Next, still in the Preferences dialog, click the External Editing tab (FIGURE 4.6).
Lightroom exports image files for editing in external editors like Photoshop and Photoshop Elements. When exporting Images to an external editor, two choices for File format appear in the pull-down menu: PSD and Tiff. Tiff is more widely preferred for publishing output, and PSD is the native file format for Adobe applications. The settings referenced here are based on a high photo quality reproduction output (resolution of 300) for inkjet printing. When producing images for the Web, an output resolution of 72 is required.
Using the native Photoshop PSD format for external editing is my preference. Lightroom is technically named Adobe Photoshop Lightroom and is made to integrate with Photoshop’s external editing features... with one little itty bitty caveat. You must remember that when you export or import an image file from or to Lightroom as a Photoshop file (PSD) that contains layers, you are required to save the file format for Lightroom with the Maximize Compatibility preference turned on. I refer to this again when we explore what I call round tripping, which means working between the two applications in harmony, in later chapters.
When determining which color space is preferred, ask yourself what the output of the file exported for external editing will be. I normally pick the native color space in which Lightroom predominantly processes raw images, which is ProPhoto RGB. ProPhoto RGB is a very large source color space supporting the most potential colors for processing images for today’s 6-, 8-, and 12-color inkjet printers. Adobe 1998 is certainly a good choice as well, with the color space supporting a wide range of color outputs in the inkjet and 4-color offset press area (books, brochures, and so forth). sRGB is the smallest color space, designed for working primarily with digital slide show projection and the Web. The color management discussion can become confusing with all the choices, but Lightroom does most of the color management internally and only allows the user to make decisions about which space to use when exporting the image(s) out of the application. If an image already has a color space profile, Lightroom honors the profile when importing.
When electing to edit a Raw image file in an external application like Photoshop, choose a bit depth of 16 to take advantage of Photoshop’s high-bit processing features. If you are exporting an image file for the Web, keep in mind that images in that environment only support 8 bits. Just remember that 16 bits results in twice the file size, but also provides more information to work with when making adjustments.
Pick a resolution that is appropriate for your ultimate output. Resolution can range from 72 (the Web) to 300 (printing). You can ignore the Additional External Editor because we will not be using any other applications within our workflow.