I'm looking for tips on how to obtain the best resolution when editing photos within Lightroom for export to publish photo books with Blurb.
The photos are original raw from a Nikon D80.
Blurb's Booksmart has a resolution warning indicator so you shouldn't need to worry about it if you are using a modern camera, like your D80, and not zooming too much when you crop.
When you put an image in BookSmart it will automatically fill the image box. This will, probably, crop out the sides or the top and bottom, depending on the aspect ratio of the picture and the aspect ratio of the image box.
You can easily control the crop. You can slide the image just by dragging it to reposition the visible area. You can also zoom the picture to show more (or less) of the image.
In this shot, notice the zoom slider right under the words Backgrounds and Ornaments. It is currently set to 210%
Now notice what happens when I zoom in even more, to 250%
See the yellow warning triangle in the upper left hand corner of the image box? That's BookSmart telling you that you do not have enough resolution to print that image without artifacts.
The Nkion D80, at maximum resolution, shoots at 3872 x 2592 pixels. BookSmart triggers the resolution warning at 300dpi. So for your camera if you try to print bigger than 12.9 inches x 8.64 images you will get this warning. If you zoom, of course the maximum size you can print at gets smaller. For example, if you zoomed 200% then you could only print at 6.45 x 4.31 inches.
But basically, don't worry about it. (Worry about the color instead, see below... :- )
Ah, I see you ask specifically about Light room. Don't worry about cropping in Lightroom. Just export them as full size images. It is far easier to do the cropping and scaling in Booksmart.
However if you are doing one of Booksmart's "pages of images" page where you have a dozen or so small images on a single printed page, you may want to downsize beforehand.. I read one blog which suggested that Booksmart's downsizing algorithm wasn't very good and that you should downsized in an image editing tool like Photoshop or Lightroom. Personally, I don't believe that at all.
I had significant color quality issues with Blurb. Love their layout tools and the "store" but the color quality is not up to my standards.
The only way I've found to get good images out of Blurb is to go with the Pro package and use the high quality paper. I also printed a test book with various brightness/contrast adjustments to the same image just to see how I would process my images for Blurb.