CN1249985C - Image processing method and device capable of adjusting photosensitive characteristic curve - Google Patents

Abstract

The invention is an image processing method and device capable of adjusting photosensitive characteristic curve, which utilizes a user interface to display the digital image data captured by the device, and let the user adjust the set value of capturing the image data through the interface, and store the set value into a parameter setting memory, and then set the user set value stored in the memory according to the parameter and the exposure reference value measured by an optical element group, and immediately calculate a new contrast control parameter of the image data, and store the contrast control parameter into a control parameter storage unit, so as to make a signal conversion unit immediately perform contrast adjustment and processing on the captured image data according to the contrast control parameter, so that the user can repeatedly correct and adjust the contrast control parameter in a feedback manner according to the preference, and use the contrast control parameter as the sampling reference value when the device captures the image, and shooting a scene image with the optimal contrast value.

Description

Image processing method and device capable of adjusting photosensitive characteristic curve

technical field

The invention relates to the field of digital cameras, in particular to an image processing method and device capable of adjusting a sensitivity curve. The user can repeatedly modify the contrast control parameters when the device shoots images in a feedback manner according to his preference, so that the contrast adjustment and processing can be performed on the captured image data in real time, and the scene image with the best contrast effect can be shot.

Background technique

In a general imaging system, the characteristic curve represents the reflection brightness (luminance, or input brightness value) on the subject captured by the imaging system and the corresponding reflection density (density, or brightness value) on the photo. output record value). Taking the field of traditional banking photography as an example, the so-called "film characteristic curve" mainly refers to the relationship between the "exposure" and "density" characteristics of the film. This curve is also called the D log H curve, as shown in Figure 1. Shown is the characteristic curve of a typical black and white photosensitive material. On this characteristic curve, the ratio corresponding to the variation of the horizontal axis (exposure) and the vertical axis (concentration) is the slope of the curve, the so-called contrast value (contrast), which is generally represented by Gamma (γ) The contrast characteristic of a material, the value γ of which is defined by the following formula:

$\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&Delta;D</span>}}{\mathrm{<span\; class="notranslate">\; \&Delta;LogH</span>}}$

, where ΔD represents the concentration difference between any two measurement points on the linear region of the characteristic curve, and ΔLogH represents the logarithmic (log) exposure value difference between the two measurement points.

In the photosensitive material of the traditional imaging system, since the contrast characteristics of the negative film are also fixed in the fixed developing time, the general photographer cannot adjust the contrast characteristics of the image when taking the scene image. When the film is developed, the contrast effect of the film can be adjusted by changing the time of developing the film to compensate the light conditions of the scene image. The world-renowned Zone System is designed for this purpose. In addition, in the U.S. invention patent US5445929 previously applied for, there is also a technology that uses a chemical photography system with variable contrast to adjust the contrast effect of the film. To make it present this effect, its contrast effect not only cannot be displayed immediately at the shooting scene, but also cannot be adjusted or changed immediately.

As mentioned above, since the contrast characteristics of general negatives are fixed, and the dynamic range of the light field of the image that can be sensed is also fixed, the photographer can only adjust the exposure value of the camera aperture and shutter when taking the scene image. It obtains image input signals with a fixed light field range in different exposure intervals. In view of this, in the US invention patent US5159384 previously applied for, the inventor used a precise and complex exposure system to improve the quality of image input signals, but still could not Change the characteristic curve value of the imaging system itself.

In addition, traditionally, scene contrast (scene contrast) is used to define the relative ratio of the brightness of the scene in the photographing scene. According to past research, the contrast ratio of the most commonly shot scenes is between 20:1 and 800:1, and 160:1 is the most common. Therefore, most of the general negatives use this as the standard contrast ratio. The fixed contrast value, i.e. the dynamic range of the light field (difference between light and dark) of the film input signal, is approximately 7 1/4 f stops. Take the film whose light field dynamic range of the input signal is 100:1 as an example, as shown in Figure 2, in its characteristic curve, the X-axis represents the logarithmic function Log H of the relative brightness ratio (ie exposure value) of different scenes in the scene (or called the dynamic domain of the input signal), and the Y axis represents the concentration value (or called the output signal value range) of the film developed. If the exposure reference value of the camera is designed in the middle of the dynamic domain of the input signal of the characteristic curve of the film, use Or when adjusting the exposure reference value of the camera, the characteristic curve of the film will shift horizontally along the X-axis direction, but the slope of the curve remains unchanged. Therefore, referring back to Figure 2, when the exposure reference value of the camera is set in the middle of curve A, the scene with a brightness value between E ₀ and E ₂ will be presented at a film density between 0 and 2, while The part of the scene with a brightness value above E ₂ will be discarded and cannot be presented; when the exposure reference value of the camera is set in the middle of curve B, the scene with a brightness value between E ₁ and E ₃ will be displayed The part of the scene whose film density is between 0 and 2 and whose brightness value is below _E1 and above _E3 cannot be recorded; similarly, when the camera’s exposure reference value is set in the middle of curve C , the film can only record scenes with luminance values in the range of E ₂ to E ₄ . It can be seen from this that no matter how the user changes the exposure reference value of the camera, since the slope of the contrast curve of the film is fixed, the film can only record scenes within the dynamic range of a fixed input signal. If it is desired to change the range of the dynamic domain of the input signal and keep the value range of the output signal (that is, the concentration range value of the film developed) fixed, it must be achieved by changing the characteristic function of the shooting system, as shown in Figure 3. As shown, taking curve B as an example, by increasing the slope of the curve, the range of the dynamic domain of the input signal can be reduced, as shown in curve A, and if the slope of the curve is reduced, the dynamic range of the input signal can be The range of the domain will be enlarged, as shown in curve C, but the range of the output signal and the exposure reference value of the camera can remain unchanged.

Therefore, in the general photography process, the characteristic curve of the film defines the range of the dynamic domain of the input signal, that is, the brightness range of the scene that can be recorded. Therefore, if the user wants to adjust the dynamic range of the light field of the scene that can be recorded, then in mathematics In the sense, it is necessary to change the characteristic curve of the photographic system function. Referring to the curve A shown in Figure 4, if four points such as X ₁ , X ₂ , Y ₁ and Y ₂ are known, then the characteristics of the curve A can be represented as a linear curve by Y=mX+c, where m is the slope , c is a constant; if another value of X ₃ is provided and added to the operation, it can be adjusted to a nonlinear characteristic function shown in curve B in Fig. 4 . Therefore, in practical applications, if X _N is the light field measurement value of a certain scene in the scene that the photographer can select, and Y _N is the range of the output signal value range that the photographer can define, then based on at least two selected groups ( X _N , Y _N ) value, the slope m of the characteristic curve can be calculated according to the following formula:

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}$

, the photographer can adjust the value of m to increase or decrease the contrast value of the system. The range of the output range Y ₁ -Y ₂ can also be set according to the user's preference, and there is no need to fix it at its limit value. Although this approach has disclosed a similar concept in U.S. Patent No. 5,539,459, how the patent controls and adjusts the contrast value of the system, or how the system is instructed by the user, the contrast value of the system is carried out. Control and adjustment, there is no specific statement.

In addition, in the existing digital camera 1, as shown in FIG. 5, a photosensitive element 11 (charges couple device, CCD for short) is used to capture the scene image through a lens (lens) group 10, and the resulting After the captured image is converted into an analog signal, it is converted into a digital image signal by an analog/digital converter 12, and then encoded by an encoding element 13, stored in a memory 14 (or in a storage device), and finally , and then through a display device 15 thereon, the stored digital images are displayed. These existing digital cameras 1 can control their gain value (Ga in) and compensation value (Offset) by pre-setting their control parameter value 16, and perform a system characteristic similar to Y=mX+c linear function. Adjustment, as shown in the US patent US4187519, but this patent cannot construct a nonlinear functional relationship, and if the user wants to set the range of the dynamic domain of the input signal, it cannot be included in the adjustment Its contrast is being processed. Since the human visual system will change its visual contrast with the intensity of light in the scene, simply automatically corresponding the dynamic range of the light field of the input scene to the range of the entire output signal value cannot allow photographers to directly follow their preferences. , to achieve real-time adjustment and control of image contrast characteristics.

Contents of the invention

In order to improve the lack of real-time adjustment and control of the image contrast characteristics of the aforementioned existing digital cameras, an image processing method and device for adjusting the photosensitive characteristic curve of the present invention is proposed, which can be used in an image processing device to adjust image contrast. processing method, so that the device can immediately calculate a new contrast control parameter according to the measured scene light image data and the control parameter input by the user, and store the parameter again in a control parameter storage unit , and then use the new contrast control parameters to adjust and process the contrast of the captured image data in real time, and immediately display it on a user interface display (such as LCD), so that users can give feedback according to their preferences In this way, the contrast control parameters are revised and adjusted repeatedly, so that the device can consider human visual characteristics (such as: Steven's Effect), and calculate the linear or nonlinear contrast characteristic curve in real time, and use it as the camera processing device (such as: digital Camera) sampling reference value when shooting images, to capture scene images with the best contrast value.

An image processing device capable of adjusting the photosensitivity characteristic curve of the present invention comprises:

An optical element group for adjusting aperture, shutter, focal length and sensing exposure value;

A light sensing unit, which is used to sense the light image data of the scene to be photographed through the optical element group, and convert it into an analog voltage signal representing the color image of the scene;

A signal conversion unit is used to convert the optical image data into digital image data in a predetermined format; the signal conversion unit includes an analog/digital converter to convert the analog voltage signal from the light sensing unit into a Digital image data; the signal conversion unit also includes:

An L-M encoder, according to the setting of its comparison table, converts the digital image data transmitted by the analog/digital converter into an M-bit digital image data;

An MN encoder converts the M-bit digital image data into an N-bit digital image data according to the setting of the comparison table, wherein M is designed to be greater than or equal to N, so that the MN code The conversion relationship of the digital digital image data can be obtained from the 2 ^M kinds of values sampled in the dynamic domain X of the input signal to the 2 ^N kinds of output signal value range Y, and the linear relationship between the sampled values can be obtained, that is:

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}$

, where Y ₂ and Y ₁ are the maximum and minimum values of the corresponding output signal range, and X ₁ and X ₂ are the upper and lower limits of the dynamic domain of the input signal, and m is its slope, which represents the so-called contrast in the visual system ;

an output image memory for storing the digital image data;

A user interface for displaying the digital image data transmitted from the image memory, and allowing the user to adjust the setting value of the captured image data through the interface;

a parameter setting memory, used to store the parameters set by the user through the user interface;

a preset parameter memory, used to store preset parameters;

a control parameter memory, used to store control parameters, so as to adjust and process the image of the signal conversion unit according to the control parameters; and

A processor, used to calculate the control parameters used to control the image capture function according to the signals respectively transmitted from the predetermined parameter memory, the optical element group, the output image memory, the parameter setting memory and the signal conversion unit, and It is stored in the control parameter memory, so that the signal conversion unit adjusts the image data captured by the light sensing unit according to the control parameters.

An image processing method capable of adjusting the photosensitive characteristic curve of the present invention uses a processor in an image processing device to control each component in the device according to the following steps to adjust the contrast value of the captured image data:

Firstly, a preset control option is read from a default parameter memory, and then displayed through a user interface for the user to select a value that can be used to adjust the image contrast, and the selected value is stored in a parameter set memory;

According to the user setting value stored in the parameter setting memory, the contrast characteristic parameter of the image data is calculated, and the parameter value is stored in a control parameter storage unit, so as to complete the contrast setting when defining the imaging;

When the device is used to take pictures of the scene, a signal conversion unit is used to convert and encode the analog voltage signal sent from a light sensing unit in sequence according to the contrast characteristic parameters stored in the control parameter storage unit, and the generated digital image data stored in an output image memory;

Then, the image data stored in the output image memory is sent to the user interface, so that the user can repeat the above steps to adjust the contrast value of the image according to his preference.

Description of drawings

Figure 1 shows a schematic diagram of the state of the characteristic curve of a typical black and white photosensitive material;

Fig. 2 shows that in the characteristic curve of the film whose input signal dynamic domain is 100:1, when the exposure reference value of the camera is changed, it represents the state schematic diagram of the contrast curve of the film in different input signal dynamic domains;

Fig. 3 shows that the value range of the output signal of the film is fixed, and when changing the range of the dynamic domain of the input signal, the state schematic diagram of the slope change of the characteristic function of the shooting system;

Fig. 4 shows the state diagram of the characteristic curve of the linear function Y=mX+c and the non-linear function of the photography system;

FIG. 5 is a schematic block diagram of components of a conventional digital camera;

FIG. 6 is a schematic block diagram of an image processing device capable of adjusting the photosensitive characteristic curve of the present invention;

FIG. 7 is a schematic diagram of an image data processing procedure when the device of the present invention captures a scene image;

Fig. 8 shows the block diagram of this signal conversion unit in the device of the present invention;

FIG. 9 is a schematic diagram showing the state between the contrast value of the characteristic curve and its input signal dynamic range X, output signal value range Y and exposure reference value Xe in the image data of the present invention;

FIG. 10 is a schematic diagram of an image data processing flow in a preferred embodiment of the present invention;

Fig. 11 is a schematic view showing the state of the optical element group aligned with the target position of the optical image data in the embodiment of Fig. 10;

FIG. 12 is a schematic diagram of an image data processing flow in another preferred embodiment of the present invention;

FIG. 13 is a schematic diagram of an image data processing flow in another preferred embodiment of the present invention.

Description of figure number:

Optical component group…………62 Light sensing unit……………70

Signal conversion unit………80 Output image memory………90

User Interface...50 Parameter Setting Memory...40

Preset parameter memory...10 Control parameter memory...30

Processor………………20 Analog/Digital Converter………82

Detailed ways

In the image processing device with adjustable photosensitive characteristic curve of the present invention, as shown in FIG. 6, the device mainly includes an optical element group 62, which is used for adjusting the aperture, shutter, focal length and sensing exposure value; A photosensitive unit (CCD) 70 is used to sense the light representation data (visualization of his scene light) of the scene 60 through the optical element group 62; a signal conversion unit 80 is used to convert the light representation data digital image data in a predetermined format; an output image memory 90 for storing the digital image data; a user interface 50 for displaying the digital image data transmitted from the image memory 90, and allowing users to 50 to adjust the set value of the image data; a parameter setting memory 40 for storing the parameters set by the user through the user interface 50; a predetermined parameter memory 10 for storing the preset parameters; a control parameter Memory 30, used to store control parameters, to adjust and process the image of the signal conversion unit 80 according to the control parameters; and a processor 20, used to output image memory 90 according to the predetermined parameter , the parameter setting memory 40 and the signals sent by the signal conversion unit 80, calculate the control parameters used to control the image capture function, and store them in the control parameter memory 30, so that the signal conversion unit 80 according to These control parameters are used to adjust the image data captured by the photosensitive unit (CCD) 70 .

When the device captures the scene image, it mainly follows the following steps, as shown in Figure 7, for processing:

(1) First, through the optical element group 62 (including: lens, aperture, shutter and reflective prism, etc.), the image of the scene 60 presented under the light is captured, and the image content is a visualization of the scene light)65, that is, the amount of light relative to the scene. If the light surface image data is read with a light meter, the exposure value can be obtained.

(2) When the light image data 65 of the scene 60 arrives at the device, it will be converted into multi-channel voltage and current signals by the sensing unit 70, so that the data content is transformed into an analog voltage signal 75 representing the color image of the scene.

(3) The analog voltage signal 75 of the color image passes through an analog/digital converter 82 (A/D Converter) in the signal conversion unit 80 again, as shown in FIG. 8, is converted into an L bit (such as: 12bit ) digital image data83.

(4) The digital image data 83 of this L bit passes through the encoder 84 of an L-M in this signal conversion unit 80 again, refer to shown in Figure 8 again, according to the setting of its comparison table, produce an M bit ( Such as: 10bit) digital image data 85 is stored in a temporary memory 86 in the signal conversion unit 80 .

(5) Finally, the M-bit digital image data 85 passes through an M-N encoder 89 in the signal conversion unit 80, and referring to Fig. 8 again, according to the setting of the comparison table, an N-bit ( Such as: 8bit) digital image data 89, and stored in the output image memory 90.

Because, in the present invention, M among these conversion values is designed under the condition greater than or equal to N, that is M≥N, according to the conversion relationship of the MN encoder 89, the digital image data can be reduced from 2 ^M kinds of data values to There are only 2 ^N kinds of values, so if in the dynamic domain X of the input signal, as shown in Figure 9, only 2 ^M kinds of values are taken, corresponding to the 2 ^N kinds of output signal value range Y, then the linear relationship between the sampled values , can be represented by the function Y=mX or (Y ₂ -Y ₁ )=m(X ₂ -X ₁ ), where Y ₂ and Y ₁ are the maximum and minimum values of the corresponding output signal range, and X ₂ It is the upper limit and lower limit of the dynamic domain of the input signal, and its slope m value is:

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="x"\; filenames="C0113070900221.png"\; state="\{\{state\}\}">x</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}$

, the corresponding relationship is the so-called contrast on the visual system.

Referring back to FIG. 9, in the present invention, if the exposure reference value _Xe of the device is a certain set point between _X2 and _X1 , then the exposure reference value _Xe of the device is not changed. Next, increasing the range of the dynamic domain of the input signal between _X2 and _X1 to between _X'2 and _X'1 will make its slope smaller and reduce the contrast of the image. Conversely, if the range of the dynamic domain of the input signal is reduced and the range of the output signal remains unchanged, the contrast of the image can be improved. The present invention utilizes this concept, and stores at least one preset slope value m in the preset parameter memory 10, so that the device can calculate a comparison table under the known exposure reference value _Xe , or input The value X ₂ , X ₁ , X _e of the signal dynamic domain and the corresponding output signal value range Y ₂ , Y ₁ , Y _e calculate a non-linear function, and then generate a comparison table according to the function, and directly pass the comparison Table, adjust the setting of the m value or the X, Y value, so as to achieve the purpose of adjusting the image contrast of the scene to be photographed in real time. Since, in the invention, there are 2 ^M types of value ranges in the dynamic domain of the input signal, and 2 ^N types of value ranges beyond the value range of the output signal, there will be no quantization phenomenon after the correspondence.

In addition, in the present invention, when the optical surface image 65 of the scene 60 arrives at the device, the processor 20 can adjust the aperture and shutter in the optical element group 62 according to the light metering mechanism on the optical element group 62, or adjust the The gain value (Gain) and the compensation value (Offset) of the analog/digital converter 20 are used to set the exposure reference value X _e of the image, and centered on the exposure reference value X _e of the image, it is adjusted in an equal manner. The range value of the dynamic domain of the input signal is not affected by the contrast adjustment due to common exposure settings. Therefore, the contrast adjustment of the present invention can be independent of the exposure control of the device and become an independent control item.

In one embodiment of the present invention, the processor 20 controls each component to adjust the contrast value of the image data according to the following procedures, as shown in FIG. 10 :

(1) First, read a default parameter setting control option from the default parameter memory 10, and then display it through the display of the user interface 50, allowing the user to directly set the control option through the control option The output signal value range of the image is Y ₂ , Y ₁ , (Y ₂ and Y ₁ are not necessarily the extreme values of the Y value range), and then by operating the optical element group 62, set the optical meter respectively on the control option The input signal dynamic domains X 1 , _{X 2 corresponding} to the target positions of the output signal value domains Y ₂ , Y ₁ , are imaged on the data 65 , and these values are stored in the parameter setting memory 40 . In this embodiment, the values of the dynamic domains X ₁ and X ₂ of the input signal can be values measured when the optical element group 62 is aligned with the target positions 1 and 2 of the optical image data 65, as shown in FIG. 11 This value generally refers to the reading of the spot meter; in addition, after setting the relative values of X ₁ and X ₂ and Y ₁ , and Y ₂ , the user can input another value more than the two points. Values X ₃ and Y ₃ are used to determine the nonlinear characteristic curve (such as curve B) as shown in FIG. 4 .

(2) According to the user setting value stored in the parameter setting memory 40, the contrast characteristic parameter of the image data is calculated, and the parameter value is stored in the control parameter memory 30 to complete the definition of the image acquisition. contrast setting;

(3) When the device takes pictures of the scene, make the signal conversion unit 80 convert and encode the analog voltage signal sent from the light sensing unit 70 according to the contrast characteristic parameters stored in the control parameter memory 30 process, and store the generated N-bit digital image data 89 in the image memory 90 .

(4) Then, the image data stored in the output image memory 90 is sent to the display of the user interface 50, so that the user can repeat the procedure of step (1), and pass the control option according to his preference. The input signal ranges X ₁ and X ₂ and the output signal ranges Y ₁ and Y ₂ of the image are reset.

In this embodiment, because the user can directly operate the optical element group 62, on the control options displayed on the display, set the input signal dynamic range X corresponding to at least two target positions on the scene light representation data 65 ₁ and X ₂ and the output signal value ranges Y ₁ and Y ₂ , and then calculate the contrast parameter value of the imaging data in real time according to these set values. Therefore, the signal conversion unit 80 converts the digital image data and During the encoding process, the conversion of L-bit to M-bit digital image data can be omitted, so the two encoders 84 and 88 can be combined, and the temporary memory 86 can be omitted.

In another preferred embodiment of the present invention, the processor 20 controls each component according to the following procedures, as shown in FIG. 12 , to adjust the contrast value of the captured image data:

(1) First, read a default index option from the default parameter memory 10, which includes at least one preset contrast parameter value, and then display it through the display of the user interface 50 , for the user to select, and store the selected value into the parameter setting memory 40; these values can be the slope of its characteristic curve, so the slope can be changed by directly selecting the preset value, as shown in the figure Characteristic curve A, B or C as defined in 3.

(2) According to the user setting value stored in the parameter setting memory 40 and the exposure reference value measured by the optical element group 62, calculate the contrast characteristic parameter of the image data (it can be a nonlinear parameter ), and store the parameter value in the control parameter memory 30 to complete the contrast setting when defining the imaging;

(3) When the user uses the device to take pictures of the scene, the signal conversion unit 80 is ordered to convert the analog voltage signal transmitted from the light sensing unit 70 according to the contrast characteristic parameters stored in the control parameter memory 30 And encoding processing, and the generated N-bit digital image data 89 is stored in the output image memory 90;

(4) Then, the image data stored in the output image memory 90 is sent to the display of the user interface 50, so that the user can repeat the procedure of step (1), and re-select from the image data according to his preference. Select the default contrast parameter value in the indicator option.

In this another embodiment, the user can directly select the preset contrast parameter value from the preset parameter memory 10 directly through the user interface 50, so the signal conversion unit 80 converts the digital image data and During the encoding process, the temporary storage 86 and the conversion of L-bit to M-bit digital image data can be omitted, and the two encoders 84 and 88 can be combined.

In yet another preferred embodiment of the present invention, the processor 20 can control each component to adjust the contrast value of the image data according to the following procedures, as shown in FIG. 13 :

(1) First, from the default parameter memory 10, read a preset index option, which includes at least one preset contrast parameter value, and then display it through the display of the user interface 50 , for the user's reference, according to his personal preference, use an input device (not shown) on the user interface 50 to reselect the contrast parameter value, and store the selected value to the parameter setting memory Within 40;

(2) Calculate the contrast characteristic parameter of the image data according to the user setting value stored in the parameter setting memory 40 and the exposure reference value measured by the optical element group 62, and store the parameter value in In the control parameter memory 30, the contrast setting when defining the imaging is completed;

(3) When the user uses the device to take pictures of the scene, make the signal conversion unit 80 modify the analog/ The data of the comparison table in the digital converter 82 is used to convert the analog voltage signal 75 sent by the light sensing unit 70 into an L-bit digital image data 83, and the image data 83 is the light image data in the light sensing unit 70 and its linear representation on digital signals, but its non-linear relationship in the domain of human visual signals.

(4) Make the L-M encoder 84 modify the data in the comparison table in the L-M encoder 84 according to the parameters stored in the control parameter memory 30, so as to perform non-linear conversion to the L-bit image data 83 to generate M-bit The digital image data 85 of the digital image data 85 representing the brightness converted into human visual perception (perceived) is stored in the temporary memory 86.

(5) Then, make the M-N encoder 86 revise the data in the comparison table in the M-N encoder 86 according to the contrast special control parameters stored in the control parameter memory 30, so as to perform the conversion of the M-bit image data 85 The value range from M bit to N bit is correspondingly converted, and the generated N bit digital image data 89 is stored in the output image memory 90 and presented on the display screen, so that the user can repeat the steps ( 1), according to its preference, re-select the default contrast parameter value from the indicator option.

In the aforementioned corresponding conversion process, since the input signal dynamic domain X in Fig. 4 is represented by the value of M bits, and the value of N bits represents the bit field Y of the output signal, the parameters defined in the comparison table are The corresponding function or characteristic curve when adjusting the contrast is by changing the range of the dynamic domain of the acceptable input signal, and determining the middle reference point position of the dynamic domain according to the exposure reference value.

(6) If the user wants to adjust the contrast of the digital scene image captured by the device, the user can use a positioning device (not shown in the figure) on the user interface 50 to select from the display according to its Preference, select the image data corresponding to the target position 1, 2, at this time, the processor 10 can read the value range corresponding to the target position 1, 2 on the M-bit image data from the temporary memory 86, And store it in the parameter setting memory 40, the value range of the M bit can be used as the input signal dynamic domain X in Figure 4, and the corresponding value range of the N bit image data is determined by the output image After being read out from the memory 90 and stored in the parameter setting memory 40, the value range of N bits can be used as the output signal value range Y as shown in FIG. 4 .

(7) Then, read the stored numerical value in this parameter setting memory 40 again, such as X _N value and Y _N value among Fig. 4, calculate new characteristic curve, and its stored value this control parameter memory 30 , and repeat the procedure of step (5), so that the encoders adjust their comparison table according to the new characteristic curve, and re-encode and convert the captured digital scene image to adjust its contrast effect.

In this way, the user can use the device of the present invention to repeatedly modify and adjust the contrast control parameters in a feedback manner according to his preference, so that the device can calculate a linear or non-linear contrast characteristic curve in real time by considering human visual characteristics , and use it as a sampling reference value when the image processing device (such as: a camera) shoots an image, and shoot a scene image with the best contrast value.

The above is only the best specific embodiment of the present invention, but the features of the present invention are not limited thereto, and any changes or modifications that can be easily conceived by those skilled in the art in the field of the present invention should be covered. Within the scope of the claims of the present invention.

Claims (14)

1, a kind of image processor of adjusting characteristic curve, this device comprises:

One optical elements sets is in order to adjust aperture, shutter, focal length and sensing exposure value;

One photoinduction unit as data, and is converted into the analog voltage signal of representing the scenery chromatic image in order to the light table by this optical elements sets induction subject;

One signal conversion unit is in order to convert this light table to the digital image data of one predetermined format as data; Comprise an analog/digital converter in this signal conversion unit, convert a digital image data in order to the analog voltage signal that this photoinduction unit is transmitted;

One image output memory is in order to store this digital image data;

One user's interface in order to the digital image data that shows that this shadow memory transmits, and makes the user can adjust the set point of pick-up image data by this interface;

One parameter setting memory is in order to store the parameter that the user sets by this user's interface;

One predefined parameter memory is in order to store default parameter;

One Control Parameter memory is in order to store Control Parameter, according to this Control Parameter this signal conversion unit is carried out image adjustment and processing; And

One processor, in order to according to this predefined parameter memory, optical elements sets, image output memory, parameter setting memory and signal that signal conversion unit transmitted respectively, calculate Control Parameter in order to the control image acquisition function, and it is deposited in this Control Parameter memory, make this signal conversion unit according to these Control Parameter, to this photoinduction unit institute picked image data, adjust; It is characterized in that: also comprise in this signal conversion unit:

The encoder of one L-M, according to the setting of its table of comparisons, the digital image data that this analog/digital converter is transmitted converts the digital image data of a M bit to;

One M-N encoder, setting according to its table of comparisons, the digital image data of this M bit is converted to the digital image data of a N bit, wherein M is that design is under the condition more than or equal to N, make transformational relation according to this M-N encoder, make the digital digital image data can be, 2 of sampling by in the input signal dynamic domain X ^MPlant numerical value, correspond to 2 ^NAmong the output signal codomain Y that plants, obtain the linear relationship between its sampling numerical value, that is:

$m=\frac{Y_2-Y_1}{X_2-X_1}$

, Y wherein ₂With Y ₁Be the maximum and the minimum value of corresponding back output signal codomain, and X ₁With X ₂Be the upper limit and the lower limit of input signal dynamic domain, m is its slope, represents so-called contrast on the vision system.

2, the image processor of adjusting characteristic curve as claimed in claim 1 is characterized in that: also comprise a temporary storage in this signal conversion unit, in order to store the digital image data of this M bit.

3, the image processor of adjusting characteristic curve as claimed in claim 1 is characterized in that: the digital image data of this N bit is stored in this image output memory.

4, a kind of image treatment method of adjusting characteristic curve is characterized in that: this method is utilized the processor in the image processor, according to the following step, controls each element in this device, to adjust the contrast value of pick-up image data:

At first, in a parameter preset memory, read a default control option, shown by user's interface, choosing for the user can be in order to adjusting image contrast's numerical value, and selected numerical value is stored in the parameter setting memory;

According to user's set point stored in this parameter setting memory, calculate the contrast-response characteristic parameter of image data, and this parameter value is stored in the Control Parameter memory cell, the contrast settings when finishing the definition capture;

When utilizing this device that scenery is taken pictures, make a signal conversion unit according to the stored contrast-response characteristic parameter of this Control Parameter memory cell, the analog voltage signal that one photoinduction unit is transmitted is changed in regular turn and is encoded, and, be stored in the image output memory the digital image data that is produced;

Then, with the image data that stores in this image output memory, be sent on this user's interface again, make the user can comply with its preference, heavily cover abovementioned steps, adjust the contrast numerical value of image.

5, the image treatment method of adjusting characteristic curve as claimed in claim 4, it is characterized in that: this method can be according to user's set point stored in this parameter setting memory, and the measured exposure reference value of an optical elements sets, calculate the nonlinear contrast degree characterisitic parameter of image data, and this parameter value is stored in this Control Parameter memory the contrast settings when finishing the definition capture.

6, the image treatment method of adjusting characteristic curve as claimed in claim 4 is characterized in that: this control option can be parameter setting control option, makes the user can directly pass through this control option, the output signal codomain Y of setting of image ₁, Y ₂Again by the operation one optical elements sets, in set respectively on this control option this light table as data on corresponding to these output signal codomains Y ₁, Y ₂The input signal dynamic domain X of target location ₁, X ₂, and these numerical value are stored in this parameter setting memory.

7, the image treatment method of adjusting characteristic curve as claimed in claim 6, it is characterized in that: the image data that stores in this image output memory, be sent to after this user's interface shown, can make the user heavily cover abovementioned steps, according to its preference, reset output image signal codomain Y by this control option ₁, Y ₂And input signal dynamic domain X ₁, X ₂

8, the image treatment method of adjusting characteristic curve as claimed in claim 6 is characterized in that: this input signal dynamic domain X ₁, X ₂Numerical value, the reading of measured some exposure meter when can be this optical elements sets and aiming at this light table as the target location of data.

9, the image treatment method of adjusting characteristic curve as claimed in claim 4, it is characterized in that: this control option can be an index option, comprise the contrast level parameter value that at least more than one is default in this index option, shown, choose for the user by user's interface.

10, the image treatment method of adjusting characteristic curve as claimed in claim 9, it is characterized in that: the image data that stores in this image output memory, after being sent to this user's interface, can make the user heavily cover abovementioned steps, according to its preference, in this index option, choose default contrast level parameter value again.

11, the image treatment method of adjusting characteristic curve as claimed in claim 4, it is characterized in that: this method also comprises:

When the user utilizes this device that scenery is taken pictures, make this signal conversion unit according to measured exposure reference value and the stored contrast-response characteristic parameter of this Control Parameter memory cell of an optical elements sets, revise the data of an analog/digital converter internal reference table, with the analog voltage signal that a photoinduction unit is transmitted, convert the digital image data of L bit to;

Make a L-M encoder according to the stored contrast-response characteristic parameter of this Control Parameter memory, revise the data of this L-M encoder internal reference table, so that this L bit image data is carried out non-linear conversion, produce the image data 85 of a M bit, and it is stored in the temporary storage;

Then, make a M-N encoder according to the stored contrast-response characteristic parameter of this Control Parameter memory again, revise the data of this M-N encoder internal reference table, carry out by the codomain corresponding conversion of M bit with image data, and, be stored in an image output memory the N bit digital image data that is produced to the N bit to this M bit, and be presented on this display screen, make the user can heavily cover abovementioned steps,, in this index option, choose default contrast level parameter value again according to its preference.

12, the image treatment method of adjusting characteristic curve as claimed in claim 11, it is characterized in that: the numerical value of this M bit is represented its input signal dynamic domain X, the numerical value of N bit is represented its output signal codomain Y, the defined parameter of this M-N encoder internal reference table is corresponding parameter or characteristic curve when adjusting contrast.

13, the image treatment method of adjusting characteristic curve as claimed in claim 12, it is characterized in that: the corresponded manner of this M-N encoder is by changing the scope of acceptable input signal dynamic domain, and determines the reference point locations of this dynamic domain according to exposure reference value.

14, the image treatment method of adjusting characteristic curve as claimed in claim 11, it is characterized in that: this method also can make the user pass through the location of one on this user's interface device, on this display, according to the following step, to the digital scenery image that this device has captured, degree of comparing adjustment:

According to the target location on selected this image data of this positioner, by reading in this temporary storage on this M bit image data to number range that should the target location, and it is stored in this parameter setting memory, the number range of this M bit can be used as input signal dynamic domain X, and the corresponding number range of this N bit image data, then by being read out in this image output memory, and be stored in this parameter setting memory, as output signal codomain Y;

Then, read stored numerical value in this parameter setting memory again, the characteristic curve that calculating makes new advances, and it is stored in this Control Parameter memory, lay equal stress on and cover abovementioned steps, make these encoders, adjust its table of comparisons according to new characteristic curve, again the digital scenery image that has captured is encoded and handle, to adjust its minus effect.

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