[LRflex] OT: Pixel Peeping in the Extreme... (not for Dr. Ted.)

From: David Young <dsy@xxxxxxxxxxxxxxx>
To: LRflex <leicareflex@xxxxxxxxxxxxx>
Date: Wed, 26 Feb 2014 18:02:11 -0800
Most of you will know about a trend, in recent years, for camera & lens makers
to correct for distortion in a lens, in firmware, in the camera, rather than in
the optics.  This often allows superb results, in a lighter, lower cost lens.

The trend has been most evident in the MicroFourThirds lenses, by Pansonic,
Leica and Olympus, though I understand these firms are not alone.

The new, very nice 12~40/f2.8 constant aperture zoom from Oly, is no exception.

However, things go a bit awry, when you develop your image from a raw file. The
in-camera jpeg conversion does not work!

Some raw developers may have profiles for this sort of thing, but Silkypix 
(which I love for it's colour rendition) and RawTherapee (which I love for it's
array of features and simplicity of use) do not.

So, I've been doing some playing... and found some fascinating results!

I've recently been in touch with Tom Niemann, creator of the distortion
correction program, PTLens.  I provided him with "target" photos, and he made
the correction files, which are now included in all versions of PTLens.

So  the question was... which is better?  The in-camera correction of JPEG 
images, or the use of PTLens, or a similar after-the-fact program.

I also wanted to compare Olympus Viewer 3 (the software Oly gives you, for use
with their cameras), and see how it did when applying the corrections when 
developing the raw data..

If you're still reading, I'm pretty sure you'll find this interesting.

Please look at this page:

http://www.furnfeather.net/Temps/12~40_Zuiko_TestImages.html

and continue reading.

Take a look at the upper left corner of the very first image.  Note where the
left edge of the leftmost vertical window is, in relation to the edge of the
image.  Then count the number of horizontal window shades there are on the left
side of image (I find it easiest to count at the intersections of the vertical
supports, as it makes it easier to estimate fractions).  I get 8 and, what, a
third?

Now look at the second image - a Jpeg of the same shot (both raw & jpeg were
saved) as it came out of the camera.  Count the horizontal window shades ... I
get 7 and about one third.  Also, look at where the left edge, of the left 
window is, in relation to the edge of the image, and compare it to the first
photo.

The third shot is Developed from the raw file in Olympus Viewer 3, and gives an
almost identical result to the second image.

Now it gets interesting...

Look at the fourth image. It was developed in RawTherapee and is virtually 
identical to the top image, developed in SilkyPix. At least, for sizing.

The fifth image is the fourth one, but with it's distortion corrected in
PTLens.  Compare where the left side of the leftmost window is, compared to
where it is in the second and third images. There is wall showing, that does
not show in the Olympus corrected versions!

Now count the horizontal window shades... I get 8, as compared to just 7 & a
bit, in the OOC jpeg, or the Jpeg developed by Olympus Viewer 3.

So, while any distortion correction does some cropping as it tweaks things 
about, it is obvious that PTLens does a much better job of making the
corrections while keeping as much of your image as possible.

At a one-time fee of $25, for a life time subscription and the ability to use
it on all your computers, I'd say it's worth the extra time & effort to use
PTLens.

Whether other programs which do this sort of correction are any better, I do
not know.  If anybody has one and wants to try it,  I'll be happy to send you a
dng of my original test shot, via DropBox.

Just thought that some of you might find it interesting.

Bests,
David.

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[LRflex] OT: Pixel Peeping in the Extreme... (not for Dr. Ted.)

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