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	blind-radial-gradient.1 - blind - suckless command-line video editing utility
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	blind-radial-gradient.1 (2181B)
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	1 .TH BLIND-RADIAL-GRADIENT 1 blind
	2 .SH NAME
	3 blind-radial-gradient - Generate a video with a radial gradient
	4 .SH SYNOPSIS
	5 .B blind-radial-gradient
	6 -w
	7 .I width
	8 -h
	9 .I height
	10 .SH DESCRIPTION
	11 .B blind-radial-gradient
	12 prints a video with a radial gradient to stdout,
	13 parameters for each from is read from each frame
	14 in stdin. The gradient is stored in all channels
	15 of the video.
	16 .P
	17 The video in stdin must contain exactly 2 or 3
	18 pixels per frame. The first pixel shall point to
	19 the beginning of the gradient (where the value is
	20 0) and the second pixel shall point to the end of
	21 the gradient (where the value is 1). In these
	22 pixels, the value of the first channel specifies
	23 the X-position and the value of the second
	24 channel specifies Y-position, the other channels
	25 are ignored.
	26 .P
	27 If there is a third pixel, in frames in stdin, it
	28 specified parameters to make the gradient elliptic
	29 or superelliptic. For a completely circular
	30 gradient its values should be 2, 2, and 1 for the
	31 first, second, and third channels, respectively;
	32 the fourth channel (the alpha channel) is ignored.
	33 If we name these values,
	34 .IR a ,
	35 .IR b ,
	36 and
	37 .IR m ,
	38 their is an imaginary superelliptic, on which the
	39 values of the gradient is 1, determined by the
	40 equation
	41 .RI \|\| p \|\|^ a +\|\| r / m \|\|^ b =1,
	42 where
	43 .I p
	44 and
	45 .I r
	46 is the projection and rejection, respectively,
	47 of the normalised vector from beginning of the
	48 gradient to a pixel onto the vector from the
	49 beginning of the gradient to the end of the
	50 gradient.
	51 .SH NOTES
	52 Pixels after the end of the gradient have values
	53 larger than 1.
	54 .BR blind-*-wave (1)
	55 commands can be used to put all values between
	56 0 and 1.
	57 .SH OPTIONS
	58 .TP
	59 .BR -w " "\fIwidth\fP
	60 The width of the video, in pixels.
	61 .TP
	62 .BR -h " "\fIheight\fP
	63 The height of the video, in pixels.
	64 .SH SEE ALSO
	65 .BR blind (7),
	66 .BR blind-from-text (7),
	67 .BR blind-cone-gradient (1),
	68 .BR blind-linear-gradient (1),
	69 .BR blind-spiral-gradient (1),
	70 .BR blind-square-gradient (1),
	71 .BR blind-double-sine-wave (1),
	72 .BR blind-round-wave (1),
	73 .BR blind-sawtooth-wave (1),
	74 .BR blind-sinc-wave (1),
	75 .BR blind-sine-wave (1),
	76 .BR blind-triangular-wave (1),
	77 .BR blind-spectrum (1)
	78 .SH AUTHORS
	79 Mattias Andrée
	80 .RI < [email protected] >