blind

suckless command-line video editing utility
git clone git://git.suckless.org/blind
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blind-matrix-shear.1 (1973B)

      1 .TH BLIND-MATRIX-SHEAR 1 blind
      2 .SH NAME
      3 blind-matrix-shear - Create an affine 2D-transformation matrix for shearing
      4 .SH SYNOPSIS
      5 .B blind-matrix-shear
      6 [-a [-d]] [-c]
      7 .SH DESCRIPTION
      8 .B blind-matrix-shear
      9 creates an affine 2D-transformation matrix for
     10 shearing. 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 2 pixel.
     16 The first pixel holds the amount the image shall
     17 be sheared horizontally, that is, how much all
     18 pixels 1 pixel above the X-axis shall be moved
     19 rightward. The second pixel holds the amount the
     20 image shall be sheared vertically, that is, how
     21 much all pixels 1 pixel right of the Y-axis shall
     22 be moved downward.
     23 .P
     24 The luma (encoding in the Y-channel, the second
     25 channel) multiplied by the alpha (the fourth channel)
     26 of the input pixels are used as the values. Each
     27 values in the resulting matrices are stored
     28 in all channels.
     29 .SH OPTIONS
     30 .TP
     31 .B -a
     32 The pixels holds the angles of the shearing rather
     33 than the amount of the shearing.
     34 .TP
     35 .B -c
     36 Create different matrices for each channel. Use
     37 values from each channel in stdin to create
     38 matrices whose values are stored in the same
     39 channels in stdout.
     40 .TP
     41 .B -d
     42 Input angles in degrees rather than radians.
     43 .SH NOTES
     44 The description assumes the Y-axis grows downwards.
     45 .P
     46 Horizontal shearing and vertical shearing is not
     47 mutually commutative, this tool performs the
     48 shearing at the same time rather than after each
     49 other. When shearing both horizontally and
     50 vertically, the transformation matrix is not
     51 necessarily invertable.
     52 .SH SEE ALSO
     53 .BR blind (7),
     54 .BR blind-from-text (1),
     55 .BR blind-matrix-orthoproject (1),
     56 .BR blind-matrix-reflect (1),
     57 .BR blind-matrix-rotate (1),
     58 .BR blind-matrix-scale (1),
     59 .BR blind-matrix-translate (1),
     60 .BR blind-matrix-transpose (1),
     61 .BR blind-multiply-matrices (1)
     62 .SH AUTHORS
     63 Mattias Andrée
     64 .RI < maandree@kth.se >