Geoff's Digicam Tools for Linux

Introduction

When I got my digital camera, I found that there was relatively spotty support for it under Linux. Some things were easy to do (e.g., displaying pictures), some were possible but inconvenient (e.g., rotating pictures 90 degrees), and some were very difficult or impossible. Over the next year, I located some software, modified some, and wrote some. This page contains the results of those efforts.

Notes on this software:

1. This software is UNSUPPORTED. I do not have time to answer questions, fix bugs, or write further documentation. Sorry.
2. There is currently no license on my own software. I consider my contributions to be too small to be worth a separate license. Note that xv is distributed under its own license.

Software You Will Need

I'm a big believer in not reinventing the wheel. To use the other software on my page, you will need to download and install the following (unless you have it already):

• The xv image viewer. Even if you already have xv, you will want to download the sources so you can apply my patches (see below).
• The metacam camera-information dumper. This handy utility will tell you the date and time your picture was taken, the shutter speed, etc.
• The jpegtran tool for doing image rotations and the rdjpgcom/wrjpgcom tools for processing JPEG image comments. Both of these are part of the jpeg-6b package of JPEG tools from the Independent JPEG group.

What I've Done

The above tools are very useful (as are some other things like The Gimp, but I wasn't satisfied. In particular, my "Exif tags" (the information appended by the camera, and read by metacam, above) weren't being preserved. Here's what I've done:

• Modified xv to make it more friendly to modern digital cameras and displays. The exact changes are listed below.
• Modified rdjpgcom and wrjpegcom to support application-specific markers, especially the APP1 marker used by digital cameras to hold Exif tags. The patches should be applied to the JPEG tool sources listed above. See the wrjpegcom manual page for an example of usage.
• Wrote a new shell script, camrename, that renames picture files from the bad names produced by most cameras to names that contain the time and date of the picture. "camrename *.jpg" is enough to do the job in most cases. See the comments in the script for documentation. Note that jhead can also do this sort of renaming, but it doesn't preserve sequence numbers, so I prefer my own script. You must have metacam installed to use camrename.
• Wrote a new shell script, camrotate, that provides a "syntactic sugar" wrapper around jpegtran to make it easy to rotate images. NOTE: camrotate is obsolete. Use jhead instead; it is more powerful and flexible. If you want to use camrotate anyway, "camrotate *.jpg" will rotate everything 90 degrees clockwise, and "camrotate -ccw *.jpg" will rotate it counterclockwise. See the comments in the script for full documentation. (Note: if the image contains a thumbnail in the Exif section, that thumbnail will NOT be rotated.)
• Wrote a new shell script, camcomment, that allows you to easily add commentary to your pictures. Use "camcomment *.jpg" to bring up your favorite editor on a scratch file where you can write comments about all of the pictures. I also bring up an image displayer so I can look at the pictures as I write them up. Don't delete the information in the scratch file; simply add comments after each title line and exit your editor. (If you delete a title line, the associated image won't be changed.) As usual, full documentation is in the script's comments.
• Wrote a new shell script, copyexif, that allows you to copy the Exif tags from one JPEG file to another. NOTE: copyexif is obsolete. Use jhead instead; it is more powerful and flexible. If you want to use copyexif anyway, copyexif source.jpg dest.jpg will copy the digicam information from source.jpg to dest.jpg. This script requires my modified versions of rdjpgcom and wrjpgcom.
• Wrote a Gimp plug-in, redeye, that corrects red-eye in photographs. To use it, you will need to have Gimp perl support installed on your system. On SuSE Linuxes, this is encapsulated in the "gimpperl" package. Copy the plug-in to ~/.gimp-1.2/plug-ins/redeye, make it executable (chmod +x ~/.gimp-1.2/plug-ins/redeye), and then restart The Gimp. Drag a selection box around the red area (it's OK to pick up a bit of the rest of the eye). Usually you'll want to do both eyes at once, so use the shift key to add a second selection around the red in the other eye. Then right-click on the image to bring up a menu, and select Filters->Misc->Auto Red-Eye. The red-eye will magically disappear. For more control, you can try Filters->Misc->Red-Eye, which will pop up a dialog box that allows you to adjust the sensitivity of the red-eye correction (but the default is usually correct).

  NOTE: redeye works with Gimp 1.2. If you are running Gimp 2.0, you should use the much nicer (and faster) C-language redeye plugin by Robert Merkel. To use it, download it into a handy directory, and then run "gimptool-2.0 --install redeye.c". (This assumes that gimptool is properly configured, which may require downloading the Gimp sources. On my SuSE system, I just had to install the "gimp-devel" package.)

Changes to xv

I have long preferred the xv image viewer for looking at my images. It is fast and flexible, and the "presets" in its color editor (type "e") can be configured to correct the poor color balance of my camera (tip: try fiddling with the gamma values for the three colors). I extended it in a number of ways. To get my extensions, download the patches, apply them to the source with patch, and recompile and reinstall xv.

Unfortunately, the author of xv has disappeared so I can't get my changes integrated into the main code stream. Another side effect is that I can't patch the official documentation, since it was written with MS-Word and is not distributed in source form. So here's a summary of my changes and how to use them:

• "Exif" information (time, date, shutter speed, etc.) about an image is preserved when the image is edited. You need do nothing to use this feature. However, it is imperfect in two ways:
  • If the Exif information contains a thumbnail, the thumbnail will not be updated to reflect the changes you made with xv.
  • If you change the image size, the size in the Exif information will not be updated.
  I'm not bothered by either of these drawbacks, since it's always easy to just get rid of the Exif information altogether if it's wrong (that's what Photoshop and The Gimp do).
• The thumbnail size used by xv's Visual Schnauzer has been made variable, and the default is now larger. To change the thumbnail size, select "Choose icon size..." from the "Misc. Commands" menu in the Visual Schnauzer. You will be prompted for a new icon width; the height is chosen automatically. If you want Gimp compatibility, choose a width of 80. You'll need to choose "update" to get new icons after you pick a new size. (Note: due to the way xv handles JPEG images, there is a compile-time limit on JPEG thumbnail sizes. You can pick a larger size, but xv won't display the bigger thumbnails.)
• You can use the Visual Schnauzer to make both hard and soft (symbolic) links to files. When you drag a file to another Schnauzer window, hold down the Ctrl key if you want to copy the file, the Shift key if you want to link it, or no keys if you just want to move it. By default, symbolic links are used. If you want to use hard links instead, choose "Use hard links" from the "Misc. Commands" menu. I use symbolic links to organize pictures; for example, if a shot shows both my wife and my daughter, I'll place it in a directory for "wife shots" and then use a symbolic link to also make it visible in the "child shots" directory.
• If you want to use your computer to show pictures to other people, try the -slideshow switch. If any picture is too small to fill the screen, it will be centered and the remainder of the screen will be black.

Stuff That's Missing

I'm still searching for Linux-based solutions to a few remaining problems relating to digital photos:

• Updating the thumbnail images in Exif tags. I don't think this is difficult, given the tools available in the jpeg-6b library, but it's not important enough to me to spend the time writing the code. (Note: with my modifications to rdjpgcom and wrjpgcom above, all that's needed is a program to update an extracted set of Exif tags. I may do this part soon, basing it on the metacam code and the netpbm library.)
• Panorama stitching. This is the toughest problem to solve well. There is a package by Helmut Dersch named Panorama Tools (panotools) that will stitch panoramas, but it's written in Java and in my experience can't handle large panoramas (it runs out of memory very quickly). It is also very inconvenient to use. Unlike commercial tools, it won't automatically find corresponding points in different images to make stitching easy. I currently use Windows software (MGI PhotoVista, which came with one of my flash cards) to stitch panoramas.

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