Samsung sensor patent application

Discussion in 'Samsung' started by RichA, Jun 4, 2008.

  1. RichA

    RichA Guest

    STAAS & HALSEY LLP
    SUITE 700, 1201 NEW YORK AVENUE, N.W.
    WASHINGTON
    DC
    20005
    US

    Assignee Name and Adress: Samsung Electronics Co., Ltd.
    Suwon-si
    KR

    Serial No.: 898373
    Series Code: 11
    Filed: September 11, 2007

    U.S. Current Class: 382/312
    U.S. Class at Publication: 382/312
    Intern'l Class: G06K 9/20 20060101 G06K009/20
    Foreign Application Data
    Date Code Application Number
    Nov 14, 2006 KR 10-2006-0112413
    Claims


    1. A high dynamic range image sensor comprising:a sensor which resets
    a pixel when the pixel has reached a saturation level;a storage unit
    which stores a number of times the pixel has been reset; anda
    measurement unit which measures a quantity of light received in the
    pixel using the number of times the pixel has been reset, which is the
    number of resets, and a quantity of charges remaining after the pixel
    is finally reset.

    2. The high dynamic range image sensor of claim 1, wherein the sensor
    senses whether the pixel has reached the saturation level using a
    trigger.

    3. The high dynamic range image sensor of claim 2, wherein the trigger
    is connected to an output port of a photodiode of the pixel.

    4. The high dynamic range image sensor of claim 1, wherein the storage
    unit stores the number of resets using at least one of a flip-flop, a
    Random Access Memory (RAM), and a counter.

    5. The high dynamic range image sensor of claim 4, wherein the number
    of resets stored in the storage unit is cleared when a new frame
    starts.

    6. The high dynamic range image sensor of claim 1, wherein:the storage
    unit includes at least one of a capacitor, a transistor, and a
    comparator, andwhen the pixel has reached the saturation level, the
    capacitor is fully charged, and the comparator eliminates an error due
    to a delayed discharge of the capacitor.

    7. The high dynamic range image sensor of claim 1, wherein the
    measurement unit measures the quantity of light received in the pixel
    during a period of one frame.

    8. A method of measuring charges in a pixel, the method
    comprising:resetting the pixel when the pixel has reached a saturation
    level;storing a number of times the pixel has been reset; andmeasuring
    a quantity of light received in the pixel using the number of times
    the pixel has been reset and a quantity of charges remaining after the
    pixel is finally reset.

    9. The method of claim 8, wherein the resetting of the pixel further
    comprises sensing whether the pixel has reached the saturation level
    using a trigger.

    10. The method of claim 9, wherein the trigger is connected to an
    output port of a photodiode of the pixel.

    11. The method of claim 8, wherein the storing of the number of times
    the pixel has been reset comprises storing the number of times the
    pixel has been reset using at least one of a flip-flop, a Random
    Access Memory (RAM), and a counter.

    12. The method of claim 11, wherein the number of times the pixel has
    been reset stored in the storage unit is cleared when a new frame
    starts.

    13. The method of claim 8, wherein:the storing of the number of times
    the pixel has been reset comprises storing the number of times the
    pixel has been reset using at least one of a capacitor, a transistor,
    and a comparator, andwhen the pixel has reached the saturation level,
    the capacitor is fully charged, and an error due to a delayed
    discharge of the capacitor is eliminated.

    14. The method of claim 8, wherein the measuring of the quantity of
    light received in the pixel comprises measuring the quantity of light
    received in the pixel during a period of one frame.

    15. At least one computer readable medium storing computer readable
    instructions that control at least one processor to implement the
    method of claim 8.

    16. A high dynamic range image sensor comprising:an image sensor
    having a pixel which receives a quantity of light and which resets the
    pixel when the pixel has reached a saturation level; anda measurement
    unit which measures the quantity of light received in the pixel using
    the number of times the pixel has been reset, and a quantity of
    charges remaining after the pixel is finally reset.
    Description


    CROSS-REFERENCE TO RELATED APPLICATIONS

    [0001]This application claims the priority benefit of Korean Patent
    Application No. 10-2006-0112413 filed on Nov. 14, 2006 in the Korean
    Intellectual Property Office, the disclosure of which is incorporated
    herein by reference in its entirety.

    BACKGROUND OF THE INVENTION

    [0002]1. Field of the Invention

    [0003]The present invention relates to a high dynamic range image
    sensor and a method and medium for measuring charges in a pixel, and
    more particularly, to a high dynamic range image sensor of resetting a
    pixel when the pixel reaches a saturation level and measuring charges
    in the pixel using the number of times the pixel has been reset,
    saturation values, and charge residues, and a method of measuring
    charges in a pixel.

    [0004]2. Description of the Related Art

    [0005]Image sensors for use in mobile devices, automobiles, or
    monitors, have dynamic ranges of approximately 60 dB. Such image
    sensors having a relatively limited dynamic range may not properly
    respond to a variation in luminance, suggesting that a large
    difference between bright and dark portions may result in a blurred
    image. Accordingly, a proper photographing operation may not be
    achieved.

    [0006]In particular, if a subject to be photographed is in a bright
    condition, pixels of an image sensor are saturated, which impedes a
    normal photographing operation.

    [0007]In a conventional complementary metal-oxide semiconductor (CMOS)
    image sensor, when a predetermined pixel receives high intensity light
    so that it reaches a saturation level and outputs a constant output
    voltage, a variation in output voltage is small with respect to an
    increase in light quantity, causing a problem of degradation in image
    quality. That is to say, if a particular pixel reaches a saturation
    level, it is not possible to normally measure an output voltage of the
    pixel for additional light quantity, which causes a reduction in
    dynamic range, ultimately resulting in degradation in performance of a
    camera module using the image sensor.

    [0008]FIG. 1 illustrates the structure and operation of a conventional
    image sensor.

    [0009]As shown in FIG. 1, a photodiode (PD) 11 includes a capacitor 13
    and an optical switch 15.

    [0010]First, if a pixel is reset, charges accumulate on the capacitor
    13 in operation 12.

    [0011]Then, the capacitor 13 starts discharging according to the
    quantity of light received in the pixel. In operation 14, if the pixel
    receives low intensity light, the discharging is performed slowly, and
    if the pixel receives high intensity light, the discharging is
    performed rapidly. In the case of a digital camera, for example, the
    discharging of a capacitor may be performed during a capture mode when
    photographing or a preview mode when focusing.

    [0012]FIG. 2 illustrates the output voltage of a pixel at a saturation
    level.

    [0013]Before a pixel reaches a saturation level, the output voltage of
    the pixel varies according to the quantity of light received in the
    pixel, and photographing is normally performed.

    [0014]However, if a capacitor is discharged by high intensity light
    received in a pixel before the pixel is reset, the pixel reaches
    saturation states 22 and 24 in which a variation in the output voltage
    according to the quantity of light additionally received in the pixel
    is very small, thereby undesirably degrading the quality of a captured
    image.

    SUMMARY OF THE INVENTION

    [0015]According to an aspect of the present invention, the present
    invention provides a high dynamic range image sensor and a method of
    extending a dynamic range to enable high dynamic range imaging.

    [0016]According to an aspect of the present invention, there is
    provided a high dynamic range image sensor including a sensor which
    resets a pixel when the pixel has reached a saturation level, a
    storage unit which stores a number of times the pixel has been reset,
    and a measurement unit which measures a quantity of light received in
    the pixel using the number of times the pixel has been reset, which is
    the number of resets, and a quantity of charges remaining after the
    pixel is finally reset.

    [0017]According to another aspect of the present invention, there is
    provided a method of measuring charges in a pixel, the method
    including resetting the pixel when the pixel has reached a saturation
    level, storing a number of times the pixel has been reset, and
    measuring a quantity of light received in the pixel using the number
    of times the pixel has been reset and a quantity of charges remaining
    after the pixel is finally reset.

    [0018]According to another aspect of the present invention, there is
    provided a high dynamic range image sensor including an image sensor
    having a pixel which receives a quantity of light and which resets the
    pixel when the pixel has reached a saturation level; and a measurement
    unit which measures the quantity of light received in the pixel using
    the number of times the pixel has been reset, and a quantity of
    charges remaining after the pixel is finally reset.

    [0019]According to another aspect of the present invention, there is
    provided at least one computer readable medium storing computer
    readable instructions to implement methods of the present invention.

    BRIEF DESCRIPTION OF THE DRAWINGS

    [0020]These and/or other aspects, features, and advantages of the
    invention will become apparent and more readily appreciated from the
    following description of exemplary embodiments, taken in conjunction
    with the accompanying drawings of which:

    [0021]FIG. 1 illustrates the structure and operation of a conventional
    image sensor;

    [0022]FIG. 2 illustrates the output voltage of a pixel at a saturation
    level;

    [0023]FIG. 3 illustrates the principle of resetting a pixel when the
    pixel is at a saturation level, according to an exemplary embodiment
    of the present invention;

    [0024]FIG. 4 is a block diagram of an image sensor according to an
    exemplary embodiment of the present invention;

    [0025]FIGS. 5 through 8 illustrate detailed diagrams of exemplary high
    dynamic range image sensors according to exemplary embodiments of the
    present invention;

    [0026]FIG. 9 is a diagram illustrating a flip-flop as an exemplary
    storage unit of outputting the number of times a pixel according to an
    exemplary embodiment of the present invention has been reset when the
    pixel reaches a saturation level a predetermined number of times; and

    [0027]FIG. 10 is a flow diagram illustrating a method of measuring the
    quantity of light received in a pixel according to an exemplary
    embodiment of the present invention.

    DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

    [0028]Reference will now be made in detail to exemplary embodiments of
    the present invention, examples of which are illustrated in the
    accompanying drawings, wherein like reference numerals refer to the
    like elements throughout. Exemplary embodiments are described below to
    explain the present invention by referring to the figures.

    [0029]The present invention may, however, be embodied in many
    different forms and should not be construed as being limited to
    exemplary embodiments set forth herein. Rather, these exemplary
    embodiments are provided so that this disclosure will be thorough and
    complete and will fully convey the concept of the invention to those
    of ordinary skill in the art.

    [0030]FIG. 3 illustrates a principle of resetting a pixel when the
    pixel is at a saturation level, according to an exemplary embodiment
    of the present invention.

    [0031]In a case where a particular pixel reaches a saturation level,
    an output voltage of the pixel may not be normally measured depending
    on the quantity of light, i.e., expressed as the quantity of charges,
    received in the pixel. To avoid this, the pixel is to be reset. For
    each pixel, there are two types of reset operation. In a first type of
    reset operation called a global reset operation, a pixel is reset upon
    initialization of a new frame. In this case, all pixels are
    concurrently recharged. In a second type of reset operation called a
    local reset operation, each pixel is recharged by triggering. In this
    case, the recharging states of each pixel may vary according to the
    quantity of light received in each pixel. In other words, some pixels
    may be recharged and some may not be recharged. In addition, some
    pixels may be recharged fast and some may be recharged slowly. The
    number of times the pixel has been reset (simply referred to
    hereinafter as "the number of resets") and the residual light quantity
    of the pixel are obtained, in order to measure the quantity of light
    received in the pixel even in an area where the pixel is saturated.

    [0032]As shown in FIG. 3, in the present invention, when a pixel
    reaches a saturation level, the pixel is reset a number of times 302,
    304, 306, and 308. In this case, since the quantity of light required
    for the pixel to reach the saturation level is determined, an
    integrated quantity of light received in the pixel can be measured by
    determining the number of resets. Preferably, the quantity of light
    received in the pixel can be expressed as follows:

    Quantity of Light Received in Pixel=SV*NRC+LIR

    [0033]where SV stands for a saturation value representing the quantity
    of light required for a particular pixel to reach a saturation level,
    NRC stands for a total number of resets, and LIR stands for a residual
    light quantity representing the quantity of light, i.e., the quantity
    of charges, remaining after the pixel is finally reset. These values
    may be measured for a single pixel during a period of one frame.

    [0034]In a first frame 310, for example, assuming that a saturation
    value is 32, the number of resets is 1, and a residual light quantity,
    that is, an output voltage level of the pixel after the pixel is reset
    is 10, the quantity of light received in the pixel is measured using
    the equation given above to obtain a total of 42 (32*1+10).

    [0035]Similarly, the quantity of light received in the pixel in a
    second frame 320 can be measured using the equation given above and
    the number of resets in a second frame 320, which is a known value,
    that is, 3.

    [0036]According to the present invention, a saturation value is stored
    in a pixel and a self-reset operation is performed in each pixel. By
    doing so, it is possible to overcome the problem with the prior art,
    that is, incapability of normally measuring an output voltage of a
    pixel at a saturation level. The present invention will now be
    described in greater detail through an exemplary embodiment.

    [0037]FIG. 4 is a block diagram of an image sensor (400) according to
    an exemplary embodiment of the present invention.

    [0038]The image sensor 400 includes a sensor 410, a storage unit 420,
    and a measuring unit 430.

    [0039]The sensor 410 senses whether the pixel has reached a saturation
    level or not. To this end, the sensor 410 determines whether an output
    voltage of the pixel is equal to or smaller than a predetermined
    threshold value.

    [0040]Here, in order to sense whether the pixel has reached a
    saturation level or not, a trigger may be connected to the output port
    of a photodiode of the pixel. If the output voltage of the pixel is
    equal to or smaller than a predetermined threshold value, charges of a
    capacitor of the photodiode of the pixel are all discharged,
    suggesting that the pixel has reached the saturation level.

    [0041]Therefore, the trigger transfers a reset signal to the pixel to
    reset the pixel. During this process, the capacitor of the photodiode
    is recharged. The sensor 410 measures the saturation value and the
    charge residue after the pixel is reset and outputs the same to the
    measuring unit 430, which will later be described.

    [0042]Since the saturated state of the pixel does not last throughout
    the process, it is possible to normally measure the output voltage of
    the pixel according to the quantity of light received in the pixel. In
    the conventional image sensor implemented such that a reset signal is
    externally applied to every frame, once a pixel is saturated, the
    pixel is kept at a saturated state until a new frame starts. In an
    exemplary embodiment of the present invention, however, when a pixel
    reaches a saturation level, the pixel is subjected to a self-feedback
    mechanism to be reset.

    [0043]The storage unit 420 stores the number of resets of the pixel.
    Preferably, the storage unit 420 may comprise a flip-flop as a memory
    device. For reference, the flip-flop is an example of a bistable
    multivibrator, that is, a device with two stable states. Since the
    flip-flop is capable of discriminating 1 from 0 and storing the
    discriminated values 1 and 0 therein, it is also called a binary value
    device. In the current exemplary embodiment, a JK or RS flip-flop is
    employed by way of example.

    [0044]If a select signal or reset signal is input, suggesting that a
    frame has expired, the flip-flop is reset. That is to say, if the flip-
    flop is reset, the stored number of resets of the pixel is cleared.

    [0045]In addition, the storage unit 420 has various devices including
    a RAM (e.g., DRAM; Dynamic Random Access Memory), a counter, a
    capacitor, a transistor, a comparator, and so on, connected thereto to
    measure the number of resets of the pixel and can be used as a storage
    device for storing the measured number of resets. Structures of
    exemplary high dynamic range image sensors will later be described in
    greater detail with reference to FIGS. 5 through 8.

    [0046]The measuring unit 430 receives the number of resets and the
    saturation value from the storage unit 420, and measures the quantity
    of light received in the pixel using the quantity of charges remaining
    after the pixel is finally reset. In this case, the measuring unit 430
    measures the quantity of light received in the pixel using the
    equation given above. As described above, the number of resets
    represents the total number of times the pixel has been reset, and the
    saturation value represents the quantity of light required for a
    particular pixel to reach a saturation level. In addition, the
    residual light quantity represents the quantity of light, i.e., the
    quantity of charges, remaining after the pixel has recently been
    reset. Therefore, the quantity of light received in the pixel can be
    measured even in a region where the pixel is saturated, thereby
    attaining enhanced image quality.

    [0047]Hereinafter, structures of exemplary high dynamic range image
    sensors will be described in detail with reference to FIGS. 5 through
    8.

    [0048]FIG. 5 is a detailed diagram of an exemplary high dynamic range
    image sensor according to an exemplary embodiment of the present
    invention.

    [0049]As shown in FIG. 5, a trigger 412 may be connected to the output
    port of a photodiode of a pixel, thereby determining whether an output
    voltage of the pixel is greater than or equal to a predetermined
    threshold value. The trigger 412 may be a modified version of a
    Schmitt trigger, which is widely used to sense whether or not the
    output voltage of a pixel is equal to or smaller than a predetermined
    threshold value. When the output voltage of the pixel is equal to or
    smaller than the predetermined threshold value, the trigger 412
    transfers a reset signal to the pixel to reset the pixel (502).

    [0050]The number of resets can be measured by the flip-flop 422 and
    then stored, and the flip-flop 422 provides the number of resets and
    saturation values to the measuring unit 430. The measuring unit 430
    measures the quantity of light received in the pixel using the number
    of resets and the saturation values received with charge residues Vout
    (504).

    [0051]In addition, if a select signal or a frame reset signal is
    input, suggesting that a frame has expired, the stored number of
    resets, which is stored in the flip-flop 422, is cleared.

    [0052]In addition to the flip-flop 422, a RAM (e.g., DRAM; Dynamic
    Random Access Memory) can be used as a memory device. Further, as
    shown in FIG. 6, when the pixel reaches a saturation level, the number
    of resets and saturation values may be output to the measuring unit
    430 using a capacitor 426 and transistors 424a and 424b. Here, in a
    case where the pixel has reached a saturation level, which is sensed
    by a charged state of the capacitor 426, it is possible to determine
    whether the pixel is saturated or not. That is to say, in a case where
    the capacitor 426 is fully charged, it is determined that the pixel
    has reached the saturation level. Based on the determination result,
    the number of resets of the pixel can be measured.

    [0053]As shown in FIG. 7, an error due to a delayed discharge of the
    capacitor 426 can be eliminated by additionally connecting a
    comparator 428 to the output port of the capacitor 426 shown in FIG. 6

    [0054]As shown in FIG. 8, a counter 427, instead of the flip-flop 422,
    may be connected to the output port of the capacitor 426, and the
    counter 427 may be used to measure the number of resets of the pixel
    by counting saturated pulses of the pixel. Here, the counter 427 may
    be either a synchronous counter or an asynchronous counter.

    [0055]FIG. 9 is a diagram illustrating a flip-flop as an exemplary
    storage unit of outputting the number of times a pixel according to an
    exemplary embodiment of the present invention has been reset when the
    pixel reaches a saturation level a predetermined number of times.

    [0056]As shown in FIG. 9, if a new frame starts, the number of resets
    stored in the flip-flop is cleared (910).

    [0057]After the pixel has reached a saturation level once, the first
    flip-flop F1 stores a saturation value 1 and then outputs the same to
    a measuring unit (430 of FIG. 4) (920). In the same manner, after the
    pixel has reached a saturation level twice, each of the first and
    second flip-flops F1 and F2 stores a saturation value 1 and then
    outputs the same to the measuring unit 430. Likewise, if the pixel has
    reached a saturation level n times, each of the first through nth flip-
    flops F1-Fn stores a saturation value 1 and then outputs the same to
    the measuring unit 430. Accordingly, the measuring unit 430 obtains a
    total number of resets of the pixel, which can be used in measuring
    the quantity of light received in the pixel.

    [0058]FIG. 10 is a flow diagram illustrating a method of measuring the
    quantity of light received in a pixel according to an exemplary
    embodiment of the present invention.

    [0059]Referring to FIG. 10 and FIG. 4, when the pixel has reached a
    saturation level, the sensor 410 transfers a reset signal to the pixel
    in operation S1002. Here, in order to sense whether or not the pixel
    has reached a saturation level, a trigger may be employed.

    [0060]In operation S1004, the storage unit 420 stores the number of
    resets of the pixel. Here, the storage unit 420 may be formed by at
    least one device among a flip-flop, a RAM, a counter, a capacitor, a
    transistor, a comparator, and so on, and the storage unit 420 measures
    the number of resets of the pixel or stores the same.

    [0061]Next, the measuring unit 430 measures the quantity of light
    received in the pixel using the number of resets, the quantity of
    light required for the pixel to reach a saturation level, and the
    quantity of charges remaining after the pixel is finally reset, in
    operation S1006.

    [0062]In addition to the above-described exemplary embodiments,
    exemplary embodiments of the present invention can also be implemented
    by executing computer readable code/instructions in/on a medium/media,
    e.g., a computer readable medium/media. The medium/media can
    correspond to any medium/media permitting the storing and/or
    transmission of the computer readable code/instructions. The medium/
    media may also include, alone or in combination with the computer
    readable code/instructions, data files, data structures, and the like.
    Examples of code/instructions include both machine code, such as
    produced by a compiler, and files containing higher level code that
    may be executed by a computing device and the like using an
    interpreter. In addition, code/instructions may include functional
    programs and code segments.

    [0063]The computer readable code/instructions can be recorded/
    transferred in/on a medium/media in a variety of ways, with examples
    of the medium/media including magnetic storage media (e.g., floppy
    disks, hard disks, magnetic tapes, etc.), optical media (e.g., CD-
    ROMs, DVDs, etc.), magneto-optical media (e.g., floptical disks),
    hardware storage devices (e.g., read only memory media, random access
    memory media, flash memories, etc.) and storage/transmission media
    such as carrier waves transmitting signals, which may include computer
    readable code/instructions, data files, data structures, etc. The
    computer readable code/instructions may be executed by one or more
    processors. The computer readable code/instructions may also be
    executed and/or embodied in at least one application specific
    integrated circuit (ASIC) or Field Programmable Gate Array (FPGA)

    [0064]In addition, one or more software modules or one or more
    hardware modules may be configured in order to perform the operations
    of the above-described exemplary embodiments.

    [0065]The term "module", as used herein, denotes, but is not limited
    to, a software component, a hardware component, a plurality of
    software components, a plurality of hardware components, a combination
    of a software component and a hardware component, a combination of a
    plurality of software components and a hardware component, a
    combination of a software component and a plurality of hardware
    components, or a combination of a plurality of software components and
    a plurality of hardware components, which performs certain tasks. A
    module may advantageously be configured to reside on the addressable
    storage medium/media and configured to execute on one or more
    processors. Thus, a module may include, by way of example, components,
    such as software components, application specific software components,
    object-oriented software components, class components and task
    components, processes, functions, operations, execution threads,
    attributes, procedures, subroutines, segments of program code,
    drivers, firmware, microcode, circuitry, data, databases, data
    structures, tables, arrays, and variables. The functionality provided
    for in the components or modules may be combined into fewer components
    or modules or may be further separated into additional components or
    modules. Further, the components or modules can operate at least one
    processor (e.g. central processing unit (CPU)) provided in a device.
    In addition, examples of a hardware components include an application
    specific integrated circuit (ASIC) and Field Programmable Gate Array
    (FPGA). As indicated above, a module can also denote a combination of
    a software component(s) and a hardware component(s). These hardware
    components may also be one or more processors.

    [0066]The computer readable code/instructions and computer readable
    medium/media may be those specially designed and constructed for the
    purposes of the present invention, or they may be of the kind well-
    known and available to those skilled in the art of computer hardware
    and/or computer software.

    [0067]As described above, the high dynamic range image sensor and the
    method and medium for measuring charges in a pixel provide according
    to the present invention provides at least the following advantages.

    [0068]First, since an error due to a delayed discharge can be
    eliminated, a delay due to multiple exposure operations is avoidable.

    [0069]Second, a reduction in the resolution of an image sensor can be
    reduced, and the image sensor can be readily used without changing the
    volume or configuration of the corresponding optical system.

    [0070]Third, the image sensor can be integrally formed in the
    production stage, and high-performance dynamic characteristics can be
    achieved.

    [0071]Although a few exemplary embodiments of the present invention
    have been shown and described, it would be appreciated by those
    skilled in the art that changes may be made in these exemplary
    embodiments without departing from the principles and spirit of the
    invention, the scope of which is defined in the claims and their
    equivalents.
     
    RichA, Jun 4, 2008
    #1
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  2. RichA

    Alan Browne Guest

    Smart idea.
     
    Alan Browne, Jun 5, 2008
    #2
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  3. Sounds similar to what I suggested here a couple of months ago, and was
    told that it was impossible......

    Cheers,
    David
     
    David J Taylor, Jun 5, 2008
    #3
  4. RichA

    Pete D Guest

    "David J Taylor"
    Just because there is a patent does not make it possible or worthwhile, just
    an idea.
     
    Pete D, Jun 5, 2008
    #4
  5. RichA

    RichA Guest

    Yes, Japanese companies are known for chasing red herrings....right?
     
    RichA, Jun 5, 2008
    #5
  6. RichA

    Bob Guest

    the idea makes sense on its own merits.
     
    Bob, Jun 5, 2008
    #6
  7. RichA

    TRoss Guest

    I see your skill with idioms is equal to your skill with cameras.
    'Chasing a red herring' is falling for a ruse, which makes no sense in
    this context. It's also what you're trying to get us to do.

    If you're gonna chase a critter, make it a wild goose. A better idioms
    describing futile endeavors would be 'running down a blind alley' or
    'herding cats'.

    FWIW, the Japan Patent Office has issued lots of patents that are
    dormant.

    If Samsung is developing a sensor based on this patent I suspect it
    would first be used surveillance and security cameras.

    TR
     
    TRoss, Jun 5, 2008
    #7
  8. RichA

    Paul J Gans Guest

    Is such a thing patentable? It is a technique that has been
    used with sensors connected to computer ports since forever.
    It was used on the old PDP-8 and early micros because they
    were small word length machines and could not accumulate
    a count directly -- and were too slow doing "multiple precision"
    which is what happens once the measurement is over.
     
    Paul J Gans, Jun 5, 2008
    #8
  9. RichA

    Pete D Guest

    Of course it does, does not mean it was exactly the same as what was
    mentioned "a couple of months ago"!

    Cheers.

    Pete
     
    Pete D, Jun 5, 2008
    #9
  10. RichA

    Alan Browne Guest

    What you wrote: ""You could empty the nearly-full wells /during/
    exposure rather than after the end of the exposure. I expect this is
    already patented! ""

    This was discussed ad nauseum. You can't "read" during the exposure.

    But you can add "counters" to the pixel sensor assigned to each pixel
    that count the saturation hits and clear the pixel on each hit.

    You were close, just not in the cup.

    Cheers,
    Alan
     
    Alan Browne, Jun 5, 2008
    #10
  11. "David J Taylor" <-this-bit.nor-this-
    bit.co.uk> wrote in
    Many people have had this idea. The basic idea sounds great, but in
    order to implement it properly, the system needs to be *very* precise in
    dealing with timing glitches, etc. In the first implementations I would
    expect to see far more noise in the highlights than expected, as is the
    case with any DR hack. There's going to be a lot more math involved than
    what one might first expect; for instance, does the RAW converter know,
    or does the comparator know what the absolute sensitivity of each pixel
    is?

    What happens with motion? With short burst flashes while a pixel is
    reseting? There's nothing like a real, deep pixel, and that is where
    super-low ISos and HR will see their real glory.
     
    John P Sheehy, Jun 6, 2008
    #11
  12. It makes sense as a general idea, but in order to make it transparent,
    there has to be no photon counting errors or blind periods for pixels while
    they are being reset. Any deviation in the comparator levels from actual
    pixel sensitivity will cause a lot of noise.
     
    John P Sheehy, Jun 6, 2008
    #12
  13. "empty" and "clear" sound similar to me. Obviously, you would have to
    count the number of times you had reset the pixel, so that you could use
    that count as part of the reported pixel value.

    Cheers,
    David
     
    David J Taylor, Jun 6, 2008
    #13
  14. Does the noise in the highlights matter that much? After all, it's where
    the photon noise is the greatest, and you do not need anything like the
    same numerical accuracy in representing the brighter pixels. It might
    provide a good result for specular highlights.

    I don't want super-low ISOs, thanks. 200-1600 ISO seems a good working
    range to me - for the sort of photos I take. But something which avoids
    the hard clipping at the top end would be nice (i.e. not a strong
    must-have). Personally, I don't fuss with RAW, as I take too many photos!

    Cheers,
    David
     
    David J Taylor, Jun 6, 2008
    #14
  15. RichA

    frederick Guest

    David J Taylor wrote:
    I think you may have that the wrong way around. Shot noise lives in
    shadows - not highlights.
     
    frederick, Jun 6, 2008
    #15
  16. Frederick,

    The amount of photon noise if proportional to the square root of the
    number of photons. So in the shadows, 100 photons for example, the photon
    noise is 10, and the signal-to-noise ration is 10:1. In the highlights,
    10,000 photons say, the noise is 100, and the SNR is 100:1. So, if the
    rest of the system is perfect, the SNR in the shadows is worse than the
    SNR in the highlights, which may be what you mean.

    However, as the photon-limited noise is the highlights is greater, the
    effect of a less accurate numerical representation is less for the
    highlights than for the shadows. If the error was 10 (for example), in
    the shadows the total noise would be 14 (noise adds as a power law), and
    this is significantly more noise than 10. In the highlights, though,
    adding a photon noise of 100 to an error noise of 10, produces a total
    noise of 100.5.

    Hence my reasoning that noise due to readout inaccuracy in the highlights
    may not matter as much.

    Would you agree?

    Cheers,
    David
     
    David J Taylor, Jun 6, 2008
    #16
  17. It's surprising what you can patent if you have good patent lawyers
    and stupid patent officials. IBM patented the use of gravity to take a
    card from one part of a computer card reader to another. In effect
    they patented card dropping as part of a card reading machine. So every
    other computer manufacturer either had to pay IBM a royalty or else
    move their cards around with motors, levers, air puffs, or whatever.
     
    Chris Malcolm, Jun 6, 2008
    #17
  18. RichA

    frederick Guest

    I don't think so. What is "photon limited noise"?
     
    frederick, Jun 6, 2008
    #18
  19. RichA

    ASAAR Guest

    Nothing odd about that - it's pretty much my working range as
    well. But if I had a camera that had a *usable* ISO range that
    extended up to or even beyond ISO 50,000, I'm sure that "the sort of
    photos I take" would no longer have 1,600 ISO as the upper limit of
    my working range. Think of all of the photographers that would love
    to no longer be denied photographic access to flash/tripod
    restricted venues (dark caverns, museums, art galleries) etc. Most
    cameras would hardly even *need* a built-in flash, and as a result,
    many of the indoor, flashless shots would end up looking much
    better! Question - before you got your DSLR, didn't most of "the
    sort of photos" you took encompass an ISO working range that had a
    much lower upper limit than ISO 1,600? :)
     
    ASAAR, Jun 7, 2008
    #19
  20. David J Taylor, Jun 7, 2008
    #20
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