Comments on: Where’d My Saturation Go? Understanding JPEG Export Woes

By: Alan

Alan — Tue, 27 Apr 2010 08:47:13 +0000

Finally figured out colorspaces. I came across your website too late, however. I think this is a great explanation of how colorspaces work. Not to mention it’s brief, candid, and written so an average person, such as myself (well at least I was a week ago before I drove myself nearly crazy dumping so much time into figuring it all out), would be able to at least have a grasp on what was happening. Definitely going to bookmark this site now.

By: Joe Decker

Joe Decker — Wed, 26 Aug 2009 17:34:13 +0000

Also: I do need to give PhotoKit a better look. 🙂

By: Joe Decker

Joe Decker — Fri, 21 Aug 2009 05:55:58 +0000

Tronam: Thanks so much for the kind words!

“Through some experimentation, I finally traced it down to the Detail module, which doesn’t make sense because the general wisdom with Lightroom has been that it performs sharpening on the luminance channel of the image only, which shouldn’t produce any color shifting or saturation loss.”

Actually, it can produce saturation loss, and that makes complete sense. Thanks for pointing that out. Yes, sharpening on the luminance channel sounds like it shouldn’t affect saturation. The problem is that the HSB color space isn’t really a cube. The most saturated colors are at the midtones, you simply can’t have complete saturation near L=0 or L=1 (black and white), the more you move away from the midtones the greater the maximum saturation you can have. There are no very very very very saturated pastels, or dark shadows.

I knew about that problem in sharpening in PS, but jsut didn’t think about the fact that sharpening was being applied here. My own tests here wouldn’t show it since the images are very smooth, but .. yeah, there you go.

I’ll probably write an update in the next week to share that, I’ll give credit. Thanks!

By: Tronam

Tronam — Thu, 20 Aug 2009 20:33:41 +0000

Thank you for maintaning such an excellent blog and photography resource site. I too have had to deal with unexpected saturation and luminance loss issues on JPEG export which “shouldn’t” really be happening in the first place because I’d assumed that most of the professional apps are properly converting large gamut colorspaces to sRGB correctly. For example, even though the LAB colorspace in Photoshop can really push colors way out of normal gamut, I’ve found that if I manually convert it to sRGB with Relative Colorimetric/Blackpoint compensation, the export is pretty flawless.

Lightroom has proven mysterious in this way to me until recently. For a long time it left me scratching my head as to why exported JPEGs kept turning out slightly (and sometimes dramatically) desaturated compared to how it looked in the Develop module, especially in high detail areas. Through some experimentation, I finally traced it down to the Detail module, which doesn’t make sense because the general wisdom with Lightroom has been that it performs sharpening on the luminance channel of the image only, which shouldn’t produce any color shifting or saturation loss. I’m still testing this, but both Sharpening and Color Noise Reduction in the Details panel contribute to this.

The weird thing is that the PhotoKit export sharpening modes (Low, Standard, High) sharpen perfectly without any loss of color or luminance. I now disable or set very low the Detail section for all exports. Try it sometime, especially with an image with a lot of intricate, colorful detail.