I use ^ Control⇧ Shift ⌘ Command4 first, then I paste it into Mail, when I double click the image that I pasted, it is TIFF format.

I try to change the screenshot format to PNG; it works. But when I change back to JPG or BMP, both of them will be saved as TIFF format.

defaults write com.apple.screencapture type jpg

How can I save it as JPG format?

  • Why do you want jpg? To save space? Compatibility?
    – Harcker
    Jan 21 '18 at 9:24
  • 1
    Because some of my clients don't know to how to open TIFF format image. Jan 21 '18 at 15:32
  • Did you use killall SystemUIServer directly after the defaults command? What version of OS X/macOS are you using? Jan 21 '18 at 15:45
  • 1
    same issue as OP. All screenshots save as JPG, except when I prepend CTRL to save screenshot to clipboard. Seems like a bug. Windows people then can't easily open TIFF for some reason
    – Paul
    Jan 26 '19 at 19:27

It Has to do with the Clipboard; not Screen Capture

Screen capture can obviously support more than these two file formats; obviously it supports GIF and JPEG/JPG, but it also supports PDF. However, the issue here isn't what Screen Capture is capable of handling, it what your clipboard is capable of. Why? Well, you're going directly from your clipboard to pasting an inline image into a mail message. Once Screen Capture "hands over" bitmap to the clipboard, it's work is done.

Now, your clipboard stores images as a RAW format so it can preserve every single detail. How it gets saved (when Screen Capture writes it to disk), the clipboard simply doesn't care if you use a high quality format like PNG or TIFF or a lossy format like JPEG or PDF; basically, you chose it, you'll get it.

But why PNG or TIFF?

The very short answer is both are image formats that support lossless compression. In other words, they can make the images much smaller than their RAW format without losing an ounce of quality.

Apple chose PNG as it's default and I can only speculate as to why...

  • PNG (Portable Network Graphic) was to be a replacement for the GIF format
  • It's web friendly
  • It was designed for transferring images over the network/Internet

TIFF on the other hand...

  • Acquired by Adobe in 1996 for desktop publishing
  • It was an attempt to standardize scanned (and faxed) documents into a single high quality file format
  • Built in support for meta data
  • Could hold multiple pages as a single document like a PDF

Why you get TIFF when pasting to your App

Coming out of the clipboard, you've got two ways to go - PNG or TIFF. Since you specifically told screen capture you didn't want PNG, it went to the only other choice available - TIFF.

How can I save it as JPG format?

Don't use your clipboard. Save to your Desktop (or other location) and just manually convert to JPEG. Then drag your item over to the app you're using. If you do this through the Preview App, you will have the opportunity to set the quality/size of your JPEG in case it's still too large for some receiving email systems. (Preview) File → Export → Format

Preview Format Slider

If this is something you do quite a bit, you can easily create an Automator action...but that's another question for another time.

  • Other then the link in your answer, which is actually for Windows, do you have a canonical reference that macOS stores an image in RAW format on the Clipboard? Jul 7 '20 at 0:37
  • It's been many, many years since I dealt with that so I'm going off memory, but I did find this in Apple Dev Documentation. It's important to note that you can put a JPEG data type into the clipboard (pasteboard) (i.e. copy a jpeg from the web) , but as for raw images, well, it goes in as a raw bitmap
    – Allan
    Jul 7 '20 at 0:51
  • "Since you specifically told screen capture you didn't want PNG, it went to the only other choice available - TIFF." This behavior has driven me crazy for two years, but that's the first I've seen that changing the screen capture choice actually works against you. I would upvote this five times if I could.
    – vr8ce
    Apr 8 at 21:08

MacOS uses TIFF as the file format for image data coming out of the Pasteboard.

You can't store an image on the clipboard as a JPEG, unless an app deliberately specifies it, and if you query the Pasteboard Manager for available types, after sending a screenshot to the clipboard, you get:

    "NeXT TIFF v4.0 pasteboard type"

To avoid a TIFF image, use a method that doesn't involve the clipboard: create the screenshot file using Command Shift 4, and drag the screenshot file directly into the email window, or click on the 'paper-clip' icon, and select it from the file dialog.

  • MacOS uses TIFF as its internal image data format... It most certainly does not! Images are stored as RAW bitmaps in the clipboard. Where did you get that info? The only reason I haven't down voted is because your second half is a good solution.
    – Allan
    Jul 6 '20 at 23:25
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    @Allan TIFF data is raw bitmap data, with a header on the top. That's why it's has been the default MacOS image format since NeXT, replacing PICT from Classic Mac. If you query the Pasteboard Manager for available types, you get only TIFF returned.
    – benwiggy
    Jul 7 '20 at 7:36
  • Having it as an available type does not make it the file format. What happened in NeXT and what it is now are two totally different things. It's a raw bitmap and and TIFF is not that.
    – Allan
    Jul 7 '20 at 8:20
  • By default when you copy an image to the clipboard in MacOS, it stores generally it as a TIFF image. Different applications can put onto the clipboard alternate formats and the built in screen capture tool does both PNG and TIFF format. You can get a clipboard viewer and see this in action. @Allan do you have something to confirm this "raw bitmap" assertion beyond a link to how Windows behaves?
    – pasamio
    Dec 28 '20 at 1:42

I am in the same boat, why does saving to the clipboard make it a .TIFF. I took two screenshots and it is larger than i can send in an email. .jpg please, when did this start happening? I used Terminal and OnyX with the same result.

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