blind-matrix-rotate.1 - blind - suckless command-line video editing utility
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       blind-matrix-rotate.1 (1656B)
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            1 .TH BLIND-MATRIX-ROTATE 1 blind
            2 .SH NAME
            3 blind-matrix-rotate - Create an affine 2D-transformation matrix for rotation
            4 .SH SYNOPSIS
            5 .B blind-matrix-rotate
            6 [-cd]
            7 .SH DESCRIPTION
            8 .B blind-matrix-rotate
            9 creates an affine 2D-transformation matrix for
           10 rotation. The parameters for the matrix is read
           11 in stdin in format of a blind video, one matrix
           12 per frame in stdin created and printed to stdout
           13 in format of a blind video.
           14 .P
           15 Each frame in stdin shall contain exactly 1 pixel,
           16 this pixel holds the number of radians the image
           17 is to be rotated clockwise around origo.
           18 .P
           19 The luma (encoding in the Y-channel, the second
           20 channel) multiplied by the alpha (the fourth channel)
           21 of the input pixels are used as the values. Each
           22 values in the resulting matrices are stored
           23 in all channels.
           24 .SH OPTIONS
           25 .TP
           26 .B -c
           27 Create different matrices for each channel. Use
           28 values from each channel in stdin to create
           29 matrices whose values are stored in the same
           30 channels in stdout.
           31 .TP
           32 .B -d
           33 Input angles in degrees rather than radians.
           34 .SH NOTES
           35 The image is rotated anti-clockwise if the Y-axis
           36 grows upwards rather than downwards.
           37 .P
           38 Due to truncation error, when rotating a multiple
           39 of 90 degrees, it is preferable to use
           40 .B -d
           41 with lets
           42 .B blind-matrix-rotate
           43 eliminate the error. If this is not done,
           44 .BR blind-invert-matrix (1)
           45 may return odd results.
           46 .SH SEE ALSO
           47 .BR blind (7),
           48 .BR blind-from-text (1),
           49 .BR blind-matrix-orthoproject (1),
           50 .BR blind-matrix-reflect (1),
           51 .BR blind-matrix-scale (1),
           52 .BR blind-matrix-shear (1),
           53 .BR blind-matrix-translate (1),
           54 .BR blind-matrix-transpose (1),
           55 .BR blind-multiply-matrices (1)
           56 .SH AUTHORS
           57 Mattias Andrée
           58 .RI < maandree@kth.se >