In what color spaces does Lightroom render colors?
In the Develop module, by default, Lightroom renders previews using the ProPhoto RGB color space. ProPhoto RGB contains all colors that digital cameras can capture, making it an excellent choice for editing images.
Library, Map, Book, and Print modules in Lightroom render colors in the Adobe RGB color space. The Adobe RGB gamut includes most colors that digital cameras can capture together with some printable colors (cyans and blues, in particular) that cannot be defined using the smaller, web-friendly sRGB color space.
Lightroom also uses Adobe RGB for:
Rendering images in the second window. For more details, see Display the Library on a second monitor.
Images printed in the Draft mode. To know more about the print settings, see Work with print job options and settings.
Books sent to Blurb.com
Lightroom uses sRGB by default for:
Slideshow and Web modules
Images exported as JPEGs destined for the web and email
Uploaded web galleries and PDF slideshows
Images published to Facebook and other photo-sharing sites using the Publish Services panel
If you export books as PDF or JPEG from the Book module, you can choose sRGB or a different color profile.