choose quality. So I can lessen the quality here and export a copy. So it is not going to change the original when you Export. This will be a new copy and you can see it is going to be smaller size but lower quality. Let's do that and if I Quick Look this image here it's definitely lower quality there but I get that smaller file size as a benefit.
Now if you're thinking that this isn't very many options when exporting. There are other formats and maybe you need to use a special format. Well, hold down the Option Key when you click this. Now you've got a ton of other formats here. So you can choose one of these if you need to. One of the things that I've showed you that you may not have liked is the fact that this image here is now different than the original. The cropping and resizing has been automatically saved and I've changed the original image. What if I didn't want to do that? 
Okay, I'm going to do Undo here and go back to the original image. So now I've taken away the cropping, I've taken away the resize. If I Get Info here you can see I'm back to a full size image. A quick way in Preview to actually Crop and create a new image at the same time is to select and then instead of cropping, do a quick Edit, Copy or just Command C. Then a quick File, New From Clipboard, or Command N. So Command C, Command N and now I've got a new unsaved document that's been cropped to the size. I have left the original one alone. Now I can go in with this new one and Adjust Size. Change the size here and then Export and then Save this out. If I want I don't even need to save this file here. I can just Delete that one and I've got my original file still intact. I've got the new file here, cropped, resized, and exported. You can also select various Command C, Command N, and do your resizing. Then instead of saving or exporting click the Share button here and then you can click, say Mail, and it will automatically attach that image to a new Mail message. You can Send this and never have to save or export a new copy.
Hope you found this useful. Thanks for watching.

Comments: 8 Responses to “Crop, Resize and Export an Image With Preview”

Bent

2 years ago

👍 👍 👍

claudio silvaggi

Awesome, always learning from you... Great gratitude... ❤️🙏

Patrick

Very helpful video, Gary. Your first tip about how to make the Crop tool come alive was a revelation. I can't count the number of times I've had to use a tool like Snapheal to crop an image because "crop" was greyed out in Preview. Your other tips were useful too, though I already knew about some of them.

Connie Duke

I don't want to forever lose the quality of tons of photos on my (older) MacBook Pro, but need to significantly lessen used storage space. If I resize photos and only save that resized file, can I then at a later date, reverse that action back to a higher quality simply by undoing? My apologies if You've addressed this already. THANKS SO MUCH for all that You share. BTW: simply by knowing how to change the greyed out crop in tools is a very helpful tip. Blessings.

Gary Rosenzweig

Connie: No, if you resize a photo file, then you can't undo it. (If you could, it wouldn't save you any space). Are these photos in your Photos app? If so, then consider using iCloud Photos Library with "Optimize" turned on to use less local storage.

Chris in CT

I often use Photoshop Elements to add white space along one side of an image for comments without marking up the original image (aka enlarge the canvas). I have long wondered is there an easy way to do this in Preview?

Chris: No good way to do that in Preview.

Eric

Have learnt something new :-) I wasn't aware of using the Option key to offer other export formats. Thanks Gary.

Comments Closed.

Crop, Resize and Export an Image With Preview

Comments: 8 Responses to “Crop, Resize and Export an Image With Preview”

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