JPS61230045A - Method for comparing luster of curved subject by degree of fading of video - Google Patents

Abstract

PURPOSE:To compare and judge the magnitude of a curved surface or spherical specimen by forming the image of a light source or an index and measuring a reflected light distribution from the video and a fading part in the vicinity of the video. CONSTITUTION:The image of the light source 1 or that of the index drawing a black circle on a white base is formed on the curved surface or the surface of the spherical specimen 2. A CCD line sensor 4 receives the reflected light beam from the fading part in the vicinity of the video and the video on the surface of the specimen 2. The intensity distribution of the received light beam is drawn on a cathode-ray oscilloscope 5. If the luster of the specimen 2 is larger, the light intensity distribution becomes a sharp normal distribution shape as figure (a) shows. On the other hand, when the luster is smaller, it is of a soft normal distribution shape as figure (c) shows. A luster evaluation value G0 considering the fading degree is obtained by utilizing the difference of the shape of the light intensity distribution or by inputting said distribution to a luster evaluation arithmetic part, and according to the magnitude of the G0 the luster of the specimen 2 is compared or decided.

Description

[Detailed Description of the Invention] According to the JIS 2 B741 gloss measurement method measured by the Japanese Standards Association. #1 surface gloss, polarized contrast gloss. Definitions of physical gloss such as θ degree contrast gloss and M angle contrast gloss and methods for measuring their gloss levels are specified, and these are mainly aimed at the gloss of flat objects. Furthermore, the same JIS
In Section 4, Tsunabe stipulates that which glossiness measurement method to use for each surface of fl1 should be selected taking into consideration the characteristics of the object surface.

The standard for determining the glossiness of an object is the glossiness perceived by humans (hereinafter referred to as psychological glossiness), so there is a difference between this psychological glossiness and the physical glossiness measured by the method described above. It is sufficient that there is a strong correlation.

However, even for curved or spherical objects made of the same material, the psychological glossiness of humans changes if the radius of curvature changes, but this psychological glossiness differs from the physical glossiness measured by the above method (according to JIS). There is almost no correlation between them.

In the method of the present invention, an image of a light source or an index (a black circle on a white background or a white circle on a black background) is formed on the surface of a curved or spherical object.
Project an image of the image, and measure the distribution of reflected light from the blurred area near the image, including the center of the image. In the case of highly glossy objects, the image is clear, so the shape of the reflected light distribution curve is generally a sharp normal distribution. On the other hand, in the case of objects with low gloss, the image will be blurred, so the shape of the reflected light distribution curve will generally be a gentle normal distribution. The gloss evaluation amount is determined from such a normal distribution type reflected light distribution curve. The magnitude relationship of gloss between curved objects having different radii of curvature can be compared based on the gloss J'F value.

A specific example of the present invention will be shown below. The method of the present invention consists of two operations: detection of a reflected light distribution curve and calculation of a gloss evaluation amount from the detection results.

First, the two methods of the present invention will be explained with reference to a schematic diagram of a gloss evaluation amount measuring apparatus shown in FIG. Image of light t111 or mmI
The distance between the light source 1 or index and the object 2 is set so that the image of the object 2 is reflected on the curved surface or the surface of the spherical object 2.1st, the distance between the light source 1 or the index and the object 2 is set so that the image of the surface of the object 2 is reflected from the blurred part near the image. The reflected light passes through a lens 3 and is received by a photoelectric detector 4 such as a CCD line sensor, a video camera, or a phototransistor array. When the intensity distribution of the received light is plotted on the oscilloscope 5, it becomes as shown in FIG.

If the curved surface or spherical object is highly glossy, the light intensity distribution will have a sharp normal distribution shape as shown in FIG. 2(a). On the other hand, if the gloss of a curved surface or a spherical object is small, the light intensity distribution becomes a gentle normal distribution as shown in Figure 2 (C). Would you like to use it?

Alternatively, input the light intensity distribution into the gloss evaluation amount calculation section to obtain the gloss evaluation amount G0 that takes into account the degree of blur, and then calculate this Go
The gloss of the object 2 is compared and determined based on the size of the object.

As described above, in the present invention, since the degree of blurring of the image on the surface of an object is taken into consideration, the level of gloss of a curved surface or a spherical object can be compared and determined.

On the other hand, in specular gloss, e-degree contrast gloss, etc. specified in JIS Z 8741, the degree of gloss is determined only by the ratio of the specular reflection light intensity and the diffuse reflection light intensity of the object surface. It seems that the magnitude relationship of degrees does not match the magnitude relationship of human psychological glossiness. As a typical example of such a case, the difference between the θ degree contrast glossiness and psychological glossiness of spherical objects made of the same material but with different radii is expressed as
As can be seen from FIG. 3, the O-degree contrast glossiness and the psychological glossiness are almost unrelated.

The psychological glossiness was measured using the following method: spherical objects with nine different radii were shown to 10 II testers, and objects with greater glossiness were given higher scores.

Objects with a low glossiness are given a low score, and the average of the 10 highest scores is taken for each spherical object.

The average score was taken as the psychological glossiness of the spherical object.

Next, the results of gloss measurement using the method according to the present invention.

and explain its effects.

(b) Glossiness side of colored enamel-coated sphere The surfaces of a regular flat plate and three types of spherical objects with different radii were painted with yellow lacquer enamel, and their glossiness Go was measured using the apparatus shown in Figure 1. Figure 4 shows the radius of the enamel-coated object and the gloss level G.

, where + Go was determined by equation (1) from the reflected light intensity distribution curve as shown in FIG. 2(d).

Here, ■. is the maximum value of the reflected light intensity distribution curve, W is the half-width of the same curve (width on the horizontal axis corresponding to I〆2), and as can be seen from Figure 2, the 1 reflected light intensity distribution curve is normal. approximated by a distribution curve. If the standard deviation (degree of spread) of the normal distribution is r, then W=K(F'-(K
= 2.35), so if this is substituted into equation (1), Go will include r, and as a result, Go will include the degree of spread of the reflected light intensity distribution curve, ie.

Includes the degree of blur in the image.

The IFI4 diagram is the G6-r curve (r is the radius of the spherical object)
, and psychological glossiness G (hu■an) -r curve.According to the tJ4 diagram, 1 both show the same tendency.Furthermore, know the strength of the relationship between Go and G (husan). Therefore, when calculating the correlation coefficient between the two, the correlation coefficient γ = 0.96. Since ■ = 1 is a perfect correlation and γ = 0 is unrelated, the value Y = 0.96 is aO and G (huma
This means that there is a fairly strong correlation between n). From this, it can be seen that aO is suitable as a gloss evaluation quantity for curved surfaces or spherical objects.

(b) Example of measuring the glossiness of a metal sphere Figure 5 shows an example of the measurement results of the glossiness G6-r curve (r is the radius of the spherical object) and the psychological glossiness G (human)-r curve of a metal sphere. According to Figure 5, both curves show the same tendency, and furthermore, r Go and G (human)
The correlation coefficient between Go and G (human) is found to be 7 = 0.95. Also in this case, there is a fairly strong correlation between Go and G (human).

(c) Example of measuring the glossiness of cultured Akoya pearls Figure 6 is from Figure 1 showing an example of the relationship between the glossiness Go of white cultured Akoya pearls with a diameter of 8 dragons and the psychological gloss G (human). When the correlation coefficient between G6 and G (hu+5an) is determined, the correlation coefficient 7=0.90, and in this case as well, there is a fairly strong correlation between Go and G (human).

(d) Examples of measurement using other gloss evaluation quantities Prepare an index with a 5-diameter mark on a white background, excluding the black part, and project the image of this index onto the surface of a spherical object. The intensity of reflected light from the area (consisting of area) is received by a CCD area analyzer or something like a video camera, and a reflected light intensity histogram (the II axis is the reflected light intensity and the MI axis is the number of minute areas) is created using a computer. Let it happen. If the spherical object is highly glossy, the boundary between the black and white parts of the image becomes clear, so the single reflected light intensity histogram is divided into two groups, a black group and a white group, as shown in FIG. 7(a).

On the other hand, when the gloss of a spherical object is low, the boundary between the black and white parts of the image becomes unclear, so the histogram continues from the black group to the white group as shown in Figure 7 (C). . Therefore, the gloss of one spherical object can be compared based on the difference in the shape of the black group in the reflected light intensity histogram.

Draw a histogram and use it to determine the rank of gloss,
Comparing this and the ranking of psychological luster G (human) of the same pearl, the two rankings were completely the same.

[Brief explanation of drawings]

Figure 1 shows a schematic diagram of the gloss evaluation fti amount measuring device, and
XI is an example of the reflected light distribution curve from a spherical object observed by the apparatus shown in Fig. 1, and Fig. 3 shows the conventional θ degree versus gloss level Go and psychological gloss Bt for spherical objects with different radii.
Figure 4 shows the relationship between G (human) and the psychological glossiness G (hum) of yellow lacquer enamel coating areas with different radii.
Fig. 5 shows a comparative example of the glossiness G0 by the method of the present invention and the psychological glossiness G (h
Figure 6 shows a comparison example of the glossiness G0 of a white cultured Akoya pearl with a diameter of 8 mm and the glossiness G6 according to the method of the present invention. FIG. 7 shows examples of reflected light intensity histograms of spherical objects with different gloss.

Claims (1)

[Claims] An image of a light source or an index image, such as a black circle on a white background (or a white circle on a black background), is projected on the surface of a curved or spherical object, and the image is captured from a large number of minute areas including the blurred area near the image. A method of comparing and determining the level of gloss of a curved surface or spherical object by measuring the reflected light intensity of the object and directly utilizing the difference in the shape of the reflected light intensity distribution, or by obtaining a gloss evaluation amount from the reflected light intensity distribution. .