EP2070312A1 - Système de réduction de gigue due au mouvement de la main pour des caméras - Google Patents

Système de réduction de gigue due au mouvement de la main pour des caméras

Info

Publication number
EP2070312A1
EP2070312A1 EP07710242A EP07710242A EP2070312A1 EP 2070312 A1 EP2070312 A1 EP 2070312A1 EP 07710242 A EP07710242 A EP 07710242A EP 07710242 A EP07710242 A EP 07710242A EP 2070312 A1 EP2070312 A1 EP 2070312A1
Authority
EP
European Patent Office
Prior art keywords
gain
exposure
exposure time
mode
auto
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP07710242A
Other languages
German (de)
English (en)
Inventor
Shuxue Quan
Chinchuan Andrew Chiu
Xiaoyun Jiang
Jingqiang Li
Ying Xie Noyes
Kalin Atanassov
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Qualcomm Inc
Original Assignee
Qualcomm Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US11/534,993 external-priority patent/US8120658B2/en
Application filed by Qualcomm Inc filed Critical Qualcomm Inc
Publication of EP2070312A1 publication Critical patent/EP2070312A1/fr
Ceased legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/60—Control of cameras or camera modules
    • H04N23/68—Control of cameras or camera modules for stable pick-up of the scene, e.g. compensating for camera body vibrations
    • H04N23/682—Vibration or motion blur correction
    • H04N23/684—Vibration or motion blur correction performed by controlling the image sensor readout, e.g. by controlling the integration time
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/60—Control of cameras or camera modules
    • H04N23/68—Control of cameras or camera modules for stable pick-up of the scene, e.g. compensating for camera body vibrations
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/70—Circuitry for compensating brightness variation in the scene
    • H04N23/72—Combination of two or more compensation controls
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/70—Circuitry for compensating brightness variation in the scene
    • H04N23/73—Circuitry for compensating brightness variation in the scene by influencing the exposure time
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/70—Circuitry for compensating brightness variation in the scene
    • H04N23/76—Circuitry for compensating brightness variation in the scene by influencing the image signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N2101/00—Still video cameras

Definitions

  • This disclosure relates to digital picture processing and, more particularly, to a hand jitter reduction system for cameras.
  • Blirriness may be caused by hand jitter.
  • Hand jitter is caused by the movement of the user's hand when taking a digital picture with a camera. Even if the user is unaware of the movement, the hand may be continually moving. The movements are relatively small, but if the movements are large relative to the exposure time, the digital picture may be blurry. An object or person in the picture may appear to be moving. Blurriness may also be caused by an object/person moving when a picture is being taken. Blurriness may also be caused by limitations of the optical system used to capture the pictures.
  • a digital camera for example, one found in a mobile unit, takes a longer time to register a picture.
  • the longer exposure time increases the probability that the slight movements produced by the hand may lead to blurriness.
  • the longer exposure time increases the chance that the movement by the object/person may be large relative to the exposure time.
  • a camera system comprising a hand jitter reduction (hjr) reduction mode and normal mode may operate by multiplying an exposure time and a gain to generate an exposure time-gain product.
  • There may be a normal mode exposure time-gain product and an hjr mode exposure time-gain product.
  • the exposure time-gain product in normal mode of the normal exposure time and normal gain may be stored in table or used as needed.
  • the exposure time-gain product in hjr mode may be also stored in a table.
  • the exposure time-gain product in hjr mode may be produced by modifying (adding, subtracting, multiplying, or dividing) entries in the exposure time-product table (or entry) in normal mode.
  • a separate table may not necessarily be needed, but an equivalent exposure time-gain product in hjr mode may be needed to compare to the exposure time-gain product in normal mode.
  • parameters are changed to reduce the difference between the exposure-time-gain-product in hjr mode and the exposure time gain product in normal model.
  • an image sensor in a camera system is able to be above a minimum average light level, the difference may be reduced.
  • Operation of a camera in normal mode may be in response to a sensed light level being above a threshold.
  • the operation of a camera in the hjr mode may be selected by the user.
  • the hjr mode may be used in response to a sensed light level being lower than the threshold.
  • FIG. 1 is a block diagram illustrating one configuration of a digital imaging process.
  • FIG. 2 is a block diagram illustrating the functionality of one configuration of one front end image processing module in a digital image processing system .
  • FIG. 3 is a block diagram illustrating the functionality of another configuration of a front end image processing module in a digital image processing system.
  • FIG. 4A is a graph illustrating exposure time versus light level for normal mode.
  • FIG. 4B is a graph illustrating gain versus light level for normal mode.
  • FIG. 5A is a graph illustrating exposure time versus light level for hand filter reduction mode.
  • FIG. 5B is a graph illustrating gain versus light level hand jitter reduction mode.
  • FIG. 6 is a flowchart illustrating a method of generating modified auto-exposure parameters.
  • FIG. 8 is a flowchart illustrating the modification of auto-exposure parameters m a camera system in handjitter reduction mode.
  • FIG. 1 is a block diagram illustrating a digital imaging process suitable for a camera device integrated into a mobile unit.
  • the mobile unit may be a wireless phone, personal digital assistant (PDA), laptop computer, or any other mobile wireless device.
  • a lens (not shown) may be used to focus ann image onto an image sensor 102, in an image sensor module 104.
  • image sensor module 104 may have a memory for storing gain and exposure parameters.
  • Image sensor module 104 may also have a control driver for modifying gain and auto-exposure parameters.
  • image sensor module 104 may be coupled to an integrated circuit, such as a Mobile Station Modem (MSMTM), or other module which has a memory and/or control driver for storing and modifying gain and auto-exposure parameters.
  • MSMTM Mobile Station Modem
  • the image sensor 102 may be a charge-coupled device (CCD), a complimentary metal oxide semiconductor (CMOS) image sensor, or any other suitable image sensor.
  • CCD charge-coupled device
  • CMOS complimentary metal oxide semiconductor
  • an array of semiconductors may be used to capture light at different pixels of the image.
  • a color filter array (CFA) (not shown) positioned in front of the image sensor 102 may be used to pass a single color (i.e., red, green or blue) to each semiconductor.
  • the most common CFAs are RGB and CMYG patterns.
  • the image sensor module 104 may drive or control image sensor 102 to modify the gain, and or exposure time.
  • a preview mode may capture a series of frames produced by the image sensor 102.
  • the whole frame or a sub-part of the frame is referred to as an Image or interchangeably a picture.
  • the sequence of frames is also known as a stream.
  • the stream may be provided to a front- end image processing module 106 where they are de-mosaiced in order to obtain full RGB resolution as an input to the still image and video compressor 108.
  • statistics may be collected on frames that aid with the production of the digital picture. These statistics may be, but are not limited to, exposure metrics, white balance metrics, and focus metrics .
  • the front-end image processing module 106 may feed various signals, which help control the image sensor 102, back into the image sensor module 104.
  • the still image and video compressor 108 may use JPEG compression, or any other suitable compression algorithm.
  • An auto-exposure control module 110 may receive a value proportional to the light level being processed by the front-end image processing module 106, and compare it to a stored light target, in order to aid in at least one of the functions of the front-end image processing module 106. Images that are processed through the modules in front-end image processing module 106 are part of digital frames.
  • the stream may also be sent to a view finder which may be located in display module 112. In the preview mode, a preview decision from the display module 112 may be used in the control of the auto-exposure.
  • the preview mode in a mobile unit having a digital camera may be used in either a normal mode or a hand jitter reduction (hjr) mode.
  • the user may select the hjr mode (shown as hjr select in FlG. 1) through a user-interface either through a menu or manually.
  • Auto-exposure parameters such as gain auto-exposure time, frame rate and number of frames to process, may be determined within moments after the user presses the button to take a snapshot and produce a digital picture.
  • the collected statistics may be used to determine auto-exposure parameters used during the snapshot in both the normal mode and the hjr mode.
  • the image processing may be different between hjr mode and normal mode. Before the user presses the button the preview mode is processing images as it would in normal mode, even if the hjr mode has been selected.
  • FIG. 2 is a block diagram illustrating the functionality of one configuration of one front end image processing module 106a in a digital image processing system.
  • the front-end image processing module 106a may be used to compensate for differences between the responses of human visual system and sensor signals generated by the image sensor 102. These differences may be corrected using various processing techniques including, by way of example, black correction and lens rolilff 202, demosaic module 204, white balance and color correction 206, gamma adjustment 208, and color conversion 210.
  • black correction and lens rolilff 202 demosaic module 204
  • white balance and color correction 206 white balance and color correction 206
  • gamma adjustment 208 gamma adjustment 208
  • color conversion 210 color conversion
  • hand jitter control module 212 may be sent to hand jitter control module 212.
  • the various parameters from the auto-exposure control module may be fed into hand jitter control module 212.
  • Hand jitter control module 212 may serve multiple purposes. Hand jitter control module 212, may determine the image processing that takes place after the snapshot. Hand jitter control module 212 may detect the value of hjr select, and determine if hand jitter reduction (hjr) needs to be performed. Even though the user has selected hjr mode, hand jitter control module 212 may determine that image processing as is done in normal mode may take place.
  • Hand jitter control module 212 may determine that image processing in hjr mode take place. Generating a digital picture image processing in hjr mode may include capturing a single frame or multiple frames. If hand jitter control module 212 determines that multiple frames will be captured, after passing through hjr control module, the frames may be sent to noise reduction/frame registration module 214, along with a parameter which indicates how many frames may be processed by noise reduction/ frame registration module 214. If a single frame is to be processed, noise reduction may take place on the single frame through the use of a noise reduction module 215. Noise reduction module may be a bayer filter, or other similar filter.
  • noise reduction/ frame registration module 214 may buffer the number of frames, numf, specified by hand jitter control module 212, and perform frame registration on them. Depending on how many frames and the light level, the purpose of the multiple frame registration may serve the purpose of noise reduction and/or blur reduction. Multiple frame registration may be done by a frame registration module 216.
  • noise reduction/ frame registration module 214 may not be used, and the output from color correction module 210, for example, may be used, even though the user selected hjr mode.
  • a signal (sel) may be used to select which multiplexer 217 output to send to post-process module 218.
  • the output of post-process module 218 may be sent to still and image video compressor 108 and/or display module 112.
  • hand jitter control module 212 may also output other parameters: new auto-exposure frame rate (ae fr_new), new auto-exposure gain (ae gain_new), new auto-exposure time (ae time_new), and the number of frames to be processed (numf). These parameters may be sent to image sensor module 104 to control image sensor 102.
  • a digital gain may also be output by hand jitter control module 212 and may be applied at any module after the image sensor module 104. As an example the digital gain may be applied during the white-balance/color correction module 206.
  • pixels are normally described, sub-pixels, or multiple pixels may also be used as inputs into front-end image processing module 106a.
  • a sub-set of these image-components or other forms: RGB, and spatial-frequency transformed pixels may also be sent to a hand jitter control module, such as hand jitter control module 212.
  • a hand jitter control module such as hand jitter control module 212.
  • hand jitter control module 212 In FlG 3 hand jitter control module 212, noise reduction/ frame registration module 214, and multiplexer 217 have been moved and inserted in-between black correction and lens roll-off module 202, and demosaic module 204.
  • the normal mode and hand jitter reduction mode may be calibrated by creating at least one auto-exposure time-gain table.
  • An auto-exposure time-gain table may have an exposure time column and a gain column. An entry in the exposure-time column and an entry in the gain column may be multiplied to produce an exposure-time gain product.
  • Each row entry or index into an auto-exposure time-gain table may represent a light level value, that is, each light level may be mapped to an auto-exposure index into the auto-exposure time-gain table.
  • the auto-exposure time-gain table(s) may have various regions of operation, such, as those designated in FIG. 4A, FlG. 4B, FIG. 5A, and FIG. 5B. In all four figures (FIG.
  • FIG. 4A, FIG. 4B, FIG. 5A, and FIG. 5B there are four possible light level regions, R1, R2, R3, and R4 illustrated on the abscissa-axis. Separation of regions may be governed by different boundaries, boundary_a, boundary_b, and boundary_c.
  • the light level shown on the far left of the abscissa-axis starts out high and then decreases to low, as shown on the far right of the abscissa-axis.
  • the exposure, time-gain product, i.e., (exposure time)*(gain) in each region should aim to be non-decreasing. As such, decreases in either exposure time or gain may lead to increases of gain or exposure time.
  • the auto- exposure time-gain table(s) may be calibrated depending on the type of sensor(s), settings and/or properties of the camera.
  • the table(s) may also be calibrated using more than one frame rate.
  • the table(s) may be stored in a memory on an integrated circuit that does the main image processing, such as front-end image processing module 106 and still image and video compressor module 108.
  • the table(s) may also be stored in a memory not on an integrated circuit that does the main image processing. In both cases, whether on the same integrated circuit as the main image processing or not, the tables may be coupled to image sensor module 104.
  • FlG. 4A is a graph illustrating exposure time versus (detected) light level for normal mode
  • FIG. 4B is a graph illustrating gain versus (detected) light level for normal mode. Because the light level is high in region R1, the exposure time is short, i.e., a low value. Similarly, in region R1 , the gain is at a nominal value, i.e., lower relative to the other regions. For slow moving objects or when the movement of the user's hand is very small, i.e., on the order of 5ms, there may be minimal advantage to correcting for blur and/or noise reduction in region R1. Even if blur and/or noise reduction were to he performed, it may not be visible to the user's eye.
  • boundary_a lies around the point where the blur and/or noise reduction is visible to the user, i.e., the combination of exposure time and gain that allows the user to visibly see a blur and/or noise reduction.
  • Boundary_a which separates region R1 and region R2, may vary from user to user and/or camera to camera. Boundary_a may also be considered the threshold between image processing in normal mode and image processing in hjr mode.
  • the camera may operate at one frame rate, e.g. fr1.
  • fr1 the exposure time
  • the exposure time increases in region R1.
  • the exposure time may continue to increase in region R2 until the exposure time reaches a maximum value for frame rate1, fr1.
  • the gain shown in FIG. 4B
  • the gain may continue to increase until a pre-determined value set during calibration is at a point where there is an acceptable level of noise. If the gain increased to the maximum, the level of noise may not be acceptable for that given exposure time.
  • boundary_b may be designated as the point where the exposure time at frame rate1, fr1, is at a maximum and the gain is at a pre-determined value where there is an acceptable level of noise.
  • Boundary_b which separates region R2 and region R3, may vary from camera to camera.
  • the exposure time-gain product at the far right in region R2 may be near or the same as the exposure time-gain product at the far left in region R3. Since the exposure time is at a maximum, as shown at the far right in region R2, the frame rate may be lowered at boundary_b. The lowering of the frame rate, i.e., changing the frame rate from fr1 to fr2, allows an increase in the exposure time. The exposure time may reach the maximum (as shown in FlG. 4B in region R3) for the new frame rate, frame rate2, fr2. In order to preserve the continuity of the exposure time-gain product between region R2 and region R3, the gain in region R3 is lowered to offset the increase in exposure time.
  • the gain may increase until it reaches a maximum.
  • a digital gain may be applied, the gain used in normal mode is typically analog.
  • Boundary_c in normal mode, is the point where the analog gain reaches a maximum.
  • bo ⁇ ndary_c in normal mode the corresponding light level may he stored as a light target to be checked in hand jitter reduction mode.
  • Hand jitter reduction (hjr) mode may be calibrated by creating another auto- exposure time-gain table. Subtraction(s), addition(s), divisions) or multiplication(s) may be performed on the normal mode auto-exposure time-gain table entries to generate an "equivalent" auto-exposure time-gain table desired in the hand jitter reduction mode.
  • the characteristics in the columns (exposure time and gain) of the other auto-exposure time-gain table or "equivalent" auto-exposure time-gain table is illustrated by figures FIG. 5A and FIG. 5B.
  • FIG. 5A is a graph illustrating exposure time versus (detected) light level for hand jitter reduction mode.
  • FIG. 5B is a graph illustrating gain versus (detected) light level hand jitter reduction mode.
  • the goal is to aim to maintain the same exposure time-gain product as in normal mode.
  • [exposure time in the hjr mode] * [gain in the hjr mode] should aim to be the same as [exposure time in the normal mode] * [gain in the normal mode].
  • the gain and exposure time in hjr mode may be the same as in normal mode.
  • image processing that takes place in normal mode, in region R1 may also take place in region R1 while in hjr mode.
  • image processing takes place in hjr mode.
  • Image processing to reduce hand jitter takes place with modified auto-exposure parameters, while image processing that doesn't require the reduction of hand jitter takes place with unmodified auto-exposure parameters.
  • preview mode uses the characteristics and (unmodified) auto-exposure time and gain table is relative to the normal mode while in preview mode.
  • boundary_b may be determined by checking when the exposure time-gain product reaches the same value as the exposure time-gain product as in the normal mode.
  • the frame rate may be increased by an amount greater than frame rate fr2.
  • the frame rate is fr2 (a rate lower than fr1).
  • fr1 is 30 frames per second (fps)
  • frame rate fr2 is 15 fps
  • L is 15 fps.
  • increasing the frame rate from 15fps to 30fps allows the exposure time to be maximized in region R3 to the value that it was in region R2 for the normal mode.
  • the increase in exposure time in region R3, may lead to a decrease in gain in region R3.
  • the analog gain in region R3 may saturate, i.e., reach a maximum (as seen in the far right of region R3) prior to boundary_c.
  • a digital gain may be added, to the analog gain. The digital gain is illustrated at the bottom of FIG. 5B in between region R3 and region R4.
  • the light level, in normal mode at boundary_c, may be stored as a predetermined light target to be checked in hjr mode.
  • hjr mode if the light level is below that of the stored light target, it may be that there is not enough light for an image sensor 102 to produce a minimum average light level for an image sensor 102.
  • a minimum average light level may be determined by adding the light value (luma and/or chrominance) at each pixel and dividing by the total number of pixels.
  • Another way to compute the minimum average light level for an image sensor 102 is to discard in the computation all pixels which are below a certain threshold. For example, pixels below the value 10 are not used, and the remaining pixels (above the certain threshold) are used to compute the minimum average light level.
  • luma light values are used, although chrominance values may also be used. For illustrative purposes the luma value is discussed. In the hjr mode, if the luma value is below the predetermined luma (light) target, the light (luma) level will be in region R4.
  • the frame rate which in preview mode was fr2
  • the exposure time may be adjusted because of the reduced amount of light and may be increased.
  • the exposure time may be increased to the maximum allowable for frame rate fr2.
  • the digital gain is decreased at boundary_c, and may continue to Increase in region R4.
  • the exposure-time-gain product between normal mode and hjr mode is aimed to be the same. That is, the difference should be reduced to make the difference between the two as close as possible to zero.
  • an image sensor 102 may not be meeting the minimum average amount of light level.
  • a digital gain may be applied to increase the gain level in region R4.
  • FIG. 6 is a flowchart illustrating a method of generating modified auto-exposure parameters.
  • frames may be captured after a snapshot 600.
  • the last frames processed in preview mode may be stored in a memory. Capturing means that retrieval of frames from the memory may be used to produce a digital picture.
  • Capturing means that retrieval of frames from the memory may be used to produce a digital picture.
  • At current frame rates and memory storage capabilities on a mobile unit there may be less than ten frames in a memory after a snapshot. Although, not every frame in the memory may be needed when producing a digital picture. Typically, up to three captured frames that may be used in producing a digital picture.
  • the camera may be in hjr mode.
  • enter hjr mode 602 may precede capture frames after a snapshot.
  • enter hjr mode 602 is illustrated subsequent to capture frames after a snapshot.
  • the detected light level is associated with unmodified auto-exposure parameters from normal mode 604.
  • the unmodified gain and exposure time may be retrieved from memory at the detected light level 606.
  • Calculation of the exposure time-gain product in normal mode may be done by multiplying the exposure lime and gain from normal mode 608.
  • the exposure time-gain product in hjr mode may be calculated by modifying the auto-exposure parameters from normal mode.
  • These auto-exposure parameters may be gain, exposure time, and/or frame rate.
  • Auto exposure parameters may be modified to reduce the difference between the exposure time-gain product in hjr mode and the exposure time-gain product in normal mode 610.
  • the correspondence should be the same. However, because of potential calculation precision differences when multiplying and potential detected light levels being slightly different between hjr mode and normal mode, the correspondence may not be the same. It is sufficient, that the difference between the exposure time-gain product in hjr mode and normal mode be reduced as much as possible.
  • an image sensor 102 may not be meeting the minimum average amount of light level. Thus, it may not be possible to maintain the same exposure time-gain product in hjr mode as in normal mode.
  • a flowchart illustrating how to operate a camera system in normal mode and hand jitter reduction mode is in FIG. 7.
  • the first act is to capture frame(s) after a snapshot 700. Once captured, a check is performed to see if hjr mode has been selected. If hjr has not been selected, unmodified auto-exposure parameters may be passed to control the image sensor 704. These parameters may be, auto-exposure frame rate (ae fr), auto-exposure time (ae time), auto-exposure gain (ae gain), measured luma, and luma target. If hjr mode is selected, modification of auto- exposure parameters takes place if needed 706.
  • a check is performed to see if the light level is in region R1 708, i.e., in a region where the same (or nearly same) parameters are present in normal mode. If the light level is greater than the light level at boundary_a (i.e., the light level is in region R1), then unmodified auto-exposure parameters may be passed to control the image sensor 704. Even though hjr mode is selected, image processing in normal mode may take place. In a subsequent act, after the unmodified, auto-exposure parameters are passed to control the image sensor, processing of the digital picture may continue 710.
  • modified auto-exposure parameters may be, a new auto-exposure frame rate (ae fr_new), a new auto-exposure time (ae time_new), a new auto-exposure gain (ae gain_new), measured luma, and luma target.
  • the number of frames to process to generate a digital picture, numf may be checked 712. If numf is greater than one, multiple frames may be registered 714. Frame registration may compensate for motions (horizontal, vertical, or angular) between frames.
  • FIG. 8 is a flowchart illustrating the modification of auto-exposure parameters in a camera system in hand jitter reduction mode. Even though selection of hjr mode may have taken place, image processing in normal mode may still be used.
  • a check is performed by decision block 800, if the light level is greater than the light level at boundary_a, the number of frames to process to generate a digital picture, numf, is set to one 802, and image processing in normal is used. In this case, there was no modification of the auto-exposure parameters. If the light level is less than the light level at boundary_a, then image processing in hjr mode may be used. The number of frames to process to generate a digital picture, numf, is set to one 804. As illustrated in FIG.
  • the exposure time may be reduced by some amount M 806.
  • M may be, however, values at or around 50% have shown good results.
  • the gain may also increase by same amount K 808. Since the exposure time-gain product in hjr more aims to be maintain the exposure-time-gain-product in normal mode, values at or around 200% for K have shown to reduce hand jitter.
  • Selection of the minimum between the increased gain by K and the max (analog) gain 810 may be used if the increased gain exceeds the maximum analog gain of the linage sensor. It may also be used in a configuration where a digital gain is used in a region like R2.
  • the ratio of the increased gain by K and the new analog gain 812(ae_gain_new) may be compared with a constant C1.
  • C1 is related to the maximum analog gain of the sensor, and a typical value may be one.
  • the minimum between C1 and the ratio of the increased gain by K and the new analog gain is selected 814, and at the minimum value a digital gain may be applied.
  • a decision block 816 compares if the light level, is greater than the light level at boundary_b. If the light level is greater than the light level at boundary_b, then modification of auto-exposure parameters if needed 706 ends. If the light level is less than at boundary b, a decision block 818 compares if the light level is greater than the light level at boundary_c. If the light level is greater than at boundary_c, then the frame rate may increase by some amount L 820. As mentioned above, in region R3, in hjr mode the frame rate fr2 may be increased up to and including frame rate fr1. Thus, L may be an amount that adjusts the frame rate closer to and including frame rate fr1.
  • the number of frames to process a digital picture, numf may be set to two 822. If the light level is less than the light level at boundary_c, the new exposure time 824 and new gain 826 in hjr mode may be the same as that used in normal mode.
  • the ratio of the luma_target with the measured luma (i.e., average luma for the image sensor) 828 may be compared with, a constant C2.
  • the minimum selection 830 between the constant C2 and the ratio of the luma_target with the measured luma may produce a digital gain.
  • a typical value of two may be used, and may correspond two using the constant instead of the ratio when the measured luma in region R4 has dropped below half of the luma_target.
  • the techniques may improve removing blurriness from images with longer exposure times.
  • the techniques and configurations may also aid in the reduction of hand jitter for practically any digital device that takes pictures.
  • the techniques and configurations may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the techniques and configurations may be directed to a computer-readable medium comprising computer- readable program code (also may be called computer-code), that when executed in a device that takes pictures, performs one or more of the methods mentioned above.
  • the computer-readable program code may be stored on memory in the form of computer readable instructions.
  • a processor such as a DSP may execute instructions stored in memory in order to cany out one or more of the techniques described herein.
  • the techniques may be executed by a DSP that invokes various hardware components, such as multiplication of an exposure time and gain, to generate an exposure time-gain product.
  • the exposure time-gain product (s) disclosed may be implemented in one or more microprocessors, one or more application specific integrated circuits (ASICs), and one or more field programmable gate arrays (FPGAs), or some other hardware-software combination.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Studio Devices (AREA)
  • Exposure Control For Cameras (AREA)

Abstract

La présente invention concerne un système de caméra en mode normal et en mode de réduction de gigue due au mouvement de la main (hjr) qui peut comprendre la génération d'un premier produit de temps d'exposition-gain en multipliant le temps d'exposition en mode normal avec le gain en mode normal. Il peut en outre comprendre la modification du temps d'exposition en mode normal et du gain et la multiplication de ces paramètres modifiés afin de générer un second produit de temps d'exposition-gain pour un mode hjr qui réduit la différence entre le premier produit de temps d'exposition-gain et le second produit de temps d'exposition-gain. Afin de réduire la différence, la vitesse de défilement de film en mode normal peut être également modifiée. Le fonctionnement d'une caméra en mode normal peut survenir en réponse à un niveau de lumière capté étant au-dessus d'un seuil. Le mode hjr peut être sélectionné par l'utilisateur tandis que la caméra fonctionne. Le mode hjr peut être utilisé en réponse à un niveau de lumière capté étant inférieur au seuil.
EP07710242A 2006-09-25 2007-01-20 Système de réduction de gigue due au mouvement de la main pour des caméras Ceased EP2070312A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US11/534,993 US8120658B2 (en) 2006-01-19 2006-09-25 Hand jitter reduction system for cameras
PCT/US2007/060809 WO2008039551A1 (fr) 2006-09-25 2007-01-20 Système de réduction de gigue due au mouvement de la main pour des caméras

Publications (1)

Publication Number Publication Date
EP2070312A1 true EP2070312A1 (fr) 2009-06-17

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EP07710242A Ceased EP2070312A1 (fr) 2006-09-25 2007-01-20 Système de réduction de gigue due au mouvement de la main pour des caméras

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EP (1) EP2070312A1 (fr)
JP (2) JP5507251B2 (fr)
KR (1) KR101120966B1 (fr)
CN (1) CN101518054B (fr)
WO (1) WO2008039551A1 (fr)

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CN101518054A (zh) 2009-08-26
JP2012182806A (ja) 2012-09-20
KR101120966B1 (ko) 2012-03-05
JP2010504718A (ja) 2010-02-12
JP5612017B2 (ja) 2014-10-22
CN101518054B (zh) 2012-11-21
KR20090057461A (ko) 2009-06-05
WO2008039551A1 (fr) 2008-04-03

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