Of the pictures I'd like to put online, I've found that in 75% of the cases where I want to retouch the photo, it's to crop it and nothing else. Since I shoot in jpeg, it's a lossy process to load the jpeg in gimp, crop it, and write the result.
It turns out that debian's jpegtran has a "-crop" flag which performs lossless cropping of jpeg images as long as the crop is to a multiple of what the manpage calls the "iMCU boundary", usually an 8x8 or 16x16 block of pixels. This feature may have been pioneered by Guido of jpegclub.org some years ago.
There's apparently a nice Windows front-end to this program, but I didn't find a Linux one. So I wrote one! It's pretty basic, but it gets the job done. You can download it below.
To run cropgui, either list files on the commandline or select them from a file browser (in the latter case, you're returned to the browser after cropping the selected file(s); hit 'cancel' to exit completely). The output filename is chosen automatically, and never overwrites the original (but it will silently overwrite an earlier cropped version). For example, if the input is "moon.jpg" then the output is "moon-cropped.jpg".
Images are automatically scaled by a power of 2 (e.g., 1/2, 1/4 or 1/8) in order to fit onscreen. While dragging, the cropped image boundary will snap to a multiple of 8 or 16 pixels; this represents the limitation that the upper-left corner must be at a multiple of the iMCU blocks.
cropgui is written in Python and requires the following packages:
- Debian: python3, python3-pil, python3-pil.imagetk, (python-tkinter, python-imaging, python-imaging-tk on older systems), libjpeg-progs, and libimage-exiftool-perl.
- Fedora:
dnf install python2-pillow libjpeg-turbo-utils pygtk2 pygtk2-libglade ImageMagick and perl-Image-ExifTool python3-pillow-tk.
The specific external programs required are:
jpegtranto crop jpeg images (debian package: libjpeg-turbo-progs or libjpeg-progs)exiftoolto clear the EXIF rotation flag from jpeg output images (debian package: libimage-exiftool-perl)convertto rotate and crop other image types (debian package: imagemagick or graphicsmagick-imagemagick-compat)magickon Windows (download from ImageMagick and install)
Although there are packages in the making, for a system-wide install, first make sure
prerequisites are met for your system and the "flavor" of cropgui you want to install.
For the GTK version, you may skip the TK dependencies. But make sure jpegtran, exiftool
and convert are installed.
Then do this on command line after cloning this repo:
$ sudo bash ./install.sh -p /usr -P /usr/bin/python
Where the -p flag tells install.sh to install to /usr instead of your home dir. And flag -P points to your python binary, which you can find via $ type python. You may set the optional -f flag to switch between tk and gtk (the default) flavor of the app.
The author (@jepler) is not actively developing this project. Issues and pull requests are not likely to be acted on. I would be interested in passing this project to a new maintainer.
cropgui is available under the terms of the GNU GPL version 2 or later.