Raw Therapee 3

Posted on 8 January 2011, 19:49

Raw Therapee (“RT”) is a free RAW converter I’ve enthused about here and elsewhere on the Interwebs for a few years now – it’s small, focused, and capable of excellent image quality once you’ve got your head round it.

The last “official” release – v 2.4.1 – was a while ago, and it might seem that things had gone very quiet on the RT front, often a precursor for an announcement that development had come to an end.

Not so in RT’s case – no sirree!

In fact the original writer – Gábor Horváth – decided about a year back to make RT Open Source, moving to the GPL licence.

Without dwelling on the implications of this change, it has meant that a number of remarkably talented Open Source developers have thrown their hats into the ring, and the result is – well – remarkable.

There will soon be a stable Beta release of RT 3: I’ve been testing the Alphas for a year now, and many early versions (and some more recent) have been extremely unstable – as befits Alpha status, of course – but it’s really getting there.

The point of this post however, isn’t simply to say “RT isn’t dead”, but to provide some idea of what’s coming – and it’s a helluva lot.

So – without further ado (and note that this list is subject to last minute additions and removals) – What’s new in Raw Therapee 3:

Now available as a Mac build as well as for Windows and Linux;

Tabbed interface where each raw opens in an new tab – the file browser and processing queue have their own tabs as well;
Still the possibility to choose the single-tab mode like in v2.4;
Single tab mode: choose between horizontal (classic) or vertical tabs;
New keyboard shortcuts for certain often used functions;
Full screen toggle button;
File browser: possibility to show rankings >= n, where n is the star ranking. This means you can say: “show all the photos with ranking 4 and all with ranking 5”, instead of “4 OR 5” as was the case before;
Option to set the surrounding color for crops. Instead of a semi-transparent border like in v2.4, one can choose a solid one, so one sees only the cropped part of the image;
More themes, including ‘slim’ versions to show as many tools as possible at the same time;
Possibility to choose fonts;
Sounds: play a sound when processing queue is done or when one RAW is processed (optional).

Batch queue:
Intermediate Batch queue saves while adding RAWs – one can stop the program, restart it and the files in the queue are still there (works the same after a crash);
Batch queue has an autostart option.

Parallellisation of lots of processing tools, so faster on multi-core CPUs;
Powerful batch editing in the directory browser tab;
Before/after option: show side by side the original and the edited photo;
Thumbnails load very fast now compared to v2.4, thanks to a new two-pass approach;
Multi-monitor support;
Command line mode.

Exposure tab – major rewrite of the exposure tools:
Exposure compensation is now real exposure compensation;
New Highlight recovery tool;
New Black slider, allowing for negative values as well (to lighten shadows;)
New Saturation slider in the Exposure section;
Tone Curve tool extended with Parametric curves and Control Cage – Parametric curves have four sliders to adjust highlights, lights, shadows and deep shadows; control cage allows for a smooth(er) curve;
New Lab Curves section in the Exposure tab (replaces Luminance curves from v2.4). Same extended tone curves for separate use on L, A and B channels.

Detail tab – major new noise reduction tools:
Impulse Noise (Spot) NR;
Noise reduction (works on luminance, chrominance and gamma);
Defringe filter;
Contrast by Detail Levels, 4 bands. This works as a noise reducer or as a sharpener; think of it as an enhanced local contrast option;
Wavelet equalizer: same idea as above, other algorithm, now with 8 bands;

Colour tab:
New HSV equalizer – allows for colour shifts on eight colours, very usable to emphasise a blue sky, or to correct skin tones.

Transform tab:
Resizing can now be applied to a cropped area as well;
New resizing algorithms;
Perspective: shifts perspective horizontally and/or vertically; very usable for say, architecture photography;
Vignette correction: placement of the vignetting correction on the photo can be better controlled with sliders for the x-axis and y-axis. New slider introduces vignetting effect (stronger);
Guide overlays in Crop mode.

New RAW processing tab:
Choice of demosaicing methods, selectable in real time from RAW to RAW. New demosaic methods include: AMaZE, DCB, Fast and Bilinear. The old ones are still available;
New preprocessing options (executed before demosaicing):
Dark Frame (usable for very long exposures);
Hot/dead pixel filter;
Automatic correction of Chromatic Abberation (CA), or manual correction of the Red and Blue channels;
Exposure correction before interpolation: linear or ‘preserve highlights’ modes;
Line Noise filter (excellent on say, Canon 5D Mk II banding);
Green equilibration slider (addressing maze artifacts caused by unequal green channels).

Now then, I didn’t write this list, I’m using it with the permission of the author, Paul Matthijsse, one of RT’s steering committee, and as I suggest, it may be subject to change.

I’ll also say that it’s far from exhaustive!

What I can tell you based on my own use of RT 3 is that some of the new NR algorithms are extremely capable, and can deal with certain kinds of noise better than any other NR I’ve used (and I’ve used lots); and that some of the new demosaicing algorithms are as good as any available anywhere and far better than are available in some commercial converters – including Capture One and Bibble 5, both of which converters I have been very enthusiastic about in the past.

RT stomps on ‘em both as far as the basic quality of conversions is concerned.

Frankly there’s too much to get my head around, and I’ve been using it for a year and I’m going to help write the user guidance material!

But for all that, it’s easy enough to use – pretty intuitive – and while there are still a few wrinkles to iron out, the results it’s capable of are deeply, deeply impressive: while I still choose Lightroom 3 for very high (more than 3200) ISO images, RT 3 can match anything else out there up to 3200 ISO, and can do some things that as far as I can tell are impossible with any other converter.

I encourage you to give it a go – it’s a remarkable piece of software, and it can do all these things from a download of less than 7 mb for the Windows version!

Free too, remember, although you really should make a donation.

What do you think?

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