Name EXT_gl_colorspace_scrgb_linear Name Strings EGL_EXT_gl_colorspace_scrgb_linear Contributors Courtney Goeltzenleuchter Lauri Hyvarinen Weiwan Liu Arun Swain Contact Weiwan Liu (weiwliu 'at' nvidia.com) IP Status No known IP claims. Status Complete Version Version 4 - August 25, 2017 Number EGL Extension #108 Dependencies This extension is written against the wording of the EGL 1.5 specification (August 27, 2014). This extension requires EGL_KHR_gl_colorspace and EGL_EXT_pixel_format_- float, and interacts with EGL_EXT_surface_SMPTE2086_metadata. This extension is closely related to the EGL_EXT_gl_colorspace_scrgb. Overview This extension provides an extended sRGB (also called scRGB) color space option for applications to choose from when creating an EGLSurface. This extension defines the linear display referred scRGB color space. It has the same white point and color primaries as sRGB, and thus is backward-compatible with sRGB. Refer to the IEC 61966-2-2:2003 standard for details on scRGB color space. This extension chooses to use floating-point formats for scRGB color space. For each color channel, the floating-point values of 0.0 and 1.0 still correspond to sRGB chromaticities and luminance levels. However, scRGB space allows for color values beyond the range of [0.0, 1.0], and can thus achieve a larger color volume than that of sRGB. As it is display referred, scRGB space makes assumptions of how the floating-point color values should map to luminance levels by the underlying display pipeline. The expected mapping is such that a color value of (1.0, 1.0, 1.0) corresponds to a luminance level of 80 nits on a standardized studio monitor. As the color value per channel goes beyond 1.0 and up to 125.0, the corresponding luminance levels also increase linearly to a maximum of 10000 nits. New Procedures and Functions None. New Tokens Accepted as attribute values for EGL_GL_COLORSPACE by eglCreateWindowSurface, eglCreatePbufferSurface and eglCreatePixmapSurface: EGL_GL_COLORSPACE_SCRGB_LINEAR_EXT 0x3350 Modifications to the EGL 1.5 Specification Insert below text in the 3rd paragraph on page 33 in 3.5.1 "Creating On- Screen Rendering Surfaces", before "The default value of EGL_GL_COLORSPACE is EGL_GL_COLORSPACE_LINEAR.": If its value is EGL_GL_COLORSPACE_SCRGB_LINEAR_EXT, then a linear scRGB color space is assumed, with a corresponding GL_FRAMEBUFFER_ATTACHMENT_- COLOR_ENCODING value of GL_LINEAR. scRGB is defined to use the same primaries and white-point as sRGB. See IEC 61966-2-2:2003 for details. Add two paragraphs after the 4th paragraph above: When using a floating-point EGL surface with EGL_GL_COLORSPACE_SCRGB_- LINEAR_EXT, the display-referred values in the range of (0.0, 0.0, 0.0) to (1.0, 1.0, 1.0) correspond to a luminance range of 0 to 80 nits, which is the same luminance range for sRGB. To achieve a larger dynamic range of up to 10000 nits, the output values can go beyond 1.0 and to a range of [0.0, 125.0] for each channel. The effective color gamut and luminance range of the content that extend beyond those of sRGB may be described via EGL_EXT_surface_SMPTE2086_metadata. It is highly recommended to supply such metadata, so the display pipeline may use this information to transform the colors in a manner that attempts to preserve the creative intent of the color data. In the "Errors" section on page 34 in 3.5.1 "Creating On Screen Rendering Surfaces", change the 3rd error definition to: * If config does not support the OpenGL colorspace, the OpenVG colorspace or alpha format attributes specified in attrib list (as defined for eglCreatePlatformWindowSurface), an EGL_BAD_MATCH error is generated. Issues * Clarifications on the scRGB colorspace extensions Revision History Version 1, 2016/10/21 - Initial draft Version 2, 2016/11/18 - Add reference to IEC 61966-2-2:2003 standard and minor wording changes Version 3, 2016/11/22 - Change status to complete Version 4, 2017/08/25 - Clarifications on the definition of scRGB colorspace