Forum: Photography


Subject: LAB Decomposed B&W Experiment

ASalina opened this issue on May 15, 2002 ยท 12 posts


ASalina posted Wed, 15 May 2002 at 12:21 PM

Attached Link: http://www.cliffshade.com/dpfwiw/b&w.htm

I was just reading a little bit about rendering a B&W image from a color original using Lab colorspace (see the link). As an experiment I started messing with the "b" channel rather than the recommended "L" channel, and came up with the image above. Color original to follow.

Looks almost like an IR image, except that the sky is very
dark.


ASalina posted Wed, 15 May 2002 at 12:22 PM

Color original.

ASalina posted Wed, 15 May 2002 at 12:28 PM

Oops.. Forgot to mention: Notice how the forground leaves
are made to stand out, and the reflections on the water's
surface are changed/reduced. The only modifications I'd
made to the "b" channel were to adjust brightness and
contrast.

I think this has interesting possibilities in B&W conversion
of color images. Needs more exploration.


bevchiron posted Wed, 15 May 2002 at 1:56 PM

Nice effect & well worth some experimenting, the effect on the reflection is really striking. Thanks for the link ; )

elusive.chaos

"You need chaos in your soul to give birth to a dancing star...." (Nietzsche)


eartho posted Wed, 15 May 2002 at 2:24 PM

Attached Link: http://www.designer.com/focus/articles/lab/lab_print.htm

ummm, i cant imagine how you got the b&w version from messing with the b channel... I'm confused. Normally the b channel is used to affect the blue and yellow of an image. The L channel is for lightness... this is where the grey of an image resides. Somehow you've managed to invert yer whites! I must say that, for the most part, i do like the results... The leaves in the foreground are especially nice. Would you post what your Lab image looked like before you made the final b&W conversion? I've tried to reproduce what you've done here, but with no luck! I did make ya a nice Lab sepia tho...

Michelle A. posted Wed, 15 May 2002 at 2:54 PM

That b&w has a surreal quality that I really like....

I am, therefore I create.......
--- michelleamarante.com


SueO posted Wed, 15 May 2002 at 4:46 PM

Very, very interesting. Thanks for sharing this.


ASalina posted Thu, 16 May 2002 at 12:15 AM

Bev, my software (GIMP) has very limited Lab colorspace
capabilities. In fact the only capability it has is
to "decompose" an image into L, a, and b channels. It
does so by creating three greyscale images, one for
each channel. (It can also do this for RGB, and CMYK)
I guess I should've mentioned that. I have no experience
with Photoshop (won't run on Linux), so I pressumed the
same thing was done in PS. I guess what this means, in
effect, is that I was working with a greyscale image
composed of just the yellow and blue values from the color
original. Hmmm... I just started tinkering with it, so I'll
have to do some more reading on it.


ASalina posted Thu, 16 May 2002 at 12:19 AM

Boy, I'm tired.... My response above should be addressed to eartho, not Bev... And yes, that is a very nice sepia version.


bevchiron posted Thu, 16 May 2002 at 12:26 AM

LOL! I still learnt something ; )

elusive.chaos

"You need chaos in your soul to give birth to a dancing star...." (Nietzsche)


CrystalWizard posted Thu, 16 May 2002 at 12:32 AM

Gimp is a very cool program however linux should be able to run a windows emulator which would allow you to run windows apps.


eartho posted Thu, 16 May 2002 at 1:15 AM

aaahaa! now it all makes sense. Hopefully i'll be able to elaborate a bit more tomorrow.... sleep calls.