Thread time: This morning I'm gonna break down the technique I found yesterday for digitizing watercolors. My end results may differ from what you'd want for yourself, but the benefits of this approach still hold up against tweaking colors and levels in Photoshop. Here we go...
First off, what's the a big deal? Why do we need this? Well, digitizing watercolor can involve a lot of post-production to get good results representative of the original. I've spent lots of time trying to make adjustments to my scans in Photoshop to clean/color tint/mask/etc...
This is work intensive. With the RAW scan approach, I can cut better than half my post-production time, get a better end result, and do basically ZERO color/saturation/level tweaks in Photoshop. No isolating blacks on a separate layer. No muss. No fuss...
Step one: Preferably after calibrating your color space (scanner, monitor, etc.), use Vuescan to scan your file with the OUTPUT set to RAW tif. Scan with bit depth as high as your scanner goes (48 for me). Your files will be bigger, but they'll have MUCH more useful data. 
Step Two: Once you have your scan, you need to grab the Camera Raw plugin for Photoshop: ( helpx.adobe.com/camera-raw/kb/… ) Once installed, you can open your RAW tif file via Photoshop's File/ 'Open As...' menu option. I always wondered what that was for! Anyway, open it as a RAW file..
You'll see something like this. EGADS! It's so underexposed, right? BUT... Hiding in all that shadowy underexposure is lots of DATA... RAW DATA... Notice that to the right, there's all manner of adjustments to be made. Let's bump up 'EXPOSURE' from '0' to '1'...
Already way better, and much closer to my original. Notice how I brightened it, but the blacks are still nice and inky dark? That's hard to do with Photoshop without losing details elsewhere. Because PS converts files to 8 bit on open/import, it has less data to work with...
You can go nuts with subtle tweaks of individual color ranges here. It's VERY powerful. And get this: Once you're done adjusting, the Camera RAW plugin will apply the same tweaks to the NEXT file you open, automatically and non-destructively. !!! You can even save your profiles.
When levels/colors match your original in Camera Raw, THEN hit 'OPEN IMAGE' to open in Photoshop. Now, I don't need to do much beyond cleaning up my word balloons and a few stray pencil lines, which is easily done on a single added layer with Black and White adjustment applied...
The black and white adjustment layer is another super-powerful tool for quickly eliminating colors under your black lines - be they blue, red, plaid, etc... But that's another story for another time.
Hope this is useful to some of you scanning watercolors! Good luck out there.
Hope this is useful to some of you scanning watercolors! Good luck out there.
One more point for emphasis: I really can't say how nice it is to have proper color/exposure adjustments automatically applied, but then be able to quickly tweak them as needed. It probably takes my post-production time per scan from 20-40 minutes to 4-10 minutes.
Important update for this thread! Camera RAW doesn't export images to 16 bit depth by default (dumb!). You must select that option in a dialog box by clicking the following:
