CN1797166A - Method for controlling exposure system - Google Patents

Abstract

The invention is an exposure system controlling method, comprising the steps of: setting a target brightness value; setting several parameters such as range and step; inputting an exposure value (EV), and regulating by the range and step to obtain an exposure regulation value; by regulation factor, obtaining a new target brightness value in a table-look-up mode; by the set exposure value, measuring and obtaining a measured brightness value and by an exposure regulating flow, obtaining a regulated exposure value. In a video processor, the method replaces the known exposure calculating mode applying complex logarithm operation with basic logic operation, addition and subtraction operations, and other operations, so as to solve the problem of electric losses and bad executing speed.

Description

Method for controlling exposure system

Technical field

The present invention relates to a kind of method for controlling exposure system, solve public complex calculation power loss or the not good problem of execution speed with basic comparison operation.

Background technology

In the digital photography system, an Exposure Control Module (exposure control system) is one of key factor that influences the digital image quality of taking out, and the factor of other influence has the control and focusing control system (focus control) of white balance (whitebalance).And exposure control means the control of light-inletting quantity in shooting process, and with the brightness range of suitable control near real world in the human eye, accurate exposure control is in the important link of digital photography system.

Usually the digital photography system is distinguished with exposure value the brightness of context, 0 to 255 equal strength grade is arranged by the darkest to the highlights branch, the exposure of equal portions is controlled at and is called exposure value EV (Exposure Value) in the general use like this, this EV value includes three main controlling elements, as shutter speed (ShutterSpeed) T, f-number F (Aperture Number) and yield value (Gain) G, its pass is as formula 1:

$\mathrm{EV}={\log }_2\left(\frac{F^2}{T\×G}\right)...\left(1\right)$

It is described that known exposure control flow sees also Fig. 1, and step begins, and digital photographic arrangement is set a target brightness value (luminance) Y after carrying out photometry with photometric system (metering system) _Target(step S11); Set initial exposure value (step S12) afterwards with shutter speed, f-number and yield value decision; The amount of brightness measured value Y that input one is drawn by subject _Measure(step S13); Carry out formula 2 afterwards, borrow the amount of brightness measured value Y of subject _MeasureRatio with the target brightness value Ytargct of initial setting produces another exposure value (EV) (step S14) with logarithm operation and initial exposure value;

$\mathrm{EV}=\mathrm{EV}+{\log }_2\left(\frac{Y_{\mathrm{measure}}}{Y_{t\arg \mathrm{et}}}\right)...\left(2\right)$

Do you and judge that this exposure value is the new exposure value different with initial value? (step S15); If exposure value has change, then this exposure control is set at new exposure value (step S16), get back to above-mentioned exposure control flow with this new exposure value, and repeating step, if the last constant exposure value that gets, then this exposure control flow finishes, and promptly draws the EV value.

But known exposure value account form is used a logarithm (log) computing, the settling mode of typical hardware, logarithm operation is to be finished by the instruction of many complexity, for a simple control system or processor, as use portable digital products such as mobile phone, digital photographing/video camera, be not suitable, and have power loss or the not good problem of execution speed.In view of this, the present invention promptly proposes the method for controlling exposure system of an improvement at the processor that can carry out computings such as basic logic, addition subtraction multiplication and division.

Summary of the invention

The present invention is a kind of method for controlling exposure system, be the exposure value account form that in image processor, replaces complicated logarithm (logarithm) computing of known utilization, to solve power loss or the not good problem of execution speed with computings such as basic logic, addition subtraction multiplication and divisions.

One embodiment step of this method includes: set a target brightness value; Set the condition of comparison operation; Activate exposure compensating, then adjust this target brightness value; Set one first exposure value; Import an amount of brightness measured value of an object; Carry out the brightness value comparison operation of this amount of brightness measured value and this target brightness value; And draw one second exposure value, and be the comparison operation through repeatedly, if exposure value need not change, then this exposure control finishes.

Its exposure value method of adjustment includes: computing draws a brightness threshold value; Progressively change this section index and this phase index and adjust this brightness threshold value, borrow adjusted this brightness threshold value and brightness target value to make comparisons; Calculate adjusted exposure value, and draw this flag value; And adjusted exposure value is defined between a maximal value and a minimum value.

Description of drawings

Fig. 1 is the exposure system controlled step for communal technique;

Fig. 2 is exposure system control flow chart of the present invention;

Fig. 3 is the method for controlling exposure system first embodiment process flow diagram of the present invention;

Fig. 4 adjusts process flow diagram for method for controlling exposure system exposure of the present invention;

Fig. 5 adjusts process step for method for controlling exposure system first exposure of the present invention;

Fig. 6 adjusts process step for method for controlling exposure system second exposure of the present invention;

Fig. 7 is the method for controlling exposure system second embodiment process flow diagram of the present invention;

Fig. 8 adjusts process step for the exposure of method for controlling exposure system second embodiment of the present invention.

Embodiment

The present invention proposes a method for controlling exposure system of improveing for improving known complex calculation at the processor that can carry out computings such as basic logic, addition subtraction multiplication and division, promptly uses simple comparison operation to reach as the arithmetic capability of known utilization to counting method.

Exposure system control flow of the present invention as shown in Figure 2.

During beginning, set a target brightness value (step S21);

Then set the condition (step S22) of comparison operation;

Need to judge whether manual adjustment? if exposure compensating activates, then target brightness value needs to adjust, and can manually carry out; (step S23)

Adjust if desired, then adjust this target brightness value (step S24);

After adjusting or under the situation about originally promptly need not adjust, then set an initial exposure value (EV value) (step S25) according to the brightness value of setting by subject;

The amount of brightness measured value (step S26) that input one is measured by subject;

The brightness value of carrying out the target brightness value of this amount of brightness measured value and manual adjustment compares (step S27);

Comparative result need to judge whether new setting value thus? (step S28)

Set new exposure value if desired, then this exposure value is set among the substitution step S26 and compared computing (step S29) with the amount of brightness measured value;

Through comparison operation repeatedly, if exposure value need not change, can draw the new exposure value of a suitable present context, then this exposure control finishes.

In the above-mentioned exposure system control flow, only need a comparison operation, significantly improve the known complexity that needs logarithm operation, can apply in the microprocessor of simple digital equipment or on the chip of some special applications (Application Specific Integrated Circuit, ASIC).

Based on above-mentioned control flow, Fig. 3 is a most preferred embodiment of the present invention.

During beginning, preestablish a target brightness value Y _Target, and all about the parameter (step S301) of brightness settings;

The setting of parameter is as adjusting several sections (range) and stage (step), wherein the setting of section is convergence (convergence) speed that defines this Exposure Control Module, and the setting in stage is to define the convergent levels of precision, just, the present invention borrows section and stage definitions to go out the exposure value adjustment capability, and each section (range1, range2, ...) definition can non-definite value, and each stage (step1, step2 ...) and definition because this be the exposure adjustment of thin portion, then suggestion is definite value, but also not as limit (step S302);

Input exposure index value EVi, this compensation index value can be on the occasion of or negative value (step S303);

Do you judge that then EVi is 0? (step S304)

If EVi is not 0, the target brightness value of expression initial setting needs to adjust, and need table look-up to draw an adjustment factor g (EVi), and this adjusts factor is to calculate good deposit in (step S305) in this table in advance according to the section (range) and the setting value in stage (step);

And adjust factor g (EVi) whereby and draw a new target brightness value Y _Target, as formula 3, this table can experimental result draw, and promptly an exposure compensating index value EVi corresponding adjusts factor g, and then draws this target brightness value (step S306);

Y _target＝Y _target×g(EVi)..............................(3)

If EVi is 0, next step sets the initial exposure value of exposure system, (step S307) to represent not recompense initial target brightness value;

Then, promptly set initial exposure and set, several exposure controlling elements in the present embodiment include (step S308) such as shutter speed T, f-number F, analog-gain value AG and digital gain value DG at least;

And above-mentioned each controlling elements are to draw by look-up table by means of its corresponding pass to exposure value, and this table borrows formula 4 to calculate in advance, are not real-time operation when carrying out this flow process.

$\mathrm{EV}={\log }_2\left(\frac{F^2}{T\×\mathrm{AG}\×\mathrm{DC}}\right)...\left(4\right)$

According to each above-mentioned exposure settings value can measure an amount of brightness measured value Y _Measure, wherein take thing and can be image/chrominance separation (Luminance-Chrominance) specification, as YUV, or RGB three colour standards (step S309);

Comparison object brightness value and amount of brightness measured value judge that whether target brightness value is more than or equal to this amount of brightness measured value (Y again _Target＞=Y _Measure)? (step S310);

Adjust flow process if target brightness value, then carries out first exposure more than or equal to this amount of brightness measured value, see also Fig. 5 of the present invention (step S311);

Adjust flow process if target brightness value, then carries out second exposure less than this amount of brightness measured value, see also Fig. 6 of the present invention (step S312);

Whether adjust flow process by exposure and draw an adjusted exposure value and a flag value (Flag) of adjusting, this flag value is 0 or 1, be need to point out this adjusted exposure value generation time step S309 is surveyed an amount of brightness measured value Y again _Measure, promptly judge whether to need to upgrade exposure value with this flag value? (step S313);

As if judging through flag value, need set the exposure control setting (as flag value Flag=1) that this control stream becomes with adjusted exposure value, then get back to step S309, get an amount of brightness measured value (step S314) again;

If judge that through flag value exposure value or not need not change (as flag value Flag=0), then control finishes.

As through the described flow process of Fig. 3, wherein after the comparison step of target brightness value and amount of brightness measured value, need flow process through exposure value adjustment, as shown in Figure 4, at first, computing draws a rational brightness ratio threshold value Y _Th(step S41); Progressively change section index i again and phase index j adjusts this threshold value, borrow adjusted threshold value make comparisons with brightness target value again (step S42); Borrow each to adjust the factor,, calculate an adjusted exposure value, and draw a flag value (step S43) as section index i and phase index j, section value range1 and Stage Value step1 etc.; Adjusted exposure value is defined between the maximal value and minimum value of system's appointment (step S44).The practical embodiments of flow process sees also Fig. 5 and Fig. 6 is described and this exposure value is adjusted.

As described in the flow process of Fig. 3, if target brightness value is more than or equal to this amount of brightness measured value (Y _Target＞=Y _Measure), expression brightness needs bright by shadow, and draws a threshold value by the amount of brightness measured value, then carries out the adjustment flow process of first exposure value, present embodiment be with the first section value range1 and phase one value step1 as the foundation of adjusting threshold value in proper order, see also Fig. 5 of the present invention.

First exposure is adjusted flow process and is begun, and establishes starting condition, promptly establishes the stage (step) index j=0 (step S501);

I.e. starting condition whereby, and by amount of brightness measured value Y _MeasureDraw brightness ratio threshold value Y _Th[j]=Y _Measure* a[j], a[j wherein] be one to adjust the factor (step S502);

Because following the segmentation in the stage (step) in the section (range), exposure value increases, be subdivided into several stages in each section, exposure value then follows this stage or section progressively to adjust, this step judges that promptly whether initial phase index j is less than phase one value step1, this phase one, value step1 was the adjustment spacing value between each stage, and this Stage Value is one of controlled variable of this flow process (step S503);

If relatively, j is worth step1 less than the phase one, then phase index adds 1 (j=j+1) (step S504);

If j also is not less than phase one value step1, expression has enough comparison threshold values to produce, and then then carries out target brightness value Y _TargetWith brightness ratio threshold value Y _Th, set section (range) index i=0 during beginning, promptly establish this and be the initial value of section (step S505);

Be setting stage (step) index j=0 (step S506) again;

Judge whether target brightness value less than adjusted brightness threshold value, be about to brightness threshold value Y _ThWhether [j] progressively make to compare after the displacement adjustment Y with stage j again _Target＜(Y _Th[j]＜＜i)? wherein＜＜expression position is to left dislocation, and promptly adjust threshold value step by step, and compare (step S507) with target brightness value;

If not, promptly target brightness value then continues whole phase index j of secondment or section index i and reaches the adjustment threshold value greater than (or equaling) this threshold value.As phase index j=j+1 (step S521);

Judge that more whether new phase index j is still less than phase one value step1 (step S522); If j still less than phase one value step1, then gets back to step S507, the adjusted brightness threshold value of target brightness value and next displacement is made comparisons;

If phase index j is not less than this phase one value step1, then section index i is added 1, promptly i=i+1 adjusts section (step S523);

The section index i and the first section value range1 are compared, judge whether less than this first section value range1? (step S524); If this section index i, then carries out step S506 adjustment phase index j wherein less than the first section value range1, adjust brightness threshold value Y whereby _Th[j]; If this section index i also is not less than the first section value range1, then can make an exposure value EV and a flag value, make exposure value EV be made as EV-i, and to establish flag value be 1 (step S511);

Does target brightness value judge whether then that less than the brightness threshold value section index i and the phase index j of this moment is all 0 if among the above-mentioned step S507? (step S508);

If this moment, section index i and phase index j were all 0, then the exposure value of expression this moment need not to adjust, and sends a flag value and be 0 message, informs that step shown in Figure 3 need not to adjust exposure value, only need use that the EV value of setting gets final product (step S510) before adjusting;

If it is 0 situation that one of section index i and phase index j has non-, then draw the exposure value EV of an adjustment, and to establish flag value be 1 (step S509) with formula 5;

$\mathrm{EV}=\mathrm{EV}-\frac{i\&times;\mathrm{step}1+\mathrm{<figure-callout\; id="1"\; label="j\; step"\; filenames="A20041010416700201.png,A20041010416700231.png"\; state="\{\{state\}\}">j</figure-callout>}}{\mathrm{step}}...\left(5\right)$

Through above-mentioned each index i, after the judgement of j, if it is 0 situation that i and j one have non-, all the exposure value that draws and the maximal value and the minimum value of default must be made comparisons, and exposure value is controlled between maximal value and the minimum value, avoid the improper exposure of system, as judge that whether exposure value EV is greater than maximum exposure value EV _Max(step S512);

If than maximum exposure value EV _MaxAlso big, serve as to adjust post-exposure value (step S513) promptly with this maximal value;

Again with minimum exposure value EV _MinComparison judges whether less than EV _Min(step S514);

If than minimum exposure value EV _MinAlso little, then the minimum value with this default is the exposure value (step S515) of adjustment;

The last first exposure adjustment flow process thus draws an exposure value EV and who adjusts and informs whether the exposure system control flow need upgrade the flag value of exposure value.

As described in the flow process of Fig. 3, if target brightness value is less than this amount of brightness measured value (Y _Target＜Y _Measure), expression brightness needs dark by high light, and draw a threshold value by target brightness value, then carry out the adjustment flow process of second exposure value, present embodiment be with the second section value range2 that is different from the described controlled variable of Fig. 5 and subordinate phase value step2 as the foundation of adjusting threshold value in proper order, see also Fig. 6 of the present invention.

Second exposure is adjusted flow process and is begun, and establishes starting condition, promptly establishes the stage (step) index j=0 (step S601);

I.e. starting condition whereby, and by target brightness value Y _TargetDraw brightness ratio threshold value Y _Th[j]=Y _Target* a[j], a[j wherein] be one to adjust the factor (step S602);

Because following the segmentation in the stage (step) in the section (range), exposure value increases, during beginning, this step judges that promptly whether initial phase index j is less than subordinate phase value step2, this subordinate phase value step2 is the adjustment spacing value between each stage, with aforesaid phase one value step1 not necessarily identical (step S603);

If relatively, j is less than subordinate phase value step2, then phase index adds 1 (j=j+1), and get back to step S601 again a threshold value (step S604);

If j also is not less than subordinate phase value step2, expression has enough comparison threshold values to produce, and then then carries out amount of brightness measured value Y _MeasureWith brightness ratio threshold value Y _Th, set section (range) index i=0 during beginning, promptly establish this and be the initial value of section (step S605);

Moreover, setting stage (step) index j=0 (step S606);

Judge whether amount of brightness measured value Y _MeasureLess than adjusted brightness threshold value Y _Th, be about to brightness threshold value Y _ThWhether [j] progressively make to compare after the displacement adjustment Y with stage j again _Measure＜(Y _Th[j]＜＜i)? wherein＜＜expression position is to left dislocation, promptly adjusts threshold value step by step, compares (step S607) with the amount of brightness measured value again;

If not, promptly the amount of brightness measured value then continues whole phase index j of secondment or section index i and reaches the adjustment threshold value greater than (or equaling) this threshold value.As phase index j=j+1 (step S621);

Judge that more whether new phase index j is still less than subordinate phase value step2 (step S622); If j still less than subordinate phase value step2, then gets back to step S607, promptly the adjusted brightness threshold value of amount of brightness measured value and next displacement is made comparisons;

If phase index j is not less than this subordinate phase value step2, then section index i is added 1, promptly i=i+1 adjusts (step S623) with section i;

The section index i and the second section value range2 are compared, judge whether less than this second section value range2? (step S624); If this section index i, then carries out step S606 adjustment phase index j wherein less than the second section value range2, adjust brightness threshold value Y whereby _Th[j]; If this section index i also is not less than the second section value range2, then can draw an exposure value EV=EV+i and a flag value is 1 (step S611);

Does the amount of brightness measured value judge whether then that less than the brightness threshold value section index i and the phase index j of this moment is all 0 if among the above-mentioned step S607? (step S608);

If this moment section index i=0 and phase index j=0, then the exposure value of expression this moment need not to adjust, and promptly sends a flag value and be 0 message, informs that step shown in Figure 3 need not to adjust exposure value, only need use that the EV value of setting gets final product (step S610) before adjusting;

If it is 0 situation that one of section index i and phase index j has non-, then draw the exposure value EV of an adjustment, and to establish flag value be 1 (step S609) with formula 6;

$\mathrm{EV}=\mathrm{EV}+\frac{i\&times;\mathrm{step}2+j}{\mathrm{step}2}...\left(6\right)$

Through above-mentioned each index i, after the judgement of j, if it is 0 situation that i and j one have non-, all the exposure value that draws and the maximal value and the minimum value of default must be made comparisons, and exposure value is controlled between maximal value and the minimum value, avoid the improper exposure of system, as judge that whether exposure value EV is greater than maximum exposure value EV _Max(step S612);

If than maximum exposure value EV _MaxAlso big, serve as to adjust post-exposure value (step S613) promptly with this maximal value;

Again with minimum exposure value EV _MinComparison judges whether less than EV _Min(step S614);

If than minimum exposure value EV _MinAlso little, then the minimum value with this default is the exposure value (step S615) of adjustment;

The last second exposure adjustment flow process thus draws an exposure value EV and who adjusts and informs whether the exposure system control flow need upgrade the flag value of exposure value.

And Figure 7 shows that the second embodiment flow chart of steps of method for controlling exposure system of the present invention.Present embodiment is with each controlled variable, the first section value range1 of embodiment, the second section value range2, phase one are worth step1 and subordinate phase value step2 etc. as described above, being set as only needs a kind of section value and a kind of Stage Value, so can simplify the flow process of Exposure Control Module.

During beginning, preestablish a target brightness value Y _Target, and all about the parameter (step S701) of brightness settings;

The setting of parameter is as adjusting several sections (range) and stage (step), wherein the setting of section is convergence (convergence) speed that defines this Exposure Control Module, and the setting in stage is to define the convergent levels of precision, just, the present invention borrows section and stage definitions to go out the exposure value adjustment capability, in the present embodiment, each section (range) all is a definite value (step S702) with the stage (step);

Input exposure compensating index value EVi, this compensation index value can be on the occasion of or negative value (step S703);

Do you judge that then EVi is 0? (step S704)

If EVi is not 0, the target brightness value of expression initial setting needs to adjust, and need table look-up to draw an adjustment factor g (EVi), and this adjusts factor is to calculate good depositing in the table (step S705) in advance according to the section (range) and the setting value in stage (step);

And adjust factor g (EVi) whereby and draw a new target brightness value Y _Target, as formula 7 (step S706);

Y _target＝Y _target×g(EVi)...............................(7)

If EVi is 0, next step is an initial exposure value (step S707) of setting exposure system to represent not recompense initial target brightness value;

Then, promptly set initial exposure and set, several exposure controlling elements in the present embodiment include (steps 708) such as shutter speed T, f-number F, analog-gain value AG and digital gain value DG at least;

And above-mentioned each controlling elements borrow its corresponding relation to exposure value to draw by look-up table, and this table borrows formula 8 to calculate in advance, are not real-time operation when carrying out this flow process.

$\mathrm{EV}={\log }_2\left(\frac{F^2}{T\&times;\mathrm{AG}\&times;\mathrm{DG}}\right)...\left(8\right)$

According to each above-mentioned exposure settings value can measure an amount of brightness measured value Y _Measure(step S709);

Comparison object brightness value and amount of brightness measured value judge that whether target brightness value is more than or equal to this amount of brightness measured value (Y again _Target＞=Y _Measure)? (step S710);

If target brightness value is more than or equal to this amount of brightness measured value (Y _Target＞=Y _Measure), then set first group of parameter, as first luminance parameter=amount of brightness measured value (Ya=Y _Measure), second luminance parameter=target brightness value (Yb=Y _Target), sign parameter s ign=-1 (step S711);

On the other hand, if target brightness value less than this amount of brightness measured value (Y _Target＜Y _Measure), then set second group of parameter, as first luminance parameter=target brightness value (Ya=Y _Target), second luminance parameter=amount of brightness measured value (Yb=Y _Measure), sign parameter s ign=+1 (step S712);

Afterwards, proceed an exposure and adjust flow process, see also the present invention the 8th figure (step S713);

Adjust flow process by exposure and draw an adjusted exposure value and a flag value (Flag) of adjusting, this flag value is 0 or 1, judge whether to need to upgrade exposure value with this flag value? (step S714);

As if judging through flag value, be 1 as flag value, need to be set at new exposure control and set, and get back to step S709 with adjusted exposure value, get an amount of brightness measured value (step S715) again;

If judge that through flag value exposure value or not need not change (as flag value Flag=0), then control finishes.

Among the step S713 of above-mentioned second embodiment, this exposure is adjusted flow process as shown in Figure 8.

Exposure is adjusted flow process and is begun, and establishes starting condition, promptly establishes the stage (step) index j=0 (step S801);

I.e. starting condition whereby, and draw brightness ratio threshold value Y by the first luminance parameter Ya _Th[j]=Ya*a[j], a[j wherein] be one to adjust the factor, Ya is then different and different (step S802) according to step S710 condition shown in Figure 7;

Increase because exposure value follows the segmentation in the stage (step) in the section (range), during beginning, this step judges that promptly whether initial phase index j is less than a Stage Value step (step S803);

If relatively, j is less than Stage Value step, then phase index adds 1 (j=j+1), and get back to step S801 again a threshold value (step S804);

If j also is not less than Stage Value step, expression has enough comparison threshold values to produce, and then then carries out second luminance parameter Yb (Yb is different and different according to step S710 condition shown in Figure 7) and brightness ratio threshold value Y _ThComparison, set section (range) index i=0 during beginning, promptly establish this and be the initial value of section (step S805);

Moreover, setting stage (step) index j=0 (step S806);

Judge whether that the second luminance parameter Yb is less than adjusted brightness threshold value Y _Th, be about to brightness threshold value Y _ThWhether [j] progressively make to compare after the displacement adjustment Yb＜(Y with stage j again _Th[j]＜＜i)? wherein＜＜expression position is to left dislocation, promptly adjusts threshold value step by step, compares (step S807) with second luminance parameter again;

If not, promptly second luminance parameter then continues whole phase index j of secondment or section index i and reaches the adjustment threshold value greater than (or equaling) this threshold value.As phase index j=j+1 (step S821);

Judge that more whether new phase index j is still less than Stage Value step (step S822); If j then gets back to step S807 still less than Stage Value step, promptly the adjusted brightness threshold value of Yb and next displacement is made comparisons;

If phase index j is not less than this Stage Value step, then section index i is added 1, promptly i=i+1 adjusts (step S823) with section i;

Section index i and section value range are compared, judge whether less than this section value range? (step S824); If this section index i, then carries out step S806 adjustment phase index j wherein in section value range, adjust brightness threshold value Y whereby _Th[j]; If this section index i also is not less than section value range, then can draw an exposure value EV=EV+sign*i (sign is different and different according to step S710 condition shown in Figure 7, sign=-1 ,+1) is 1 (step S811) with a flag value;

Does Yb judge whether then that less than the brightness threshold value section index i and the phase index j of this moment is all 0 if among the above-mentioned step S807? (step S808);

If this moment section index i=0 and phase index j=0, then the exposure value of expression this moment need not to adjust, and promptly sends a flag value and be 0 message, informs that step shown in Figure 7 need not to adjust exposure value, only need use that the EV value of setting gets final product (step S810) before adjusting;

If it is 0 situation that one of section index i and phase index j has non-, then draw the exposure value EV of an adjustment, and to establish flag value be 1 (step S809) with formula 9;

$\mathrm{EV}=\mathrm{EV}+\mathrm{sign}\&times;\frac{i\&times;\mathrm{step}+j}{\mathrm{step}}...\left(9\right)$

Through above-mentioned each index i, after the judgement of j, if it is 0 situation that i and j one have non-, all the exposure value that draws and the maximal value and the minimum value of default must be made comparisons, and exposure value is controlled between maximal value and the minimum value, avoid the improper exposure of system, as judge that whether exposure value EV is greater than maximum exposure value EV _Max(step S812);

If than maximum exposure value EV _MaxAlso big, serve as to adjust post-exposure value (step S813) promptly with this maximal value;

Again with minimum exposure value EV _MinComparison judges whether less than EV _Min(step S814);

If than minimum exposure value EV _MinAlso little, then the minimum value with this default is the exposure value (step S815) of adjustment;

The last adjustment of exposure thus flow process draws an exposure value EV and who adjusts and informs whether the exposure system control flow need upgrade the flag value of exposure value.

In sum, the present invention is a method for controlling exposure system, is that the exposure value in exposure system is borrowed basic logical and mathematical operation, solves the logarithm operation of public complexity.

But the above only is a preferable possible embodiments of the present invention, non-so inflexible limit protection scope of the present invention, and therefore all utilizations instructions of the present invention and the icon content equivalent structure of doing changes, and all in like manner is contained in the claim of the present invention, closes and gives Chen Ming.

Claims (10)

1. method for controlling exposure system, it is characterized in that: this method step includes:

Set a target brightness value;

Set the condition of comparison operation;

Activate exposure compensating, then adjust this target brightness value;

Set first exposure value;

Import the amount of brightness measured value of an object;

Carry out the brightness value comparison operation of this amount of brightness measured value and this target brightness value; And

Drawing second exposure value, is this comparison operation through repeatedly, if exposure value need not change, then this exposure control finishes.

2. method for controlling exposure system as claimed in claim 1 is characterized in that: be that step with the brightness value comparison of carrying out this amount of brightness measured value and target brightness value judges whether the exposure settings value that needs are new.

3. method for controlling exposure system as claimed in claim 1 is characterized in that: be that step with the brightness value comparison of carrying out this amount of brightness measured value and target brightness value judges whether and need compare computing with new exposure settings value.

4. method for controlling exposure system, it is characterized in that: this method step includes:

Set a target brightness value;

Set parameters such as several sections and several stages;

Set an exposure value, and adjust according to this section, this stage and to draw an exposure adjusted value;

Measure an amount of brightness measured value;

Relatively this target brightness value and this amount of brightness measured value;

Carry out an exposure and adjust flow process; And

Draw an adjusted exposure value and a flag value.

5. method for controlling exposure system as claimed in claim 4 is characterized in that: the step that flow process is adjusted in this exposure includes:

Computing draws a brightness threshold value;

Progressively change this section index and this phase index and adjust this brightness threshold value, borrow adjusted this brightness threshold value and this brightness target value or brightness measurement value to make comparisons;

Calculate this adjusted exposure value, and draw this flag value; And

Should adjusted exposure value standard between a maximal value and a minimum value.

6. method for controlling exposure system as claimed in claim 4 is characterized in that: this exposure adjusted value then need borrow an adjustment factor to draw a new target brightness value with a look-up method if be not 0.

7. method for controlling exposure system as claimed in claim 4 is characterized in that: this flag value is 0 or 1, and whether be needs to survey once this amount of brightness measured value to upgrade this exposure value so as to pointing out again.

8. method for controlling exposure system as claimed in claim 4 is characterized in that: in the step of relatively this target brightness value and this amount of brightness measured value, if this target brightness value is more than or equal to this amount of brightness measured value, exposure value EV that then should exposure adjustment flow process is $\mathrm{EV}=\mathrm{EV}-\frac{i\&times;\mathrm{step}1+j}{\mathrm{step}1},$ Wherein i is the section index of this section, and step1 is the Stage Value in these several stages, and j is the phase index in this stage.

9. method for controlling exposure system as claimed in claim 4 is characterized in that: in the step of relatively this target brightness value and this amount of brightness measured value, if this target brightness value is less than this amount of brightness measured value, exposure value EV that then should exposure adjustment flow process is $\mathrm{EV}=\mathrm{EV}+\frac{i\&times;\mathrm{step}2+j}{\mathrm{step}2}$ Wherein i is the section index of this section, and step2 is the Stage Value in these several stages, and j is the phase index in this stage.

10. method for controlling exposure system as claimed in claim 4, it is characterized in that: after the step of relatively this target brightness value and this amount of brightness measured value, also set a parameter group, wherein parameter comprises first luminance parameter, second luminance parameter and symbolic parameter, in the step of relatively this target brightness value and this amount of brightness measured value, if target brightness value is more than or equal to this amount of brightness measured value, then set this first luminance parameter and equal this amount of brightness measured value, this second luminance parameter equals this target brightness value, and symbolic parameter is-1; If target brightness value less than this amount of brightness measured value, is then set this first luminance parameter and equaled this target brightness value, this second luminance parameter equals this amount of brightness measured value, and symbolic parameter is+1.

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