Dear Hans, I read the “luametafun.pdf” and run the codes one by one. It is a really nice to have those figures easily. During the reading, I found that there is a difference between the figure in the manual and the output of my run. I run the following code at page 24-25 in “luametafun.pdf”. \startMPcode{doublefun} draw lmt_contour [ xmin = 0, xmax = 4*pi, xstep = .05, ymin = -6, ymax = 6, ystep = .05, levels =7, height = 5cm, preamble = "local sin, cos = math.sin, math.cos", function = "cos(x) + cos(y)" background = "bitmap", foreground = "edge", linewidth = 1/2, cache = true, ]; \stopMPcode In the output, the background of text is gray while the background of text in the manual is white. Here are versions of LuaMetaTeX and ConTeXt which I use. %%%%%%% This is LuaMetaTeX, Version 2.03.4 open source > level 1, order 1, name 'cont-yes.mkiv' system > system > ConTeXt ver: 2019.12.16 18:54 MKIV beta fmt: 2019.12.17 int: english/english system > %%%%%%%%% Is there anything that I miss? Would you please to check it? Thank you. Best regards, Dalyoung