I use darktable, and also of note is RawTherapee. Both are free, in contrast with the $150+ alternatives he shows off.
Edit: ~~Can you tell me why I'm being downvoted?~~ Sorry, I'm new to /r/photography. If there's a rule here I don't know about, please tell me!
Edit 2: From -2 to +5? What gives? I've been on reddit for a year and I still don't always get it… :P
Personally, I don't like the HDR look, especially not when it's so obvious that I can classify it as such. But the software used in this tutorial is truly great. I'm only using open source software in my toolchain and will never switch back to Lightroom/Photoshop.
In addition to Darktable mentioned in the article, there's also RawTherapee which is IMHO easier to operate than Darktable but still has very advanced features. I especially love its noise reduction and demosaicing algorithms.
If you are just adjusting levels and colours then there are better tools than GIMP. have a look at RawTherapee http://www.rawtherapee.com/ or DarkTable http://www.darktable.org/ . Compared to GIMP you get 16bit editing, non-destructive editing and lens distortion correction.
There are two distinct steps here:
There are programs such as lightroom which let you do both. Me? I mostly delete pictures rather than edit them. So I use the open-source/free conversion program called RawTherapee:
You can mass-convert there, and play around with curves, colours, and so on. Its very easy to get started so you shouldn't struggle.
Also on Linux you should check out RawTherapee. Or if you are willing to shell out some money Bibble Pro 5 is supposed to be excellent (although I've never tried it).
I find that I shoot jpg for everything unless I'm doing a "shoot" (portraits, event, etc). When I'm just taking pictures for myself, it's always jpg.
I’d say the two big Free Software options would be either darktable or RawTherapee.
I don’t personally manage my photos with them, but I do use them for raw processing and they’re fantastic for it.
If you want to stay with free software, but find that Picasa has too few options for post-processing, you could try RawTherapee. It's not as good as the Adobe Camera RAW converter (because, frankly, nothing is), but it's a good software for trying different settings.
My upgrade from Ryzen 7 1800X to Ryzen 9 3950X was similarly trouble-free, but also involved replacing the liquid cooler with an AMD-recommended 280mm radiator (went from H100i v2 to H115i RGB Platinum).
But things went wrong elsewhere when it turns out the existing G.SKILL memory modules had failed, returning errors in a localized memory region at speeds that were previously known to work properly on the old processor (DDR4-2933 14-16-16-36). I ended up having to run to the local Best Buy to grab some replacement modules (Corsair Vengeance RGB Pro CMW32GX4M2C3200C16, 2x16GB, DDR4-3200 16-18-18-36). Astaroth started right up and ran the memory modules at rated speed with no hesitation at all, and managed to complete one full pass of Memtest86+ without any errors. (I'll be sending the faulty modules to G.SKILL for replacement under warranty once I get a chance.)
This upgrade opened up new possibilities on the Demon (as I like to call it). Assassin's Creed Odyssey, which often stuttered in complex scenes because of a processor bottleneck on the Ryzen 7 1800X (it'll happily max out 16 hardware threads), now runs consistently smoothly. I can even do high-quality CPU-based recording at a full 1440p and 60 fps with only a limited impact on performance, something I could never do on the Ryzen 7 1800X. Batch-processing 24-megapixel RAW images in RawTherapee (an open-source alternative to Lightroom; I used to be a sports photographer for my college) now takes half the time, processing each photo in less than five seconds.
As for benchmarks... Cinebench R20 scores were as high as 9507 with Precision Boost Overdrive enabled, 9335 at stock. I haven't spent huge amounts of time benching this thing beyond this and the RawTherapee test, but anything that can make use of all these cores simply gets destroyed by this monster of a processor.
Astaroth unchained. 'Nuff said.
There's a free tool called RawTherapee http://www.rawtherapee.com/ that can edit and convert your DNG (digital negative) files. This way you don't need to stress about the trial and you can take your time with it.
If you just want to export them to JPG it takes only a few clicks.
There are some tutorials and documentation if you want to learn about tweaking the exposure and color (something you can't do without losing quality after converting the photos to JPG).
Raw Therapee - I've since switched to Bibble Pro, but version 2.4.1 was pretty awesome, and the early v3 builds had some nice workflow improvements but were unstable when I tried them some months ago.
EDIT: I'm an idiot. But you can definitely see all photos in a folder in RT. Or am I missing something when you say you want that, I assumed thumbnail browser.