JPEG (Joint Photographic Experts Group) is a widely-used image format known for its lossy compression, which allows for significant reduction in file size with minimal loss of quality. This format is essential for web images, photography, and various digital media. In the context of macOS, working with JPEG files can involve viewing, editing, and converting these images using built-in tools and command-line utilities. This article will guide you through various methods to handle JPEG files on macOS, including using Preview, Terminal commands, and Automator workflows.

Examples:

1. Viewing and Editing JPEG Files with Preview: Preview is the default image viewer on macOS, and it offers basic editing capabilities.

   • To open a JPEG file with Preview:
     1. Locate the JPEG file in Finder.
     2. Double-click the file, and it will open in Preview.
   • Basic editing in Preview:
     1. Open the JPEG file in Preview.
     2. Use the toolbar to crop, rotate, annotate, or adjust the color of the image.
     3. Save the changes by selecting File > Save.

2. Converting Images to JPEG via Terminal: macOS includes the sips (Scriptable Image Processing System) command-line tool, which can be used to convert images to the JPEG format.

   • To convert an image to JPEG using sips:

     sips -s format jpeg input_image.png --out output_image.jpg

     Replace input_image.png with the path to your input file and output_image.jpg with the desired output file name.

3. Batch Converting Images to JPEG using Automator: Automator is a powerful macOS application that allows you to automate repetitive tasks.

   • To create an Automator workflow to batch convert images to JPEG:
     1. Open Automator from the Applications folder.
     2. Select Workflow and click Choose.
     3. In the Library, find and drag the Get Specified Finder Items action to the workflow area.
     4. Click Add and select the images you want to convert.
     5. Find and drag the Change Type of Images action to the workflow area.
     6. Choose JPEG from the dropdown menu.
     7. Save the workflow and run it to convert the selected images.

4. Resizing JPEG Images via Terminal: The sips tool can also be used to resize JPEG images.

   • To resize a JPEG image to a specific width:

     sips --resampleWidth 800 input_image.jpg

     Replace 800 with the desired width in pixels and input_image.jpg with the path to your JPEG file.