Re: Optimizations, etc.

Am 11.11.06, 04:03 -0500 schrieb Bradley A. Hare:

> > They seems to be used for image manipulation. Other than 
> > app/expose_image.c, app/depth/gamma_expose.c is not just a wrapper.
> > Even though visual results of both appear the same to a user.
> > 
> > But try and see. The dialog use gamma_expose.c is in <Image> -> Image -> 
> > Colors -> Gamma-Expose .
> 
> 
> They are not invoked by view->expose.  They are initialized from the 
> tool dialog but never used.  I'll have to keep playing with gdb and 
> cscope, seems to be dead code.
> 
> Brad Hare

Brad,

Expose and Gamma-Expose is maybe irritating. <Image> -> View-> Expose is 
in a completely other rendering path than <Image> -> Image -> Colors -> 
Gamma-Expose.

<Image> -> View-> Expose
is a intermediate thing for displaying only. The gui is in 
app/expose_image.c and set only some variables to gdisplay. The 
rendering occures in app/depth/image_render.c 
render_image_tile_fault_expose() and render_image_tile_fault().

render_image_tile_fault_expose() call in the end cms_transform_buffer() to 
do the ICC stuff. The problem is, gamma code is applied to native bit 
depths as the ICC transformation. 
It would be nice to do the downgrading not in the 
render_image_gray/rgb_a//_u8/u16/... functions but some step earlier. To 
make things worse the scaling code and alpha handling is all separate.

The most clear way would be to handle float only and have only one 
function instead of a whle bunch each for a special kind of pixel layout 
and depth. But I am afraid this would slow down 8 and 16 bit paths.

Anyway it would be very desireable to improve this part of rendering.


For <Image> -> Image -> Colors -> Gamma-Expose  app/depth/gamma_expose.c 
the transfers are ignored to make the behaviour consistent with
desiplay rendering. Possibly the transferes can be reactivated to speed 
things up for u8/u16 bit depths.

regards
Kai-Uwe Behrmann
                                + development for color management 
                                + imaging / panoramas
                                + email: [email protected]
                                + http://www.behrmann.name


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