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show-focuspoints

When photo editing, see where the camera's Autofocus points were. Marks present, enabled, and used points.

This is a little helper program that you run on your images that were taken with a camera that has autofocus and leaves the autofocus points in the picture's metadata. You can generally see the AF points on the camera's display, but they are usually not available in tools.

This tool has two modes (select with "-m"):

  • mode 1: make a new photo containing a copy of the original photo and overlay focus points. You can then watch it in any picture viewer.

  • mode 2: make a new picture that has a transparent background and semi-transparent focus point markers (and does not contain the original picture). You then import that as a layer into GIMP or whatever, and from then on you can turn it on and off, change transparency of my layer etc. This layer will also survive cropping and rotating while moving the focus point markers along with the rest of the picture. I plan to change my workflow to always put one of these in first thing before doing any cropping.

    You can also use mode 2 transparent layers to play more games with GMIC.

Requirements:

CURRENT LIMITATIONS:

This is just my working version for now. Sophistication will be added after I get a feeling for what people want.

Current limitations:

  • Canon only for now. Send me other Cameras' pictures.
  • How the marking is done is not configurable right now, it's just one scheme I used. Let me know what you want.
  • You should be, but current are not, able to request that only focus points actually used are plotted. It plots all the camera's focus points in semi-visible red. I find that it helps in finding out what's going on. Send me wishes.
  • GMIC must be version 2.0+. Debian-stable and some other OSes do not have it yet.
  • exiftool is also not too common in distributions.
  • When using mode 2 to make a mostly transparent layer you must use an output image format that supports transparency. I don't check that.

PERMANENT LIMITATIONS:

When cropping or rotating pictures, editing tools generally do not adjust the markings for the focus points. In GIMP, for example, they are left in, but not adjusted, so that the points show up in the wrong place. However, as I said earlier, if you import a transparent layer from this script into your editor session before you do any cropping or rotating then this layer will from then on move correctly.

SECURITY:

This is a Python script parsing the text output of a commandline utility (exiftool), that is calls via popen. It then (optionally) calls GMIC on a commandline generated, including the original picture name. This is a generally a high-risk situation because an attacker can try to send a picture with special characters in the filename, which will then try to escape shell quoting, executing shell commands.

At the time of this writing this script does not invoke an shells. Both the initial popen and the optional GMIC invokation are done with pre-parsed arrays of commandline arguments. Some testing has been done to make sure that filenames, no matter how exotic, are interpreted verbation as one commandline argument and are not being passed through a shell.

This script has the option to either invoke GMIC for you, or to print a commandline to stdout that you can run on your own later (flag "-n"). The second option is higher risk because now you are using a shell.

Both exiftool and GMIC might be vulnerable to exploits in picture data, picture metadata or picture names, regarless of whether you use my script or not. There is a lot of parsing going on there. In a public setting privilege separation seems in order.