You may consider printing your next political pamphlet on a B/W printer...
:)
Gerhard
------------------------------------------------
Still On the Subject of Laser Printers
In last Friday's newsletter, you recall, I talked about the danger we all
face with out-of-control laser printers. Now let's look at the
controversial side of these nefarious machines.
Fanning the flames of controversy, MIT Media Labs has launched a project
called SeeingYellow.com to protest printer manufacturers whose laser
printers secretly monitor use.
The project gets its name from some color laser printers that produce a
nearly invisible grid of yellow dots on documents that store the serial
number of the printer and the date stamp of the printed page -- something
Benjamin Mako Hill and other members of MIT Media Labs' Computing Culture
research group see as an incursion on our civil liberties. Among other
things, the yellow-dot "watermark" lets the government and manufacturers
track counterfeit currency generated on laser printers, as previously
reported in Seeing Yellow Protests 'Big Brother' Laser Printers.
The Electronic Frontier Foundation has taken note posted a DocuColor
Tracking Dot Decoding guide that explains how the Xerox DocuColor model
printers produce the yellow dot pattern. It also provides a utility for
translating your particular dot pattern to determine what information it
stores. The DocuColor pattern is a repeating 15-x-8 grid of yellow dots on
the entire page that encodes up to 14 7-bit bytes of data, such as model
number, serial number, and date of printing. Other manufacturers such as
Brother, HP, and so on also produce similar tracking patterns. (Question:
Does my reporting on this qualify as "yellow journalism"?)
So while we're getting riled up about this, we should also take note that
most digital cameras have similar features. Serial numbers identifying the
camera are embedded in images, thereby making it possible to identify the
unique camera that took the photo.
------------------------------------------------
> The project gets its name from some color laser printers that
> produce a
> nearly invisible grid of yellow dots on documents that store the
> serial
> number of the printer and the date stamp of the printed page
You could presumably create a utility which added additional dots to
the preprinted image to randomise the "data" while only minimally
degrading the image.
Sales opportunity :-) ?
> So while we're getting riled up about this, we should also take note
> that
> most digital cameras have similar features. Serial numbers
> identifying the
> camera are embedded in images, thereby making it possible to
> identify the
> unique camera that took the photo.
Is this meant to refer to the EXIF and IPTC information which is
digitally encoded and clearly decodeable, or to "hidden" data encoded
within the image proper.
If it means the former then it is by no means secret, is regularly
viewed by many users and is easily modified or removed if desired. I'm
not aware that the actual camera serial number is recorded in this
way, although it may be. The camera model is. If the serial number is
recorded then it would be stripped by "unaware" formatting processes.
If it refers to data hidden in the image proper, I am not aware that
this exists AND it would continue to do so with certainty only as long
as the image was not compressed in any way, unless the compression
algorithm used was specifically engineered to avoid this. While a
significant proportion of professionals tend to use RAW or TIF file
formats which are not compressed or use loss free compression, the
overwhelming majority of camera files use JPG/JPEG format which has
variable loss compression depending on user settings. Such compression
would destroy most forms of in-image data unless it was of peculiarly
robust design. This seems exceedingly unlikely.
Russell
________________________
File: - f:\PIX\NSA_visit\Skyshots\PICT4937 Aurora at about 80000 feet,
SoCal - about 9am - note small contrails.jpg
ImageDescription - Minolta DSC
Make - Minolta Co., Ltd.
Model - DiMAGE 7Hi
Orientation - Top left
XResolution - 72
YResolution - 72
ResolutionUnit - Inch
Software - Ver.1.00e
DateTime - 2003:08:07 08:45:27
YCbCrPositioning - Centered
ExifOffset - 364
ExposureTime - 1/750 seconds
FNumber - 3.50
ExposureProgram - Manual control
ISOSpeedRatings - 100
ExifVersion - 0220
DateTimeOriginal - 2003:08:07 08:45:27
DateTimeDigitized - 2003:08:07 08:45:27
ComponentsConfiguration - YCbCr
BrightnessValue - 8.70
ExposureBiasValue - 0.00
MaxApertureValue - F 3.36
MeteringMode - Multi-segment
LightSource - Auto
Flash - Not fired, compulsory flash mode
FocalLength - 50.28 mm
FlashPixVersion - 0100
ColorSpace - sRGB
ExifImageWidth - 800
ExifImageHeight - 578
InteroperabilityOffset - 13444
CustomRendered - Custom process
ExposureMode - Manual
WhiteBalance - Auto
DigitalZoomRatio - 0 x
FocalLengthIn35mmFilm - 199 mm
SceneCaptureType - Standard
GainControl - None
Contrast - Normal
Saturation - Normal
Sharpness - Hard
SubjectDistanceRange - Distant view
On Aug 6, 2007, at 4:30 PM, Russell McMahon wrote:
> Is this meant to refer to the EXIF and IPTC information which is
> digitally encoded and clearly decodeable, or to "hidden" data encoded
> within the image proper.
>
> If it means the former then it is by no means secret, is regularly
> viewed by many users and is easily modified or removed if desired. I'm
> not aware that the actual camera serial number is recorded in this
> way, although it may be. The camera model is. If the serial number is
> recorded then it would be stripped by "unaware" formatting processes.
EXIF data includes vendor-specific fields that could presumably include
manufacturer-specific data like serial numbers. It's a good thing that
americans are required to register the serial numbers of all their
cameras.
That way the traitors handing digital pictures to terrorist
organizations
can be tracked down and sent to prison camps in Cuba.
Does anyone know of a utility like unix "find" (baroque thought it may
be) that lets you search/filter through a bunch of jpg images based on
the contained EXIF data?
> EXIF data includes vendor-specific fields that could presumably
> include
> manufacturer-specific data like serial numbers. It's a good thing
> that
> americans are required to register the serial numbers of all their
> cameras.
> That way the traitors handing digital pictures to terrorist
> organizations
> can be tracked down and sent to prison camps in Cuba.
Sounds like climate change to me!
> Does anyone know of a utility like unix "find" (baroque thought it
> may
> be) that lets you search/filter through a bunch of jpg images based
> on
> the contained EXIF data?
