[Digikam-users] A modern auto-fix?
nvlplx at yahoo.fr
Sat May 17 15:36:47 BST 2014
You're right about the behavior of camera within the light. But you're wrong
for ohter items.
Firtly, DK local contrast tool doesn't remain mid and hight tones, their local
contrast is modified too, as far as I've experienced (but I admit that I've
tried differents adjustments and I use 2 parallel lines of adjustments)
Secondly, the page suggested by Gilles is interesting, but the expression
"tone mapping" is an abuse. Tone mapping is strictly the process to
transform an HDR picture in a LDR one. The doc linked by Gilles is about an
emulation of the rendering of some tone mapping algorythms, but not a
real tone mapping one.
Nevertheless, I really love the local contrast dK tool, which is a faboulus
tool. Thank you Gilles ;-)
Le samedi 17 mai 2014, 09:56:02 Paul Verizzo a écrit :
Well, just as I start to think it's a matter of semantics, now I'm really
confused. I agree that the human eye has no problem, let's
say, seeing good detail in shadows. But the camera can't capture
that dynamic range, so it shuts the shadows down in favor of mid and
high tones. But the data is still there in the shadows, just like with
slide film. So, yes, the dK Local Contrast tool does certainly look
at the (lack of) shadow contrast and, um, locally, increases it in the
low dynamic range areas, and leaves the mid and high tones alone.
Not that dK needs to mimic Photoslop terminology, but they are the
big boys out there, and Local Contrast means what we used to call in
film developing characteristics, "Micro contrast." (A chemical Unsharp
Mask using border effects!) Best as I can see, anyway. As to
what you say, Paulux, "The tone mapping process......", I guess it's
the old "If it walks like a duck....." thing. Even the page Giles
suggested, which I had found earlier,
http://zynaddsubfx.sourceforge.net/other/tonemapping/ calls the
function "Tone Mapping" and says that "Local Contrast" is a function
within it. Regardless, I'm very glad it's there. As always, so
grateful to the dK team! Paul
On 5/17/2014 8:57 AM, Paulux wrote:
"Local contrast" is adjust and optimize contrast inside local zones of a
picture in order to approach human eyes perception. That's exactly
what the local contrast tool in DK does.
The tone mapping process consists in matching repartition of colors
from a 32 bits picture in a 8 bits one (for instance). That's totally
different, even if some tone mapping algorythms have deep influence
of local contrast.
It's Windows, Carl, and the processor is a P.O.S. dual core that was
meant for a laptop, but it's in my desktop. My comment on speed
was relative to the Canon program, and even the Windows Phone
one. But it's fine, it is what it is, I'm just grateful for the discovery.
On the topic, and further internet research, that the use of "Local
Contrast" in dK might be a bit of a misnomer. As mentioned, in PS,
the plug-in does work with local contrast, not overall tones. In fact,
I'm seeing "Tone mapping" being used for what dK calls "Local
Contrast." Seems to be more accurate, grammatically.
On 5/17/2014 8:22 AM, Carl McGrath wrote:
Paul I scanned quickly for what OS you are running but did not find
it; I run openSUSE 13.1 dK 4.0.0 arrived a few days ago, with all the
fixes Gilles reported that enable multicore. Local Contrast
and Sharpness tools now blazing fast(by comparison)
On 05/17/2014 07:58 AM, Paul Verizzo wrote:
Wow, that's it! I finally had time to locate some of the lousy
original photos I had successfully improved with a couple of other
programs, including, oddly, that Nokia (Windows Phone) Fix.
Putzed with dK Local Contrast, works beautifully. Just what I was
after. I tried to find information and help in the dK PDF, but
could not. Searching online, "local contrast" brings up a lot of
Photoslop entries, but they necessitate using layers and unsharp
mask. So much for the expensive program. If I add "digikam" to the
search, I just keep getting repeats from a blog posting.
I'd like to learn how to manually control adjustments for best results.
Any further help to be found? Oh, yes. Kind of slow, but if I
factor in the need to open another program, rename, shuffle files,
Local Contrast is another dK winner! Thanks, Giles (and
all others!) Paul
On 5/10/2014 12:11 PM, Gilles Caulier wrote:
digiKam has LocalContrast tool which make the same correction to
image. In fact it emulate pseudo HDR rendering.
2014-05-10 18:07 GMT+02:00 Paul Verizzo <paulv at paulv.net>:
Background: I've been in digital photography since 2000, decades of film
before and since. I'm certainly familiar with the use of curves to correct
bad photos. But so tedious, and if the photos are snapshots, hard to
justify the time. It appears to me, although I can't prove it, that digital
cameras, discrete or within phones, seem to be doing a much better job
automatically adjusting curves than my old Minolta A2, for instance.
I recently became aware of a new free Canon program, My Image Garden,
has a much improved Auto-fix than its forerunner. As an example, a backlit
photo processed in MIG will bring up only the shadows while leaving the
normal and highlights alone. It allegedly uses a zone by zone analysis. It
is a terrible program in every other regard, clunky interface, bloated, etc.
But I used it for some recent pics to advantage.
Some of those pictures were originally on my Windows Phone 8, which I had
copied to the HD. Before I deleted them from the phone, I poked around
the options at that point. I found an auto-fix, pushed the "button," and my
jaw dropped. Literally. A very dark, underexposed shot made perfect! This
feature is within the Nokia programs! It is so good, I can see myself
transferring photos from other sources into the phone for correction! And
it's fast, even so.
I went back through the digiKam manual and looked on screen, and I see
old standbys there, but nothing like what I've experienced with the above.
Oh, upon lots of research, I found a 2007 $40 program called Photoright
upon test, seems to be doing similar zone adjustments.
Bottom lines: Are my observations valid? Do you think DK might get
something like this? Oh, yes, all Windows although MIG is available for
Thanks, Paul Verizzo
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