Shadows differ in Photoshop vs Lightroom

Question

SUMMARY: Photos saved in Adobe RGB (1998) from Photoshop has much better shadow performance than the same unmodified image in Lightroom. Artifacts pop up deep down in the shadows, despite the rest of the image is rendered almost identical in the two programs. I can not find a way around the issue, and I wonder what it is?
DESCRIPTION:
I have scanned photos at high resolution (profiled by inCamera), which are treated and optimized in Photoshop CS3 and then saved as JPEG quality 12 in Adobe RGB to be imported into Lightroom 1.3.1 on a MacBook Pro. (I don't want to use TIFF since those are more than 100 MB each, whereas the JPGs are just under 10MB.)
In Lightroom, I make sure there are no develop settings being applied by using the preset called Zeroed. But since Lightroom has touched the image, metadata is changed and written to the file, and when I reopen the image in Photoshop, it invokes CameraRaw! A bit strange, but I guess it is because LR has written some metadata to it, although all the develop settings are zero(?)
Except for those deep shadows, the image look identically in Photoshop and Lightroom, so profiles appear ok. My monitor is a good one: SpectraView 2690 profiled by Gretag eye-one and SpectraView Profiler 4.1.7 (same as basiccolor).
Shadows are deep, and have been lifted in photoshop, so they are a bit noisy and grainy, and it is really critical to get those right without artifacts. When zooming to 1:1, and just looking at a deep shadow section, it is obvious that the carefully balanced noise and black point settings are being mangled by Lightroom, creating blotchy artifacts and color casts.
To make sure it was not a cache issue, I deleted all previews, thereby forcing LR to rebuild them, and I also restarted the machine. It is also pretty strange that the shadows look different in the Library module from the Develop module!?
The following are links to screen captures of that dark section (PNG images, between 600 and 800 kB each):
(These are dark, so close everything brighter than mid gray on your screen, otherwise you won't see much. The images are in Adobe RGB, but it doesn't really matter if you see them with the correct profile or not, since the important and strange thing is that they are different. The best is of course if you download and view them in Photoshop.)
In Photoshop: http://photo.bragit.com/pics/Shadow_LR_PS/PS.png
In Lightroom, Library module: http://photo.bragit.com/pics/Shadow_LR_PS/LR_L.png
In Lightroom, Develop module: http://photo.bragit.com/pics/Shadow_LR_PS/LR_D.png
Lightroom uses Perceptual rendering intent, and claims to be using ProPhoto internally.
To see if I could change settings in Photoshop to make it look like Lightroom (just for testing purposes), I changed the color settings in Photoshop to perceptual and also tried the Apple CMM instead of Adobe (ACE). But that didn't make any difference.
To see if the reason Lightroom makes it bad is caused by a roundtrip to ProPhoto, I converted the image in Photoshop into ProPhoto, and then to my monitor profile; but also in this case it didn't make any difference.
QUESTION:
So, there must be something else causing this.
What is it?
I want Photoshop to be the norm, and don't like Lightroom inventing shadow casts of its own. But I want to make slide shows and prints from Lightroom...
Regards, Harald

Answer 1

>In Lightroom, I make sure there are no develop settings being applied by using the preset called Zeroed. But since Lightroom has touched the image, metadata is changed and written to the file, and when I reopen the image in Photoshop, it invokes CameraRaw! A bit strange, but I guess it is because LR has written some metadata to it, although all the develop settings are zero(?)
The way to prevent this is to NOT use a preset. Lightroom will not apply any settings to non-RAW files. Second, you should NOT enable "automatically write metadata to xmp" as you appear to have done in Catalog Settings. This will ensure that Lightroom will not touch your originals and will make Lightroom much faster.
>Shadows are deep, and have been lifted in photoshop, so they are a bit noisy and grainy, and it is really critical to get those right without artifacts. When zooming to 1:1, and just looking at a deep shadow section, it is obvious that the carefully balanced noise and black point settings are being mangled by Lightroom, creating blotchy artifacts and color casts.
Probably a rendering intent issue (see below)
>It is also pretty strange that the shadows look different in the Library module from the Develop module!?
This is due to the fact that Library uses a preview jpeg that is generated from your file in adobeRGB. You do NOT see the actual data in Library. In develop, Lightroom renders the file into prophotoRGB. Perceptual rendering into the monitor profile from prophotoRGB will give different results than perceptual from adobeRGB, even if you have the same absolute color data. This is why you want to have no perceptual rendering intent defined in your monitor profile (see below)
>Lightroom uses Perceptual rendering intent
Indeed, and this is how it differs from Photoshop. You cannot setup Photoshop to use perceptual rendering for the screen profile. If your monitor profile has both intents, your display will differ between Photoshop and Lightroom. To get rid of this recalibrate using your profiler, making sure you only create a relative colorimetric intent, forcing Lightroom to go through that.
>To see if the reason Lightroom makes it bad is caused by a roundtrip to ProPhoto, I converted the image in Photoshop into ProPhoto, and then to my monitor profile; but also in this case it didn't make any difference.
Apart from the fact that Lightroom doesn't use prophotoRGB but uses a linear version of prophoto (i.e. a color space with prophotoRGB primaries and a linear gamma instead of 1.8), you should get similar results if you use perceptual rendering when you convert into your monitor profile. Lightroom uses the exact same color engine as Photoshop, so if you set it up correctly, you should get almost identical results.
Lastly, many of these differences seen between photoshop and Lightroom are caused by corrupt monitor profiles. Many of these are canned profiles from the monitor manufacturer. Trash them and never touch them again. Only use profiles from a hardware calibrator. Also, make sure your graphics card driver is up-to-date. Lots of these problems are caused by outdated graphics drivers.