mirror of https://github.com/GNOME/gimp.git
27e8f452b3
When the result of compositing has an alpha value of 0, the corresponding color value is not mathematically defined. Currently, all out layer modes opt to preserve the destination's color value in this case. However, REPLACE mode is different enough to warrant a different behavior: Unlike the other layer modes, when the compositing opacity approaches 0 or 1, the output color value approaches the destination or source color values, respectively, regardless of the output alpha value. When the opacity doesn't approach 0 or 1, the output color value generally doesn't approach a limit as the output alpha value approaches 0, however, when both the destination and source alpha values are equal, the output color value is always a simple linear interpolation between the destination and source color values, according to the opacity. In other words, this means that it's reasonable to simply use the above linear interpolation for the output color value, whenever the output alpha value is 0. Since filters are commonly combined with the input using REPALCE mode with full opacity, this has the effect that filters may now modify the color values of fully-transparent pixels. This is generally desirable, IMO, especially for point filters. Indeed, painting with REPLACE mode (i.e., with tools that use gimp_paint_core_replace()) behaved excatly as described above, and had this property, before we switched gimp_paint_core_replace() to use the common compositing code; this created a discrepancy between painting and applying filters, which is now gone. A side effect of this change is that we can now turn gimp:replace into a NOP when the opacity is 100% and there's no mask, which avoids the compositing step when applying filters. We could previously only apply this optimization to PASS_THROUGH mode, which is a subclass of REPLACE mode. Note that the discussion above concerns the UNION composite mode, which is the only mode we currently use REPLACE in. We modify the rest of the composite modes to match the new behavior: CLIP_TO_BACKDROP always preserves the color values of the destionation, CLIP_TO_LAYER always preserves the color values of the source, and INTERSECTION always produces fully-zeroed pixels. |
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| etc | ||
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| libgimp | ||
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| libgimpconfig | ||
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| libgimpmodule | ||
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| HACKING | ||
| INSTALL.in | ||
| LICENSE | ||
| MAINTAINERS | ||
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| NEWS | ||
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README
------------------------------
GNU Image Manipulation Program
2.99 Development Branch
------------------------------
This is an unstable development release, an intermediate state on the
way to the next stable release: GIMP 3. GIMP 2.99 may or may not do what
you expect. Save your work early and often. If you want a stable
version, please use GIMP 2.10 instead.
If you think you found a bug in this version, please make sure that it
hasn't been reported earlier and that it is not just new stuff that is
still being worked on and obviously not quite finished yet.
If you want to hack on GIMP, please read the file HACKING. For
detailed installation instructions, see the file INSTALL.
1. Web Resources
================
GIMP's home page is at:
https://www.gimp.org/
Please be sure to visit this site for information, documentation,
tutorials, news, etc. All things GIMP-ish are available from there.
The automated plug-in registry is located at:
https://registry.gimp.org/
There you can get the latest versions of plug-ins, using a convenient
forms-based interface.
The latest version of GIMP can be found at:
https://www.gimp.org/downloads/
2. Mailing Lists
================
We have several mailing lists dedicated to GIMP user and development
discussion. There is more info at
https://www.gimp.org/mail_lists.html
Links to several archives of the mailing lists are included in that page.
Gimp-user-list is a mailing list dedicated to user problems, hints and
tips, discussion of cool effects, etc. Gimp-developer-list is oriented
to GIMP core and plug-in developers. Gimp-gui-list is for discussing
about GIMP interface to improve user experience. Most people will only
want to be subscribed to gimp-user-list. If you want to help develop
GIMP, the gimp-developer mailing list is a good starting point; if you
want to help with GUI design, the gimp-gui list is where you want to
subscribe.
3. IRC
======
And finally, for the real junkies, there is an IRC channel devoted to
GIMP. On GIMPNet (a private free software oriented network) there is
#gimp. Many of the developers hang out there. Some of the GIMPNet
servers are:
irc.gimp.org:6667
irc.us.gimp.org:6667
irc.eu.gimp.org:6667
4. Customizing
==============
The look of GIMP's interface can be customized like any other GTK+ app
by editing files in `${XDG_CONFIG_HOME}/gtk-3.0/` (settings.ini and
gtk.css in particular) or by using "themes" (ready-made customizations).
Additionally, GIMP reads `${XDG_CONFIG_HOME}/GIMP/2.99/gimp.css` so you
can have settings that only apply to GIMP.
Included is a set of keybindings similar to those in Adobe Photoshop.
You can find them in the ps-menurc file. To use them, copy this file
to `${XDG_CONFIG_HOME}/GIMP/2.99/menurc`. You can also manually change
the keybindings to any of your choice by editing:
`${XDG_CONFIG_HOME}/GIMP/2.99/menurc`.
Have fun,
Spencer Kimball
Peter Mattis
Federico Mena
Manish Singh
Sven Neumann
Michael Natterer
Dave Neary
Martin Nordholts