Fri, 16 Dec 2011
/SW/graphics:
Fixing Simple Photo Issues at the Command Line
(Without having to startup a huge program like gimp or photoshop.)
These utilities are also drawn from the ImageMagick[1] graphics
suite. Imagemagick is available for all of Linux, Windows, and the Mac
environment[2]. Some examples:
- Rotation: Do you sometimes turn your camera 90 degrees to get
that "tall" shot? Rotate the photo back clockwise with the convert
command:
convert -rotate 90 image1.jpg image2.jpg
- Resize: How about a whole directory full of photos that you
want to reduce in size, without having to edit every photo to do it?
Again use convert to do the job, this time in a little Unix shell
script. First create the directory "convert-folder" in the same
directory as the one containing your "big" photo directory. Then cd into
the "big" photo directory and run this scrip:
for i in *.jpg ; do convert $i -resize 800x800 ../convert-folder/$i
; done
This may take a while if you have a lot of photos. In this example,
photos will be resized such that they have a maximum width or heighth of
800 pixels, with no change in aspect ratio.
- mogrify: resize while preserving aspect ratio. 600x500 are
therefore maximum dimensions of the result. Use of the quality option
with a value less then 100 reduces the size of the resulting file a
little:
mogrify -resize 600x500 -quality 70 Gabe.jpg
Note that the key difference between mogrify and convert are that
morgify over-writes the original file, and convert writes to a different
file.
- format: file format can also be changed:
convert input.jpg output.png
- Annotate: an image with some text:
# convert -font helvetica -fill white -pointsize 36 \
-draw 'text 10,50 "This is the annotation text"' \
floriade.jpg comment.jpg
- Thumbnailing: all the JPEGs in the current directory (note
that this is a Unix shell script):
for img in *.jpg ; do convert -sample 25%x25% $img thumb-$img ; done
- Sub-Directories: shrinking a bunch of jpg files spread out through a
number of sub-directories:
nice ionice -c3 find . -type f -name "*.jpg" -exec mogrify -resize 200x200 -quality 70 {} \;
(Note that "nice" and "ionice" lower the priority of the operations' claim on CPU
and disk resources, respectively. Especially useful for a production server.)
I have not yet found an Imagemagick manual that has the gift of
making difficult tasks seem easy. Here[3][4][5] are some suggestions for
manuals.
[1] http://www.imagemagick.org/script/index.php
[2] http://www.imagemagick.org/script/binary-releases.php
[3] http://www.imagemagick.org/script/command-line-tools.php
[4] http://linux.about.com/library/cmd/blcmdl1_ImageMagick.htm
[5] http://www.imagemagick.org/Usage/
posted at: 09:22 | path: /SW/graphics | permanent link to this entry
Sun, 05 Oct 2008
/SW/graphics:
Problem: How to Edit / Fax / Print a Web Page
First I used Firefox to print the web page to a postscript file
"file.ps". If I just wanted to fax the web site, at this point "ps2pdf
file.ps" would generate a "file.pdf" which I could upload to my fax
website no problem (ps2pdf comes from the "gs-common" package of the
Ghostscript[1] software suite).
However, I want to edit this file first.
I used the "convert" utility from the ImageMagick[2] graphics suite
(the "imagemagick" package in the Debian distribution) to "convert
file.ps file.jpg". Edit file.jpg with gimp[3]. Then "convert file.jpg
file.pdf". Fax or print file.pdf.
[1] http://www.ghostscript.com/awki/Ghostscript
[2] http://www.imagemagick.org/script/index.php
[3] http://www.gimp.org/
posted at: 10:08 | path: /SW/graphics | permanent link to this entry
