Bad Peggy Documentation
Usage
Scanning is a simple thing to accomplish:
- Select a folder under File..Scan. Drag and drop files and/or folders into Bad Peggy.
- Wait until the scan has finished. You can stop the scan via File..Stop Scan or by pressing the [Esc] key.
- Check out the potentially damaged files in the list.
Options
BadPeggy scans all JPEG image files in the selected folder(s). If Include Subfolders
is activated the whole content will be searched, otherwise only the files in the
actual folder itself.
By using File Extensions... you can select what files should be considered
as JPEG files based on their names or extension respectively (as a
comma-separated list). The default selection is usually sufficient. Capitalization
does not have to be considered.
Scanning might be accelerated by using Use all CPU cores if one or more
multi-core processors are available in the system. In this case Bad Peggy tries
to keep all cores occupied, yet it also depends on the storage speed how fast
the actual scan is going to turn out. Using Low Priority you can run
Bad Peggy in the background so other programs won't be influenced too much by
its activity.
Using Colorize the messages will get displayed in a colored fashion,
which helps to distinguish between the different issues in an easier manner.
You can switch languages with the Language... menu. At the time of this
writing German and English were available.
Post-Scan
Potentially damaged files show up in the list together with their complete path
and a description of the issue. By clicking on an entry you can view a particular
image and check out the actual impact of the damage. The viewer itself can be
enabled and disabled by double-clicking on it. An external image viewer (or
whatever is associated with JPEG images) can be started with a double-click on
a list item. Notice that the list can also be sorted by clicking on the headers
of the columns.
Some defects are hardly visible, if at all, for some pictures, while other ones
might not be presentable at all. If you want to remove an entry from the list
because you consider the image still to be usable then simply mark it an press
the [Del] button. The entry goes away yet the physical file won't be touched.
Not ever defect reported is a reason to delete an image. If you actually want to
remove though then open the context menu with a right-click. You can then click
on Delete to remove the file permanently. You can also move the selected
files to a different location with the Move... entry. Drag and drop of
the selected to an external file manager is also supported - there you can move
or copy. And with Export List... you can create a text file at the
location of your choice with the full paths of all of the selected files, which
you can then use further e.g. in a shell script.
The context menu also offers general operations like Clear List or
Select All.
Remarks
Bad Beggy uses the
Java Image IO (JIIO) library to examine JPEG files.
Its decoder emits warnings and errors while an image gets loaded. Thus the
results do depend on it being up-to-date and also its changes in functionality.
Bad Peggy checks though on startup if general, well-known errors in JPEG get
detected, i.e. if JIIO is still functioning in detecting damaged images as
expected.
What "damaged" truly means depends and can be
- small difference from the official format, e.g. extra data appended after the
actual image.
- non-critical issues like unknown values, which do not affect displaying the
image at all.
- minor damage which only disturb smaller parts of the image.
- major damage, which causes the display to be corrupted after a particular position.
- completely truncated or i.e. incomplete images.
- errors at the beginning of the files, so that decoding can't even commence.
- files with are not JPEG images at all, but accidentally carry the file extension.
- JPEG files which don't get recognized b the JIIO, but can be processed by
other image viewers, e.g. if additional information is stored before the image
data starts (which smarter or more aggressive decoders then skip).
- an image which looks damaged because it got loaded as such on saved again
in another application and thus is structurally fine.
- an image which is logically damaged but does not cause complains by the JIIO,
although the flaws are clearly visible - this is one of the most problematic
cases, since such files won't be detected by Bad Peggy - detection for such
problems is difficult, you can compare this with a text editor loading and
displaying a file with the word "text pr{cessor" in the, where the 'a' to '{'
change was caused by a faulty transmission but the text still makes sense to
the editor itself.
In general it is not recommended to just discard every image reported as damaged
but to check out if repairing or re-saving the file in other applications into
a generally valid JPEG format is possible.