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1995-02-13
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FANT(1) FANT(1)
NNAAMMEE
fant - perform simple spatial transforms on an image
SSYYNNOOPPSSIISS
ffaanntt [ --aa _a_n_g_l_e ] [ --bb ] [ --oo _o_u_t_f_i_l_e ] [ --pp _x_o_f_f _y_o_f_f ] [
--ss _x_s_c_a_l_e _y_s_c_a_l_e ] [ --vv ] [ _i_n_f_i_l_e ]
DDEESSCCRRIIPPTTIIOONN
_F_a_n_t rotates or scales an image by an arbitrary amount.
It does this by using pixel integration (if the image size
is reduced) or pixel interpolation if the image size is
increased. Because it works with subpixel precision,
aliasing artifacts are not introduced (hah! see BUGS).
_F_a_n_t uses a two-pass sampling technique to perform the
transformation. If _i_n_f_i_l_e is "-" or absent, input is read
from the standard input.
OOPPTTIIOONNSS
--aa _a_n_g_l_e
Amount to rotate image by, a real number from 0 to
45 degrees (positive numbers rotate clockwise).
Use rleflip(1) first to rotate an image by larger
amounts.
--bb Blur the resulting image. Always interpolate
between pixels of the input image. This results in
fewer artifacts but a slightly blurry resulting
image. Recommended for pathological cases such as
single pixel wide lines in the input image.
--oo _o_u_t_f_i_l_e
Specifies where to place the resulting image. The
default is to write to stdout. If _o_u_t_f_i_l_e is "-",
the output will be written to the standard output
stream.
--pp _x_o_f_f _y_o_f_f
Specifies where the origin of the image is - the
image is rotated or scaled about this point. If no
origin is specified, the center of the image is
used.
--ss _x_s_c_a_l_e _y_s_c_a_l_e
The amount (in real numbers) to scale an image by.
This is often useful for correcting the aspect of
an image for display on a frame buffer with non
square pixels. For this use, the origin should be
specified as 0, 0 (see --pp above). If an image is
only scaled in Y and no rotation is performed, _f_a_n_t
only uses one sampling pass over the image, cutting
the computation time in half.
--vv Verbose output. Primarily for debugging.
1 June 15, 1990 1
FANT(1) FANT(1)
SSEEEE AALLSSOO
_a_v_g_4(1), _r_l_e_f_l_i_p(1), _u_r_t(1), _R_L_E(5),
Fant, Karl M. "A Nonaliasing, Real-Time, Spatial Transform
Technique", _I_E_E_E _C_G_&_A, January, 1986, p. 71.
AAUUTTHHOORRSS
John W. Peterson, James S. Painter
BBUUGGSS
_F_a_n_t uses a rather poor anti-aliasing filter (a box fil
ter). This is usually good enough but will exhibit
noticeable aliasing artifacts on nasty input images.
1 June 15, 1990 2