So I wrote a proper proposal. It differs slightly from my
implementation (EGL_DEFAULT_MESA is added), so I'll have to revise
that. Could someone point me in the correct direction to get enums
allocated from Khronos?
Name
MESA_image_sRGB
Name Strings
EGL_MESA_image_sRGB
Contact
John Kåre Alsaker <john.kare.alsa...@gmail.com>
Status
Proposal
Version
Version 1, October 9, 2012
Number
EGL Extension #not assigned
Dependencies
EGL 1.2 or later is required.
EGL_KHR_image_base is required.
This extension is written against the wording of the EGL 1.2
specification.
Overview
This extension provides a way for applications to allocate sRGB
or linear gamma views for EGLImage sources. This means that
sampling from the resulting EGLImage should convert from sRGB's
gamma into linear gamma.
IP Status
Open-source; freely implementable.
New Tokens
Accepted in the <attrib_list> parameter of eglCreateImageKHR:
EGL_GAMMA_MESA #not assigned
Accepted as values for the EGL_GAMMA_MESA attribute:
EGL_DEFAULT_MESA #not assigned
EGL_LINEAR_MESA #not assigned
EGL_sRGB_MESA #not assigned
Additions to the EGL 1.2 Specification:
Add to section 2.5.1 "EGLImage Specification" (as defined by the
EGL_KHR_image_base specification), in the description of
eglCreateImageKHR:
"Attributes names accepted in <attrib_list> are shown in Table bbb
+----------------+-------------------------+------------------+
| Attribute | Description | Default Value |
+----------------+-------------------------+------------------+
| EGL_GAMMA_MESA | Specifies the gamma | EGL_DEFAULT_MESA |
| | view of the | |
| | EGLImage created. | |
+----------------+-------------------------+------------------+
Table bbb. Legal attributes for eglCreateImageKHR
<attrib_list> parameter
...
If the value of attribute EGL_GAMMA_MESA is EGL_DEFAULT_MESA (the
default), then the gamma view of the resulting EGLImage will be
the same as the EGLImage source.
If the value of attribute EGL_GAMMA_MESA is EGL_LINEAR_MESA,
then the gamma view of the resulting EGLImage will be linear
and no gamma conversions will be done when sampling the image
in client APIs.
If the value of attribute EGL_GAMMA_MESA is EGL_sRGB_MESA,
then the gamma view of the resulting EGLImage will be an sRGB
view and the red, green and blue color components will be
converted from sRGB gamma to linear gamma when sampling the image
in client APIs. This conversion should ideally take place before
any filtering, but that is not required. The conversion from an
sRGB gamma component, cs, to a linear gamma component, cl, is as
follows.
{ cs / 12.92, cs <= 0.04045
cl = {
{ ((cs + 0.055)/1.055)^2.4, cs > 0.04045
Assume cs is the sRGB gamma component in the range [0,1]."
Add to the list of error conditions for eglCreateImageKHR:
"* If the value specified in <attrib_list> for EGL_GAMMA_MESA
is not EGL_DEFAULT_MESA, and the implementation does not
support creating the specified gamma view, the error
EGL_BAD_ACCESS is generated.
* If the value specified in <attrib_list> for EGL_GAMMA_MESA
is EGL_sRGB_MESA, and the EGLImage source does not have
red, green and blue color components, the error
EGL_BAD_ACCESS is generated."
Issues
1) Should creating multiple EGLImages from the same source
with a different gamma view be allowed?
RESOLVED: Yes.
This is so applications can easily switch between using
an sRGB and a linear gamma view for a single EGLImage
source.
Revision History
Version 1, October 9, 2012
Initial draft (John Kåre Alsaker)
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/mesa-dev
