Digital Camera Patent AbstractA system wherein already-existing computing and memory resources
in an electronic camera are used to process an image for printing.
Rather than duplicating, in printers, computing and memory resources
that are already in digital cameras, significant computing and memory
resources need exist only in the camera. A digital camera can support
many different printers, each with its own set of parameters such
as for example print size, pixel size, colorimetry, sensitometry,
and artifacts compensation. Printer parameters are uploaded from
the printer to the camera to provide a basis for image processing
specific to the associated printer; whereby compensation may be
done for variations in the printer characteristics which may occur
as a result of printer manufacturing variations, and further so
that compensation may be done for different media types which may
be installed in the printer.
Digital Camera Patent ClaimsWhat is claimed is:
1. A digital camera for use with a separate color printer having
predetermined characteristics, said camera comprising: a housing;
an image sensor adapted to capture analog image data; an analog-to-digital
converter adapted to convert the analog image data captured by the
image sensor to digital image data; an image processor adapted to
perform first processing and compression of the digital image data
to create a first-processed digital image file; digital memory in
the camera housing, a plurality of first-processed digital image
files from the image processor being stored in the digital memory;
and an interface to the separate color printer to which a digital
image file, which is selected from the digital memory, is applied,
wherein the image processor is adapted to perform second processing
on the selected digital image file before the selected digital image
file is applied to the interface.
2. A digital camera as set forth in claim 1 wherein color records
of the selected digital image file are converted to multi-tone values
during said second processing.
3. A digital camera as set forth in claim 2 wherein the multi-tone
values are determined using a predetermined number of density levels
provided by the separate color printer over the interface.
4. A digital camera as set forth in claim 3 wherein the multi-tone
values are determined using a predetermined density for each of
the density levels.
5. A digital camera as set forth in claim 1 wherein color records
of the selected digital image file are processed during said second
processing to provide ink limiting.
6. A digital camera as set forth in claim 5 wherein the ink limiting
is effected using type of printer, ink, and receiver media information
provided by the separate color printer over the interface.
7. A digital camera as set forth in claim 1 wherein: the separate
color printer uses four ink colors; and the color records of the
selected digital image file are converted to three image planes
and are color corrected during said second processing to provide
a set of color planes corresponding to each ink color of the separate
color printer.
8. A digital camera as set forth in claim 7 wherein the provided
set of color planes corresponding to each ink color of the separate
color printer include at least four colors.
9. A digital camera as set forth in claim 7 wherein the provided
set of color planes corresponding to each ink color of the separate
color printer include light cyan, dark cyan, light magenta, dark
magenta, yellow, and black.
10. A digital camera as set forth in claim 1 wherein: the separate
color printer uses four ink colors; the color records of the selected
digital image file are converted to three image planes; and sequentially
during said second processing: the three image planes are color
corrected to provide a set of color planes corresponding to each
ink color of the separate color printer, color records of the user-selected
digital image file are processed to provide ink limiting, and color
records of the user-selected digital image file are converted to
multi-tone values.
11. A digital camera as set forth in claim 1 wherein: the housing
includes a color image display for providing user-observable images
of first-processed digital image files stored in the removable digital
memory; and user controls coupled to the processor for selecting
a digital image file to be second processed by said image processor.
12. A digital camera as set forth in claim 1 wherein: the first
processing includes: interpolation to provide red, green and blue
image data values to provide red, green, and blue color planes,
color correction of the red, green, and blue color planes, and image
compression; and the second processing includes decompression of
the selected digital image file before the selected digital image
file is applied to the interface.
13. A digital camera as set forth in claim 12 wherein: the separate
color printer uses four ink colors; the color records of the user-selected
digital image file are converted to three image planes; and sequentially
during said second processing: the decompression of the selected
digital image file is effected, the three image planes and are color
corrected to provide a set of color planes corresponding to each
ink color of the separate color printer, color records of the user-selected
digital image file are processed to provide ink limiting, and color
records of the selected digital image file are converted to multi-tone
values.
14. A digital camera for use with a separate color printer having
predetermined characteristics, said camera comprising: a housing;
an image sensor adapted to capture analog image data; an analog-to-digital
converter adapted to convert the analog image data captured by the
image sensor to digital image data; an image processor adapted to
perform first processing and compression of the digital image data
to create a first-processed digital image file; digital memory removably
mounted in the camera housing, a plurality of first-processed digital
image files from the image processor being stored in the removable
digital memory; and an interface to the separate color printer to
which a digital image file, which is user-selected from the digital
memory, is applied, wherein the image processor is adapted to perform
second processing on the user-selected digital image file before
the user-selected digital image file is applied to the interface. Digital Camera Patent DescriptionFIELD OF THE INVENTION
The present invention relates to digital cameras and associated
printers for producing hardcopy images captured by such cameras.
BACKGROUND OF THE INVENTION
Typically, images captured by digital cameras must be processed
before they are printed. This processing is carried out in the printer.
Significant computing and memory resources are required to process
an image for printing. Accordingly, the printer must be provided
with expensive computing and memory resources. One solution known
in the prior art is to provide access to a stand-alone computer
that is connectable to both the camera and the printer, either directly
or by portable memory. This solution is inappropriate when the printer
is to be used in remote locations distanced from the computer.
DISCLOSURE OF THE INVENTION
According to a feature of the present invention, we have come to
appreciate that computing and memory resources, which already exist
in electronic cameras in order for the camera to capture, process,
compress, and store images, can be used to provide the computing
and memory resources that are required to process an image for printing,
particularly for printing on a portable, low cost ink jet printer.
It is an object of the present invention to provide a system wherein
already-existing computing and memory resources in an electronic
camera are used to process an image for printing. This is possible
because the existing computing and memory resources are otherwise
generally idle during the printing stage. Accordingly, it is a feature
of the present invention that, rather than duplicating, in printers,
computing and memory resources that are already in digital cameras,
the present invention provides for camera and printer systems wherein
significant computing and memory resources need exist only in the
camera. Because such resources are already required by the camera
in order to perform the camera functions, the cost of the camera
is not increased. Because the resources are no longer required in
the printer, the overall system cost is greatly reduced.
It is another object of the present invention to provide a digital
camera that can support many different printers, each with its own
set of parameters such as for example print size, pixel size, colorimetry,
sensitometry, and artifacts compensation. Accordingly, it is a feature
of the present invention to provide for uploading print drivers
and printer parameters to the camera to provide a basis for image
processing specific to an associated printer; whereby compensation
may be done for variations in the printer characteristics which
may occur as a result of printer manufacturing variations, and further
so that compensation may be done for different media types which
may be installed in the printer, in particular different types of
ink jet media installed in an ink jet printer.
According to another feature of the present invention, a digital
camera includes an image sensor and a lens adapted to focus a scene
onto the image sensor such that the image sensor captures analog
image data. An analog-to-digital converter converts the analog image
data captured by the image sensor to digital image data. An image
processor performs first processing and compression of the digital
image data to create a first-processed digital image file. A plurality
of first-processed digital image files from the image processor
are stored in removable digital memory. A digital image file, which
is user-selected from the digital memory, is applied to a separate
color printer having predetermined characteristics via an interface,
wherein the image processor is adapted to perform second processing
on the user-selected digital image file before the user-selected
digital image file is applied to the interface.
According to a preferred embodiment of the present invention, color
records of the user-selected digital image file are converted to
multi-tone values during the second processing.
According to another preferred embodiment of the present invention,
color records of the user-selected digital image file are processed
during the second processing to provide ink limiting. The ink limiting
is effected using type of printer, ink, and receiver media information
provided by the separate color printer over the interface.
According to another preferred embodiment of the present invention,
the separate color printer uses four ink colors, and the color records
of the user-selected digital image file are converted to three image
planes and are color corrected during said second processing to
provide a set of color planes corresponding to each ink color of
the separate color printer.
According to another preferred embodiment of the present invention,
a color image display provides user-observable images of first-processed
digital image files stored in the removable digital memory. User
controls are coupled to the processor for user-selecting a digital
image file to be second processed by the image processor.
According to another preferred embodiment of the present invention,
the first processing includes: interpolation to provide red, green
and blue image data values to provide red, green, and blue color
planes; color correction of the red, green, and blue color planes;
and image compression. The second processing includes decompression
of the user-selected digital image file before the user-selected
digital image file is applied to the interface.
The invention, and its objects and advantages, will become more
apparent in the detailed description of the preferred embodiments
presented below.
BRIEF DESCRIPTION OF THE DRAWINGS
In the detailed description of the preferred embodiments of the
invention presented below, reference is made to the accompanying
drawings, in which:
FIG. 1 is a schematic block diagram of a digital camera according
to the present invention;
FIG. 2 is a schematic block diagram of a digital printer according
to the present invention;
FIG. 3 is a schematic block diagram of a camera-printer system
according to another embodiment of the present invention;
FIG. 4 is a detailed block diagram of a digital camera according
to the present invention;
FIG. 5 is a flow diagram depicting the camera-related image processing
operations provided by the digital camera of FIG. 3 in the process
of capturing and storing images; and
FIG. 6 is a flow diagram depicting the printer-related image processing
provided by the digital camera of FIG. 3 in the process of reading
and printing images.
DETAILED DESCRIPTION OF THE INVENTION
The present description will be directed in particular to elements
forming part of, or cooperating more directly with, apparatus in
accordance with the present invention. It is to be understood that
elements not specifically shown or described may take various forms
well known to those skilled in the art.
Referring to FIG. 1, a digital camera 10 provides significant image
processing and memory resources to capture, process, compress, and
store images. An imager 12 includes an array of image sensors such
as, for example, light sensitive photoelements. Conventionally,
a complete image frame is available in digital form from imager
12, only for a short time interval. Thus, the captured image is
temporarily stored in raw form in a volatile memory 14. Various
image processing algorithms are stored in a program memory 16, and
are executed by an image processor 18 in order to process the image
data stored in volatile memory 14. For example, the image processing
algorithms may include all or some of the processes of image sensor
tone scale compensation, color filter array interpolation, color
space transformation, re-sizing, spatial filtering, and compression,
as will be described in greater detail later in reference to FIG.
5. The resulting processed image data is then typically stored in
a nonvolatile memory 20.
This stored image must be further processed prior to printing.
Such further processing may include some or all of the steps of
decompression, color space transformation into color planes that
coincide with the process colors of the particular printer, re-sizing,
rotation, and compensation for the printing process, as will be
described in greater detail later in reference to FIG. 6. In prior
art systems, this further processing has been effected by computing
and memory resources in the printer or in a stand-alone computer.
According to the present invention, this further processing is performed
using the resources which are already in camera 10. It is advantageous
to perform all of the processing using the resources in camera 10
in order to avoid the additional expense of including similar resources
in the printer. To effect such image processing in camera 10, the
camera is provided with a parameter memory 22 and a printer interface
24, both to be further described hereinafter.
Referring to FIG. 2, a printer 30 includes a camera interface 32,
an inexpensive simple processor 34, a media transport mechanism
36, an image memory 38, a program memory 40, and a marking apparatus
42. A processed image, received from camera 10 of FIG. 1 via interface
32, may be stored by printer 30 in image memory 38 for subsequent
printing by marking means 42 under the control of simple processor
34 and a program stored in program memory 40, or the processed image
may be printed immediately. Simple processor 34 need not be capable
of executing printer compensation algorithms.
Parameters, which may vary as a result of manufacturing variations
in the printer, may be measured by an external means 44 at the time
of manufacture. Said parameters may then be stored in a variable
parameter table 46, which is part of the printer. Camera 10 may
query printer 30 to establish whether the printer will perform compensation
for the variable parameters, or whether the camera should request
and accept the variable parameters from the printer, and subsequently
perform compensation for said variable parameters. The printer provides
both fixed parameters from a fixed parameter table 48 and variable
parameters from its variable parameter table 46 to the camera by
means of camera and printer interfaces 24 and 32, respectively.
The camera stores these parameters in local parameter memory 22.
When an image in either volatile memory 14 or nonvolatile memory
20 is selected for printing, image processor 18 processes the selected
image, using the fixed and variable parameters which are stored
in parameter memory 22, and transmits the processed image to the
printer by means of interfaces 24 and 32. Processing may include
all or part of the operations of image sensor tone scale compensation,
color filter array interpolation, decompression, color space transformation,
re-sizing, rotation, cropping, spatial filtering, and compensation
for the printing process, but is not limited to these specific operations.
In addition, parameters which can vary during printing may also
be transmitted by the printer to the camera during the printing
process and used by image processor 18 to further compensate the
image for printing process variations during the printing operation.
The parameters may include temperature, ink viscosity, measured
density, and any other parameters which are known to vary with the
specific printing process employed by the printer.
Further, parameters characteristic of particular media material
at media transport mechanism 36 may be determined by simple processor
34 over an interface 50 and transmitted to the camera. The media
parameters may include parameters which vary with media type and
parameters which vary between different batches of media due to
manufacturing variations. Thus, compensation for the media parameters
may be done by image processor 18 in the camera.
Any such media parameters, fixed parameters, and variable parameters
may be transferred from printer 30 to camera 10 by means of a removable
non-volatile memory cartridge 52 shown in FIG. 3. The memory cartridge
may also be used to transfer images between the camera and the printer.
As used herein, the phrases "camera interface and printer interface"
are intended to include cable connections, transferable memory,
radiation transmission (light, microwave, infrared, etc.), and other
forms of information transfer between components.
FIG. 4 is a block diagram showing portable digital camera 10 depicted
in more detail than was shown in FIG. 1. Digital camera 10 stores
images on a removable flash memory card 330, which is a specific
type of non-volatile memory 14 (shown in FIG. 1). Digital camera
10 includes a zoom lens 312 having zoom and focus motor drives 310
and an adjustable aperture and shutter (not shown). Zoom lens 312
focuses light from a scene (not shown) on image sensor 12. Image
sensor 12 may be, for example, a single-chip color CCD image sensor,
such as a Toshiba model TCD5603D CCD sensor, available from Toshiba
America Electronic Components, Irvine Calif. The model TCD5603D
sensor has approximately 1536 columns and 1024 rows of photoelements,
and uses the well-known Bayer color filter pattern. Other CCD or
CMOS image sensors, having various image array sizes and color filter
patterns, may alternatively be used.
Image sensor 12 is controlled by clock drivers 306. Zoom and focus
motors 310 and clock drivers 306 are controlled by control signals
supplied by a control processor and timing generator circuit 304.
The control processor and timing generator 304 receives inputs from
autofocus and autoexposure detectors 308 and controls a flash 302.
The analog output signal from image sensor 12 is amplified and converted
to digital data by the analog signal processing (ASP) and analog-to-digital
(A/D) converter circuit 316. The A/D converter may alternatively
be included a part of image sensor 12, particularly if a CMOS image
sensor is used. The digital data is stored in a DRAM buffer memory
318, which is a specific type of volatile memory 14 (shown in FIG.
1). The digital image data stored in DRAM buffer memory 318 is subsequently
processed by a processor 18 controlled by the firmware stored in
program memory 16, which can be provided by a flash EPROM memory
328. Flash EPROM memory 328 can be a single memory chip which can
also provide parameter memory 22.
The processed digital image file is provided to a memory card interface
324 which stores the digital image file on removable memory card
330. Removable memory cards are known to those skilled in the art.
For example, removable memory card 330 may be adapted to the Compact
Flash interface standard, such as described in the CompactFlash
Specification Version 1.3, published by the CompactFlash Association,
Palo Alto, Calif., Aug. 5, 1998. Alternatively, removable memory
card 330 can be adapted to the PCMCIA card interface standard, as
described in the PC Card Standard, Release 2.0, published by the
Personal Computer Memory Card International Association, Sunnyvale,
Calif., September 1991. Removable memory card 330 can also be adapted
to the well known secure digital (SD), solid state floppy disk card
(SSFDC) or Memory Stick formats. Other types of non-volatile digital
memory devices, such as magnetic hard drives, magnetic tape, or
optical disks, could alternatively be used to store the digital
images.
Processor 18 performs color interpolation followed by color and
tone correction, in order to produce rendered sRGB image data as
defined in IEC 61966-2-1 Multimedia systems and equipment--Color
measurement and management--Part 2-1: Color management--Default
RGB color space--sRGB available from the International Electrotechnical
Commission, Geneva, Switzerland. The rendered sRGB image data is
then JPEG compressed and stored as a JPEG image file on removable
memory card 330 using an JPEG/Exif version 2.1 image file as defined
in Digital Still Camera Image File Format Standard (Exchangeable
Image File Format for Digital Still Camera: Exif), version 2.1,
JBIDA-49-1998 available from the Japan Electronic Industry Development
Association, Tokyo, Japan. The JPEG/Exif image files can be utilized
by many different image capable devices, such as computers and imaging
kiosks.
Processor 18 also creates a "thumbnail" size image that
is stored in RAM memory 326 and supplied to color LCD image display
332, which displays the captured image for the user to review. Electronic
camera 300 is controlled by user controls 303, such as a series
of user buttons including a shutter release (e.g., capture button)
(not shown) which initiates a picture taking operation. The graphical
user interface displayed on color LCD image display 332 is controlled
by the user interface portion of the firmware stored in program
memory 16. The graphical user interface is also used to select images
for printing, and can optionally be used to select the number of
copies and the print layout (e.g. the number images printed on one
page). The images selected for printing may be immediately printed,
if digital camera 10 is connected to printer 30. If not, image processor
18 creates an "image utilization" file listing the image
to be printed, the number copies for each image, and the print size,
as described in commonly assigned U.S. patent application Ser. No.
08/977,382, filed by Parulski on Nov. 24, 1997, the disclosure of
which is herein incorporated by reference. This "image utilization"
file, which can conform to the well-known digital print order format
(DPOF) is stored on removable flash memory card 330 along with the
digital images captured by digital camera 10.
FIG. 5 is a flow diagram depicting the image processing operations
that are performed by image processor 18 in digital camera 10 in
order to process the images from image sensor 12 stored in DRAM
buffer memory 318.
The Bayer pattern color filter array data (block 500) which has
been digitally converted by A/D converter 16 is interpolated in
block 510 to provide red, green and blue (RGB) image data values
at each pixel location in order to provide complete RGB color planes.
Color filter array interpolation in block 510 can use the luminance
CFA interpolation method described in commonly assigned U.S. Pat.
No. 5,652,621, entitled "Adaptive color plane interpolation
in single sensor color electronic camera" to Adams et al.,
the disclosure of which is herein incorporated by reference. The
color filter array interpolation in block 510 can also use the chrominance
CFA interpolation method described in commonly assigned U.S. Pat.
No. 4,642,678, entitled "Signal processing method and apparatus
for producing interpolated chrominance values in a sampled color
image signal", to Cok, the disclosure of which is herein incorporated
by reference.
A color space transformation is applied to the interpolated RGB
color planes in order to provide color correction, prior to image
storage. The RGB color planes are color corrected in block 520 using,
for example, the 3.times.3 linear space color correction matrix
20 depicted in FIG. 4 of commonly assigned U.S. Pat. No. 5,189,511,
entitled "Method and apparatus for improving the color rendition
of hardcopy images from electronic cameras" to Parulski et
al., the disclosure of which is incorporated herein by reference.
The color correction matrix coefficients which are stored in program
memory 16 in digital camera 10 can be, for example: Rout=1.50 Rin-0.30
Gin-0.20 Bin Gout=-0.40 Rin+1.80 Gin-0.40 Bin Bout=-0.20 Rin-0.20
Gin+1.40 Bin
The color corrected color planes are tone corrected in block 530.
This tone correction 530 can use, for example, the lookup table
corresponding to FIG. 2 of U.S. Pat. No. 5,189,511 cited above.
This lookup table is stored in program memory 16 in digital camera
10. Alternatively, color correction image processing operations
520 and tone correction image processing operations 530 can be provided
by a three-dimensional lookup table (3D LUT). An example of such
a 3D LUT is described in commonly assigned U.S. patent application
Ser. No. 09/540,807 filed Mar. 31, 2000 in the names of Geoffrey
Woolfe et al., the disclosure of which is incorporated herein by
reference. The 3D LUT is more complex than the 3.times.3 matrix
and single-channel LUT approach described above. However, it allows
better control of color saturation. For example, it allows increased
color saturation for most memory colors without increasing the saturation
of flesh tone colors and near-neutral colors.
The image sharpening provided in block 540 of FIG. 5 can utilize
the method described in commonly assigned U.S. Pat. No. 4,962,419
('419 patent), entitled "Detail processing method and apparatus
providing uniform processing of horizontal and vertical detail components"
to Hibbard et al., the disclosure of which is incorporated herein
by reference.
The image compression provided in block 550 of FIG. 6 can use the
method described in commonly assigned U.S. Pat. No. 4,774,574 (the
'574 patent), entitled "Adaptive block transform image coding
method and apparatus" to Daly et al., the disclosure of which
is incorporated herein by reference.
The compressed image files are stored on removable flash memory
card 330 as Exif image files. After a series of images have been
taken and stored on removable memory card 330, removable memory
card 330 can optionally be inserted into a memory card reader in
the user's host computer (not shown) in order to transfer the images
captured by the digital camera to the host computer, where they
can be viewed, e-mailed via the Internet, etc. To print images without
using a host computer, an interface cable 342 can be used to connect
between printer interface 24 in digital camera 10 and the corresponding
camera interface in digital printer 30. Printer interface 24 may
conform to, for example, the well-know universal serial bus (USB)
interface specification. Alternatively, printer interface 24 may
conform to the RS-232 interface specification, the IEEE 1394 (Firewire)
interface specification, or other cable interface specifications.
Alternatively, the interface may utilize a wireless interface such
as the well-known IrDA (Infrared Data Association) interface or
an RF (radio frequency) interface such as the well-known Bluetooth
RF interface.
FIG. 6 is a flow diagram depicting the printer-related image processing
provided by image processor 18 in digital camera 10 in the process
of reading and printing images on an ink jet printer. The images
to be printed are selected by the user as described earlier. In
block 600, the image file to be printed is retrieved from non-volatile
memory 20 in FIG. 1, such as removable flash memory card 330 in
FIG. 4. If digital camera 10 compressed images prior to storage,
for example by creating the JPEG/Exif image files described earlier,
the image file is decompressed in block 605 to provide red, green
and blue (RGB) color planes. In block 610, each decompressed RGB
color plane is sharpened in order to compensate for the sharpness
degradation of the ink jet printing process. A preferred sharpening
algorithm uses the well-known unsharp masking technique to produce
a sharpened color plane Xs by creating a blurred version Xb of the
original decompressed color plane Xo, and then computing Xs=1+k(Xo-Xb)
where X is each of the R, G, and B color planes, and k is a gain
factor. Gain factor k can be a parameter stored in fixed parameter
table 48 in printer 30 for all printers of a given model, or alternately
in variable parameter table 46 for a particular printer, which is
measured for each batch of printers as they are manufactured. The
gain factor is provided from printer 30 to digital camera 10 by
means of camera and printer interfaces 24 and 32 respectively, when
printer 30 is connected to camera 10. The camera stores the gain
factor k in camera parameter memory 22.
The sharpened RGB color planes are color corrected in block 615.
The color correction block preferably uses a 3D LUT. The input to
the 3D LUT is the RGB color plane, and the output is, for example,
cyan, magenta, yellow, and black (CMYK) color planes corresponding
to the color inks used as the process colors for printer 30. This
3D LUT is preferably provided using the ICC profile format defined
by the International Color Consortium. The 3D LUT profile values
can be parameters stored in fixed parameter table 48 in printer
30 for all printers of a given model, or alternately in variable
parameter table 46 for a particular printer, which is measured for
each batch of printers as they are manufactured. The ICC profile
is provided from printer 30 to digital camera 10 by means of camera
and printer interfaces 24 and 32 respectively, when printer 30 is
connected to camera 10. The camera stores the ICC profile values
in camera parameter memory 22.
If printer 30 is an ink jet printer using more than four color
inks, the CMYK color planes are further processed in block 615 to
provide color planes corresponding to each ink. This processing
preferably uses ink rendering processing to convert a single color
plane (e.g. the cyan channel C) into two color planes (e.g. light
cyan Cl and dark cyan Cd). Therefore, the output of color correction
block 615 is set of color planes corresponding to the color inks
used in the inkjet printer, which may for example use light cyan,
dark cyan, light magenta, dark magenta, yellow, and black color
inks as the process colors.
In block 620, the color records are calibrated in order to correct
for variations in tone scale. These variations may be may be the
result of manufacturing variations in printer 10 or media (e.g.
ink jet head or paper receiver) used by the printer. The calibration
is provided by a one-dimensional lookup table applied to each color
plane. The lookup table can be provided by parameters stored in
variable parameter table 46 for a particular printer, which is measured
for printer 30 as it is manufactured. Alternatively, the lookup
table can be created by image processor 18 in digital camera 10
using parameters or settings provided by printer 30. The parameters
or settings can include, for example, data indicating the type of
media (e.g. ink jet head or paper receiver) used by the printer,
or data such as the ink viscosity, humidity, etc. The lookup tables,
parameters, or settings are provided from printer 30 to digital
camera 10 by means of camera and printer interfaces 24 and 32 respectively,
when printer 30 is connected to camera 10. The camera stores this
data in camera parameter memory 22.
In block 625, the calibrated color planes corresponding to the
inks of the inkjet printer are processed to provide ink limiting.
This processing reduces the amount of ink that is deposited on the
receiver media in high ink laydown areas. This is required in order
to minimize deglossing and ink bleeding problems that reduce the
image quality. It also reduces the stickiness, long drying time
and delamination problems caused by laying down too much ink. The
ink limiting step typically limits the total ink provided by all
ink color planes to a maximum of 2 to 3 times the maximum amount
of ink provided by a single color plane. The exact limit depends
on the combination of the printer, ink, receiver media, and, to
some extent, the humidity. To determine the appropriate limit to
make a print, the type of printer, ink, and receiver media can be
communicated from printer 30 to digital camera 10. In some embodiments,
ahumidity sensor in printer 30 can be used to sense the approximate
humidity. A corresponding humidity parameter can be communicated,
along with the type of printer, ink, and receiver media, from printer
30 to digital camera 10 by means of camera and printer interfaces
24 and 32 respectively, when printer 30 is connected to camera 10.
The camera stores this data in camera parameter memory 22.
In block 630, the color records corresponding to the process colors
of the ink jet printer are resized and rotated if necessary. This
converts the pixels captured by the digital camera (e.g. the 1536
columns.times.1024 rows) to the appropriate number of pixels required
by printer 30 in order to produce a selected image size. To perform
this conversion, the number of pixels per inch used by printer 30
is communicated to digital camera 10, when printer 30 is connected
to camera 10. The camera stores this data in camera parameter memory
22.
In block 635, the color records are converted to multi-tone values.
Multi-toning is the process of reducing the bit depth of the image
in a manner that reduces the spatial resolution while increasing
the density resolution. Multi-toning is required in ink jet printers
because the ink jet printers have few density levels (e.g. two density
levels corresponding to ink or no ink, or four density levels corresponding
to various ink drop sizes). Multi-toning using two density levels
is also known as half-toning. Multi-toning may be provided using
a variety of algorithms, such as the well-known "error diffusion"
and "blue noise dithering" algorithms. In order for image
processor 18 in digital camera 10 to provide multi-toning appropriate
for printer 30, the number of density levels, and the density of
each level, is provided by printer 30. More specifically, the density
levels for each multi-tone level are stored in fixed parameter table
48 in printer 30 for all printers of a given model. The density
levels are provided from printer 30 to digital camera 10 by means
of camera and printer interfaces 24 and 32 respectively, when printer
30 is connected to camera 10. The camera stores the density levels
in camera parameter memory 22.
In step 650, the multi-tone color records corresponding to the
inks used in printer 30 are communicated from digital camera 10
to printer 30 by means of camera and printer interfaces 24 and 32
respectively. Printer 30 produces an ink jet print using the multi-tone
color records by controlling the marking apparatus 42 and media
transport mechanism 36 using simple processor 34.
In an alternative embodiment, some or all of the printer parameters
are provided on a removable media, such as a floppy disk (not shown)
or removable flash memory card 330, rather than being stored in
fixed parameter table 48 or variable parameter table 46. The removable
media is provided along with printer 30, and is inserted into digital
camera 10 so that the parameters can be downloaded and stored in
parameter memory 22. In the case of a floppy disk, the disk may
be inserted into a separate host computer (not shown) and downloaded
to the camera using a computer interface. The computer interface
can use the same type of connection (e.g. USB, RS-232, IEEE 1394)
as printer interface 24. Alternatively, the parameters may be included
as part of a printer driver which performs all of the processing
described in relation to FIG. 6. In this case, the printer driver
firmware is downloaded from the removable media (supplied along
with printer 30) and stored in the program memory 16 of digital
camera 10.
In another alternative embodiment, some or all of the printer parameters,
such as an ICC profile appropriate for particular "printer
consumables" sold as a package, are provided as part of the
printer consumables package. The printer consumables package can
include, for example, printer receiver media (e.g. a quantity of
photo grade ink jet paper) and a replacement color ink jet head
for a particular type of printer. This printer consumables package
can be provided with a nonvolatile digital memory, such as an EPROM,
provided as part of the replacement color ink jet head. The parameters,
such as the ICC profile, can be read from the EPROM memory by the
simple processor 34 via the interface to the marking apparatus 42
when the color ink jet head is inserted into the printer 30, and
transferred to the digital camera 10 via the interface 32.
The invention has been described in detail with particular reference
to preferred embodiments thereof, but it will be understood that
variations and modifications can be effected within the spirit and
scope of the invention. |