Digital Camera Patent Abstract
A system for detecting a digital camera failure captures an image
with the digital camera. The system compresses the image into a
compressed image file and compares the size of the compressed image
file with a predetermined file size. A digital camera failure is
indicated if the size of the compressed image file is greater than
a predetermined upper limit file size or less than a predetermined
lower file size limit. The system may also compare the number of
pixels of a predetermined color with the total number of pixels
of the captured image. A digital camera failure is indicated if
the number of pixels of the predetermined color is greater than
a predetermined percentage of the total number of pixels of the
captured image. Digital Camera Patent Claims
What is claimed is:
1. A method of detecting a digital camera failure, which comprises
the steps of: capturing an image with said digital camera; compressing
said image into a compressed image file having a file size: comparing
the size of said compressed image file with a predetermined file
size; and indicating a failure of said digital camera if the size
of said compressed image file is greater than a predetermined upper
limit file size.
2. A method of detecting a digital camera failure, which comprises
the steps of: capturing an image with said digital camera; compressing
said image into a compressed image file having a file size; comparing
the size of said compressed image file with a predetermined file
size; and indicating a failure of said digital camera if the size
of said compressed image file is less than a predetermined lower
limit file size.
3. A method of determining a digital camera failure, which comprises
the steps of: capturing an image with said digital camera; compressing
said image into a compressed image file having a file size; comparing
the size of said compressed image file with a predetermined file
size; comparing the number of pixels of a predetermined color with
the total number of pixels of said captured image; and indicating
a failure of said digital camera if the size of said compressed
image file is greater than a predetermined upper limit file size.
4. A method of determining a digital camera failure, which comprises
the steps of: capturing an image with said digital camera; compressing
said image into a compressed image file having a file size; comparing
the size of said compressed image file with a predetermined file
size; and indicating a failure of said digital camera if the size
of said compressed image file is less than a predetermined lower
limit file size.
5. A method of providing security to an automated postal kiosk,
said automated postal kiosk including a digital camera, said method
comprising the steps of: initiating a postal transaction; capturing
an image with said digital camera; compressing said image into a
compressed image file having a file size; comparing the size of
said compressed image file with a predetermined file size; and terminating
said postal transaction if said step of comparing determines that
the size of said compressed image file is greater than a predetermined
upper limit file size.
6. A method of providing security to an automated postal kiosk,
said automated postal kiosk including a digital camera, said method
comprising the steps of: initiating a postal transaction; capturing
an image with said digital camera; compressing said image into a
compressed image file having a file size; comparing the size of
said compressed image file with a predetermined file size; and terminating
said postal transaction if said step of comparing determines that
the size of said compressed image file is less than a predetermined
lower limit file size.
7. A automated postal kiosk, which comprises: a digital camera
for capturing an image; and, a processor connected to said digital
camera for compressing said image into a compressed image file having
a file size, and comparing the size of said compressed image file
with a predetermined file size; and means connected to said processor
for enabling completion of a postal transaction if said processor
determines that the size of said compressed image file is greater
than a predetermined lower limit file size and less than a predetermined
upper limit file size otherwise terminating said transaction.
Digital Camera Patent Description
FIELD OF THE INVENTION
The present invention relates general to the field of digital image
capture, more particularly to a method of and system for detecting
the failure to capture a usable image by a digital camera. The method
and system of the present invention find application security systems
that capture a digital image. The present invention is particularly
adapted for use in an automated postal kiosk environment.
DESCRIPTION OF THE PRIOR ART
Many systems use cameras for security purposes. Such systems include
a relatively inexpensive digital cameras that capture images either
at regular intervals or upon the occurrence of an event. The captured
images may be stored for later review by a human.
The digital cameras used in security systems may fail to capture
an image that is acceptable for identification. For example, the
there may be a system failure due to hardware, mechanical, or communication
problems. The camera may also fail to capture an acceptable image
on account of there being inadequate lighting. Additionally, the
subject may defeat the camera by placing an object, such as his
hand, over the camera lens. Currently, there is no mechanism for
detecting such camera failures.
An example of such a system is an unattended automated postal kiosk,
which includes a digital camera. The postal kiosk includes user
interface, such as a touch screen display, by which a customer can
select a postal transaction type, e.g. Express Mail, Priority Mail,
etc., a scale, by which the system may determine the proper amount
of postage for the transaction, a payment acceptor, and a postage
dispenser. Federal Aviation Administration (FAA) regulations require
that the United States Postal Service obtain positive identification
from any person that mails a Priority Mail package weighing more
than one pound. A standalone kiosk can comply with FAA regulations,
and process Priority Mail requests, because it can take a picture
of every customer that attempts to mail such a package, and associate
the picture with the package. However, currently, the pictures taken
at the kiosk are not reviewed by a human unless the FAA requests
the picture associated with a particular Priority Mail piece mailed
from the kiosk. If there is a failure of the digital camera, then
there is a failure of security.
SUMMARY OF THE INVENTION
The present invention provides a method of and system for detecting
a digital camera failure. The system of the present invention captures
an image with the digital camera. The system compresses the image
into a compressed image file and compares the size of the compressed
image file with a predetermined file size. A small file size implies
that there is insufficient color differentiation in the image to
make the image usable. A large file size implies that there is extraneous
random noise in the image. Thus, according to the present invention,
a digital camera failure is indicated if the size of the compressed
image file is greater than a predetermined upper limit file size
or less than a predetermined lower file size limit. The upper and
lower limits are determined empirically. Additionally, the predominance
of one particular color in the image implies that the subject has
place an object, such as his hand, over the lens of the camera.
Accordingly, the system may also compare the number of pixels of
a predetermined color with the total number of pixels of the captured
image. A digital camera failure is indicated if the number of pixels
of the predetermined color is greater than a predetermined percentage
of the total number of pixels of the captured image.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a system according to the present
invention.
FIG. 2 is a flowchart of processing according to the present invention.
FIG. 3 is a flowchart of captured image analysis according to the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, and first to FIG. 1, a block diagram
of an unattended, postal kiosk system according to present invention
is designated generally by the numeral 11. The postal kiosk of the
present invention is adapted for self-service use by customers.
The postal kiosk is preferably housed as a unit in a suitable case.
The system of the present invention includes a central processing
unit (CPU) or processor 13 that is programmed according to present
invention to process postal transactions. A touch screen display
15 provides a user interface by which a customer can initiate transactions
and respond to prompts from processor 13. Touch screen display 15
is adapted to present information messages and selection choices
to the customer. As will be recognized by those skilled in the art,
alternative user interface devices, such as a display and keyboard
or keypad, or a display and pointing device, may be provided.
System 11 includes a digital camera 17 operably connected to processor
13. As is well known, digital camera 17 includes an optical lens
system and an electro- optical system for capturing digital images.
Digital camera 17 is positioned to capture an image of a customer
using touch screen display 15. Preferably, digital camera 17 is
positioned in the housing of the kiosk behind a transparent glass
or plastic protective barrier.
System 11 includes a scale 19 adapted for weighing an item to be
mailed. Scale 19 provides a digital weight output to processor 13.
Processor 13 is programmed to calculate the postage required to
mail an article of a particular weight according to a selected class
and to display weight and postage rate information on touch screen
display 15. As will be explained in detail hereinafter, processor
13 is also programmed to actuate digital camera 17 to capture an
image and perform security processing according to the present invention
if the user has selected Priority Mail and the item to be mailed
weighs more than one pound.
System 11 also includes a payment acceptor 21 and a postage dispenser
23, each operably connected to processor 13. Payment acceptor 21
preferably includes a currency/coin acceptor and a change machine,
for enabling a customer to make cash transactions, and a card reader,
for enabling a customer to make credit, debit, and ATM card transactions.
Suitable communications hardware and interfaces are provided for
card transactions. Postage dispenser 23 includes a stamp machine,
for dispensing standard denomination postage stamps, as well as
a printer device for printing special postage stickers and identifying
indicia for trackable items, such as Priority Mail packages.
Referring now to FIG. 2, there is shown a high level flowchart
of transaction processing according to the present invention. At
the start of a transaction, the system prompts the customer to select
a transaction type, at block 31, and waits for input. Preferably,
the system displays selection items such as First Class Mail, Priority
Mail, Express Mail, etc., on touch screen display 15. If, as determined
at decision block 33, the customer selects Priority Mail, the system
prompts the customer to place the item to be mailed on the scale,
at block 35. If the customer selects a transaction type other than
Priority Mail, the system performs other processing, as indicated
generally at block 37, and processing ends.
Referring again to block 35, after the customer has placed the
item on the scale, the system tests, at decision block 39, if the
item weighs more than one pound. FAA regulations require positive
identification of person who uses Priority Mail to mail an item
weighing more than one pound. If the item weighs less than one pound,
the system performs Priority Mail processing, as indicated generally
at block 41, and processing ends. If the Priority Mail item weighs
more than one pound, then the system actuates digital camera 17
to capture an image, at block 43. The system then analyzes the captured
image, as indicated generally at block 45. As will explained in
detail with respect to FIG. 3, image analysis according to the present
invention, determines if the digital camera has failed to capture
a usable image. After image analysis, the system tests, at decision
block 47, if the analysis is OK. If not, the system displays a message
reading "Unable to process transaction at this time" or
words to that effect, at block 49, and processing ends. The system
may report the camera failure to a servicing entity so that the
failure may be investigated and corrective action taken. If the
image analysis is OK, then the system completes the Priority Mail
transaction, at block 51.
Referring now to FIG. 3, there is shown a high level flowchart
of the image analysis of block 45 of FIG. 2. The system first performs
compression of the captured image file, preferably according t,o
the Joint Photographic Experts Group (JPEG) standard, at block 61.
The JPEG standard is well known to those skilled in the art. Generally,
the algorithm uses the discrete cosine transform (GCT) technique
to encode 8.times.8 blocks of pixels at a time. The coefficients
resulting from the GCT are quantized according to a quantization
table. Then, a process known as zig-zag ordering arranges the DCT
coefficients serially so that zero-value coefficients tend to be
together at the end of each block. Finally, the system performs
statistical coding, such as Huffman coding, to produce a compressed
image file.
According to the present invention, the quality of the image can
be inferred from the size, in bytes, of the compressed image file.
A small file size implies that there is insufficient color differentiation
in the image to make the image usable. A large file size implies
that there is excessive extraneous random noise in the image. Thus,
the system tests, at decision block 63, if the compressed image
file size is less than an empirically determined upper limit. If
not, image analysis returns "IMAGE NOT OK" to FIG. 2.
If the compressed image file size is less than the predetermined
upper limit, the system tests, at decision block 65, if the compressed
image file size is greater than an empirically determined lower
limit. Again, if not, the system returns "IMAGE NOT OK."
Preferable, after determining at decision blocks 65 and 67 that
the compressed image file size is between the predetermined upper
and lower limits, and if processing time permits, the system analyzes
the color values of the captured, uncompressed, image. A predominant
color of black or near black indicates that the subject placed an
object, such as his hand, over the camera lens, and the image is
assumed to be unusable. Thus, the system compares the number of
black pixels of the captured image file to the total number of pixels,
at block 67. If, as determined at decision block 69, the number
of black pixels is less than 40% of the total, the system returns
"IMAGE OK." If not, the system returns "IMAGE NOT
OK."
From the foregoing, it may be seen that the present invention provides
a quick and efficient method and system for detecting the failure
of digital camera. The system of the present invention is implemented
in software and thus requires no additional hardware. The computer
processing time required to achieve the bulk of the invention's
processing is minimal. The invention can detect a range of common
digital camera failures.
The invention has been illustrated and described with respect to
a presently preferred embodiment. Those skilled in the art, given
the benefit of the foregoing disclosure, will recognize alternative
embodiments. Certain features of the invention may be utilized or
implemented independent of other features. Accordingly, the foregoing
description is intended for purposes of illustration and not of
limitation. |