Re: Fisheye Hemi Serial Mac
Sofie Kovalcheck
Fisheye-Hemi is superior to these, though, as instead of using a standard remapping to a rectilinear projection that softens the edges and requires an aggressive crop it uses a custom mapping algorithm that preserves much more of the original image and sharpness and still straightens out lines.
This blog post is interesting, the guy fed an image of a grid pattern through the Fisheye-Hemi plugin and then created a warp transform in Photoshop that approximately matches the deformation on the grid. Pretty clever.
I use Gimp and theMathMapplugin, together with a fewscripts of mineto convert the fisheye image into whatever projection better fits the subject: either rectilinear, stereographic, or Mercator. Mercator is my favorite: it's a kind of panoramic cylindrical projection that looks quite similar to the Fisheye-Hemi projection and is free of local distortions (mathematically speaking, it's a conformal mapping of the sphere).
More recently, I've written a script to provide theLambert conformal conic projection. This one is useful for pictures taken with the camera pointing slightly upwards or downwards, and when you want verticals to be rendered straight, yet preserving their convergence and thus the the upward/downward perspective. This projection, like Mercator, is free of local distortions (it's conformal). Actually, the Mercator projection is just a special case of Lambert's conformal conic.
Most fisheye lenses have lens profiles for Lightroom that can defish. I use the Samyang 7.5mm fisheye for micro four-thirds, and the lens profile not only lens corrects, but can also remap to equal area, equidistant, rectilinear, and stereographic. If you can't find one specific to your lens, using a similar fisheye profile can also work.
Footnote: I got my profiles from the first post in this dpreview thread. Installing was just moving the profile files into the appropriate profiles folder and restarting Lightroom. I think. Been a while.
The Image geometry correction software now allows for fine tuning of adjustment parameters whilst still keeping the three basic adjustment options for correcting the distortions of fisheye type lenses.
To get true verticals after correction, you do need to have taken the shot with the camera level. There are many adjustments available in version 2, but a bit of forethought will often make corrections easier.
Keith has written a book that looks at the many ways that tilt/shift lenses can benefit your photography from a technical and creative point of view. If not in the UK check for import issues and maybe try an on-line bookshop. Keith has no connection with sales of the book.
We've a whole section of the site devoted to Digital Black and White photography and printing. It covers all of Keith's specialist articles and reviews. Other sections include Colour management and Keith's camera hacks - there are over 1200 articles/reviews here...
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Nice article. I have independently ended up mostly using the Photoshop Warp Filter after trying some of the other possibilities described by authors on the web, including in particular PtGui and PT Lens. PtGui is a Panorama program which can be used to try various projections on single fisheye images. PtLens is a general lens distortion program which has defishing functionality. I have found both to give useful results, but concluded that the advantage of the warp filter is that it allows me to correct only for fisheye distortions that are visually distracting, thus minimising lost resolution.
Rob,
Very interesting video and advice, thanks for taking the time!
I have just returned from a photography tour of Myanmar and did not have a rectilinear wide angle lens which I was regretting, but now I can convert my landscape and architecture shots and maintain the fov, very happy. Its not perfect but who need perfect, I am much happier with the appearance of the one test shot I have just finished with and very grateful for the insights in to FH and the work-around for the horizontal horizon ?
Off to buy the full version of Fisheye-Hemi right now!
Thanks again
Simon
Thanks for the contents, pretty good.
Onde question, I have a sunex fisheye lens, and I get that dark circle around the picture. I am using a Nikon d7100. Any clue? Thanks and keep up with the good jog.
Take care.
Yes I know but it was ambiguous where it was tried, so wanted to highlight that the plug-in was also compatible with affinity and confirmed as working. It does visibly affect a fisheye image when presets or manual adjustments are applied via hemi but maybe not enough for the OP.
Fisheye Hemi is a paid for plugin and standalone app and has clear help pages for installation and set up, it's nice to see plugins start to cater for Affinity Photo in their installations. This is a followup page for completing the install to Affinity Photo: -us/articles/360022975493
Most fisheye correction tools works by mapping 180-degree fisheye view into a rectilinear view. Essentially, this straightens all of the lines of the image and gives you a field of view very similar to that of an ultra-wide angle lens. This can be great for certain applications (architecture, landscape) but usually results in heavy perspective distortion of people or objects. It also results in the loss of a good amount of the original image data (mostly on the edges). Below is an example of what transforming a fisheye image to a rectilinear image would look like.
The Fisheye-Hemi is compatible with most camera and fisheye lens combinations (a full list can be found here). Circular fisheyes are corrected with Hemi 1, full frame (180-degree view) fisheyes with Hemi 2, and cropped fisheyes with Hemi 3. Unfortunately I was not able to get any images from a circular fisheye for the review, but I was able to get a shot from a cropped fisheye:
The distortion and amount of correction is not as great in this case since you are using a fisheye designed for a full-frame sensor on a slightly cropped body. Even though there is only a slight amount of correction with this filter, you can clearly see it makes a difference on the people.
So, if you want a wide FOV, we all know the drill: either you choose fisheye, and put up with excessive barrel distortion that is fun at first, and tiring after, or you get the widest rectilinear lens, and either put up with excessive shearing and stretching at the edges, or the fact that its not really that wide at all.
The top and bottom one correspond to the way pretty much all photographic lenses you can buy work, the top being a typical full frame fisheye, and the bottom is its rectilinear version (which is actually wider than most any real rectilinear lens would give you, but good for comparison).
Now, the fisheye is equisolid, which is actually the worst kind of fisheye projection from the perspective of deformation at the edges. Stereographic projection (shot #2) is superior visually to what most any photgraphic fisheye lens does.
But can we do better? I think yes: notice how mathematically, rectilinear and stereographic are closely related, both taking the tan() of the scaled angle, at factors 1 and 2 respectively. For some reason, when people talk about projections, you only ever see these formulas with 1 and 2, but what happens if you use other values? That's right, you get a projection that is a blend between rectilinear and stereographic, giving a good compromise that minimizes the distortions of either approach.
I dubbed this "semi-stereographic", as in the third picture. Notice how in this picture the barrel distortion has been reduced compared to the 1st and second picture, and how the extreme stretching of the 4th picture is also not present. I personally think this is the ideal wide angle perspective. Note that I chose factor 1.4, but you could choose 1.5, or 1.3 or whatever, if you prefer a different balance between the 2 kinds of distortion.
Note: you can simulate "semi-stereographic" in hugin by lying about your lens, i.e. when I load in a fisheye photo, rather than specifying its fisheye and 16mm (as is my lens), I say it is 10mm instead, and on the stereographic re-projection I specify a wider angle than normal as well. This will give you a similar effect as the tan(phi/1.4) above.
I have used the first one, the Fisheye-Hemi software which partially corrects the barrel distortion in fisheye lenses. It straightens vertical lines, lets horizontal ones remain curved and makes people's faces look natural. I use it a lot and love it. It is a digital version of the Noblex swing lens camera.
What both those links do is what I'd call a panoramic projection, i.e. it keeps fisheye horizontally (equidistant in this case), but rectilinear vertically. This does indeed look more pleasant than either just fisheye or just rectilinear, because it makes use of the fact that horizontal you have more angle to deal with than vertical. It gets rid of the typical "banana shaped people" on the edges of fisheye.
But in terms of minimizing distortion, it is still inferior to "semi-stereographic", because it makes for very straight lines vertically, but still very round ones horizontally (as can be seen on some example images on the first link). semi-stereographic gives you mild roundness in both directions.
As for humans, yes, this reduces the "banana" effect, but unlike the hemi software it doesn't pull them straight entirely. The disadvantage of the hemi software however is that it can stretch things near the top or the bottom of the image quite a bit, but since faces are often near the middle, I guess you don't notice that much.
Now, I have to admit, fisheye hemi is indeed better for people, still. But you can also see how semi-stereographic is the more neutral of the 3: look at the pillar and the ceiling right behind the guys head. In fisheye, both are very round. In fisheye hemi, one is very round, the other very straight. In semi-stereographic, they both are mildly round.