ART – Another RawTherapee

(Actually a fork of RawTherapee)

ART is written by the Italian programmer Alberto Griggio, who aimed to keep the best of RawTherapee (RT) whilst making it easier to use. One of the new features is local masking.

I recently discovered ART when I wanted to apply 2 grad filters to an image. (RT) only allows one application of the effect. There is the obvious workaround of applying one grad filter, save the image, reopen the saved image in RT and apply a second grad filter.

I was hoping that ART would allow more than one application of a grad filter but it does not. However for my immediate requirement the masking feature of ART (Not present in RT) solves the problem.

Above is the image with just some basic global adjustments. What I now want to do is to apply a grad to darken the sky. But the sky is reflected in the water so that will require some darkening too, probably a reflection of the first grad filter.

Enter the Mask

The required mask divides the image into 3 horizontal bands: sky, ground, and water by creating a blurred or feathered rectangular mask across the middle, i.e. the ground.

We would then expect any adjustment to affect the area that is not masked, but the author of ART seems to use the word in the opposite sense – no problem, just click the “invert” button. Whatever adjustment is then applied will affect the sky and the water in a similar way to 2 grad filters.

Whilst this is a very specific case of requiring 2 grads I am sure it is not uncommon; whenever a sky is reflected in a lake any adjustment to the sky must be reflected in an adjustment to the surface of the lake. Below is the result.

Hugin 2017.0.0 — Stitching HDR and LDR Panoramas

Having been an occasional user of Hugin for many years, I have described my recent experience of stitching High-dydnamic-range (HDR) and normal, (Low-dynamic-range) panoramas from a set of 9 images shot one evening at Salford Quays. The article should prove interesting and useful to anyone new to Hugin, or to those, like me, who use Hugin infrequently and never quite become “experts”.

P1548 - P1559_hdr_pregamma_1_mantiuk08_auto_luminancecolorsaturation_1.4_contrastenhancement_1.71

As usual, Hugin did an excellent job of stitching, but I recommend outputting an HDR file in EXR format for tone-mapping in, for example, Luminance HDR.

Read the full article

Noise in Digital Camera Raw Files – How to Measure it

After writing two articles on the Nature of Light and its relevance to digital photography, I found that the subject of noise still fascinated me and decided that I had to make some measurements. Looking at the wiggly waveforms of my previous article might indicate that camera A is noisier than camera B but can we measure the noise in a rigorous way? This present article explains how to do that using free software. As well as presenting graphs of the measurements I have attempted to explain the results from physical principles – and evidently the noise is predominantly photon noise (aka shot noise).Selection_026

Click here to read the article

Raw Processors: Which Demosaicing Method?

Comparison of Demosaicing Methods available in Free, Open Source Raw Processors

My previous article included a table listing the various demosaicing algorithms offered by the four raw processors considered and I wondered why we (as users) needed such a wide choice. The table is reproduced below.DemosaicI decided to investigate those offered by RawTherapee by looking closely at the detail in an image of tree branches against the sky – the same part of the same raw file processed by each of the algorithms.

Read the full article



Which Raw Processor?

Comparison of four free raw file processors: RawTherapee, Darktable, Lightzone and Photivo

With the exception of Darktable, which is not yet available for Windows, all of the applications are available for Windows, Mac and Linux. All are free and open source downloads.

I am looking for a raw file processor that will allow me to develop raw images to produce files ready for projection (at 1400 x 1050 pixels) and files at full resolution for further development, as necessary, to make high quality prints. I don’t expect to print directly from the raw processing application though this might be an advantage.

I have used both RawTherapee and Darktable for over a year and have recently tried Lightzone and Photivo so I will restrict my comments to these four.

Read the full article


Photography and free software

Today I’m launching my new website. Initially it’s about photography and in particular panoramic photography, but I shall no doubt digress into areas of digital image processing and computing generally as time goes on. As an amateur photographer familiar with Photoshop and Lightroom, I have been looking at alternatives since I first installed Ubuntu 8.04 (Linux) on my 2nd computer in 2008.

After spending some time over the last few years trying Gimp, Cinepaint and Rawtherapee, I have concluded that an unbiassed assessment is very difficult because of the steep learning curve involved. It is said that “You can’t teach an old dog new tricks” but I am no less enthusiastic about the potential of these applications and intend to follow their development further.

I have been very satisfied with the use of entirely free software to produce a stitched panorama.The above pano was produced using Rawtherapee (Raw converter), Hugin (Panorama stitcher) and Cinepaint (Image processor) running on Ubuntu (Operating System). The result is as good as any produced by ‘commercial’ software. The full resolution version (over 30 Megapixels) viewed at 100%, shows no defects.

Incidentally this website looks pretty good on the Midori browser running on my Raspberry Pi – but that’s another story.