get screen shots

xwd is a command line utility for getting screen shots of windows on your Linux desktop. Do:

xwd -out shot.wd

Then click in the window you want a shot of

To get a screen shot of your desktop

xwd -root -out desktop.wd

Image Magick with open this type of file (display desktop.wd) but there is another command line program for viewing these files: xwud

xwud -in desktop.wd

create thumbnails

This one liner will create thumbnail shots from the images you have in a certain directory. You must have the 'netpbm' utilities installed. First, create a directory called 'thumbnail'. Then issue this command:

for i in *.gif ; do giftopnm $i | pnmscale -xsize 40 - | ppmquant 128 \
- | ppmtogif - > thumbnail/$i ; done

If you're working with *.jpg images, change giftopnm and ppmtogif to jpegtopnm and pnmtojpeg respectively.

author notice on photos

If you've taken some photos and you want to display them publicly, you can put your name on them in some corner of them to show who owns them. Using a part of the Image Magick suite called 'convert' on the command line, this is done easily. You can even use your favorite font.

convert -font somefont.ttf -fill red -pointsize 12 -draw \

'text 200,20 "Photo by Joe Smith"' image.jpg new_image.jpg

The Gimp

The Gimp is the most popular image manipulation program for Linux.

rounded corners with the gimp

If you want to round the corners of a rectangle, just follow these instructions. This method works well for creating website buttons.

First, create an image with your desired background and create a rectangle in the center in your desired foreground color. I normally choose a dark blue for the background and a dark red for the foreground.

Then apply a Gaussian blur (Filters --> Blur -- Gaussian blur) of about 20.

Then choose Image --> Colors --> Levels and enter levels of 120 1.20 and 130 respectively in the fields. You can change these values to suit you. Experiment a bit until you get something you like.

You can then use the Image --> Colors --> Hue and Balance tool to change the colors to your liking.

djvu

djvu is an image format, originally designed by AT&T, that aims at providing the best quality images from scanned material (old books, documents). At the same time, it produces a very small file size, which is ideal for storage. You'll need the djvulibre package available from: http://djvulibre.djvuzone.org/

djvu from jpg

After you've scanned a document and saved it in *.jpg format, simply issue this command:

c44 file.jpg

one djvu from multiple documents

You can create one djvu file with multiple pages.

djvm -c big_file.djvu file*.djvu

This inserts pages in the order of the invididual file names. You can also insert and delete pages:

djvm -i big_file.djvu contract.djvu 4

will insert the contents of contract.djvu at page 4

djvm -d big_file.djvu 4

will remove that same page

[ return to main tips page ]