CN100433812C - Air-domain infinite impulse response filter automatic contrast limiting circuit and method thereof - Google Patents
Air-domain infinite impulse response filter automatic contrast limiting circuit and method thereof Download PDFInfo
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Abstract
The present invention relates to an automatic contrast limiting circuit and a method for air-domain infinite impulse response filters. The automatic contrast limiting circuit for air-domain infinite impulse response filters comprises an air-domain infinite impulse response filter for receiving an input signal and generating an air-domain infinite impulse response filtering value of the input signal, a peak value detector which is coupled with the air-domain infinite impulse response filter and is used for generating a peak value at a recording unit interval according to the air-domain infinite impulse response filtering value, and a contrast estimator which is coupled with the peak value detector to estimate the contrast according to the peak value and a preset critical limiting value. The present invention uses the air-domain infinite impulse response filter for generating an air-domain infinite impulse response filtering value corresponding to an input signal, uses the peak value detector in order to generate a peak value of an air-domain infinite impulse response filtering value at a preset recording unit interval, and then uses the contrast estimator in order to estimate a required contrast grade according to a peak value and a preset critical limiting value.
Description
Technical field
The present invention relates to a kind of auto contrast's restriction (Automatic Contrast Limiting, be called for short ACL) circuit and method thereof, particularly relate to a kind of spatial domain infinite impulse response filter (SpatialDomain Infinite Impulse Response Filter) auto contrast's restricting circuits and method thereof.
Background technology
In the various product of the correction of image, as TV, LCD Panel, digital camera, the personal computer camera (PC camera) of hardware aspect; The software aspect similarly is photo-shop and image processing software miscellaneous etc., all has the function of adjustment contrast (contrast), to improve the display quality of image frame.Usually the formula of adjusting the contrast use is as follows:
Yo＝Yi*contrast................(1)
Wherein, Yi is an input signal, and Yo is an output signal, and contrast is the contrast for setting then, and the input/output relation curve that different contrast is set as shown in Figure 1.
The contrast adjustment of early production all is to be adjusted voluntarily according to individual's hobby by the user, so, when at darker picture, it is bigger that the user may establish contrast, so that when the brightness of input signal uprises, saturated situation will take place, shown in the A of Fig. 1, B curve.Otherwise, when at brighter picture, then contrast may be established a little less than, cause the picture that can't know that display brightness is lower, shown in the E of Fig. 1, F curve.
Therefore desirable contrast settings method preferably can this intimate function of auto contrast's restriction (ACL) occur along with different input signals is dynamically adjusted.The principle that ACL adjusts contrast is not take place under the saturated situation, transfer big contrast as much as possible, therefore, except default threshold value (threshold of needs reference, t as Fig. 1) outside, needing a reference value relevant with input signal to decide in addition can be much with contrast settings.General design at present all is with the accurate position of average picture (average picture level, be called for short APL) as the reference value, just when the input signal of picture was brighter, the accurate position of average picture also can be higher, it is less that will establish contrast this moment, to avoid taking place saturated situation.Otherwise when the input signal of picture was dark, that then contrast is established was bigger, showed to obtain preferable picture.
Yet, use the accurate position of average picture as method with reference to value, its tangible a lot of low occasions of background luminance are impracticable, for example in outdoor, the basement at indoor, night, sewer, cavern, occasion such as in the ancient tomb, in the forest, because the relation that background luminance is very low, so all can use photography light to shine photographic subjects, so that the brightness of object is higher.At this moment, only account for the sub-fraction of full frame as object, the accurate position of then whole average picture is still very low, and the contrast of setting with reference to this accurate position of average picture also will be bigger, causes the picture supersaturation of object part, the demonstration of having blured picture on the contrary.
This shows, above-mentioned existing auto contrast's restricting circuits and method thereof still have many defectives, and demand urgently further being improved, in order to solve the defective of existing auto contrast's restricting circuits and method thereof, relevant manufacturer there's no one who doesn't or isn't seeks solution painstakingly, but do not see always that for a long time suitable design finished by development, this obviously is the problem that the anxious desire of relevant dealer solves.
Because the defective that above-mentioned existing auto contrast's restricting circuits and method thereof exist, the inventor is based on being engaged in this type of product design manufacturing abundant for many years practical experience and professional knowledge, actively studied innovation, in the hope of founding a kind of new spatial domain infinite impulse response filter auto contrast restricting circuits and method thereof, can improve general existing auto contrast's restricting circuits and method thereof, make it have more practicality.Through constantly research, design, and after studying sample and improvement repeatedly, create the present invention who has practical value finally.
Summary of the invention
The objective of the invention is to, overcome the defective that existing auto contrast's restricting circuits and method thereof exist, and provide a kind of new spatial domain infinite impulse response filter auto contrast restricting circuits and method thereof, technical problem to be solved is to make it produce a spatial domain infinite impulse response filter peak value in a record unit interval, and adjust contrast with reference to this peak value, and can improve quality of display pictures, thus be suitable for practicality more, and have the value on the industry.
The object of the invention to solve the technical problems realizes by the following technical solutions.A kind of spatial domain infinite impulse response filter auto contrast restricting circuits according to the present invention's proposition. be applicable to estimation one contrast, it comprises: a spatial domain infinite impulse response filter, in order to receiving an input signal, and produce a spatial domain infinite impulse response filter value of this input signal; One peak sensing device couples this spatial domain infinite impulse response filter, in order to according to this spatial domain infinite impulse response filter value, and produces a peak value in a record unit interval; An and contrast estimation device, couple this peak sensing device, in order to estimate this contrast according to this peak value and a default threshold value, wherein when this contrast estimation device judges that this peak value is higher than this default threshold value, setting this contrast is a preset value, otherwise sets this contrast for presetting threshold value divided by this peak value.
The object of the invention to solve the technical problems also can be applied to the following technical measures to achieve further.
Aforesaid spatial domain infinite impulse response filter auto contrast restricting circuits, wherein said spatial domain infinite impulse response filter comprises: one first multiplier in order to this input signal be multiply by one first factor value, produces one first output valve; One adder couples this first multiplier, in order to ask for this first output valve and one second output valve sum, produces this spatial domain infinite impulse response filter value; And one second multiplier, in order to this spatial domain infinite impulse response filter is on duty with one second factor value, produce this second output valve; Wherein this first factor value and this second factor value sum are 1.
Aforesaid spatial domain infinite impulse response filter auto contrast restricting circuits, wherein this preset value is 1.
Aforesaid spatial domain infinite impulse response filter auto contrast restricting circuits, wherein more comprise: a prime spatial domain infinite impulse response filter, in order to receiving a prime input signal, and produce a prime spatial domain infinite impulse response filter value of this prime input signal; An and prime peak sensing device, couple this prime spatial domain infinite impulse response filter, in order to according to this prime spatial domain infinite impulse response filter value, and in prime record unit interval, produce a prime peak value, with this input signal as this spatial domain infinite impulse response filter.
Aforesaid spatial domain infinite impulse response filter auto contrast restricting circuits, wherein said prime spatial domain infinite impulse response filter comprises: one first multiplier in order to this prime input signal be multiply by one first factor value, produces one first output valve; One adder couples this first multiplier, in order to ask for this first output valve and one second output valve sum, produces this prime spatial domain infinite impulse response filter value; And one second multiplier, in order to this prime spatial domain infinite impulse response filter is on duty with one second factor value, produce this second output valve; Wherein this first factor value and this second factor value sum are 1
The object of the invention to solve the technical problems also adopts following technical scheme to realize.According to a kind of spatial domain infinite impulse response filter auto contrast method for limiting that the present invention proposes, be applicable to estimation one contrast, it comprises the following steps: to receive an input signal, and produces a spatial domain infinite impulse response filter value of this input signal; According to this spatial domain infinite impulse response filter value, in a record unit interval, produce a peak value; And preset threshold value according to this peak value and and estimate this contrast, wherein when this peak value was higher than this default threshold value, setting this contrast was a preset value, otherwise set this contrast for presetting threshold value divided by this peak value.
The object of the invention to solve the technical problems also can be applied to the following technical measures to achieve further.Aforesaid spatial domain infinite impulse response filter auto contrast method for limiting, its this preset value is 1.
The present invention compared with prior art has tangible advantage and beneficial effect.By above technical scheme as can be known, in order to reach aforementioned goal of the invention, major technique of the present invention thes contents are as follows:
The invention provides a kind of spatial domain infinite impulse response filter auto contrast restricting circuits, be applicable to estimation one contrast.This spatial domain infinite impulse response filter auto contrast restricting circuits comprises: spatial domain infinite impulse response filter, peak sensing device and contrast estimation device.Wherein, the spatial domain infinite impulse response filter is in order to receive an input signal, and a generation spatial domain infinite impulse response filter value peak sensing device relevant with input signal couples the spatial domain infinite impulse response filter, in order to according to spatial domain infinite impulse response filter value, in the predetermined recording unit interval, produce a peak value.Contrast estimation device then couples the peak sensing device, in order to estimate contrast according to an aforementioned peak value and a default threshold value.
In the preferred embodiment of the present invention, its spatial domain infinite impulse response filter comprises: first multiplier, adder and second multiplier.Wherein, first multiplier is in order to multiply by input signal one first factor value, and produces first output valve.Adder couples first multiplier, in order to ask for first output valve and the second output valve sum, produces aforesaid spatial domain infinite impulse response filter value.Second multiplier is then in order to producing second output valve with one second factor value with aforesaid spatial domain infinite impulse response filter is on duty, and first factor value wherein and the second factor value sum are 1.
In the preferred embodiment of the present invention, when contrast estimation device judges that its peak value is higher than default threshold value, be 1 with contrast settings, otherwise set contrast for default threshold value divided by peak value.
Among the two dimensional application embodiment of the present invention, this spatial domain infinite impulse response filter auto contrast restricting circuits more comprises: prime spatial domain infinite impulse response filter and prime peak sensing device.Wherein, prime spatial domain infinite impulse response filter is in order to receiving a prime input signal, and a generation prime spatial domain infinite impulse response filter value relevant with the prime input signal.Prime peak sensing device then couples prime spatial domain infinite impulse response filter, in order to according to prime spatial domain infinite impulse response filter value, in predetermined prime record unit interval, produce a prime peak value, with input signal as aforementioned spatial domain infinite impulse response filter.
Wherein, prime spatial domain infinite impulse response filter comprises: first multiplier, adder and second multiplier.First multiplier produces first output valve in order to the prime input signal be multiply by one first factor value.Adder couples first multiplier, in order to ask for first output valve and one second output valve sum, produces aforesaid prime spatial domain infinite impulse response filter value.Second multiplier is then in order to producing second output valve with one second factor value with aforesaid prime spatial domain infinite impulse response filter is on duty, and first factor value wherein and the second factor value sum are 1.
The present invention provides a kind of spatial domain infinite impulse response filter auto contrast method for limiting in addition, is applicable to estimation one contrast, comprises the following steps: to receive an input signal, and a generation spatial domain infinite impulse response filter value relevant with input signal; According to spatial domain infinite impulse response filter value, in a record unit interval, produce a peak value; And preset threshold value according to aforementioned peak value and and estimate contrast.
Wherein, the step of estimation contrast is when peak value is higher than default threshold value, is 1 with contrast settings, otherwise sets contrast for presetting threshold value divided by peak value.
Via as can be known above-mentioned, the invention relates to a kind of spatial domain infinite impulse response filter auto contrast restricting circuits and method thereof, be to use the spatial domain infinite impulse response filter, produce the spatial domain infinite impulse response filter value relevant with input signal, use the peak sensing device, in the predetermined recording unit interval, to produce the peak value of spatial domain infinite impulse response filter value, use contrast estimation device then, estimate required contrast with foundation peak value and default threshold value.
In sum, spatial domain infinite impulse response filter auto contrast restricting circuits and method thereof that the present invention is special, it can produce a spatial domain infinite impulse response filter peak value in a record unit interval, and adjust contrast with reference to this peak value, and can improve quality of display pictures, thereby be suitable for practicality more.It has above-mentioned plurality of advantages and practical value, and in like product and method, do not see have similar structures design and method to publish or use and really genus innovation, no matter it all has bigger improvement on product structure, method or function, have technically than much progress, and produced handy and practical effect, and more existing auto contrast's restricting circuits and method thereof have the multinomial effect of enhancement, thereby be suitable for practicality more, and have the extensive value of industry, really be a new and innovative, progressive, practical new design.
Above-mentioned explanation only is the general introduction of technical solution of the present invention, for can clearer understanding technological means of the present invention, and can be implemented according to the content of specification, below with preferred embodiment of the present invention and conjunction with figs. describe in detail as after.
Description of drawings
Fig. 1 is the input/output relation curve synoptic diagram that shows that different contrast is set.
Fig. 2 is a kind of spatial domain infinite impulse response filter auto contrast restricting circuits schematic diagram of the preferred embodiment according to the present invention.
Fig. 3 is the spatial domain infinite impulse response filter auto contrast restricting circuits schematic diagram of the two dimensional application of the preferred embodiment according to the present invention.
Fig. 4 (a), Fig. 4 (b), Fig. 4 (c) show different input signals and peak value output waveform figure respectively.
Fig. 5 (a), Fig. 5 (b) show different example picture views respectively.
200,300: spatial domain infinite impulse response filter auto contrast restricting circuits
210,310: the spatial domain infinite impulse response filter
211,212,311,312: multiplier
213,313: adder
220,320: the peak sensing device
250: contrast estimation device
Embodiment
Below in conjunction with accompanying drawing and preferred embodiment, to spatial domain infinite impulse response filter auto contrast restricting circuits and its concrete structure of method, method, step, feature and the effect thereof that foundation the present invention proposes, describe in detail as after.
Seeing also shown in Figure 2ly, is a kind of spatial domain infinite impulse response filter auto contrast restricting circuits schematic diagram of preferred embodiment of the present invention.This spatial domain infinite impulse response filter (Spatial DomainInfinite Impulse Response Filter) auto contrast limits (Automatic ContrastLimiting, be called for short ACL) circuit 200, it comprises: spatial domain infinite impulse response filter 210, peak sensing device 220 and contrast estimation device 250.Wherein, spatial domain infinite impulse response filter 210 comprises first multiplier 211, adder 213 and second multiplier 212.
As shown in the figure, first multiplier 211 multiply by the first factor value a with the input signal that receives, and produces first output valve, and inputs to an input of adder 213.Second multiplier 212 is on duty with the second factor value 1-a with the spatial domain infinite impulse response filter of adder 213 outputs, produce second output valve, and input to another input of adder 213, set the first factor value a herein and the second factor value 1-a sum is 1, for example work as a=0.1, then 1-a=0.9.So adder 213 can calculate obtain 10 up-to-date input signal and 90 percent past accumulation input signal and, produce and the relevant spatial domain infinite impulse response filter value of input signal in past.
This spatial domain infinite impulse response filter value will input to peak sensing device 220, so that peak sensing device 220 can produce a peak value according to spatial domain infinite impulse response filter value in the booking situation unit interval that for example is a scan line.Contrast estimation device 250 then couples peak sensing device 220, presets threshold value t in order to the peak value and of foundation peak sensing device 220 outputs and estimates contrast.Its evaluation method is when being higher than default threshold value t when peak value, the expression input signal has big brighter zone, should not increase the contrast of picture at this moment, thus be 1 with contrast settings, to avoid taking place saturated and situation distortion.In addition when peak value was lower than default threshold value t, the expression input signal was dark partially, should increase this moment picture to recently strengthening the definition of image, be to preset threshold value t so set contrast divided by peak value.
Seeing also shown in Figure 3ly, is the spatial domain infinite impulse response filter auto contrast restricting circuits schematic diagram of the two dimensional application of preferred embodiment of the present invention.This spatial domain infinite impulse response filter auto contrast restricting circuits 300, except the spatial domain infinite impulse response filter 210, peak sensing device 220 and the contrast estimation device 250 that comprise Fig. 2, more comprise prime spatial domain infinite impulse response filter 310 and prime peak sensing device 320.Wherein, prime spatial domain infinite impulse response filter 310 same comprising: first multiplier 311, adder 313 and second multiplier 312, its function all is same as first multiplier 211, adder 213 and second multiplier 212, so that can produce the spatial domain infinite impulse response filter value of prime.
The resolution (resolution) of supposing the input picture is 1024 * 768 o'clock, and then prime spatial domain infinite impulse response filter 310 and prime peak sensing device 320 can in the booking situation unit interval of totally 1024 display dot, produce a peak value at each scan line.Spatial domain infinite impulse response filter 210 and peak sensing device 220 then can in the booking situation unit interval of totally 768 scan lines, produce a peak value, so that contrast estimation device 250 can be estimated contrast according to this at each picture.Certainly, as have the knack of this skill person and should know, as long as mode is analogized and come sequential circuit according to this, spatial domain then of the present invention infinite impulse response filter auto contrast restricting circuits is also applicable to three-dimensional or more high-dimensional application.
In sum, can conclude a kind of spatial domain infinite impulse response filter auto contrast method for limiting, be applicable to estimation one contrast.This spatial domain infinite impulse response filter auto contrast method for limiting comprises the following steps: to receive an input signal, and a generation spatial domain infinite impulse response filter value relevant with input signal; According to spatial domain infinite impulse response filter value, in a record unit interval, produce a peak value; And preset threshold value according to aforementioned peak value and and estimate contrast.
Wherein, when peak value is higher than default threshold value, be 1 with contrast settings, to avoid taking place saturated and situation distortion.When peak value is lower than default threshold value, set contrast for default threshold value divided by peak value, to strengthen the definition of image.
Below will consult Fig. 4 and shown in Figure 5, illustrate that the effect of a kind of spatial domain infinite impulse response filter auto contrast restricting circuits of the present invention and method thereof compares.In the oscillogram of the (a) and (b) of Fig. 4, (c), transverse axis is represented the booking situation unit interval, and the longitudinal axis is represented the brightness of input signal S.The accurate position of the average picture of the input signal S of 3 waveforms (average picture level wherein, be called for short APL) be the same, when setting contrast with reference to the accurate position of average picture with existing prior art method, its result is not that (a) waveform will take place will disappear than the bright area profile saturated causing, exactly (b) comparison of wave shape spend low cause not obvious than the dark areas profile.But as using method of the present invention and circuit, then as shown in the figure by the peak value of spatial domain infinite impulse response filter output, will be different along with the difference of input signal.That is to say that heal brightly when concentrating again as (a) figure when input signal, the peak value of output is higher, the setting of contrast also can be lower; Otherwise, when input signal darker as (b) figure, though or as (c) figure is bright when not concentrating, then Shu Chu peak value is lower, the setting of contrast is also just higher.
See also shown in Figure 5, (a) of Fig. 5 and (b) figure are similar to (a) of Fig. 4 and (b) figure, that is to say, though (a) figure is identical with the accurate position of the average picture of (b) figure, but (a) figure concentrates again because of picture is brighter, so that the spatial domain infinite impulse response filter will be exported higher peak value, and will be excessive to avoid contrast settings, cause taking place saturated and situation distortion.And (b) the Tu Zeyin picture is darker, so the spatial domain infinite impulse response filter will be exported lower peak value, to set bigger contrast, strengthens the definition of image.
The above, it only is preferred embodiment of the present invention, be not that the present invention is done any pro forma restriction, though the present invention discloses as above with preferred embodiment, yet be not in order to limit the present invention, any those skilled in the art, in not breaking away from the technical solution of the present invention scope, when the method that can utilize above-mentioned announcement and technology contents are made a little change or be modified to the equivalent embodiment of equivalent variations, but every content that does not break away from technical solution of the present invention, according to technical spirit of the present invention to any simple modification that above embodiment did, equivalent variations and modification all still belong in the scope of technical solution of the present invention.
Claims (7)
1, a kind of spatial domain infinite impulse response filter auto contrast restricting circuits is applicable to estimation one contrast, it is characterized in that it comprises:
One spatial domain infinite impulse response filter in order to receiving an input signal, and produces a spatial domain infinite impulse response filter value of this input signal;
One peak sensing device couples this spatial domain infinite impulse response filter, in order to according to this spatial domain infinite impulse response filter value, and produces a peak value in a record unit interval; And
One contrast estimation device, couple this peak sensing device, in order to estimate this contrast according to this peak value and a default threshold value, wherein when this contrast estimation device judges that this peak value is higher than this default threshold value, setting this contrast is a preset value, otherwise sets this contrast for presetting threshold value divided by this peak value.
2, spatial domain according to claim 1 infinite impulse response filter auto contrast restricting circuits is characterized in that wherein said spatial domain infinite impulse response filter comprises:
One first multiplier in order to this input signal be multiply by one first factor value, produces one first output valve;
One adder couples this first multiplier, in order to ask for this first output valve and one second output valve sum, produces this spatial domain infinite impulse response filter value; And
One second multiplier in order to this spatial domain infinite impulse response filter is on duty with one second factor value, produces this second output valve;
Wherein this first factor value and this second factor value sum are 1.
3, spatial domain according to claim 1 infinite impulse response filter auto contrast restricting circuits is characterized in that wherein this preset value is 1.
4, spatial domain according to claim 1 infinite impulse response filter auto contrast restricting circuits is characterized in that wherein more comprising:
One prime spatial domain infinite impulse response filter in order to receiving a prime input signal, and produces a prime spatial domain infinite impulse response filter value of this prime input signal; And
One prime peak sensing device, couple this prime spatial domain infinite impulse response filter, in order to according to this prime spatial domain infinite impulse response filter value, and in prime record unit interval, produce a prime peak value, with this input signal as this spatial domain infinite impulse response filter.
5, spatial domain according to claim 4 infinite impulse response filter auto contrast restricting circuits is characterized in that wherein said prime spatial domain infinite impulse response filter comprises:
One first multiplier in order to this prime input signal be multiply by one first factor value, produces one first output valve;
One adder couples this first multiplier, in order to ask for this first output valve and one second output valve sum, produces this prime spatial domain infinite impulse response filter value; And
One second multiplier in order to this prime spatial domain infinite impulse response filter is on duty with one second factor value, produces this second output valve;
Wherein this first factor value and this second factor value sum are 1.
6, a kind of spatial domain infinite impulse response filter auto contrast method for limiting is applicable to estimation one contrast, it is characterized in that it comprises the following steps:
Receive an input signal, and produce a spatial domain infinite impulse response filter value of this input signal;
According to this spatial domain infinite impulse response filter value, in a record unit interval, produce a peak value; And
Estimate this contrast according to this peak value and a default threshold value, wherein when this peak value was higher than this default threshold value, setting this contrast was a preset value, preset threshold value divided by this peak value otherwise set this contrast for being somebody's turn to do,
7, spatial domain according to claim 6 infinite impulse response filter auto contrast method for limiting is characterized in that wherein this preset value is 1
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4654710A (en) * | 1985-01-04 | 1987-03-31 | Thomson Csf | Contrast amplifier for video images |
| JPH0678239A (en) * | 1992-08-25 | 1994-03-18 | Toshiba Corp | Acl circuit |
| JPH1013714A (en) * | 1996-06-24 | 1998-01-16 | Matsushita Electric Ind Co Ltd | Video image luminance signal processing circuit |
| CN1041684C (en) * | 1992-05-22 | 1999-01-13 | 汤姆森消费电子有限公司 | Non-linear customer contrast control for acolor television with autopix |
-
2003
- 2003-11-26 CN CNB2003101154901A patent/CN100433812C/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4654710A (en) * | 1985-01-04 | 1987-03-31 | Thomson Csf | Contrast amplifier for video images |
| CN1041684C (en) * | 1992-05-22 | 1999-01-13 | 汤姆森消费电子有限公司 | Non-linear customer contrast control for acolor television with autopix |
| JPH0678239A (en) * | 1992-08-25 | 1994-03-18 | Toshiba Corp | Acl circuit |
| JPH1013714A (en) * | 1996-06-24 | 1998-01-16 | Matsushita Electric Ind Co Ltd | Video image luminance signal processing circuit |
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