Linux System Administration :: Resources :: Ldp LDP LGNET Issue82 Tougher

My Guide To Digital Photography LG #82

...making Linux just a little more fun!

My Guide To Digital Photography
By Rob Tougher

Introduction
Storing Photographs
Manipulating Photographs
Sharing Photographs
Conclusion

Introduction

Since its initial installation on my machine in 2000, Linux has fulfilled my computing needs. I use Linux for the following:

web browsing and email
software development
writing articles
web site hosting
digital photography

This article focuses on the last item, digital photography, and describes how I use Linux to store, manipulate, and share my digital photographs.

Storing Photographs

I store my photographs in two places: on my hard drive, which acts as short-term storage, and on CD-ROM, where the photographs are permanently stored. I keep the last few months of photographs on my machine so they can be recalled quickly, and I transfer the older ones to CD-ROM to free up space on my drive.

To download photographs from my camera to my computer, I use the USB Mass Storage Driver. This driver is part of the Linux kernel, and lets me mount my camera as a SCSI device. I then use the mv command to transfer the photographs to my hard disk. My session usually looks like the following:

prompt$ mount -n /dev/sdb1 /mnt/camera
prompt$ mv /mnt/camera/dcim/100msdcf/* /home/robt/docs/photographs/
prompt$ umount -n /mnt/camera

Pretty simple, right? I mount the camera, move the photographs to a directory on my hard disk, and then unmount the camera.

(The USB Mass Storage Driver works with only a few camera models. Mine is a Sony DSC-F707. Many other cameras such as the Canon PowerShot series are recognized by the Gphoto2 program. Some cameras don't work yet under Linux -- it all depends on the camera manufacturer giving us, the free software community, enough technical specifications that we can write a driver.)

When my hard disk becomes filled, I transfer the older photographs to CD-ROM. I accomplish this by placing a blank CD-ROM in my CD Writer and typing the following at a command prompt (see the CD Writing HOWTO for information on how to use your CD Writer):

prompt$ mkisofs -o cd_image /home/robt/docs/photographs
prompt$ cdrecord -v speed=4 dev=0,0,0 -data cd_image

This creates a cd image containing my photographs, and burns the image to a fresh CD-ROM.

Manipulating Photographs

In photography, composition deals with the placement of objects within the frame of the photograph. A photographer makes many important decisions when composing a photograph:

Should I include X in the photograph?
Should I shoot this horizontally, or vertically?
How much depth-of-field should there be?

As a novice photographer, my composition skills are lacking. I usually include too much background in my photographs, and I am oblivious to the camera's numerous features.

I use the GIMP to salvage my poor photographs. GIMP stands for the GNU Image Manipulation Program - it is a full-featured image manipulation application, similar to Adobe's Photoshop. I use it to perform the following:

crop photographs that are not composed correctly
change the saturation of colors in photographs
sharpen photographs that are blurry

These are only a few of the GIMP's features, but they greatly improve the quality of my photographs. I look forward to learning more about the GIMP.

Sharing Photographs

I share my digital photographs with friends and family. I accomplish this by posting the photographs to a publicly-accessible web site. Before posting, however, I do the following:

resize the photographs to a suitable web size
create thumbnails of the photographs
generate the HTML needed to display the photographs on a web page

I use two Python scripts to perform these operations automatically. The first is named generate_photographs. This script uses the convert command to create web-sized photographs and thumbnails (convert is part of the ImageMagick suite of tools. Definitely check them out). The following is the complete script:

#!/usr/bin/env python

import os

#
# Prints the call to
# stdout, and then sends it
# to the OS.
#
def system_call(s):
	print s
	os.system(s)


#
# Clear out the directories. "small"
# contains thumbnails, and "medium"
# contains web-sized photographs.
#
for d in ("small", "medium"):

	system_call("rm -rf " + d)
	system_call("mkdir " + d)



files = os.listdir("photographs")

for file in files:

	if file != ".directory":

		system_call("convert -resize 640x480 photographs/" + file + " medium/" + file)
		system_call("convert -resize 160x120 medium/" + file + " small/" + file)

The second script is named generate_html. It loops through the photographs, and creates the HTML needed to display them on a web page. The following is the script, trimmed to show the Python code only:

#!/usr/bin/env python

import os

#
# HTML-related stuff removed....
#
html = ""


files = os.listdir("photographs")
br = 0

for file in files:

	html += '<a href="medium/' + file + '">'
	html += '<img src="small/' + file + '"></img>\n'
	html += '</a>'

	if br:
		html += '<br>\n'
		br = 0
	else:
		br = 1

#
# HTML-related stuff removed....
#


f = open("index.php","w+b")
f.write(html)
f.close()

After running these two scripts, I post the files to my web site, and email the address to everyone.

Conclusion

In this article I described how I use Linux to store, manipulate, and share my digital photographs. Hopefully I explained my techniques clearly enough so that you can use them for your digital photography needs.

Rob Tougher