The Fx special effects image operator is used to apply a mathematical expression to an image or image channels.

$cmd = "$input -fx \"(1.0/(1.0+exp(10.0*(0.5-u)))-0.006693)*1.0092503\" "; 
exec("convert $cmd fx.jpg");

Level of gamma correction.

$cmd = "$input -gamma 0.8 "; 
exec("convert $cmd gamma.jpg");

Blur the image with a Gaussian operator.

$cmd = "$input -gaussian-blur 0x4 "; 
exec("convert $cmd gaussian-blur.jpg");

Geometry sets the coordinates for the modification.

$cmd = "$input -fill white -pointsize 40".
" -gravity center -geometry +30+30 -annotate +0+0 \"Geometry\" "; 
exec("convert $cmd geometry.jpg");

( If -gravity is used as well it is in relation to the gravity position otherwise it is from the top left corner. )

Gravity sets the location of the modification.

$cmd = "$input -gravity north -annotate +0+0 \"North\" "; 
exec("convert $cmd gravity.jpg");

( Points of the compass are used e.g. North, North west, West etc. )

Convert image to grayscale.

 
$cmd = "$input -grayscale Rec709Luminance ";   
exec("convert $cmd grayscale.jpg");

Green chromaticity primary point.

( For each color, x+y must be positive and less than 1.0. If you specify one you should specify all six plus the white_point x and y. )

Apply a Hald color lookup table to the image.

$cmd = "$input $input5 -hald-clut";
exec("convert $cmd hald_clut.jpg");

Display the help file

( A couple of lines from the help file )

When comparing images, emphasize pixel differences with this color.

Specify the icon geometry.

Iconic animation

Identify the format and characteristics of the image.

system("convert $input -identify ");
 

( More information can be desplayed by adding -verbose )

Implements the inverse discrete Fourier transform (DFT).