* @demtwop shows applications of the two-point filters
* adne, adre, sune, sure;
* adne A B pow dir adds part of 
* previous inpixel to current inpixel;
* adre A B pow dir adds part of 
* previous outpixel to current inpixel;
* sune A B pow dir subs part of 
* previous inpixel from current inpixel;
* sure A B pow dir subs part of 
* previous outpixel from current inpixel;
* pow determines part: 0=full, 1=half,,,, 7= 1/128;
* dir determines direction: 0=East, 1= NE,,,, 7=SE;
* adne and sure are each other's inverse;
* adre and sune are each other's inverse;
read trui
his A
sune A B 1 0
his B
sune B C 1 2
his C
sune C B 1 4
his B
sune B C 1 6
his C
sure C B 1 0
his B
sure B C 1 2
his C
sure C B 1 4
his B
sure B C 1 6
cop C D
his D
 * coded!
adne C B 1 6
his B
adne B C 1 4
his C
adne C B 1 2
his B
adne B C 1 0
his C
adre C B 1 6
his B
adre B C 1 4
his C
adre C B 1 2
his B
adre B C 1 0
his C
 * decoded!