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+.TH BLIND-RADIAL-GRADIENT 1 blind
+.SH NAME
+blind-radial-gradient - Generate a video with a radial gradient
+.SH SYNOPSIS
+.B blind-radial-gradient
+-w
+.I width
+-h
+.I height
+.SH DESCRIPTION
+.B blind-radial-gradient
+prints a video with a radial gradient to stdout,
+parameters for each from is read from each frame
+in stdin. The gradient is stored in all channels
+of the video.
+.P
+The video in stdin must contain exactly 2 or 3
+pixels per frame. The first pixel shall point to
+the beginning of the gradient (where the value is
+0) and the second pixel shall point to the end of
+the gradient (where the value is 1). In these
+pixels, the value of the first channel specifies
+the X-position and the value of the second
+channel specifies Y-position, the other channels
+are ignored.
+.P
+If there is a third pixel, in frames in stdin, it
+specified parameters to make the gradient elliptic
+or superelliptic. For a completely circular
+gradient its values should be 2, 2, and 1 for the
+first, second, and third channels, respectively;
+the fourth channel (the alpha channel) is ignored.
+If we name these values,
+.IR a ,
+.IR b ,
+and
+.IR m ,
+their is an imaginary superelliptic, on which the
+values of the gradient is 1, determined by the
+equation
+.RI || p ||^ a +|| r / m ||^ b =1,
+where
+.I p
+and
+.I r
+is the projection and rejection, respectively,
+of the normalised vector from beginning of the
+gradient to a pixel onto the vector from the
+beginning of the gradient to the end of the
+gradient.
+.SH NOTES
+Pixels after the end of the gradient have values
+larger than 1.
+.BR blind-*-wave (1)
+commands can be used to put all values between
+0 and 1.
+.SH OPTIONS
+.TP
+.BR -w " "\fIwidth\fP
+The width of the video, in pixels.
+.TP
+.BR -h " "\fIheight\fP
+The height of the video, in pixels.
+.SH SEE ALSO
+.BR blind (7),
+.BR blind-from-text (7),
+.BR blind-double-sine-wave (1),
+.BR blind-round-wave (1),
+.BR blind-sawtooth-wave (1),
+.BR blind-sinc-wave (1),
+.BR blind-sine-wave (1),
+.BR blind-triangular-wave (1),
+.BR blind-cone-gradient (1),
+.BR blind-linear-gradient (1),
+.BR blind-spiral-gradient (1),
+.BR blind-square-gradient (1)
+.SH AUTHORS
+Mattias Andrée
+.RI < maandree@kth.se >