Today’s Question: I have an image that shows posterization [the loss of smooth gradations of tone and color in an image] in the Library module [in Lightroom] but when I go to the Develop module it does not show up. I have seen it 3 or 4 times and was wondering if you could explain this.
Tim’s Quick Answer: The short answer here is that the Develop module presents a more accurate preview, and that the Library module presents a JPEG preview of your photo. Therefore, the preview quality in the Library module will not always reflect the true quality of the underlying photo.
More Detail: There are several factors that affect the preview you see in the Library module in Lightroom. To begin with, that preview is a JPEG version of your original capture, which by definition will not reflect the full quality of the original capture in many cases.
In addition, you can actually adjust the resolution and quality of the preview that is rendered for the Library module. To do so, first bring up the Catalog Settings dialog by choosing Catalog Settings from the Lightroom menu in the Macintosh version of Lightroom or from the Edit menu on the Windows version. On the File Handling tab you can adjust settings for the size of the preview image to be generated as well as the overall quality of that preview. This latter setting relates to the Quality setting when saving a JPEG image.
The aim of the Library module is really to enable you to quickly browse and manage your photos, and so the JPEG preview approach makes sense. But of course in some cases you need to evaluate the true quality with the most accurate view of your photo as possible. In those cases I highly recommend using the Develop module within Lightroom. There might be a slight delay in updating the previews for your photos in the Develop module, but in some cases it is worth accepting that delay in return for a more accurate view of your photos.
As a general rule, I recommend using the Library module when you are organizing and performing a basic review of your photos. When you need to evaluate the true quality of your photos, use the Develop module to browse the images. And when you need to evaluate sharpness I recommend using the 1:1 zoom setting within the Develop module.