CN112839180B - Exposure control method and device, image acquisition equipment and intraoral scanner - Google Patents
Exposure control method and device, image acquisition equipment and intraoral scanner Download PDFInfo
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- CN112839180B CN112839180B CN201911165261.8A CN201911165261A CN112839180B CN 112839180 B CN112839180 B CN 112839180B CN 201911165261 A CN201911165261 A CN 201911165261A CN 112839180 B CN112839180 B CN 112839180B
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- 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
Abstract
The invention discloses an exposure control method, an exposure control device, image acquisition equipment and an intraoral scanner, wherein the exposure control method comprises the following steps: acquiring a gray level histogram corresponding to a current frame picture; generating a gray scale integral distribution curve according to the gray scale histogram, wherein the gray scale integral distribution curve is used for expressing the distribution condition of the proportion of the number of pixels with gray scale values equal to or larger than the gray scale value to the total number of the pixels in a gray scale value interval; the exposure time is adjusted according to the shape of the gray scale integral distribution curve, the method adjusts the exposure time according to the shape of the gray scale integral distribution curve, the adjustment of the brightness of the current frame picture is realized, the exposure failure can be avoided, the stability of exposure control is ensured, the adjustment speed is improved, and further the brightness oscillation can be avoided.
Description
Technical Field
The invention relates to the technical field of intraoral scanning, in particular to an exposure control method and device, image acquisition equipment and an intraoral scanner.
Background
In the related art, exposure time is controlled by comparing the average gray value of the whole picture or the weighted average gray value of the divided regions with an expected gray value, and iteration is performed to obtain a shot picture with moderate brightness. However, this technique has the following problems: firstly, a background area cannot be ignored in a shooting environment with high brightness and dark contrast, so that the average brightness value of the whole picture is moderate, but local overexposure or underexposure is caused; secondly, the gray scale expected value is selected in different shooting environments, and particularly, in the oral environment, the bright and reflective teeth, dark soft tissues and extremely dark tooth gaps exist, and the areas between the upper tooth row and the lower tooth row are difficult to determine a proper gray scale expected value, so that exposure control is ineffective; thirdly, the iterative process easily causes the adjustment time to be too long, and further the brightness may oscillate, that is, the slight jitter may cause the picture to flash bright and dark.
In order to solve the above problems, the following three technical solutions are proposed in the related art, which have the following disadvantages: dividing all gray values of the picture into areas, and selecting a proper weighted value to distinguish background areas, but the selection of the weighted value is closely related to the shooting environment as the gray expected value, so that the selection is not easy; for the stability of exposure control, a picture is subjected to region segmentation in advance to highlight a main body region, and the brightness of a non-main body region is ignored, so that the stability of exposure is improved, but generally, the region where a main body is located is not a fixed position, so that the main body region cannot be accurately judged, and particularly for handheld products such as an intraoral scanner, the main body region is often unfixed due to flexible movement of hands; the average brightness value and the expected gray value are multiplied by a smaller coefficient to make the result easier to satisfy the setting condition, but the exposure control may become coarser, and the brightness of the actually output picture still cannot satisfy the actual requirement.
Disclosure of Invention
The present invention is directed to solving, at least in part, one of the technical problems in the related art.
Therefore, a first objective of the present invention is to provide an exposure control method, which can avoid exposure failure, ensure stability of exposure control, increase the adjustment speed, and further avoid brightness oscillation.
A second object of the present invention is to provide an exposure control apparatus.
A third object of the invention is to propose an image acquisition device.
A fourth object of the present invention is to provide an intraoral scanner.
To achieve the above object, an embodiment of the present invention provides an exposure control method, including: acquiring a gray level histogram corresponding to a current frame picture; generating a gray scale integral distribution curve according to the gray scale histogram, wherein the gray scale integral distribution curve is used for representing the distribution condition of the proportion of the number of pixels with gray scale values equal to or larger than the gray scale value to the total number of the pixels in the gray scale value interval; and adjusting the exposure time according to the shape of the gray scale integral distribution curve.
The exposure control method of the embodiment of the invention comprises the steps of firstly, obtaining a gray level histogram corresponding to a current frame picture; then generating a gray scale integral distribution curve according to the gray scale histogram; and finally, adjusting the exposure time according to the shape of the gray scale integral distribution curve. Therefore, the exposure time is adjusted according to the shape of the gray scale integral distribution curve, the adjustment of the brightness of the current frame picture is realized, the exposure failure can be avoided, the stability of exposure control is ensured, the adjusting speed is increased, and further the brightness oscillation can be avoided.
In addition, the exposure control method according to the above-described embodiment of the present invention may also have the following additional technical features:
according to an embodiment of the present invention, the obtaining of the gray level histogram corresponding to the current frame picture includes: eliminating pixel points with the gray values smaller than a gray threshold value in the current frame picture; and generating the gray level histogram according to the gray level value of the pixel point after the elimination.
According to an embodiment of the present invention, the adjusting the exposure time according to the shape of the gray scale integration profile includes: acquiring a first gray value corresponding to a preset first proportion according to the gray integral distribution curve; and if the first gray value is smaller than a preset first gray threshold, the exposure time is prolonged.
According to an embodiment of the present invention, if the first gray scale value is smaller than a preset first gray scale threshold, the increasing the exposure time includes: if the first gray value is smaller than the first gray threshold and equal to or larger than a preset second gray threshold, the exposure time is increased by a first time value; if the first gray value is smaller than the second gray threshold value, the exposure time is increased by a second time value, and the second time value is larger than the first time value.
According to an embodiment of the present invention, the adjusting the exposure time according to the shape of the gray scale integration distribution curve further includes: if the first gray value is equal to or greater than the first gray threshold, acquiring a second gray value corresponding to a preset second proportion according to the gray integral distribution curve, wherein the second proportion is greater than the first proportion; and if the second gray value is larger than a preset third gray threshold, reducing the exposure time.
According to an embodiment of the present invention, the reducing the exposure time if the second gray scale value is greater than a preset third gray scale threshold value includes: if the second gray value is larger than the third gray threshold and equal to or smaller than a preset fourth gray threshold, reducing the exposure time by a third time value; if the second gray value is greater than the fourth gray threshold, decreasing the exposure time by a fourth time value, wherein the fourth time value is greater than the third time value.
According to an embodiment of the present invention, the adjusting the exposure time according to the shape of the gray scale integration distribution curve further includes: and if the second gray value is equal to or smaller than the third gray threshold value, keeping the exposure time unchanged.
To achieve the above object, an embodiment of a second aspect of the present invention provides an exposure control apparatus, including: the acquisition module is used for acquiring a gray level histogram corresponding to the current frame picture; the generation module is used for generating a gray scale integral distribution curve according to the gray scale histogram, wherein the gray scale integral distribution curve is used for representing the distribution condition of the proportion of the number of pixels with gray scale values equal to or larger than the gray scale value to the total number of the pixels in the gray scale value interval; and the adjusting module is used for adjusting the exposure time according to the shape of the gray scale integral distribution curve.
According to the exposure control device, the gray level histogram corresponding to the current frame picture is obtained through the obtaining module; generating a gray scale integral distribution curve according to the gray scale histogram through a generating module; and adjusting the exposure time according to the shape of the gray scale integral distribution curve through an adjusting module. Therefore, the exposure time is adjusted according to the shape of the gray scale integral distribution curve, the adjustment of the brightness of the current frame picture is realized, the exposure failure can be avoided, the stability of exposure control is ensured, the adjusting speed is increased, and further the brightness oscillation can be avoided.
To achieve the above object, a third aspect of the present invention provides an image capturing apparatus, including: the embodiment of the second aspect of the invention provides an exposure control device.
According to the image acquisition equipment provided by the embodiment of the invention, the exposure time is adjusted according to the shape of the gray scale integral distribution curve through the exposure control device provided by the embodiment of the invention, so that the adjustment of the brightness of the current frame image is realized, the exposure failure can be avoided, the stability of exposure control is ensured, the adjustment speed is improved, and further the brightness oscillation can be avoided.
To achieve the above object, an intraoral scanner according to a fourth aspect of the present invention includes an image capturing device according to the fourth aspect of the present invention.
According to the intraoral scanner provided by the embodiment of the invention, through the image acquisition equipment provided by the embodiment of the invention, the exposure time is adjusted according to the shape of the gray scale integral distribution curve, so that the adjustment of the brightness of the current frame image is realized, the exposure failure can be avoided, the stability of exposure control is ensured, the adjustment speed is improved, and further the brightness oscillation can be avoided.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which
FIG. 1 is a flowchart of an exposure control method according to an embodiment of the present invention;
FIG. 2 is a grayscale histogram of one embodiment of the invention;
FIG. 3 is a gray scale integration profile of one embodiment of the present invention;
FIG. 4 is a flowchart of step S1 of FIG. 1 according to an embodiment of the present invention;
FIG. 5 is a flow chart of an exposure control method of one example of the present invention;
FIG. 6 is a flow chart of an exposure control method according to another example of the present invention;
FIG. 7 is a diagram illustrating the effect of adjusting the exposure time of a current frame picture according to an exemplary embodiment of the present invention;
FIG. 8 is a block diagram showing the structure of an exposure control apparatus according to an embodiment of the present invention;
fig. 9 is a block diagram of the configuration of an image pickup apparatus of the embodiment of the present invention;
fig. 10 is a block diagram of an intraoral scanner of an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
An exposure control method, an exposure control apparatus, an image pickup device, and an intraoral scanner according to embodiments of the present invention are described below with reference to the drawings.
Fig. 1 is a flowchart of an exposure control method according to an embodiment of the present invention.
As shown in fig. 1, the exposure control method includes the steps of:
and S1, acquiring a gray level histogram corresponding to the current frame picture.
Specifically, a current frame picture may be acquired (captured) by the image sensor, and then the processor obtains the frame picture from the image sensor, so as to generate a gray histogram h (x) as shown in fig. 2 according to the frame picture. The horizontal coordinate of the gray level histogram represents the gray level value, and the vertical coordinate represents the number of pixel points corresponding to each gray level value.
And S2, generating a gray scale integral distribution curve according to the gray scale histogram, wherein the gray scale integral distribution curve is used for representing the distribution condition of the proportion of the number of the pixels with the gray scale value equal to or greater than the gray scale value to the total number of the pixels in a gray scale value interval. That is to say, the abscissa corresponding to the gray scale integral distribution curve represents the gray scale value, and the ordinate represents the proportion of the number of the pixels of which the gray scale value is equal to or greater than the gray scale value to the total number of the pixels.
Specifically, the processor may accumulate the number of pixel points corresponding to all gray values in the gray histogram h (x) to obtain the total number of pixel points, then calculate the number Σ h (i) of pixel points equal to or greater than each gray value, where i is a set of gray values equal to or greater than x, further obtain the number of pixel points equal to or greater than the gray value, and finally calculate the ratio of the number of pixel points equal to or greater than the gray value to the total number of pixel points, that is, perform normalization calculation, that is, h (x) norm (∑ h (i)), obtain the ordinate of the gray integral distribution curve (that is, the normalized pixel number), and the abscissa of the gray integral distribution curve represents the gray value, thereby generating the gray integral distribution curve as shown in fig. 3.
For example, referring to fig. 3, in the gray scale integration distribution graph, 100 on the abscissa indicates a gray scale value of 100, and the corresponding ordinate includes the following physical meanings: the number of pixels having a gray value equal to or greater than 100 is proportional to the total number of pixels.
S3, the exposure time is adjusted according to the shape of the gray scale integration profile.
Specifically, referring to fig. 3, no matter how the brightness of the current frame picture is, the gray scale integral distribution curve of the current frame picture decreases with the increasing of the gray scale value of the abscissa, and the brightness of the frame picture is reflected on the slope change of the decreasing curve, so that the slope of the curve can be defined by selecting a plurality of ordinate points, and the shape of the curve can be defined, thereby achieving the purpose of controlling the brightness of the picture. In addition, when the intra-oral environment is shot, the main body (teeth) is always a part with higher brightness, and the background brightness is lower, so that the brightness of the shot main body is always distributed in an area to the right of the function H (x) curve, and the brightness detection only needs to refer to the area with a smaller value of the ordinate y.
Specifically, the brightness of the current frame picture is determined according to the gray scale values corresponding to the ordinate points y ═ a and y ═ b of the gray scale integral distribution curve, and then the brightness of the current frame picture is changed by adjusting the exposure time of the image sensor, that is, the brightness of the shooting subject (tooth) is adjusted until the brightness of the current frame picture reaches a moderate level. Wherein a can be a first proportion, b can be a second proportion, and a and b can range from 0.1 ≦ a ≦ 0.4, and 0.1 ≦ b ≦ 0.4.
In the embodiment, the exposure time is adjusted according to the shape of the curve of the gray scale integral distribution function, so that the control on exposure failure can be avoided, the adjustment speed is high, the proper brightness can be adjusted after the frame picture is collected for 2-3 times generally, and the phenomenon that the picture flickers in bright and dark due to the brightness oscillation of the frame picture can be further avoided. Compared with the scheme of dividing the gray value into areas and selecting a proper weighted value to distinguish the background area, the exposure control method of the embodiment does not need to select the size of the weighted value, and can avoid the failure of exposure control; compared with the scheme that the main body area is highlighted by carrying out area division on the frame picture in advance, the brightness of the non-main body area is ignored, the main body area does not need to be judged, the stability of exposure control can be ensured, and the failure of exposure control can be avoided; the adjustment accuracy is higher compared to a scheme in which both the luminance mean value and the desired value are multiplied by a smaller coefficient.
Therefore, the exposure time is adjusted according to the shape of the gray scale integral distribution curve, the adjustment of the brightness of the current frame picture is realized, the exposure failure can be avoided, the stability of exposure control is ensured, the adjusting speed is increased, and further the brightness oscillation can be avoided.
In an embodiment of the present invention, as shown in fig. 4, the step S1 of obtaining the gray-scale histogram corresponding to the current frame picture may include the following steps:
and S11, eliminating the pixel points with the gray value smaller than the gray threshold value in the current frame picture.
And S12, generating a gray histogram according to the gray value of the eliminated pixel points.
Specifically, a current frame picture can be collected (shot) through an image sensor, then the processor obtains the frame picture from the image sensor, and then the processor eliminates pixel points (namely dark pixel points) with the gray value smaller than a gray threshold k (namely dark point gray value) in the current frame picture, namely the pixel points lower than the gray threshold k are not counted in gray distribution statistics, and then the gray value of the pixel points larger than or equal to the gray threshold k is counted in gray distribution to generate a gray histogram h (x).
In this embodiment, the gray threshold k may be set according to practical situations, for example, for an 8-bit gray image, k may be set to 20, and a region in the frame picture with a gray value smaller than 20 is a generally black background, often a region between teeth gaps or between upper and lower rows of teeth during intraoral scanning.
Specifically, the pixel points corresponding to the gray scale value smaller than 20 are removed, so that when the gray scale value is smaller than 20, the number of the corresponding pixel points is 0, and then the number of the pixel points corresponding to the gray scale value equal to or larger than 20 is counted to generate the gray scale histogram shown in fig. 2. That is, referring to fig. 2, when x is 0, 1, 2.., k-1, y is 0; and when x is larger than or equal to k, y is equal to h (x), wherein k is equal to 20. Referring to fig. 3, since the pixel points corresponding to the gray-scale values smaller than 20 are removed, when x is less than or equal to 20, all the gray-scale values are not less than x, so y is 1, and therefore, the gray-scale integration distribution curve decreases from y being 1 along with the increasing of the gray-scale value of the abscissa, regardless of the brightness of the current frame picture.
That is, the brightness of the subject (tooth) is adjusted by ignoring the background region (soft tissue in the mouth), so that local overexposure or underexposure is avoided and the uniformity of the brightness is ensured under the condition that the average brightness value of the whole frame picture is ensured to be moderate.
In one embodiment of the present invention, adjusting the exposure time according to the shape of the gray integration profile may include: acquiring a first gray value m corresponding to a preset first proportion a according to a gray integral distribution curve; if the first gray-scale value m is smaller than the preset first gray-scale threshold TH1, the exposure time is increased.
Further, adjusting the exposure time according to the shape of the gray scale integration distribution curve may further include: if the first gray value m is equal to or greater than a first gray threshold TH1, acquiring a second gray value n corresponding to a preset second proportion b according to the gray integral distribution curve, wherein the second proportion b is greater than the first proportion a; if the second gray value n is greater than the preset third gray threshold TH3, the exposure time is decreased.
Further, adjusting the exposure time according to the shape of the gray scale integration distribution curve may further include: if the second gray value n is equal to or less than the third gray threshold TH3, the exposure time is kept unchanged.
Referring to fig. 3, the first ratio a may be 0.1, the second ratio b may be 0.5, the first grayscale threshold TH1 is a threshold indicating that a frame picture is dark, and the third grayscale threshold TH3 is a threshold indicating that a frame picture is bright.
Specifically, if the first gray value m is smaller than the first gray threshold TH1, it indicates that the frame picture is darker and the exposure time needs to be slightly increased; on the contrary, a second gray value n corresponding to the preset second proportion b is obtained according to the gray integral distribution curve, if the second gray value n is greater than a third gray threshold TH3, the frame picture is brighter, and the exposure time needs to be slightly reduced; if the second gray value n is less than or equal to the preset third gray threshold TH3, it indicates that the brightness of the current frame picture is moderate, and the exposure time does not need to be adjusted, i.e., the current exposure time is kept unchanged.
That is, step S3 of the above embodiment may include the following steps: step S31, step S32, and step S33, therefore, as shown in fig. 5, the exposure control method in this example may include the steps of:
s0, the current frame picture is obtained.
And S11, eliminating the pixel points with the gray value smaller than the gray threshold value in the current frame picture.
And S12, generating a gray histogram according to the gray value of the eliminated pixel points.
S2, a gray scale integration distribution curve is generated from the gray scale histogram.
S31, judging whether the first gray value m is smaller than a first gray threshold TH1, if so, increasing the exposure time, and returning to the step S0; if not, step S32 is performed.
S32, judging whether the second gray value n is larger than a third gray threshold TH3, if so, reducing the exposure time, and returning to the step S0; if not, step S33 is performed.
And S33, keeping the exposure time unchanged.
In an example of the present invention, if the first gray scale value m is smaller than the preset first gray scale threshold TH1, the step S31 may include: if the first gray scale value m is smaller than the first gray scale threshold value TH1 and equal to or greater than a preset second gray scale threshold value TH2, increasing the exposure time by a first time value u 1; if the first gray value m is smaller than the second gray threshold TH2, the exposure time is increased by a second time value u2, and the second time value u2 is greater than the first time value u 1.
In this example, if the second gray scale value is greater than the preset third gray scale threshold, the decreasing the exposure time, i.e. the step S32, may include: if the second gray value n is greater than the third gray threshold TH3 and equal to or less than a preset fourth gray threshold TH4, decreasing the exposure time by a third time value u 3; if the second gray value n is greater than the fourth gray threshold TH4, the exposure time is decreased by a fourth time value u4, and the fourth time value u4 is greater than the third time value u 3.
The second grayscale threshold TH2 is a threshold indicating that the luminance of the frame picture is extremely dark, and the fourth grayscale threshold TH4 is a threshold indicating that the luminance of the frame picture is extremely bright.
Specifically, if the first gray scale value m is smaller than the second gray scale threshold value TH2, it indicates that the brightness of the current frame picture is extremely dark, and the exposure time is increased by a second time value u 2; if the first gray value m is equal to or greater than the second gray threshold TH2 and less than the first gray threshold TH1, it indicates that the brightness of the current frame picture is darker, and the exposure time is increased by a first time value u 1; if the first gray value m is equal to or greater than a first gray threshold TH1, acquiring a second gray value n corresponding to a preset second proportion b according to the gray integral distribution curve, and if the second gray value n is greater than a fourth gray threshold TH4, indicating that the brightness of the current frame picture is extremely bright, reducing the exposure time by a fourth time value u 4; if the second gray value n is equal to or less than a preset fourth gray threshold TH4 and greater than a third gray threshold TH3, indicating that the brightness of the current frame picture is brighter, decreasing the exposure time by a third time value u 3; if the second gray value n is less than or equal to the preset third gray threshold TH3, it indicates that the brightness of the current frame picture is moderate, and the exposure time does not need to be adjusted, i.e. the current exposure time is kept unchanged.
That is, step S31 in the above example may include: step S311, step S312, and step S32 may include: step S321, step S322. Therefore, as shown in fig. 6, the exposure control method in this example may include the steps of:
s0, the current frame picture is obtained.
And S11, eliminating the pixel points with the gray value smaller than the gray threshold value in the current frame picture.
And S12, generating a gray histogram according to the gray value of the eliminated pixel point.
S2, a gray scale integration distribution curve is generated from the gray scale histogram.
S311, judging whether the first gray value m is smaller than a second gray threshold TH2, if so, increasing the exposure time by a second time value u2, and returning to the step S0; if not, step S312 is performed.
S312, judging whether the first gray value m is smaller than a first gray threshold TH1, if so, increasing the exposure time by a first time value u1, and returning to the step S0; if not, step S321 is performed.
S321, judging whether the second gray value n is larger than a fourth gray threshold TH4, if so, reducing the exposure time by a fourth time value u4, and returning to the step S0; if not, step S322 is performed.
S322, judging whether the second gray value n is larger than a preset third gray threshold TH3, if so, reducing the exposure time by a third time value u3, and returning to the step S0; if not, step S33 is performed.
And S33, keeping the exposure time unchanged.
In step S321, if the brightness of the current frame picture is detected to be very bright, that is, as shown in fig. 7(a), the exposure time is decreased by the fourth time value u4, and then the process returns to step S0, that is, the next frame picture is obtained, and the brightness of the picture is continuously detected, if the brightness of the picture is detected to be brighter, that is, as shown in fig. 7(b), the exposure time is decreased by the third time value u3, and if the second gray value n is detected to be less than or equal to the preset third gray threshold TH3, that is, the brightness of the picture is moderate, that is, as shown in fig. 7 (c).
That is, when the step S0 is returned after the exposure time is increased or decreased, the next frame of picture is obtained, and the brightness of the frame of picture is detected according to the above steps, so as to adjust the exposure time accordingly, thereby achieving the purpose of adjusting the brightness.
It can be understood that the exposure time can be divided into a plurality of gears, and the exposure time sequentially increases from a low gear to a high gear, so that after the brightness of the current frame picture is detected, the exposure time can be adjusted through adjusting the gears until the brightness of the current frame picture is moderate. In the gear adjustment process, if the gear is adjusted to the minimum or maximum gear, the brightness of the current frame picture is still in brighter or darker and above a brighter or darker level (for example, extremely bright or extremely dark), that is, when the adjustment of the exposure time reaches the limit, the brightness of the current frame picture cannot be adjusted to a moderate level, and the current exposure time is kept unchanged.
In summary, the exposure control method according to the embodiment of the present invention adjusts the exposure time according to the shape of the curve of the gray scale integral distribution function, can avoid exposure failure, ensure the stability of exposure control, has a fast adjustment speed, and can generally adjust to a proper brightness after sampling the picture for 2-3 times, thereby avoiding brightness oscillation; the function adopted for brightness judgment is of an accumulation type of the number of pixel points, and brightness adjustment can be effectively carried out on a shooting main body (teeth) to a certain extent while a background (soft tissue in the mouth) is ignored; the exposure time control is realized through gear adjustment, and the refinement degree of the exposure gear can be flexibly set to ensure the convergence of the exposure adjustment; the method has the advantages of simple calculation, resource saving, no multiplication/division step, convenient realization on a hardware platform, high calculation speed and suitability for high-frame-frequency application occasions.
Based on the same inventive concept, an exposure control apparatus is provided in an embodiment of the present invention, and fig. 8 is a block diagram of the exposure control apparatus in an embodiment of the present invention.
As shown in fig. 8, the exposure control apparatus 10 includes: an acquisition module 11, a generation module 12 and an adjustment module 13.
The obtaining module 11 is configured to obtain a gray level histogram corresponding to a current frame picture; the generation module 12 is configured to generate a gray scale integral distribution curve according to the gray scale histogram, where the gray scale integral distribution curve is used to represent a distribution condition of a proportion of the number of pixels with gray scale values equal to or greater than the gray scale value to the total number of pixels in a gray scale value interval; the adjusting module 13 is used for adjusting the exposure time according to the shape of the gray scale integral distribution curve.
Specifically, the obtaining module 11 may include an image sensor, the generating module 12 may include a processor, the obtaining module 11 sends the obtained gray histogram to the generating module 12, so that the generating module 12 generates a gray integral distribution curve according to the gray histogram, and finally the adjusting module 13 adjusts the exposure time according to the shape of the curve, so as to adjust the brightness of the current frame picture until the brightness is moderate.
It should be noted that, for other specific embodiments of the exposure control apparatus according to the embodiment of the present invention, reference may be made to the specific embodiments of the exposure control method according to the foregoing embodiments, and in order to avoid redundancy, details are not described here.
The exposure control device of the embodiment of the invention adjusts the exposure time according to the shape of the gray scale integral distribution curve, realizes the adjustment of the brightness of the current frame picture, can avoid exposure failure, ensures the stability of exposure control, improves the adjustment speed, and further can avoid brightness oscillation.
Fig. 9 is a block diagram of the configuration of the image pickup apparatus of the embodiment of the invention.
As shown in fig. 9, the image pickup apparatus 100 includes the exposure control device 10 of the above-described embodiment of the present invention.
According to the image acquisition equipment provided by the embodiment of the invention, the exposure control device provided by the embodiment of the invention is used for adjusting the exposure time according to the shape of the gray scale integral distribution curve, so that the brightness of the current frame image is adjusted, the exposure failure can be avoided, the stability of exposure control is ensured, the adjustment speed is improved, and further the brightness oscillation can be avoided.
Fig. 10 is a block diagram of an intraoral scanner of an embodiment of the present invention.
As shown in fig. 10, the intraoral scanner 1000 includes the image capture device 100 of the above-described embodiment of the present invention.
According to the intraoral scanner provided by the embodiment of the invention, through the image acquisition equipment provided by the embodiment of the invention, the exposure time is adjusted according to the shape of the gray scale integral distribution curve, so that the adjustment of the brightness of the current frame image is realized, the exposure failure can be avoided, the stability of exposure control is ensured, the adjustment speed is improved, and further the brightness oscillation can be avoided.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specified otherwise.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (8)
1. An exposure control method, comprising:
acquiring a gray level histogram corresponding to a current frame picture;
generating a gray scale integral distribution curve according to the gray scale histogram, wherein the gray scale integral distribution curve is used for representing the distribution condition of the proportion of the number of pixels with gray scale values equal to or larger than the gray scale value to the total number of the pixels in the gray scale value interval;
adjusting the exposure time according to the shape of the gray scale integral distribution curve;
the adjusting of the exposure time according to the shape of the gray scale integration distribution curve includes:
acquiring a first gray value corresponding to a preset first proportion according to the gray integral distribution curve;
if the first gray value is smaller than a preset first gray threshold, the exposure time is prolonged;
the adjusting of the exposure time according to the shape of the gray scale integration distribution curve further comprises:
if the first gray value is equal to or larger than the first gray threshold, acquiring a second gray value corresponding to a preset second proportion according to the gray integral distribution curve, wherein the second proportion is larger than the first proportion;
and if the second gray value is larger than a preset third gray threshold, reducing the exposure time.
2. The exposure control method according to claim 1, wherein the obtaining of the gray-scale histogram corresponding to the current frame picture comprises:
eliminating pixel points with the gray values smaller than a gray threshold value in the current frame picture;
generating the gray level histogram according to the gray level value of the eliminated pixel points;
and if the first gray value is smaller than a preset first gray threshold, the exposure time is prolonged.
3. The method of claim 1, wherein if the first gray-level value is smaller than a preset first gray-level threshold, the increasing the exposure time comprises:
if the first gray value is smaller than the first gray threshold and equal to or larger than a preset second gray threshold, the exposure time is increased by a first time value;
and if the first gray value is smaller than the second gray threshold, increasing the exposure time by a second time value, wherein the second time value is larger than the first time value.
4. The method of claim 1, wherein the decreasing the exposure time if the second gray scale value is greater than a preset third gray scale threshold value comprises:
if the second gray value is larger than the third gray threshold and equal to or smaller than a preset fourth gray threshold, reducing the exposure time by a third time value;
if the second gray value is greater than the fourth gray threshold, decreasing the exposure time by a fourth time value, wherein the fourth time value is greater than the third time value.
5. The exposure control method according to claim 1, wherein the adjusting of the exposure time according to the shape of the gray-scale integration distribution curve further comprises:
and if the second gray value is equal to or smaller than the third gray threshold value, keeping the exposure time unchanged.
6. An exposure control apparatus, comprising:
the acquisition module is used for acquiring a gray level histogram corresponding to the current frame picture;
the generation module is used for generating a gray scale integral distribution curve according to the gray scale histogram, wherein the gray scale integral distribution curve is used for representing the distribution condition of the proportion of the number of pixels with gray scale values equal to or larger than the gray scale value to the total number of the pixels in the gray scale value interval;
the adjusting module is used for adjusting the exposure time according to the shape of the gray scale integral distribution curve;
the adjusting of the exposure time according to the shape of the gray scale integration distribution curve includes:
acquiring a first gray value corresponding to a preset first proportion according to the gray integral distribution curve;
if the first gray value is smaller than a preset first gray threshold, the exposure time is prolonged;
the adjusting of the exposure time according to the shape of the gray scale integral distribution curve further comprises:
if the first gray value is equal to or greater than the first gray threshold, acquiring a second gray value corresponding to a preset second proportion according to the gray integral distribution curve, wherein the second proportion is greater than the first proportion;
and if the second gray value is larger than a preset third gray threshold, reducing the exposure time.
7. An image acquisition apparatus, characterized by comprising: the exposure control device according to claim 6.
8. An intraoral scanner, comprising: the image capturing device of claim 7.
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