Today’s Question: How can Lightroom export at higher than the native resolution of the file? I thought Lightroom never created pixels but apparently it can. I tested it and sure enough, a capture from my camera at 5472 pixels on the long side was successfully exported to JPEG with 6000 pixels on the long side. Who made those extra pixels and is this as good as upsizing in Photoshop?
Tim’s Quick Answer: While Lightroom does not enable you to, for example, create composite images, that isn’t the same as saying that Lightroom can’t create pixels. Lightroom can indeed create pixels, including the ability to resample an image upon export so that the exported image contains a smaller or larger number of pixels than the original capture. The quality of this resampling in Lightroom is comparable to Photoshop.
More Detail: Lightroom is non-destructive, so when you are working in the Develop module you aren’t actually replacing the pixels in your original capture. Even things that might appear destructive at first glance, such as replacing pixels to clean up blemishes, are actually non-destructive. However, I think it is fair to say that Lightroom is creating pixels (perhaps in an indirect way) when you perform this type of work.
But when Lightroom is really creating pixels is when you export a photo. That is when your original capture is processed based on the adjustments you’ve applied in the Develop module to create a new image file. So, for example, you might use Lightroom to create pixels in the form of a JPEG image based on your original RAW capture.
When exporting a photo, you also have the option to change the pixel dimensions of the photo. Based on the typical display resolution for computer monitors, when presenting an image online (such as on a website) you don’t need much more than perhaps around 500 pixels or so of width for the image. Viewed at the actual pixel dimension size, an original capture that was over 5,000 pixels wide would be too big for a web page.
Similarly, if you are exporting an image so it can be printed, you might want to produce a larger file to create a larger print. For example, if you want to prepare an image to be printed 20 inches wide at 300 pixels per inch, you need 6,000 pixels across for the photo. If the original capture is “only” 5,000 pixels wide, the image would need to be resized to produce the desired print size.
Whenever an image file is created with pixel dimensions that differ from the dimensions of the original capture, pixels must be added or removed to produce the final pixel dimensions for the new image. This is a somewhat complicated process that involves calculations to ensure that color and tonal fidelity, fine detail, and overall sharpness, for example, are retained. Lightroom (and other applications) do a generally good job with this resampling work.
So yes, Lightroom is most certainly able to create (or destroy) pixels in the context of a derivative image being created through the Export facility, by virtue of being able to resize the image being exported to specific pixel dimensions based on your specific needs for the photo.