Some notes on IDL color: how the background was made

The background image is a JPEG made in IDL in 24 bit color mode. The IDL commands used are given below. The APL IDL library routine maken was used. It makes an n element array from a given starting value to a given ending value.

	;----  Work in HSV color space  --------
	;----  Make an image 1300 x 10 pixels in size  -----
	h = fltarr(1300,10)			; Hue.
	s = fltarr(1300,10) 			; Saturation.
	v = fltarr(1300,10)+1.			; Value.

	;----  Make 60 pixel wide rainbow  ------
	hh = maken(0,300,60)			; Rainbow hues.
	for i=0,9 do h(0,i)=hh			; Insert in image hue array.
	ss = maken(1.,0.,60)			; Reduce color saturation.
	for i=0,9 do s(0,i)=ss			; Insert in image sat array.

	color_convert,h,s,v,r,g,b,/hsv_rgb	; Convert to R,G,B mode.
	z = [[[r]],[[g]],[[b]]]			; Pack 3 color channels.
	write_jpeg,'back.jpg',z,true=3		; Save as JPEG image.