Get histogram table
void glGetHistogram(GLenum target, GLboolean reset, GLenum format, GLenum type, GLvoid * values);
glGetHistogram returns the current histogram table as a one-dimensional image with the same width as the histogram. No pixel transfer operations are performed on this image, but pixel storage modes that are applicable to 1D images are honored.
If a nonzero named buffer object is bound to the
GL_PIXEL_PACK_BUFFER target (see
glBindBuffer) while ...