Specify the offset for tile images, relative to the background image it is tiled on.

exec("convert $input1 -thumbnail 50x50 temp.png");
// Tile the image
$cmd = " -size 213x160 -tile-offset +10+10 tile:temp.png ";  
exec("convert $cmd tile_offset.jpg"); 

( This is the offset from the datum position NOT the offset between the tiles. The default position is the top left corner. )

Tint the image with the fill color.

$cmd = "$input -fill Blue -tint 30"; 
exec("convert $cmd tint.jpg");

Assign a title to displayed image.

Transform the image.

Make this color transparent within the image.

$cmd = "$input -fuzz 10% -transparent #7b1216 "; 
exec("convert $cmd transparent.png");

( Save as a png to retain the transparency. -fuzz can be used to select a range of colours.
Also see Transparent inverted )

Set the transparent colour.

$cmd = "$input -transparent-color Black"; 
exec("convert $cmd transparent_color.jpg");

( This does not make a colour transparent, it only defines what colour the transparent colour is in the colour palette of the saved image. )

Make all colours except this color transparent within the image.

$cmd = "$input -fuzz 10% +transparent #7b1216 ";  
exec("convert $cmd plus_transparent.png"); 

( Save as a png to retain the transparency. -fuzz can be used to select a range of colours. )

Mirror the image along the top-left to bottom-right diagonal.

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

Mirror the image along the images bottom-left top-right diagonal.

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

Tree depth for the color reduction algorithm.

Trim an image.

$cmd = "strokewidth.jpg -trim "; 
exec("convert $cmd trim.png");

( -fuzz can be added if the the border colour varies slightly. )

The image type.

$cmd = "$input -type Grayscale";  
exec("convert $cmd type.jpg");
 

( Choose from: Bilevel, Grayscale, GrayscaleMatte, Palette, PaletteMatte, TrueColor, TrueColorMatte, ColorSeparation, or ColorSeparationMatte. )

Set the color of the annotation bounding box.

$cmd = "$input -fill Black -pointsize 40 -gravity center". 
" -undercolor NavajoWhite -annotate +0+0 \"Undercolor\""; 
exec("convert $cmd undercolor.jpg");

Discard all but one of any pixel color from the image.

$cmd = "$input4 -unique-colors -resize x20"; 
exec("convert $cmd unique_colors.jpg");

( Will create an image 1px high and VERY wide if your image contains a lot of colours. I have resized the height to 20px to see the colours. )