You can export a still frame image from a video many different ways with the software that comes with your Mac. If you are already in iMovie, you can use the sharing function to export an image from the current frame in the timeline or a library clip. In Photos you can save a frame in a video to your Photos library as a picture, and you can also copy the current frame and paste it into another app. The easiest way is with QuickTime Player where you can copy the current frame and then paste it into Preview or any other app that handles images.
The Selective Color tool allows you to adjust all of the pixels that are a similar color in a photo. You have six slots to make up to six color adjustments. You can use this to change a color in a photo, make colors stand out more, or desaturate colors to change the emphasis objects.
The main Photo library view in Mac Photos doesn't let you choose a sort order. But you can easily view your photos sorted by time or title by creating a Smart Album and using that to view your photos instead. You can also sort your list of Photo albums by viewing all of the albums and choosing a sort option, or manually dragging and dropping the albums.
You can create calendars in the Photos app that use your photos as the pictures. You can customize each month to include one or more photos, plus captions. You can also specify the items to be included on each date by using your own calendars. When done, you can order the calendars from Apple or print them yourself.
A useful new feature of Photos 3.0 is the ability to see all of your imported photos organized by the time they were imported. You can see all of your imports going back in time. You can use this view like any other, jumping directly to editing or organizing.
With High Sierra there is now native functionality for editing your photos in external editors. You can edit them in apps like Acorn and Photoshop without needing to export the photo and bring it back in when done. And edits you make can be removed by reverting back to the original photo.
With macOS High Sierra you can unlock new features of your iPhone Live Photos. You can choose a new frame as the still image. You can set the video to loop or bounce. You can also use the video to simulate a long exposure photo. You can even export a loop or bouncing video as an animated GIF.
If you take a photo of someone with your iPhone and they have an iPhone too, you can immediately share the photo with them using AirDrop. To use AirDrop, you don't need to be on the same Wi-Fi network or have set up anything in advance. The photo sent is the full resolution image. This can be easier than exchanging phones to take pictures of each other or trying to take the same photo twice.
Learn how to preview a large number of images in macOS Finder. You can use the Preview pane, large icons, cover flow, the Quick Look window, the Preview app and the Finder slideshow feature. See how these techniques can help you quickly locate the right image.
The Retouch tool in the Mac Photos app makes it easy to remove spots and blemishes from your photos. You can simply click and drag to remove spots, or pull colors from another area of the photo.
You can use the Image Capture app to scan documents and pictures instead of any software that may have come with your scanner. This can extend the life of scanners with incompatible software and may give you more features.
Two of the most useful adjust controls in Photos are the Shadows and Highlights adjustments. You can bring out detail in dark or bright portions of a photo without changing the rest. An overall light adjustment slider also can bring out the real color of a photo.
The People function in Photos for Sierra will recognize faces in your pictures and with some curation will allow you to label all of the people in your photos. There are many ways to assign faces to names.
Building a photo slideshow in Keynote is very quick and easy. You can simply drag and drop them into Keynote, add a transition and some music and then export as video. It is also easy to add text to any slide as captions.
You can alter the creation date of a file using the touch command in the Terminal. This can come in handy if you want to export a photo and have the creation date match the date the photo was taken.
It is easy to create a slideshow with iMovie using a photo album. In less than three minutes you can import the photos, add transitions, insert titles, and include music. You can then export the slideshow as a video to use on YouTube, your social networks, or show during a presentation.
On iPhones that support 3D Touch, you can quickly access camera functions and also preview and access photo functions. To get to the Camera functions, tap hard on the Camera icon. To get to the Photos functions, tap hard on a photo and swipe up.
If you have been taking Live Photos with your iPhone, you may find it useful to be able to extract the 3-second videos from the photos to upload to social media or use in video collages.
You can use the Add To iCloud Drive option in iOS Photos to essentially export a photo as a file. You can access it in the iCloud Drive app, or on your Mac in the Finder. You can even filter or markup the picture before exporting.