[Harrison]

So pretty much, in Lightroom, shadows appear "blotchy", but upon export (or on other people's computers, they appear fine. It's a bit hard to explain, so here are examples:

Lightroom:


Export:


As you can see, that's a massive difference. Does anyone have an idea as to what's caused this?

[Bob from Aus]

I will start with a left field theory. Maybe it is your monitor or graphic card that does something weird in lightroom only and not to jpgs outside lightroom. A question. Are you using RAW or jpgs. If using RAW download some jpgs and see if you have the same issue.

[davidreilly3207]

What module were you in when you viewed the 'blotchy' image and how did you save it?

[Smeggypants]

I would guess that Lightroom isn't rendering the image to as much accuracy for it's own displays as it's got to do it in realtime and re-render everytime you alter a parameter. Lightroom isn't the speediest of programs so I welcome any speed efficiencies as long as the real-time display isn't compromised too much.

Anyway, just en educated guess

[rawr]

Posterization I would say.

In relation to Lightroom,

"There is one remaining issue, however, but that is nothing you can do much about: Since the Develop module in Lightroom renders the image in a linear 16-bit version of ProPhoto RGB, whereas the Library and Slideshow modules render from 8-bit jpg-compressed previews, there will be a difference. In addition, when the Preview Quality in Catalog Settings is set to High, it uses ProPhoto RGB, whereas if set to Medium it uses Adobe RGB.

Images rendered by the Library module usually look very similar to the same imgages rendered by the Develop module, but since previews in the Library module are compressed by jpg, based on only 8 bits, and might even be in the ProPhoto RGB color space, they can become blotchy and with posterization, especially in deep shadows. And because of this limitation, the blotches can appear to have a slightly different color than in the Develop module simply because in Develop the "blotch area" contains a variety of pixel values (almost like dithering), whereas in Loupe or in Slideshow they have the same pixel value. The net effect can sometimes appear as an off-neutral "black". Sometimes ugly with severe posterization, sometimes not.

With the preview quality set to Medium, the posterization is primarily caused by a much too strong jpg compression in the deep shadow areas, but the colors will usually be fairly okay. With the preview quality set to High, the posterization is primarily caused by 8 bits being way too little for the extremely wide gamut of ProPhoto RGB. It is made even worse by the fact that ProPhoto RGB has a gamma of 1.8 making the bit steps in deep shadows in this wide gamut space even larger; this generally causes colors in deep shadows to be way off, in addition to posterization.

from:
Lightroom Color Management Hints & Tips

There's also lots of Google chatter on lightroom and posterization. Not sure what the solution is - I have never experienced the problem.

[Smeggypants]

"8bits". this would make a lot of sense as the accuracy of lowlights ( shadows ) will be seriously reduced when calculations are performed on low level signals in 8 bit.

[Harrison]

Hey all! Sorry it took me a bit to reply.

I shoot in RAW only, so this is from the RAWs themselves.

Rawr, from what you've posted, it sounds like posterization should appear only in the library module? However, this is appearing in both the library and develop module.

It would make sense that Lightroom is taking some shortcuts on rendering though, especially considering that my computer is, for lack of a better word, absolute crap.