Monday, October 21, 2013

LensFun


RAW Proc'd with Photivo and LensFun

I was very recently on an overnight trip (again, for another "waste of time" medical appointment - oh well...), but on the plus side, also had visits with two old friends, as well as my daughter and grandsons. I took a lot of photos, (some here) but couldn't really think of much to write about them, except for a processing "treatment" I kind of stumbled upon for one of them in particular.

LensFun is software that is bundled with a handful of open-source Photography packages, with it's main intent being to accommodate and make appropriate corrections to lens and camera imperfections - an idea which is getting very common now in the mainstream, with lots of camera makers actually incorporating something similar right in the camera, so that corrections are made at the time of shooting. I've never paid any attention to it personally, as I have a strong preference toward accepting imperfections - in people as well as cameras. But LensFun, at least in how it's incorporated in Photivo (my favourite Photo Editor by far) offers far more than simply tweaking your camera and lens combination to perfection (again, that doesn't interest me in the slightest)... it's also great for creativity, and as it's very name implies, lots of fun too!

In the photo above, I got poking about in Photivo, besides giving it my usual treatment, and discovered the LensFun module. What I wanted to do was to stretch this picture, and also kind of "rotate" the tree stump away from centre -

JPEG Straight From Camera, no Treatment At All

What I'd discovered is that not only does LensFun allow you to "de-fish" a fish-eye lens, but you can also apply a fish-eye effect to a normal lens, and in so doing, keeping all of the picture's content intact (as opposed to simply stretching and cropping)... very cool! This was a case where I felt a fish-eye effect would work well, because it's little more than an abstraction of a pattern (as opposed to a bit of scenery, or a portrait of something). But on it's own, the picture is forgettable, because the composition wasn't so great - I would've done much better by  crouching down closer to the circle of leaves, with a wider lens, and made sure the tree trunk was intersecting a line off-centre, to make a much stronger composition. LensFun allowed me to easily (even I could figure it out) make all of this happen right on my computer! The processed picture gives a much stronger impression that I was crouching down, even though I wasn't, the fish-eye effect makes the view look like I used a much wider lens, and the neatest thing of all was that I was able to "turn" (as opposed to "rotate") the whole scene, as if the circle of leaves were on a huge horizontal platter, to locate the tree trunk where I wanted it. When all was done, I was forced to "crop" the picture vertically, simply because of the geometry of what I was doing, but I'm still pleased - it's still a very attractive 2:1 Crop that did not leave anything out that was essential. Most of all, I love how the effect flattens the photo in the "Z-Axis", giving a much stronger feeling of being able to walk into the picture.

Check out LensFun if you've never tried anything like this before. If you have Photoshop, I'm sure there must be something similar in there, but if not, give Photivo a try - it's the most comprehensive 16-bit colour Photo Processing package that Open-Source has to offer, and it has versions available for Windoze and Mac too!

1 comment:

  1. I really like Photivo and it integrates LenFun. But Lensfun has a "lens database". In my version of Photivo that is not used. Moreover I could not find a way of having automatic distortion correction - that is distortion correction tied to the used focal length. I'm not even asking for lens detection.
    Yes I appreciate accepting imperfection, but in my case I am using an Olympus micro four thirds kit zoom lens with big amount of distortion at the (otherwise optically great) wider angle. It seems that software correction was integrated into the lens design and the camera and Olympus software does not even give you an option to disable it - so in this case it is more than a simple little imperfection. If I wanted a fisheye I'd have bought one! But I don't want my kit lens to behave like a fisheye, even though, I am exagerating things a bit, it is true.
    The Photivo manual vaguely mentions something about the distortion correction being tied to lens parameters but I was not able to make that work in any way.
    I am not against manual editing, but in the case where I have a bunch of photos that I'd like to batch process, this will force me to manually process them, and in some cases photos lack visual references that allows manual correction, so that is not practical at all.

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