Banding / Posterization during LR export to JPEG

whitericewhiterice Registered Users Posts: 555 Major grins
edited October 3, 2009 in Finishing School
I've searched this forum and read several threads about posterization, but none of those threads really answered my question.

So first, is what I'm seeing in these images "banding" /posterization - particularly in the vignette area where I notice rainbow-ish bands and a non-smooth gradient.

655283591_guMnP-M.jpg

655556450_JEB2D-M.jpg

655581292_6YfR6-M.jpg

These images were taken in RAW, converted to DNG on import to LR. In LR they look great, it's the when I export to JPEG at 90, 95, even 100% quality that they look horrid - and this is viewing the LR image side-by-side with the JPEG export on the monitor - you would NOT believe the difference. Oh, and the purpose of the JPEG export is solely for uploading to my personal SmugMug site for sharing - no printing, etc.

I've never noticed this before (which doesn't say much, as I've only been using LR for a few months :wink ). I've taken a liking recently to a LR preset, one of the creative catalyst presets from Wonderland Presets, which I used for these shots (and tweaked). This was when I noticed the problem.

I think I understand why posterization occurs - high bit to low bit conversion, extreme editing that causes degradation of image quality - I just don't know how to prevent it in instances where I want to use a vignette.

Any help would be much appreciated. :bow
- Christopher
My Photos - Powered by SmugMug!

Comments

  • malchmalch Registered Users Posts: 104 Major grins
    edited September 27, 2009
    In Photoshop the "standard" way to fix gradient banding is to add a tiny amount of Gaussian noise. Preferably you do that selectively to a region and sometimes to a channel.

    I'm not sure if and how you do that in Lightroom.
  • TheSuedeTheSuede Registered Users Posts: 23 Big grins
    edited October 3, 2009
    AFAIK there's no way to do this in LR right now (I don't know of any plugin that can add dither or noise) - so your best bet is to do the roundabout via PS.

    Export ALL your pictures as 16-bit tif in the intended colour-space, to a separate folder. Make a batch action that runs an "add noise" filter (you'll have to experiment with the noise strength - use "monochrome noise") converts to 8-bit, and save for web as jpg. This is all available directly in PS, in "File/scripts/image processor".

    It's an extra step, but once you're set up, it's a quick one. And well worth it.
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