Measuring device, electronic apparatus, and measuring method
A measuring device includes a first light receiving element that receives measurement light and outputs a first output value, and a second light receiving element that receives the measurement light and outputs a second output value which is different from the first output value. A weighted composition is performed on the first output value and the second output value.
1. A measuring device comprising:
a first light receiving element that receives measurement light from a target object so as to output a first output value, the first light receiving element having first light sensitivity, the first output value corresponding to a first exposure time during which the first light receiving element receives the measurement light;
a second light receiving element that receives the measurement light from the target object so as to output a second output value which is different from the first output value, the second light receiving element having second light sensitivity which is different from the first light sensitivity, the second output value corresponding to a second exposure time during which the second light receiving element receives the measurement light, the second exposure time being different from the first exposure time;
a memory configured to store computer-readable instructions; and
a processor configured to execute the computer-readable instructions so as to:
calculate first and second weight values based on a ratio between the second output value and a maximum output value of the second light receiving element, the first and second weight values being different from each other;
calculate a composite reflectance value of the target object based on the first and second weight values; and
calculate a color measurement result of the target object based on the composite reflectance value.
2. The measuring device according to claim 1 ,
wherein the second output value is larger than the first output value.
3. The measuring device according to claim 2 ,
wherein the second weight value becomes smaller as the second output value increases.
4. The measuring device according to claim 3 ,
wherein the second weight value of the second output value becomes zero when the second output value becomes the maximum output value.
5. An electronic apparatus comprising:
the measuring device according to claim 4 ; and
a printer configured to print an image on a medium,
wherein the target object is the image on the medium.
6. The measuring device according to claim 3 ,
wherein the second weight value of the second output value is a value of a n-th degree function of the second output value, and
wherein the n-th degree function has a maximum value when the second output value is zero.
7. An electronic apparatus comprising:
the measuring device according to claim 6 ; and
a printer configured to print an image on a medium,
wherein the target object is the image on the medium.
8. The measuring device according to claim 3 ,
wherein, when the first output value is D 1 , a reference value of the first output value is Dref 1 , the second output value is D 2 , a reference value of the second output value is Dref 2 , the maximum output value of the second output value is Dmax, and the composite reflectance value is R HDR , an Equation (1) described below is satisfied:
R
HDR
=
D
1
D
ref
1
×
(
D
2
D
max
)
2
+
D
2
D
ref
2
×
{
1
-
(
D
2
D
max
)
2
}
.
(
1
)
9. The measuring device according to claim 3 ,
wherein the second weight value of the second output value
remains at a first value when the second output value is smaller than a first threshold value,
the second weight value decreases as the second output value increases when the second output value is between the first threshold value and a second threshold value, and
the second weight value remains at a second value which is smaller than the first value when the second output value exceeds the second threshold value.
10. The measuring device according to claim 9 ,
wherein, when the second output value is between the first threshold value and the second threshold value, the second weight value of the second output value is a value of a n-th degree function of the second output value, and
wherein the n-th degree function has a maximum value when the second output value is the first threshold value.
11. The measuring device according to claim 9 ,
wherein, when the second output value is between the first threshold value and the second threshold value, the second weight value of the second output value is a value of a n-th degree function of the second output value, and
wherein the n-th degree function has a minimum value when the second output value is the second threshold value.
12. The measuring device according to claim 9 ,
wherein, when the first output value is D 1 , a reference value of the first output value is Dref 1 , the second output value is D 2 , a reference value of the second output value is Dref 2 , the first threshold value is d 1 , the second threshold value is d 2 , and the composite reflectance value is R HDR , an Equation (2) described below is satisfied:
R
HDR
=
D
1
Dref
1
×
{
-
2
×
(
D
2
-
d
1
d
2
-
d
1
)
3
+
3
×
(
D
2
-
d
1
d
2
-
d
1
)
2
}
+
D
2
Dref
2
×
{
2
×
(
D
2
-
d
1
d
2
-
d
1
)
3
-
3
×
(
D
2
-
d
1
d
2
-
d
1
)
2
+
1
}
.
(
2
)
13. An electronic apparatus comprising:
the measuring device according to claim 3 ; and
a printer configured to print an image on a medium,
wherein the target object is the image on the medium.
14. An electronic apparatus comprising:
the measuring device according to claim 2 ; and
a printer configured to print an image on a medium,
wherein the target object is the image on the medium.
15. The measuring device according to claim 1 , further comprising:
a spectroscope that spectrally disperses light from the target object, the spectroscope providing the measurement light to the first light receiving element and the second light receiving element.
16. An electronic apparatus comprising:
the measuring device according to claim 1 ; and
a printer configured to print an image on a medium,
wherein the target object is the image on the medium.
17. A measuring method for a measuring device, the measuring device including:
a first light receiving element that receives measurement light from a target object so as to output a first output value, the first light receiving element having first light sensitivity, the first output value corresponding to a first exposure time during which the first light receiving element receives the measurement light;
a second light receiving element that receives the measurement light from the target object so as to output a second output value which is different from the first output value, the second light receiving element having second light sensitivity which is different from the first light sensitivity, the second output value corresponding to a second exposure time during which the second light receiving element receives the measurement light, the second exposure time being different from the first exposure time;
a memory configured to store computer-readable instructions; and
a processor configured to execute the computer-readable instructions, the method comprising executing on the processor the steps of:
acquiring the first output value and the second output value;
calculating first and second weight values based on a ratio between the second output value and a maximum output value of the second light receiving element, the first and second weight values being different from each other;
calculating a composite reflectance value of the target object based on the first and second weight values; and
calculating a color measurement result of the target object based on the composite reflectance value.
18. The measuring method according to claim 17 ,
wherein the second output value is larger than the first output value.
19. The measuring method according to claim 18 ,
wherein the second weight value becomes smaller as the second output value increases.
20. The measuring method according to claim 19 ,
wherein, when the first output value is D 1 , a reference value of the first output value is Dref 1 , the second output value is D 2 , a reference value of the second output value is Dref 2 , the maximum output value of the second output value is Dmax, and the composite reflectance value is R HDR , an Equation (1) described below is satisfied:
R
HDR
=
D
1
D
ref
1
×
(
D
2
D
max
)
2
+
D
2
D
ref
2
×
{
1
-
(
D
2
D
max
)
2
}
.
(
1
)