Today’s Question: If I send a JPEG to Photoshop from Lightroom Classic and want to create a copy rather than editing the original JPEG, I assume that I’m creating a 16-bit per channel image from the 8-bit per channel JPEG based on the External Editing settings in Preferences. If so, should I change that setting before sending a JPEG to Photoshop from Lightroom Classic?
Tim’s Quick Answer: My recommendation in this context is to keep the Preferences set to the 16-bit per channel option, but then convert the image to 8-bit per channel mode in Photoshop before saving the finished image.
More Detail: When you create a new file when sending a photo from Lightroom Classic to Photoshop, the new file is created based on the settings established on the External Editing tab of the Preferences dialog in Lightroom Classic. That means you’re either creating a Photoshop PSD or TIFF file, and that by default the new file will be set to a bit depth of 16-bits per channel (per component).
When you send a JPEG image with a bit depth of 8-bits per channel to Photoshop and the resulting PSD or TIFF file is set to a bit depth of 16-bits per channel, you’re creating a file that is twice as big as it needs to be, with no real benefit in terms of the quality of the derivative image you’re creating.
While it is possible to change the settings on the External Editing tab of Preferences before sending a JPEG image to Photoshop, I don’t recommend taking that approach. Put simply, you might change the setting before sending a JPEG image to Photoshop, and then forget to change the setting back to 16-bit per channel option before sending a raw capture to Photoshop. I therefore recommend keeping the setting at 16-bits per channel, which is the safest and preferred setting.
Instead, when you create an image in 16-bit per channel mode based on a source image that was only captured at 8-bits per channel, I recommend changing the bit depth for the derivative image in Photoshop before saving the final result. To do so, go to the menu in Photoshop and choose Image > Mode > 8 Bits/Channel.
This approach ensures that by default you’re creating derivative images when sending a photo from Lightroom Classic to Photoshop with a bit depth of 16-bits per channel, which provides greater latitude in terms of color and tonal values. You can then convert the derivative image to 8-bits per channel for images that were created based on an 8-bit per channel original. With this workflow, the worst thing that might happen is that you forget to convert an image created from a JPEG to the 8-bit per channel bit depth. That would just mean that the file was twice as large as it needed to be, but there’s no problem in terms of image quality. More to the point, taking this approach means you won’t inadvertently create a derivative image at 8-bits per channel for a source image that was 16-bits per channel.