This page describes some investigations that I have made over some years. I'm gradually
collecting themhere, but I'm not done yet, and I may never be. Consider this a historical
document. The last update was in July 2016.
I've used Viewer 2 before,
and didn't like it. But they've changed the user interface now and made it much
worse. Here's the startup screen of Viewers 2 and 3:
This is after I found out how to put the menu bar at the top of the Viewer 3 display, but I
still haven't found out how to remove old images.. You don't “open” the files: you “import” entire “folders”:
It tells me that it doesn't copy them, and indeed I can't find anywhere where it might have
copied them, but the import takes a very long time and can't be interrupted. This display
shows both the original raw images and
the JPEGs converted by DxO. Still, this is
just an experiment. How do I process them? “File” maybe? The only likely selection there
is “Open file destination folder”, and it is greyed out:
The correct answer is “Photos”/“Open Raw Development Window”. You can also get there via
the item “Menu” at top right. And then there are selections with the same options as Viewer
2 has, but with different tab names. “RAW 2” is the interesting one:
So Viewer does claim to know about the distortion characteristics of the lens, but not the
CA characteristics. That puts it at a disadvantage to DxO for combinations that DxO
supports.
But those aren't the photos I wanted to process; they just got added because they were
there. The ones with the 18-180 mm lens were taken yesterday. Here's one of them processed
by DxO, Viewer and ufraw respectively. Run the cursor over each image to see a comparison with the next one. Click
on the images up to three times to get successively larger views. This page is probably
best viewed at the second image size.
The comparison is complicated because Viewer crops the image differently from DxO. The
native raw images of the Olympus E-30 are 4096×3084 pixels in size, but most software trims it to the
maximum JPEG size that the camera delivers,
4032×3024. ufraw doesn't, which is why I have included it in this comparison. And
Viewer does not centre the cropped image: it cuts off more at the top and less at the
bottom. Run the cursor over the second and third image to see this: the second image
(Viewer without the cursor, ufraw with the cursor) shows that more appears at the top
than at the bottom of the image. The third image (ufraw without the cursor, DxO with
the cursor) shows that it cuts off equal amounts from the top and the bottom.
Out of the box, the Olympus output is brighter and appears sharper. I'm sure that DxO can
be made to give the same appearance, but it's not the standard. But the corrections I'm
looking for, for distortion and chromatic aberration, don't seem to have been done at all.
Chromatic aberration is another matter: it seems that DxO does do some reduction, while
Viewer doesn't. Here details from top left of each image. There's clear CA on the pole and
the edge of the house, but DxO seems to handle it best:
I thought that the lack of distortion correction may be specific to this particular lens
(Zuiko 18-180 mm), so I tried again with a different image, this time taken with other
lenses: Zuiko Digital ED 9-18mm F4.0-5.6 and Zuiko Digital ED
70-300mm F4.0-5.6. Again, Viewer claims to be able to correct distortion, but not
chromatic aberration. Here the results:
It's interesting that the results for the second image look better from DxO than from
Viewer. But it seems that Viewer does not perform any distortion correction at all. What
use is it?
February 2014: DxO and Viewer with the M.Zuiko 14-150
OK, we know that the 14-150, like the ZUIKO DIGITAL
18-180mm F3.5-6.3, doesn't have the best image quality. But as I've discovered with
that lens, it's convenient. And the µFT lens has the advantage of being wider, and
potentially focusing faster on the Olympus OM-D E-M1. So I did
some comparisons with images from Jashank's lens, in the process also comparing the
corrections applied by DxO Optics “Pro” and Olympus
“Viewer” 3. The following images are the same photo, first without correction, then
corrected with DxO, then corrected with “Viewer” Run the cursor over
the images to compare with the next:
The second image, taken at 14 mm focal length, shows an amazing amount of barrel distortion,
and both that one and the last one show considerable vignetting. The first image, taken
over two years ago, doesn't show the vignetting. In each case, DxO removes both vignetting
and nearly all the distortion. “Viewer” doesn't do nearly as well in either function. It's
a pity that DxO support for µFT is so poor.
October 2015: Viewer, DxO and RawTherapee
Raw conversion revisited
It's been over 4 years since
I last compared raw image converters. I've learnt a lot since then, and on the whole I'm
happy with DxO Optics
“Pro”. But 3 days
ago I had reason to examine things, and it took a while.
I have now read the documentation for RawTherapee. The first discovery was that it doesn't use lensfun, but instead profiles from
Adobe Camera Raw, and you have to install them manually. In addition, the Adobe page
states that only preliminary support is available for the Olympus OM-D E-M1, and newer
models aren't mentioned at all. In general, the list looks about 2 years out of date. I
didn't bother with this step. I was, however, able to use RawTherapee to convert images.
I now have output from DxO, both with my standard settings and without any correction at
all, and also UFRaw, RawTherappe and
Olympus
Viewer 3, and unlike 4 years ago, I can now compare the output directly.
But how do you do a good comparison? I can compare each with its neighbour, or each with
the uncorrected version, but that doesn't necessarily help. I've decided to go each with
the uncorrected version first. Here goes. In sequence, they're converted by Viewer 3, DxO,
UFRaw and RawTherapee. Run the cursor over an image to compare it with the uncorrected
version, and click to enlarge.
It's interesting to see how differently Olympus and DxO handle distortion, and it's also
difficult to compare. Here's an alternation between the two, Viewer on the left and DxO on
the right:
The difference in field of view is particularly noticeable.
UFRaw uses lensfun, but the results aren't very convincing (despite the pincushion
framing of the resultant image). And RawTherapee manages to do some distortion correction
although it says it can't. Here RawTherapee on the left, DxO on the right:
Surprise, surprise: Olympus doesn't
correct chromatic aberration
correctly! Neither does UFRaw, though it's still better than Olympus. RawTherapee does.
Here an excessively enlarged view of the up pipe:
I'm particularly impressed by the results from RawTherapee. Yes, they're not as good as
from DxO, but without lens profiles, that's not surprising. And I really can't understand
why Olympus can't do better. Looking at the controls, it seems that it doesn't do automatic
aberration correction:
Why not? I'm sure it happens in-camera. This makes Viewer even less desirable than I had
thought it to be.
Apart from the chromatic aberration, most of the converters seem to misinterpret the shape
of the tank: it looks like this (two more tanks of the same kind):
But there's a step in all the conversions except for RawTherapee. It's most obvious with
Viewer, but it's there with UFRaw and even DxO.
The most interesting conclusion here is that RawTherapee is definitely worth a look. The
results weren't as good as with DxO, but this was out of the box, and I really don't
understand how it managed any lens correction at all, since I didn't download the modules.
