Reformer

This plugin probably is better suited than Reform plugin as it performs much better even if the rectangle is rotated by 90 degrees. Reform fails in such a situation. This Reformer uses matrix algebra for transformations unlike Reform which does a geometric transform.

Reformer has two functions viz: r2q and q2r. As the names suggest r2q transforms rectangle to a quadrilateral, while q2r transforms quadrilateral to rectangle. Lanczos or cubic or linear or nearest point interpolation methods can be opted. The parameters are identical to both functions (and to the Reform plugin.) and the coordinates can be specified as floating point or (since avisynth accepts integers as floating point) in integer format.

While there are no limits for specifying parameters, it has to be ensured that the specified parameters do not twist or fold the Quadrlateral. In the table of parameters R stands for Rectangle and Q stands for Quadrilateral.

Most of the parameters can be linearly varied over the length of the clip, and so it can be used to distort or correct distorted faces or objects progressively. Also can be used by proper scripting as transition. All color formats supported by Avisynth version are accepted. For reading coordinates correctly my plugin Grid can be used.

Description of parameters. Q stands for Quadrilateral and R for rectangle.

Parameter	Parameter name	Variable type	Limits of values	Default value
clip to be skewed into quadrilateral or deskewed into rectangle		clip		none
clip to be used as background		clip		none
Q left top x coordinate	ltopx	float	none	0
Q left top y coordinate	ltopy	float	none	0
Q left bottom x coordinate	lbotx	float	none	0
Q left bot y coordinate	lboty	float	none	frame height-1
Q right top x coordinate	rtopx	float	none	frame width-1
Q right top y coordinate	rtopy	float	none	0
Q right bottom x coordinate	rbotx	float	none	frame width-1
Q right bot y coordinate	rboty	float	none	frame height-1
R left x coordinate	leftx	float	none	0
R right x coordinate	rightx	float	none	frame width-1
R top y coordinate	ytop	float	none	0
R bottom y coordinate	ybot	float	none	frame height-1
End frame Q left top x coordinate	eltopx	float	none	ltopx
End frame Q left top y coordinate	eltopy	float	none	ltopy
End frame Q left bottom x coordinate	elbotx	float	none	lbotx
End frame Q left bot y coordinate	elboty	float	none	lboty
End frame Q right top x coordinate	ertopx	float	none	rtopx
End frame Q right top y coordinate	ertopy	float	none	rtopy
End frame Q right bottom x coordinate	erbotx	float	none	rbotx
End frame Q right bot y coordinate	erboty	float	none	rboty
End frame R left x coordinate	eleftx	float	none	leftx
End frame R right x coordinate	erightx	float	none	rightx
End frame R top y coordinate	eytop	float	none	ytop
End frame R bottom y coordinate	eybot	float	none	ybot
resize interpolation to use	resize	string	"lanczos" "cubic" "line" "point"	"lanczos"

Script examples:-
ColorBars(). converttorgb32()
bg = blankclip(last)
r2q(bg,leftx = 100,rightx = 400, ytop = 200, ybot = 480,ltopx=200,ltopy=150, rbotx = 500, rboty = 400, resize= "lanczos")

 ColorBars(). converttoYV12()
bg = blankclip(last)
Subtitle("Flying Colorbars()",text_color=$d0c000,align=5,size=40)
 ScriptClip("""
c= last

	bg = blankclip(last)
	h = height(bg)-1
	w = width(bg)-1	
    t = 0.061 *(current_frame)
    t2 = 0.127 *( current_frame)
    a = 0.501 + 0.5 * sin(t/pi)
    t1x = (-0.2*cos(t2)) * w
    t1y = (0.5-0.5*cos(t2)) * h
    t2x = (1.0+0.2*cos(t2)) * w
    t2y = (0.5-0.5*cos(t2)) * h
    t3x = (1.0+0.2*cos(t2)) * w
    t3y = (0.5+0.5*cos(t2)) * h
    t4x = (-0.2*cos(t2)) * w
    t4y = (0.5+0.5*cos(t2)) * h
    c1x = (0.5+a*cos(t)) * w
    c1y = (0.5+a*sin(t)) * h
    c2x = (0.5-a*sin(t)) * w
    c2y = (0.5+a*cos(t)) * h
    c3x = (0.5-a*cos(t)) * w
    c3y = (0.5-a*sin(t)) * h
    c4x = (0.5+a*sin(t)) * w
    c4y = (0.5-a*cos(t)) * h
	# comment out call to r2q or to q2r or leave as it is
	r2q(c, bg,leftx=t1x,rightx=t2x,ytop=t1y,ybot=t3y,ltopx=c1x,ltopy=c1y, rtopx=c2x,rtopy=c2y,  rbotx=c3x,rboty=c3y,lbotx=c4x,lboty=c4y, resize = "point")

	q2r( bg,leftx=t1x,rightx=t2x,ytop=t1y,ybot=t3y,ltopx=c1x,ltopy=c1y, rtopx=c2x,rtopy=c2y,  rbotx=c3x,rboty=c3y,lbotx=c4x,lboty=c4y, resize = "point" )

 """)