Re: [Lcms-user] What does cmsFLAGS_NOOPTIMIZE actually do?

[Elle S. <l.e...@gm...>]

On 7/28/12, Marti Maria <mar...@li...> wrote:

> An example of ill-formed  spaces are those that are operating in linear XYZ
> gamma space.
. . .
> For users, I would recommend to NEVER use
> linear XYZ spaces. They are good for nothing, nor for storage, nor for image
> processing.

Is the only source of the ill-formedness of  linear gamma XYZ profiles
the fact that at 8-bits there simply aren't enough levels to store or
process the shadow information when using a linear gamma profile? But
what if you store and process at 16-bits or higher?

> In a 17 nodes grid, most image dynamic
> range will fall in 5 or 6 nodes. And this is the reason you got
> posterization in shadows: most of dark tones falls in just 1-2 nodes and
> linear interpolation cannot deal with the non-linear nature of the transform
> linear-gamma 2.2.
>

> Placing a NOOPTIMIZE in all transforms
> would prevent problems, but at big performance penalty that is hard to
> explain just to fix this specific case. It is like you have a Ferrari but
> you go always at 25Mph just because once upon a time you faced a winding
> road.

"25Mph in a Ferrari" sounds like the editing application would just be
crawling. How big of a performance hit is there when doing 16-bit to
16-bit color conversion without optimizing? In other words, how is it
manifested (disk IO? cpu usage? really slow drawing to the screen upon
making edits to the image?, etc) and what triggers the performance hit
in such a way as to be apparent to the end user (the display to
screen? doing a whole lot of conversions all in a row at the command
line? having many layers in the image?, etc)?