We use the Mac Screen Capture tool almost daily. It makes it very easy to take a quick snapshot of a comp, snippet, or site to be able to send to clients, use for project examples, etc.
With our clients who use Macs and need to upload photos to their site, we recommend using screen capture to prepare their photos for their websites. The reason being is that most of the time those photos are coming from a digital camera and the file size is way too large for the web. Taking a screenshot of the file is a quick and easy way to save a smaller version of that photo to your desktop without needing any fancy programs like Photoshop.
How To Take A Screen Snapshot
To take a screenshot (technically coined Screen Capture) on a Mac, you want to use the following keyboard command:
Shift + Command + 4
With Screen Capture enabled you should notice that your mouse cursor has changed. Click, hold and drag a rectangle of what you would like to capture, then release the click and you will find a new file on your desktop. The filename notes that it is a screen shot and also has the date and time included for organization.
A Need For Change
By default, the screenshot file format is a PNG file, which is fine when we are using the files locally. However, when we want to be able to upload those screenshots to a site like we had mentioned above, or send them to a client, it is more beneficial to have a standard JPG file instead which is much smaller in file size than a PNG file.
To do this we need to open Terminal which you can find by going to Applications » Utilities. The Terminal application can be a bit intimidating as it is purely code. However, we only have 2 steps to do here, so you can get in and out quickly.
Copy and paste the following line into the Terminal window and replace <format> with the format you want to use.
defaults write com.apple.screencapture type <format>
For example, for a JPG file, you would want to use the following:
defaults write com.apple.screencapture type jpg
Or for a GIF file, you would want to use the following:
defaults write com.apple.screencapture type gif
After you have pasted the code into Terminal, hit the Return (or Enter) key on your keyboard. On a side note, you can also change the file format to other popular formats like PDF (using pdf), TIFF (using tif), or BMP (using bmp).
Next, you will want to paste in the following code in Terminal and hit enter:
And with that, you are all set! No need to shut down or restart your system. From there, you can quit Terminal and use screen capture with the format type from your choosing. We have tested this with success on Mac OS running Snow Leopard or Lion.