make RawTherapee work like Lightroom 4.1, C3/5n

Started Jul 5, 2012 | Discussions thread
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RussellInCincinnati
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make RawTherapee work like Lightroom 4.1, C3/5n
Jul 5, 2012

Let's start with a low-ISO raw file, from a Nex C3 on a tripod, with the ridiculously inexpensive Alpha mount 18-55 kit zoom at its lowest-resolution focal length. We'll run it through the latest (process 2012) defaults of LR4 Adobe Lightroom v4.1. (Well maybe fiddle with LR4 sharpening a bit, but color and contrast are the main point of this post, not sharpening.) Camera first set to custom white balance, against a white card.

Now, do you process raw files with the freeware RT RawTherapee? If so, here's a RawTherapee version 4.0 "profile",
https://dl.dropbox.com/u/15387676/Default-ISO-Medium-likeLightroom.pp3

intended for low ISO 200 images. That if you manage to copy into your " RawTherapee/profiles " folder, and apply the profile to a Nex C3 or 5n raw file, will make the output image's color strength, exposure and contrast look "pretty much" like LR4's defaults (as shown in sample above). Except in the RawTherapee example below, you may notice a touch more shadow and highlight detail. Look at the darkest part of the model's hair, and the watch band. Kind of exquisitely delicate color and detail preservation.

(This default preservation of a bit more highlight and shadow details may be a source of great glee, if you're finicky enough about images to want to fool around with raw files in the first place.)

The RT profile above also does quite a bit of RL Deconvolution sharpening, which is why am keeping mentioning it's for low-ISO Nex images.

Don't Use My RawTherapee Profile, Make Your Own

Or forget my RT profile, go make your own, maybe starting with what's shown here if the idea of imitating Lightroom intrigues you. Run RT, double-click on an image in the file browser so that you get to the development screen, and load up RT's "Default-ISO-Medium" pre-supplied profile. Then go to the exposure tab, and start fiddling with "LAB adjustments" (Got the idea for this from something John Bean said a while back, about working with LAB color space. ). Bump up the "Contrast" to 23, and the "Saturation" to 8, and you'll have pretty much the same color intensity and contrast as my profile above.

My profile above furthermore enables Automatic Chromatic Aberration Correction, under RT's "Raw" tab. Also under the Raw tab, my profile enables Impulse Noise Reduction, with a numerical masking setting slid down from the default of 80, down to 63. Then go to the Detail tab, and activate Sharpening, choosing the RL Deconvolution algorithm. It's pretty important to have adjusted the Impulse Noise Reduction if you're going to use RT RL Deconvolution, if you want to avoid "zipper effects" on thin diagonal lines, and also "salt noise".

An interesting thing about RL Deconvolution sharpening (which you can apparently also get in Lightroom simply by moving the "Detail" slider of the sharpening panel all the way to the right) instead of more "traditional" Unsharp Mask sharpening. For all its strengths and weaknesses, RL Deconvolution will brighten a thin light line, without putting a dark halo around the light edges. Am able to make quite crisp images without obvious unsharp mask halos with RT's RL Deconvolution. Thanks in part to the nice Impulse Noise Reduction slider, which helps you get a good deal of big-feature sharpening without magnifying tiny noise variations into speckling as much.

Anyway, after you've got the image looking the way you want, you can click on a tiny RT icon just below the line saying "Processing Settings", to save your current raw-processing settings as a "profile" (i.e. packaged bundle of preset settings), with some kind of name that suits you.

Lightroom and RawTherapee Do Not Replace Each Other

Am not saying you can't do almost the same sharpening, etc in Adobe Lightroom v4.1 as you can do in RawTherapee (recall the point above, about moving "Detail" slider to the right to use LR4's RL Deconvolution exclusively). I.e. am not putting up this profile to "get people to not use Lightroom". Lightroom is so different than RawTherapee in its image archiving functions, and Lightroom's controls for exposure, highlight and shadow details are fabulously good and easy. It is trivial to boost shadow and highlight detail in just a few seconds in Lightroom, my point here is not to say that RawTherapee holds onto shadow and highlight detail better.

In fact my workflow always starts out everything in Lightroom, including by default converting all my .ARW files into .DNG files. Latest RawTherapee handles latest .DNG format perfectly, nice. But then use both Lightroom and RawTherapee at different times for finished output. Maybe usually Lightroom, which has awesome purple and green correction sliders, suppressing highlight purple fringing around underexposed bright edges. Purple fringing suppression handy quite often, with backlit scenes like this (lots of detail, had to crop it to make the JPEG less than 20 megs).

But RawTherapee's freeware (well I did send a voluntary contribution), that's one reason to talk about it. And it so happens on my system, for some reason, the darn development screen preview of color saturation is much less accurate in Lightroom than with RT (am sure it's a monitor calibration profile/color management problem). So fiddling with exact color saturation and brightness is a touch easier for me in RT, as is getting my preferred exact sharpening.

Why Imitate Lightroom in RawTherapee?

Have this quasi-social theory that about a bazillion images that we see nowadays have been put through Lightroom's defaults, conditioning all of us to sort of "like" those defaults. So it seems important to me to easily call up, in RawTherapee, a default process that works like Lightroom 4.1. To increase the chance of a satisfying outcome for the average viewer. Plus it's been fun and instructive, trying to make the two programs imitate each other.

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