Several extensions to OpenGL 1.1 are incorporated as standard commands in OpenGL 1.2 as part of the optional imaging subset:
The imaging subset provides color table support (glColorTable()) in the pixel transfer pipeline before the convolution operation (GL_COLOR_TABLE), after convolution and before application of the color matrix (GL_POST_CONVOLUTION_COLOR_TABLE), and after the color matrix (GL_POST_COLOR_TABLE). Scale and bias are available for each color table.
The subset provides 1D, 2D and separable convolutions (glConvolutionFilter*D() and glSeparableFilter2D()) in the pixel transfer pipeline, including scale and bias parameters.
Histogram and min and max functions are provided through glHistogram() and glMinMax().
The imaging subset also provides support for glBlendEquation() and glBlendColor() and the blending modes GL_CONSTANT_COLOR, GL_ONE_MINUS_CONSTANT_COLOR, GL_CONSTANT_ALPHA, and GL_ONE_MINUS_CONSTANT_ALPHA.
If an implementation supports the imaging subset, all of the above features are supported. If the implementation doesn't support it, using these features will result in GL_INVALID_OPERATION or GL_INVALID_ENUM.
You can determine if an OpenGL 1.2 implementation implements the imaging subset by checking the result of glGetStringGL_EXTENSIONS(GL_EXTENSIONS) for the substring ``ARB_imaging''.
The imaging subset of OpenGL 1.2 is supported by the following vendors as of April, 1999: