Mercurial > cgi-bin > hgweb.cgi > JpegWasher
changeset 31:3b0546fa0d74
Add documentation in alternative formats to HTML.
| author | David Barts <davidb@stashtea.com> |
|---|---|
| date | Sat, 18 Apr 2020 09:08:23 -0700 |
| parents | 9bb5dfef3d2a |
| children | c06edc56669b |
| files | Makefile.doc Readme.pdf Readme.rst custom.tmac |
| diffstat | 4 files changed, 183 insertions(+), 0 deletions(-) [+] |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Makefile.doc Sat Apr 18 09:08:23 2020 -0700 @@ -0,0 +1,21 @@ +.PHONY: clean + +all: Readme.rst Readme.pdf + +clean: + -rm *.rst *.pdf *.ps *.nrf + +%.rst : %.html + echo "[This file automatically generated by pandoc from '$<'.]" > $@ + echo "" >> $@ + pandoc --from=html --to=rst $< >> $@ + +%.nrf : %.html + echo ".so custom.tmac" > $@ + pandoc --from=html --to=ms $< | sed -e 's/^\.LP/.PP/' >> $@ + +%.ps: %.nrf custom.tmac + groff -Tps -t -ms -mpdfmark $< > $@ + +%.pdf : %.ps + ps2pdf $<
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Readme.rst Sat Apr 18 09:08:23 2020 -0700 @@ -0,0 +1,159 @@ +[This file automatically generated by pandoc from 'Readme.html'.] + +Introducing JpegWasher +====================== + +Executive Summary +----------------- + +This program makes it easy to remove metadata from the digital images +you create. + +What is “Metadata” and Why Would I Want to Remove It? +----------------------------------------------------- + +You may not realize it, but image files can (and typically do!) contain +more than just image data. These data can include your camera make, +model, and serial number; the location where you took the photo; the +software you used to edit the photo (and what editing steps you did); +etc. + +One of the most powerful uses of photography is to graphically document +things that the wealthy and powerful might wish to remain concealed. The +evils of slavery, child labor, poverty, war, and imperialism have all +been documented photographically, and such photographs have often proved +instrumental in helping to motivate social change. + +Because of the metadata they contain, digital photographs contain data +which has been used to determine who took them, and in some cases to +exact retribution against those photographers. JpegWasher makes it easy +to see and remove the privacy-compromising metadata in your images. + +Even if your images are not of such a sensitive nature, that extra data +takes up space. It is not uncommon for a 100 KiB image to contain 20 KiB +of metadata in it; if that image is on a web page, that makes for 20 KiB +of wasted network usage each time the image is sent. + +What Makes JpegWasher Different from Other Metadata Editors? +------------------------------------------------------------ + +Simply put, it is designed to *safely* remove *unimportant* metadata +from JPEG files. + +There are plenty of general-purpose image metadata editors out there, +and these tools can be employed to remove unimportant metadata. The +trouble is, they are not user-friendly: it is up to you, the user, to +know which metadata are unimportant, and to delete it. + +There can be literally *hundreds* of bits of metadata in an image, and +*not all are safe to remove*. In particular, if you accidentally remove +color-management metadata, computers that don’t handle images without +color-management metadata properly (I’m talking about *you*, Apple +Computer, Inc.) will display colors that often look all “washed-out” or +otherwise incorrect. + +Likewise, there are already plenty of simple-to-use, user-friendly tools +out there for cleaning the metadata out of image files, but they +inevitably delete *all* metadata, resulting in files that often display +improperly. Also of concern, many of these “tools” are actually online +services. If you’re concerned about your privacy, why would you trust +the images you’re processing to some unknown third party, who may be +linked somehow to those who might want to retaliate against you? + +I wrote this program because I wanted there to be a quick, easy way to +scrub images before they even left a photographer’s computer and made +their way onto the Internet, and for that program to leave vital +metadata alone, so that the resulting images continue to display +properly. + +JpegWasher Washes More than Just Exif Metadata +---------------------------------------------- + +Jpeg is the most common type of metadata, but image files commonly +contain compromising XMP or IPTC data, particularly if they have been +edited with a tool like Photoshop. JpegWasher will seamlessly deal with +these kinds of metadata, too. It tries to do as thorough a job as +possible of scrubbing possibly compromising metadata from your images. + +Using JpegWasher +---------------- + +Just double-click on the JpegWasher icon and a main window should open +up. Either choose the File… Wash from the menu bar, or just drag image +files onto the main JpegWasher image. + +When JpegWasher opens an image, it displays all the metadata it finds. +That metadata will be run through an internal whitelist, and any data +whose “key” is not found on the whitelist will be automatically selected +for deletion. + +If you disagree with JpegWasher’s decisions, you can check or uncheck +the boxes next to the metadata in question. When you are satisfied with +the choice of metadata to be scrubbed, click “Wash” and all offending +metadata will be removed. A dialog will pop up showing the metadata +remaining in the new, washed file. + +Important: Run JpegWasher Last! +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Most image-editing tools insert telltale bits of metadata into the +output they create. Thus, only way you can create a file with the +minimum amount of metadata in it is to run JpegWasher as the final step +in your image preparation. + +Washing Non-JPEG Images +~~~~~~~~~~~~~~~~~~~~~~~ + +In short: it’s possible, but it is not recommended unless you *really* +know what you’re doing. + +JpegWasher is called JpegWasher for a reason: it is geared to cleaning +metadata in *JPEG* files. Different types of images use metadata +differently; metadata that would be extraneous deadwood in a JPEG can be +critical to interpreting other image file formats correctly. +JpegWasher’s built-in whitelist is geared to what must be retained when +washing JPEG images, so *careless use of JpegWasher is likely to damage +non-JPEG files.* It is for this reason that JpegWasher will warn you if +you attempt to open and wash a non-JPEG file with it. + +Output Files +------------ + +JpegWasher never modifies an existing image file. Instead, it creates a +new file of the same type but with “_washed” appended to its name. For +example, processing ``foo.jpg`` will create ``foo_washed.jpg``. By +default, the new file will be created in the same directory as the file +being washed. + +JpegWasher is Configurable +-------------------------- + +Both the whitelist and the destination directory for the washed files +are user-configurable in the Preferences menu. + +Configuring the Whitelist +~~~~~~~~~~~~~~~~~~~~~~~~~ + +There are two kinds of whitelist entries: those that match an entire +metadata key, and those that match a key prefix. The latter end in an +asterisk. The whitelist is case-sensitive; i.e. the entry +``exif.image.colormap`` *will not* match the ``Exif.Image.ColorMap`` +key. + +That’s about It +--------------- + +JpegWasher does not, and probably never will, do anything but remove +extraneous metadata from JPEG files. + +First, I have no desire to re-invent the wheel. There are already +excellent open-source tools like Gimp for image editing, and ExifTool +and Exiv2 for general-purpose metadata editing (in fact, JpegWasher is +built on top of Exiv2). If you need the functionality of some other +tool, download and use it! + +Second (and more importantly), I want JpegWasher to be simple, and +therefore easy to learn and easy to use. The more challenging an +information-security tool is to use, the less likely it is to be used +frequently, and the more likely it is that compromising information gets +disclosed.