Today’s Question: We’d like to know why we can’t take a Photoshop PSD file directly into Adobe Camera Raw? We are able to take a PSD from Bridge directly into Photoshop, but not into Camera Raw. Yes, a workaround is Lightroom or Camera Raw as a filter in Photoshop, but we would still like to know we have this problem with PSDs?
Tim’s Quick Answer: Conceptually, the key challenge with a Photoshop PSD file in Adobe Camera Raw is that a PSD very often will include layers, which complicate processing with Camera Raw. For example, TIFF images with layers are also not supported in Camera Raw.
More Detail: I suppose the “real” answer here is that Adobe has thus far not chosen to support processing Photoshop PSD file via Camera Raw. If they wanted to add this support, it certainly could be done.
As many photographers may be aware, it is possible to open TIFF and JPEG images directly with Camera Raw, similar to how you can open proprietary raw captures (or Adobe DNG images) with Camera Raw. However, layered images would create a complication for this workflow.
So, while you can open a JPEG or TIFF image with Camera Raw, that support does not extend to TIFF images saved with layers. Only flattened TIFF images can be opened in Camera Raw in this way.
I imagine Adobe has decided that there isn’t much of a need to open PSD images in Camera Raw, in part because a PSD image file is perhaps more likely to contain multiple layers. As noted in the question, of course, Photoshop CC does include a Camera Raw filter, so you can apply Camera Raw adjustments as a filter to any image layer in any image format supported by Photoshop.