TW201541435A - Device and method for standalone image calibration of LCD display - Google Patents

Abstract

The present invention provides a device and a method for standalone image calibration of an LCD display. The calibration device comprises a front optical sensor and a calibration reference device, in which the front optical sensor is used for calibration of gray scale and color temperature of the display and the calibration reference device is used for pre-calibration of the front optical sensor. An advantageous effect of the present invention is that the front optical sensor is subjected to image calibration in advance before being shipped and the calibrated front optical sensor is used to directly adjust the gray scale and color temperature of a display screen so that the installation is easy and the image of the display can be effectively inspected and calibrated. As such, human resources can be saved and the operation of overall maintenance and production can be shortened.

Description

Self-image correcting device and method for liquid crystal display

The invention belongs to the field of display image correction technology, in particular to a self-image correction device and method for a liquid crystal display, thereby achieving the saving of human resources and shortening the overall maintenance and manufacturing engineering.

According to the general display image correction technology, it can be divided into two types: hardware correction and software correction. The hardware correction is a storage device that stores the adjusted data in the display, and the software is corrected to use the color profile (ICC Profile). Through the computer's operating system to achieve image correction purposes.

Traditional display calibration, whether it is hardware or software calibration, requires the use of external devices such as computers, colorimeters, etc., as well as the professional software required to calibrate the display. It is not convenient to set up the above-mentioned external devices in some cases. Such as buried wall displays, displays in the operating room, and so on. Especially in the medical system equipment where frequent use and imaging are required to maintain high standards, external devices and professional software are also a small overhead for maintenance costs.

However, because each display panel has slight differences in its production, even if the physical characteristics are slightly different, the maximum brightness is inconsistent. After gamma correction and color temperature compensation, the brightness difference is more obvious. In particular, medical systems that use high frequency and need to accurately display hue need to maintain high standard reference values in order to provide doctors with a correct judgment.

In the prior art, Taiwan Patent Publication No. 200627369, only one method of adjusting the image color temperature is provided, which is to record an image or the like by transmitting the physical characteristics of the electronic circuit.

[Patent Document 1] Taiwan Patent Publication No. 200627369

In order to effectively solve the above problems, the present invention utilizes a light sensor and cooperates with a display. The sensing component provided on the device can be used to achieve independent self-image correction of the display without any external device and software setting, as long as the photo sensor is calibrated at the factory. It can be used in situations where it is not convenient to install an external device and reduce the cost of correcting maintenance of the display.

The main object of the present invention is to provide a self-image correction method for a liquid crystal display, wherein the correction method is to correct the gray scale and color temperature of the display by means of a front light sensor disposed on the display, the light sense The detector needs to be pre-calibrated before application. To maintain a consistent and stable reference value.

Further, the method specifically includes the following steps: (1) erecting a front light sensor of the display; (2) verifying the front light sensor using the calibration reference device; (3) gamma of the front light sensor to the display The value and color temperature are corrected.

The present invention also provides a self-image correcting device for a liquid crystal display, the correcting device comprising a front light sensor, a correction reference device, the front light sensor being disposed in front of the liquid crystal display panel, and the correction reference device being disposed in the liquid crystal An intermediate position of the display, the correction reference device and the display are connected to a computer, the front light sensor for correcting gray scale and color temperature of the display, the correction reference device for sensing light in front The detector is pre-calibrated.

The invention discloses the beneficial effects: pre-image correction is performed on the installed photo sensor at the time of shipment, and the calibrated photo sensor is directly used to adjust the gray scale and color temperature of the display screen, and the installation is simple, and the detection can be effectively detected. Display image.

1‧‧‧ display

2‧‧‧ Front light sensor

3‧‧‧Correction reference device

4‧‧‧Test screen

1 is a schematic diagram of correction of a front light sensor according to the present invention; and FIG. 2 is a schematic diagram of self-correction of a front light sensor of the present invention.

The above and other structural and functional features of the present invention will be further described with reference to the accompanying drawings and specific embodiments. FIG. 1 and FIG.

The present invention includes a flow chart and a flow chart of the following three steps.

The first step: erecting the front light sensor of the display

By arranging the front light sensor 2 in front of the panel of the liquid crystal display 1, it is possible to avoid factors such as brightness degradation caused by the deterioration of the liquid crystal display panel, and to obtain more accurate measurement data.

The second step: verifying the front light sensor, and implementing the following method to obtain the measured data, and comparing with the calibration reference device to obtain a difference. If the difference is smaller than the error range Delta E (2000) < 5, the calibration is successful.

1. Set up a colorimeter or spectrometer at the appropriate position of the display as the calibration reference device 3; 2. Connect the display 1 and the calibration reference device 3 to the computer; 3. Adjust the brightness of the display 1 to the lowest value of the use range, and display all black Test screen. After waiting for the brightness to stabilize, at this time, the photosensor 2 measures the measured values of the three channels of Red, Green, and Blue. At the same time, the chromaticity space coordinates x, y and brightness (lightness) Y measured by the reference device 3 are corrected. .

4. Display 1 displays test screen 4, and calibration reference device 3 measures data such as chromaticity space coordinates x , y and brightness (lightness) Y , and stores the measured data, while front light sensor measures Red, Green, Blue value and Clear Channel data, and store the data obtained by the measurement; the application test screen is rgb=(255 0 0), rgb=(0 255 0), rgb=(0 0 255) Test screen, the data measured by the calibration reference device is three sets of data The corresponding front light sensor measures the data .

5. The relationship equation between the chromaticity space and the color stimuli value is applied, where x and y in the formula are chromaticity space coordinates, and X , Y , and Z are color stimuli values: Converting the data measured by the calibration reference device in steps 3 and 4 into color stimulus values, and obtaining four sets of color stimulation values. ;

6. Establish a transformation matrix between the data measured by the front light sensor and the color stimulus value of step four and find the transformation matrix coefficients to create a conversion equation:

among them For color stimuli, Information measured for the front light sensor.

The data measured by the front light sensor in the above steps 3, 4, and 5 and the color stimulus value measured and converted by the calibration reference device are brought into the conversion equation to obtain the conversion matrix M.

7. The display shows other test screens. The front light sensor measures, obtains the measured data and converts the measured data into ( x ) and (2) and (1) into x , y , Y values, and x . y , Y is compared with the calibration reference device to obtain a difference. If the difference is smaller than the error range, the calibration is successful.

Third step: front light sensor self-correcting display

First, use the front light sensor to measure the darkest brightness value L _min and the brightest brightness value L _max of the display, and calculate the contrast value of the display C = L _max / L _min to confirm that the contrast value of the display complies with the DICOM specification.

Second, adjust the gamma value in the following way

a. The feedback control is adjusted by the front front light sensor to adjust the backlight of the display to the appropriate brightness, the brightness must be greater than the minimum brightness specified in DICOM; b. The display produces a 32-step gray scale test picture, which is measured by the front light sensor and Recording the brightness characteristic curve as the reference, establishing the brightness characteristic curve of the display; c. interpolating the reference brightness by cubic spline interpolation according to the requirements of the display chip, obtaining the brightness reference required by the display chip Luminance reference table, the size of the brightness reference table is n ; d. The target gamma value is obtained according to the gamma value formula (5), and the brightness value required for each step is obtained, and the closest correspondence is taken out in the brightness reference table. Order, fill it into the gamma table (GAMMA table).

Equation (5), L ( x )= L ₀ +( L _{n -1} - L ₀ )×( x / n ) ^γ x =0,1... n -1

e. The display firmware loads the gamma table adjusted in step d, and re-measures the gray scale curve to verify that the calibration result is correct and completes the gamma correction.

Third, adjust the color temperature in the following ways

a. Use the front light sensor to perform feedback control to adjust the backlight of the display to the appropriate brightness, the brightness must be greater than the minimum brightness specified in DICOM; b. The display shows the all-white test picture, and the front light sensor uses the conversion matrix to measure The display's current chrominance space coordinates x , y and luminance (lightness) Y values, the display R, G, B-Gain (red gain, green gain, and blue gain) values in the scratchpad, where R-Gain and The color coordinate (x, y) corresponding to the color temperature is proportional to x, G-Gain is proportional to y, and B-Gain is inversely proportional to x and y. In addition, R Gain, G Gain and B Gain and the brightness Y of the display screen satisfy the following formula: Y = 0.299 * R Gain + 0.587 * G Gain + 0.114 * B Gain, thus adjusting the display R, G in the register , B-Gain to adjust the color temperature of the display screen; c. Load the adjusted R, G, B-Gain values from the firmware and measure again to confirm whether the display chromaticity space coordinates x , y and brightness (lightness) Y value fall Into the error tolerance range, the color temperature adjustment is completed.

The invention performs pre-image correction on the installed front light sensor, and directly adjusts the gray scale and color temperature of the display screen by using the front light sensor, and the installation is simple, and the corrected display image can be effectively detected.

The above examples are intended to illustrate the invention and not to limit it. Any modifications to the invention are intended to fall within the scope of the invention.

1‧‧‧ display

2‧‧‧ Front light sensor

3‧‧‧Correction reference device

4‧‧‧Test screen

Claims (10)

A self-image correction method for a liquid crystal display, characterized in that the correction method is to correct a gray scale and a color temperature of a display by means of a front light sensor on the display, the front light sensor before application Need to be corrected in advance. The method of claim 1, wherein the method comprises the following steps: (1) erecting a light sensor in front of the display; (2) verifying the front light sensor using a calibration reference device; (3) The front light sensor corrects the gamma value and color temperature of the display. The method of claim 2, wherein the step (2) further comprises the steps of: (21) erecting a calibration reference device in front of the display; (22) connecting the display and the calibration reference device to Computer; (23) display display test screen, calibration reference device measurement chromaticity space coordinates x, y and brightness value Y and stored by computer, front light sensor to measure the display and store measurement data; (24) the above steps (23) obtaining the color stimulus value by substituting the data measured by the correction reference device into the relationship equation between the chromaticity space and the color stimuli value; (25) establishing the data measured by the front light sensor in step (23) and step (24) a conversion matrix between the obtained color stimulus values, and the transformation matrix coefficients are obtained; (26) The display displays other test pictures, which are measured by the front light sensor, and the measured data is converted into chromaticity space coordinates and brightness values, and compared with the space coordinates and brightness values obtained by the calibration reference device, the error is smaller than the error range. Delta E (2000) < 5, verification is complete. The method of claim 2, wherein the correction reference device is a colorimeter or a spectrometer. The method of claim 2, wherein the correcting the gamma value by the front light sensor comprises the following steps: (311) the front light sensor performs feedback control to adjust the backlight of the display to make the brightness Greater than the minimum brightness specified in DICOM; (312) the display displays the test picture, the front light sensor measures and records as the reference brightness, and establishes the brightness characteristic curve of the display according to the reference brightness; (313) according to the requirements of the display chip, Interpolating the reference brightness to obtain the brightness reference table required by the display wafer, the brightness reference table size is n ; (314) the target gamma value according to the gamma value formula L ( x ) = L ₀ + ( L _{n -1} - L ₀ )×( x / n ) ^γ x =0,1... n -1 Find the required luminance value for each order, and take the closest corresponding order in the luminance reference table, and fill it with gamma In the table, (315) the display firmware loads the gamma table adjusted in step (314), and re-measures the gray scale curve to verify whether the tuning result is correct, and completes the gamma correction. The application method of claim 5 patentable scope item, characterized in further comprising prior to said step (311): measured using the forward light sensor darkest luminance value L _min and L _max luminance values of the brightest display, Calculate the contrast value of the display C = L _max / L _min to confirm that the contrast value of the display complies with the DICOM specification. The method of claim 5, wherein the step (313) applies a cubic curve interpolation method to interpolate the reference brightness. The method of claim 2, wherein the correcting the color temperature by the front light sensor comprises the following steps: (321) the front light sensor performs feedback control to adjust the backlight of the display, so that the brightness is greater than DICOM. The lowest brightness specified in the specification; (322) the display shows the test picture, the front light sensor measures the data and obtains the current chromaticity space coordinates and the brightness value of the display through the conversion matrix, according to the R, G, B-Gain value and the chromatic space The coordinates of the coordinates, adjust the display R, G, B-Gain in the scratchpad to adjust the color temperature of the display screen; (323) load the adjusted R, G, B-Gain values from the firmware and re-measure to confirm the display color Whether the degree of space coordinates and the brightness value fall within the error tolerance range Delta E (2000) < 5, the color temperature adjustment is completed. A self-image correcting device for a liquid crystal display, the correcting device comprising a front light sensor, a correction reference device, the front light sensor being disposed in front of the liquid crystal display panel, and the correction reference device being disposed at an intermediate position of the liquid crystal display And the correction reference device and the display are connected to the computer, wherein the front light sensor is configured to correct gray scale and color temperature of the display, and the correction reference device is used for front light perception The detector is pre-calibrated. The calibration device of claim 9, wherein the correction reference device is a colorimeter or a spectrometer.