A method for measuring and comparing the clarity of handwriting on a writing board

Abstract

The present invention provides a method for measuring and comparing the clarity of handwriting on a writing board. The method for measuring the clarity of handwriting on a writing board comprises: drawing the handwriting to be tested on a writing board with a writing pen; selecting a test area of ​​the writing board, the test area comprising a writing board area and a handwriting area, adjusting the ambient light source so that the illumination of the test area reaches a target illumination; using a non-contact brightness tester to measure the brightness of the test area, recording the reflection brightness value of the writing board area as Lv1, recording the reflection brightness value of the handwriting area as Lv2, and representing the handwriting clarity with M, and calculating M=︱Lv1-Lv2︱ / (Lv1+Lv2). When comparing the clarity of writing boards, with the same target illumination, the M value is obtained according to the method for measuring the clarity of handwriting on writing boards, and the larger the M value, the higher the clarity of the writing board. The present invention realizes the quantitative measurement and comparison of the clarity of handwriting on writing boards, and the test consistency is very high, the stability is good, and the reproducibility is high.

Description

Technical Field

[0001] The invention belongs to the field of display devices, and in particular relates to a method for measuring and comparing the clarity of handwriting on a writing board. Background Art

[0002] In the smart blackboard series of interactive smart tablets, the middle main screen is mainly used for electronic courseware display, and the left and right sub-screens are mainly used for chalk writing on the blackboard. Generally speaking, the clarity of chalk writing on the writing board depends on the powder adhesion effect of the chalk after rubbing on the writing board. However, in the prior art, the judgment of the powder adhesion effect of chalk writing on the writing board is generally made through subjective judgment of a single product (for example, the handwriting feels smooth, full, the strokes are even, the lines are clear, etc.), or through subjective comparison and judgment by a comparison machine. However, the evaluation conclusions of this judgment method vary from person to person, the consistency is unstable, and the reproducibility is not high.

[0003] Therefore, it is necessary to formulate quantitative indicators to measure the handwriting clarity of writing boards (including traditional blackboards, whiteboards, and smart blackboards, etc.), to provide a reliable evaluation basis for horizontal comparison and evaluation of the advantages and disadvantages of various devices and to improve the writing powder effect of writing boards. Summary of the invention

[0004] Based on this, the purpose of the embodiment of the present invention is to provide a method for measuring the clarity of handwriting on a writing board, which realizes the quantitative measurement of the clarity of handwriting on the writing board, and has very high test consistency, good stability and high reproducibility.

[0005] A method for measuring the clarity of handwriting on a writing board comprises the following steps:

[0006] Use a writing pen to draw the handwriting to be tested on the writing board;

[0007] Selecting a test area of ​​the writing board, the test area including the writing board area and the handwriting area, and adjusting the ambient light source so that the illumination of the test area reaches the target illumination;

[0008] Use a non-contact brightness tester to measure the brightness of the test area, record the reflection brightness value of the writing board area as Lv1, record the reflection brightness value of the handwriting area as Lv2, and the handwriting clarity is represented by M, and M=︱Lv1-Lv2︱ / (Lv1+Lv2) is calculated.

[0009] The embodiment of the present invention selects a test area including a writing board area and a handwriting area on the writing board, and measures the reflection brightness values ​​Lv1 and Lv2 of the writing board area and the handwriting area respectively, and uses the M value calculated according to the formula ︱Lv1-Lv2︱ / (Lv1+Lv2) to represent the handwriting clarity. The larger the ratio, the clearer it is. 1 is the optimal value and 0 is the worst value. The handwriting clarity of the writing board can be quantified, the evaluation criteria are more objective, and the test consistency, stability and reproducibility are high. The writing board can include various traditional or new writing boards such as conventional blackboards, whiteboards, and smart blackboards. The test area can be selected by manual circling or by machine selection.

[0010] Preferably, the non-contact brightness tester is a non-contact high-resolution brightness tester with a resolution of not less than 2000 × 2000. By using a non-contact high-resolution brightness tester, the obtained Lv1 and Lv2 values ​​are more accurate, thereby making the handwriting clarity more accurate.

[0011] Furthermore, when the non-contact brightness tester measures the brightness of the test area, it first records the reflection brightness value Lv of each pixel in the test area, discards the measured value between the writing board brightness threshold and the handwriting brightness threshold according to the set writing board brightness threshold and handwriting brightness threshold, divides the remaining Lv values ​​into several Lv1 and several Lv2, calculates the reflection brightness average value Lv1_avg of the writing board area and the reflection brightness average value Lv2_avg of the handwriting area, and calculates the handwriting clarity M = ︱Lv1_avg-Lv2_avg︱ / (Lv1_avg+Lv2_avg). This is a specific method for measuring with a non-contact high-resolution brightness tester, which classifies the reflection brightness value Lv of each pixel in the test area, discards the result that neither represents the writing board nor the handwriting, and substitutes the reflection brightness average value of the writing board area and the reflection brightness average value of the handwriting area into the formula, so that the calculation result of the handwriting clarity M can be more accurate.

[0012] Furthermore, when the writing board is a blackboard, the measurement values ​​not greater than the writing board threshold are collected as Lv1, and the measurement values ​​not less than the handwriting threshold are collected as Lv2; when the writing board is a whiteboard, the measurement values ​​not less than the writing board threshold are collected as Lv1, and the measurement values ​​not greater than the handwriting threshold are collected as Lv2. For different types of writing boards, the Lv value is divided into the writing board area value and the handwriting area value, which are not the same.

[0013] As an implementation mode, the processor processes all the measured values ​​of the non-contact brightness tester. When the processor receives the reflected brightness value Lv of each pixel output by the non-contact brightness tester, the processor discards the measured value between the handwriting threshold and the writing board threshold, and determines and collects a number of Lv1 and a number of Lv2, calculates Lv1_avg and Lv2_avg, and then calculates the handwriting clarity according to M=︱Lv1_avg-Lv2_avg︱ / (Lv1_avg+Lv2_avg). In this implementation mode, the processing of the measured value Lv is completed by the processor to realize automatic evaluation.

[0014] Preferably, the handwriting to be tested drawn on the writing board with a writing pen is a plurality of line segments. When the handwriting is a plurality of line segments, more Lv2 values ​​can be included when selecting the test area, and the average value thereof is more accurate, thereby effectively improving the accuracy of the handwriting clarity M value.

[0015] Furthermore, the step of drawing the handwriting to be tested is: placing the writing board horizontally, making the writing pen perpendicular to the writing surface of the writing board, using a 1kg special weight to press the writing pen, and drawing several 50mm line segments at a drawing speed of 20mm / s to 25mm / s. This method of drawing the handwriting to be tested refers to the test method of GB 28231, so that the handwriting drawn on each writing board adopts the same standardized method, which can reduce the comparison error.

[0016] Preferably, the test area is rectangular. Since the non-contact brightness tester divides the test area into a plurality of pixels, and each pixel is in a square shape, if the test area is rectangular, the final result will be more accurate.

[0017] Preferably, the target illumination is not less than 500 Lux. Since the national standard for classrooms is about 500 Lux, testing the clarity of handwriting on a writing board under this target illumination is conducive to simulating a real classroom environment, making the final clarity closer to the scene during actual use and more accurate.

[0018] The embodiment of the present invention also provides a method for comparing the clarity of handwriting on writing boards. At least two writing boards are selected, and the handwriting clarity M of each writing board is obtained according to the method for measuring the clarity of handwriting on writing boards at the same target illumination. The M values ​​are compared, and the writing board with a larger M value has a higher clarity. The method for comparing the clarity of handwriting on writing boards of the embodiment of the present invention is independent of the type of writing board and has a wide range of applications. It can be used to compare writing boards of the same type, such as both blackboards or both whiteboards; it can also be used to compare writing boards of different types, such as one blackboard and the other whiteboard; the clarity between writing boards can be quantitatively compared, and the evaluation criteria are more objective. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The writing board of Embodiment 1 of the present invention is provided with a schematic diagram of handwriting to be tested;

[0020] Figure 2 This is a schematic diagram of selecting a test area on a writing board with handwriting to be tested drawn on it according to Embodiment 1 of the present invention;

[0021] Figure 3 This is a schematic diagram of a method for drawing handwriting to be tested in Embodiment 1 of the present invention.

[0022] Among them: 1-writing board, 2-handwriting, 3-testing area, 31-writing board area, 32-handwriting area, 4-special weight, 5-writing pen. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the following is a detailed description through specific embodiments of the present invention.

[0024] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from the present invention described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the embodiments disclosed below.

[0025] Example 1

[0026] The method for measuring the clarity of handwriting on a writing board of the present embodiment comprises the following steps:

[0027] like Figure 1 As shown, use a writing pen to draw the handwriting 2 to be tested on the writing board 1;

[0028] like Figure 2 As shown, the test area 3 of the writing board is selected, and the test area 3 includes the writing board area 31 and the handwriting area 32, and the ambient light source is adjusted so that the illumination of the test area 3 reaches the target illumination;

[0029] Use a non-contact brightness tester to measure the brightness of the test area, record the reflection brightness value of the writing board area as Lv1, record the reflection brightness value of the handwriting area as Lv2, and the handwriting clarity is represented by M, and M=︱Lv1-Lv2︱ / (Lv1+Lv2) is calculated.

[0030] In this embodiment, a test area 3 including a writing board area 31 and a handwriting area 32 is selected on the writing board 1, and the reflection brightness values ​​Lv1 and Lv2 of the writing board area 31 and the handwriting area 32 are measured respectively, and the handwriting clarity is represented by the M value calculated according to the formula |Lv1-Lv2| / (Lv1+Lv2), the larger the ratio, the clearer it is, 1 is the optimal value, and 0 is the worst value. The handwriting clarity of the writing board can be quantified, the evaluation criteria are more objective, and the test consistency is high, the stability is good, and the reproducibility is high.

[0031] In this embodiment, the writing board 1 is specifically a smart blackboard. In other embodiments, it can also be a common writing board such as a blackboard or a whiteboard. In this embodiment, the handwriting to be tested drawn on the writing board 1 with a writing pen is a plurality of line segments. The specific drawing method is: Figure 3 As shown, place the writing board 1 horizontally, make the writing pen 5 perpendicular to the writing surface of the writing board 1, use a 1kg special weight 4 to fix and press on the writing pen 5, and draw several 50mm line segments at a drawing speed of 20mm / s to 25mm / s. This method of drawing the handwriting to be tested refers to the test method of GB 28231, so that the handwriting drawn on each writing board uses the same standardized method, which can reduce the comparison error when comparing the clarity; in addition, the handwriting to be tested has several line segments. When selecting the test area, the test area can include more Lv2 values, and the average value is more accurate, thereby effectively improving the accuracy of the handwriting clarity M value.

[0032] In this embodiment, the non-contact brightness tester specifically uses a CCD grayscale color analyzer with a resolution of 3000*2700. The test area 3 is manually circled and the test area is rectangular. In other embodiments, the test area can also be automatically selected by a processor such as a computer, and the test area can certainly be other shapes. Since the non-contact brightness tester divides the test area into multiple pixels, and each pixel is in a square shape, a rectangular test area will make the final clarity calculation result more accurate. Figure 2As shown, the test area in this embodiment contains 8*5=40 imaging pixels in total. In this embodiment, the ambient light source adopts a directional light source, and in other embodiments, real ambient light can also be adopted; the target illumination is 500 Lux. According to the debugging setting, the writing board brightness threshold is 15nits and the handwriting brightness threshold is 250nits. The specific measurement method is: first record the reflection brightness value Lv of each pixel in the test area 3, as shown in Table 1 below; discard the measurement values ​​between 15nits and 250nits (the third row of Table 1), and the measurement values ​​not greater than 15nits are taken as Lv1 (the first to second rows of Table 1), and the measurement values ​​not less than 250nits are taken as Lv2 (the fourth to fifth rows of Table 1); calculate the average reflection brightness Lv1_avg of the writing board area according to all Lv1 values, calculate the average reflection brightness Lv2_avg of the handwriting area according to all Lv2 values, and calculate the handwriting clarity M = |Lv1_avg-Lv2_avg| / (Lv1_avg+Lv2_avg).

[0033] Table 1 List of reflective brightness values ​​Lv of the writing board test area of ​​Example 1 (unit: nits)

[0034] 10.2 10.8 11 10.5 9.05 9.34 10.4 10.4 10.8 9.53 10.9 10.6 9.17 10.4 10.4 9.25 159 157 154 151 151 156 156 157 297 303 303 300 303 296 301 297 296 297 297 305 302 297 295 305

[0035] It is calculated that Lv1_avg = 10.2 nits, Lv2_avg = 299 nits, and the clarity of the writing board of this embodiment is M = |Lv1_avg-Lv2_avg| / (Lv1_avg+Lv2_avg)=|299-10.2| / (299+10.2)=0.934.

[0036] Example 2

[0037] The method for measuring the clarity of handwriting on the writing board of this embodiment is basically the same as that of the first embodiment, except that the whole writing board frame is automatically selected as the test area by the computer, and the handwriting clarity is automatically calculated by the computer according to the formula M=︱Lv1_avg-Lv2_avg︱ / (Lv1_avg+Lv2_avg). Finally, the clarity of the writing board M=0.933 is obtained.

[0038] Example 3

[0039] The method for measuring the clarity of handwriting on the writing board of this embodiment is basically the same as that of Example 1, with the only difference being that: the writing board of this embodiment is a whiteboard, the ambient light source is real ambient light, and the test area contains 6*11 imaging pixels; according to the debugging setting, the writing board brightness threshold of 250nits and the handwriting brightness threshold of 15nits, the specific measurement method is: first record the reflection brightness value Lv of each pixel in the test area 3, as shown in Table 1 below; discard the measurement values ​​between 15nits and 250nits (the third, sixth, and ninth rows of Table 2), and the measurement values ​​not less than 250nits are taken as Lv1 (the first to second rows, the seventh to eighth rows of Table 2), and the measurement values ​​not greater than 15nits are taken as Lv2 (the fourth to fifth rows, the tenth to eleventh rows of Table 2).

[0040] Table 2 List of reflective brightness values ​​Lv of the writing board test area in Example 3 (unit: nits)

[0041] 299.2 268.9 278.2 295.8 285.0 288.8 275.3 299.3 279.7 267.5 250.7 299.6 199.3 192.0 218.2 203.0 198.8 195.6 9.4 13.8 11.4 14.4 8.9 14.4 13.1 11.7 9.8 8.0 9.6 13.1 217.9 217.4 214.6 196.8 210.5 219.3 266.4 259.3 268.4 250.6 257.9 259.3 271.8 272.2 295.2 254.6 282.0 274.6 195.8 206.5 191.3 212.1 219.0 202.9 13.0 11.1 14.1 13.6 9.6 9.0 13.7 9.2 14.6 14.3 8.5 8.6

[0042] It is calculated that Lv1_avg = 275 nits, Lv2_avg = 11.5 nits, and the clarity of the writing board of this embodiment is M = |Lv1_avg-Lv2_avg| / (Lv1_avg+Lv2_avg)=|275-11.5| / (275+11.5)=0.920.

[0043] Example 4

[0044] This embodiment provides a method for comparing the clarity of handwriting on writing boards. Two writing boards of Embodiment 1 and Embodiment 3 are selected. Since they use the same illumination of 500 Lux when measuring the clarity of handwriting, the clarity M values ​​of the writing boards can be directly compared. The value of Example 1 is larger, so the clarity of the writing board of Embodiment 1 is relatively higher.

[0045] The method for comparing the clarity of handwriting on writing boards according to the embodiment of the present invention is independent of the type of writing boards and has a wide range of applications. It enables the clarity of writing boards to be quantitatively compared and the evaluation criteria are objective, simple and easy to implement.

[0046] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for measuring the clarity of handwriting on a writing board, characterized in that: The following steps are involved: Use a writing pen to draw the handwriting to be tested on the writing board; Selecting a test area of ​​the writing board, the test area including the writing board area and the handwriting area, and adjusting the ambient light source so that the illumination of the test area reaches the target illumination; The brightness of the test area is measured using a non-contact brightness tester, the reflection brightness value of the writing board area is recorded as Lv1, the reflection brightness value of the handwriting area is recorded as Lv2, the handwriting clarity is represented by M, and M=︱Lv1-Lv2︱ / (Lv1+Lv2); Among them, when the non-contact brightness tester measures the brightness of the test area, it first records the reflection brightness value Lv of each pixel in the test area, and discards the measurement value between the writing board brightness threshold and the handwriting brightness threshold according to the set writing board brightness threshold and handwriting brightness threshold, and divides the remaining Lv values ​​into several Lv1s and several Lv2s, calculates the reflection brightness average value Lv1_avg of the writing board area and the reflection brightness average value Lv2_avg of the handwriting area, and calculates the handwriting clarity M=︱Lv1_avg-Lv2_avg︱ / (Lv1_avg+Lv2_avg).

2. The method for measuring the clarity of handwriting on a writing board according to claim 1, characterized in that: The non-contact brightness tester is a non-contact high-resolution brightness tester with a resolution of no less than 2000×2000.

3. The method for measuring the clarity of handwriting on a writing board according to claim 1, characterized in that: When the writing board is a blackboard, the measurement values ​​not greater than the writing board threshold are collected as Lv1, and the measurement values ​​not less than the handwriting threshold are collected as Lv2; when the writing board is a whiteboard, the measurement values ​​not less than the writing board threshold are collected as Lv1, and the measurement values ​​not greater than the handwriting threshold are collected as Lv2.

4. The method for measuring the clarity of handwriting on a writing board according to claim 1, characterized in that: The processor processes all the measurement values ​​of the non-contact brightness tester. When the processor receives the reflection brightness value Lv of each pixel output by the non-contact brightness tester, the processor discards the measurement value between the handwriting threshold and the writing board threshold, and determines and collects several Lv1s and several Lv2s, calculates Lv1_avg and Lv2_avg, and then calculates the handwriting clarity according to M=︱Lv1_avg-Lv2_avg︱ / (Lv1_avg+Lv2_avg).

5. The method for measuring the clarity of handwriting on a writing board according to claim 2, characterized in that: The handwriting to be tested drawn on the writing board with a writing pen is a plurality of line segments.

6. The method for measuring the clarity of handwriting on a writing board according to claim 5, characterized in that: The steps of drawing the handwriting to be tested are: placing the writing board horizontally, making the writing pen perpendicular to the writing surface of the writing board, using a 1kg special weight to press on the writing pen, and drawing several 50mm line segments by hand at a drawing speed of 20mm / s to 25mm / s.

7. The method for measuring the clarity of handwriting on a writing board according to claim 1, characterized in that: The test area is rectangular.

8. The method for measuring the clarity of handwriting on a writing board according to claim 1, characterized in that: The target illumination is not less than 500 Lux.

9. A method for comparing the clarity of handwriting on a writing board, characterized in that: Select at least two writing boards, and obtain the handwriting clarity M of each writing board according to the method for measuring handwriting clarity of writing boards as described in any one of claims 1 to 8 at the same target illumination; Comparing the M value, the larger the M value, the higher the clarity of the writing board.

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