Re: [Gimp-user] Time to fork BABL and GEGL

[Elle Stone <ellestone ninedegreesbelow com>]

On 11/14/2014 12:01 PM, Alexandre Prokoudine wrote:
> Øyvind, having a last say in every dispute typically makes one look
> like a jerk. I am a living proof of that.

My apologies to Simon and Alex for continuing this discussion, and yes I 
guess I'll be "the jerk with the last word" unless Pippin wants to respond.


On 11/14/2014 11:47 AM, Øyvind Kolås wrote:
> I was saying that one can construct a scene, that photographed with
> your camera, would yield the type of desired black and white - when
> done in sRGB or some other non sensor RGB space. So yes; for the
> purposes of black and white conversion and using a single channel for
> it - I still call that image a corner case.

I have no idea what Pippin means by "one can construct a scene, that 
photographed with your camera, would yield the type of desired black and 
white - when done in sRGB or some other non sensor RGB space." If 
someone can help me out here, I'd be grateful.

In the meantime, as a note to Pippin, it sort of sounds like you expect 
photographers to change their workflow and their way of taking pictures 
to suit your unbounded sRGB architecture.

The yellow flower in question is long dead. So if there ever was a 
possibility of reshooting the scene in a way that would make the blue 
channel information available for use in the sRGB color space, that 
possibility is gone.

The flower's blue channel has interesting detail that is missing in the 
red and green channels. I used the blue channel as a blending layer over 
a straight luminance-based conversion to black and white. Here's a link 
to my envisioned black and white conversion:

http://ninedegreesbelow.com/gimpgit/gimp-srgb/channel-mix-blend/flower-blue-channel-over-luminance.jpg

This article shows what happened when I tried to do the envisioned 
conversion to black and white in the unbounded sRGB color space:

Channel blending when converting to black and white can fail completely 
in the unbounded sRGB color space 
(http://ninedegreesbelow.com/photography/unbounded-srgb-channel-blend-convert-black-white.html)

Frankly I am appalled that Pippin says my yellow flower image represents 
a "corner case". How many of *your* images will he dismiss as corner cases?

Elle