ImageMagick

ImageMagick / Image Magick

Increase gamma for all jpgs in ths folder

mogrify -gamma 1.45 $(find -name \*.jpg)

Join images on top of each other

composite -gravity SouthEast -geometry +20+20 hinzu.jpg quelle.jpg ergebnis.jpg
Options:
-gravity [NorthWest, North, NorthEast, West, Center, East, SouthWest, South, SouthEast]
-geometry [width]x[height][+/-xoffset][+/-yoffset]

Join images besides each other, aligned in a row

convert a.png  b.png +append joined.png

Convert

convert creates a new image while mogrify replaces the original

convert -size 120x120 cockatoo.jpg -resize 120x120 +profile "*" thumbnail.jpg

'-size 120x120' gives a hint to the JPEG decoder that the image is going to be

downscaled to 120x120, allowing it to run faster by avoiding returning full-resolution images to ImageMagick for the subsequent resizing operation.

'-resize 120x120' specifies the desired dimensions of the output image.

It will be scaled so its largest dimension is 120 pixels.

'+profile "*"' removes any ICM, EXIF, IPTC, or other profiles that might

be present in the input and aren't needed in the thumbnail.

To convert a directory full of JPEG images to thumbnails, use:

mogrify -size 120x120 -resize 120x120 *.jpg +profile "*"
123x456
123x
123x456! exact this values
123x456> only if greater

add a textbox under the image

convert xc:white -resize 1xHEIGHT! BLANK
convert -append INFILE BLANK TMPFILE
convert TMPFILE -gravity "South" -family FAMILY -pointsize FONTSIZE -draw "text 0,3 'This text is added to the picture'" OUTFILE

transparent color on existing file

mogrify -transparent white <FILE.png>

make a negative:

mogrify -negate <FILE.png>

Rotate and mirror images

-flip = waagerecht
-flop = senkrecht
-transpose = diagonal (linksoben-rechtsunten)
-transverse = diagonal (rechtsoben-linksunten)

Trim

mogrify -trim
mogrify -trim +repage QD-vs-NC.png
convert $old -trim +repage -colorspace Gray -type GrayScale $new

PDF -> jpg

convert -density 150 a.pdf a-%d.jpg
convert a.pdf -colorspace Gray -type GrayScale a-%d.jpg

JPEG Compression

convert -quality 85 a.png a.jpg

Draw

convert FILE -draw "rectangle   0,0  100,100" OUTFILE

convert FILE -gravity "Center" -family FAMILY -pointsize FONTSIZE -draw "text 0,3 'This text is added to the picture'" OUTFILE

FAMILY: times,arial,serif,courier,...

perl function to paint a black frame around an image

sub draw_frame {
  my $file = shift;
  my $width = shift;
  my $height= shift;
  my $thickness = shift;
  
  $_ = "convert $file ".
  "-draw \"rectangle   0,0    ".($width-1).",  ".($thickness-1)."\" ".
  "-draw \"rectangle   0,0    ".($thickness-1)." ,".($height-1)."\" ".
  "-draw \"rectangle ".($width-1).",0    ".($width-$thickness).",".($height-1)."\" ".
  "-draw \"rectangle   0,$height  $width,".($height-$thickness)."\" ".   $file;
  system($_);
}