# Capturing a Light

### 1. Prerequisites

This function needs a spectrophotometer to work (Konica Minolta MYIRO, XRite Eye One Pro 1, 2 or 3)

{% tabs %}
{% tab title="Booth" %}
![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-LjCcnNw2pNMdonyMjU9%2F-LjCd7c8rcQdm_sxPFsO%2FViewing-device.jpg?alt=media\&token=154094e0-f573-421c-ae25-c8c354212781)
{% endtab %}

{% tab title="Room" %}
![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-LmoMe6kZsc6wMQk1bY3%2F-LmofTkvXFPoBw20MPny%2FI1Pro-Light.jpg?alt=media\&token=1ae364e3-a617-4c11-8bd7-ce743ef9baf3)
{% endtab %}
{% endtabs %}

### 2. How to use Illum Reader

Click on the icon "Create Light" in the toolbar of Coraye

![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-MF5-R0DzoN6k0ioEGbf%2F-MF59Nj5vmbpARxsQbsi%2FLight%201.png?alt=media\&token=df70be8b-5090-4021-add6-55b574d0aa20)

Make sure your spectrophotometer is connected. When the "Read target" window appears, click on "I'm ready".

![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-MF5-R0DzoN6k0ioEGbf%2F-MF5A2En54cgJDpYBZq_%2FLight%202.png?alt=media\&token=c8cf3a5c-5190-46b4-a0b0-9e220de40525)

A new window will appear to calibrate your spectrophotometer.

![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-MF5-R0DzoN6k0ioEGbf%2F-MF5ALd_OBGWYGvJ9eQy%2FLight%203.png?alt=media\&token=ce3ef408-9730-406a-8a74-9775b358361c)

Put the spectrophotometer into the calibration position\
Then click on the Start calibration button.

{% tabs %}
{% tab title="Konica Minolta MYIRO" %}
![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-MF1h9qj-2yoI5DyUoTI%2F-MF1kORVlnT-Mcw_W-wL%2FCalibration%20Myiro.JPG?alt=media\&token=73109082-a166-44b1-a674-c457eb51dab5)
{% endtab %}

{% tab title="XRite I1 Pro" %}
![Calibration position](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-LjCcnNw2pNMdonyMjU9%2F-LjCdWIXz4eH5y4Pt3QC%2FCalibratei1.jpg?alt=media\&token=377c5603-b79c-49f1-bf18-c2c3953340d7)
{% endtab %}

{% tab title="XRite I1 Pro 2" %}
![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-MBmLqJB8xS_-EM1nWne%2F-MBmacetMFAnXH6pkv2I%2FI1Pro2%20Cal.png?alt=media\&token=b3804b87-c246-4970-b5a5-f56a261d9ba5)

Then click on the **Start calibration** button.
{% endtab %}

{% tab title="XRite I1 Pro 3" %}
![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-MF1h9qj-2yoI5DyUoTI%2F-MF1l1t-XToZ7Cg0JqwT%2FCalibration%20I1%20Pro%203.JPG?alt=media\&token=73cce95f-86f2-44f5-9d11-7cf46859d4d7)
{% endtab %}
{% endtabs %}

When the calibration is done, a new window will appear.

![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-MF5-R0DzoN6k0ioEGbf%2F-MF5KbWNUT3V0f2WmV3p%2FLight%204.png?alt=media\&token=067bae5f-1fda-4bae-b594-3694fe867e9c)

{% hint style="warning" %}
Be aware, you have to use the cap to read the light with the Konica Minolta MYIRO, I1 Pro 1, 2 & 3.
{% endhint %}

{% tabs %}
{% tab title="Konica Minolta MYIRO" %}
![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-MF5-R0DzoN6k0ioEGbf%2F-MF5JxL5wux6VaaJk7EE%2FIMG_2703.JPG?alt=media\&token=b49c324d-6c76-4eb9-ac54-32c65fd81695)
{% endtab %}

{% tab title="XRite I1 Pro" %}
![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-LmoMe6kZsc6wMQk1bY3%2F-LmoXixsOSnDVKRd4zzK%2FMesure%20lumiere%20I1%20Pro.jpg?alt=media\&token=9e57fdf2-83a8-4539-8f28-99adc985846f)
{% endtab %}

{% tab title="XRite I1 Pro 2" %}
![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-LmoMe6kZsc6wMQk1bY3%2F-LmoY3NNcXpfsmb5HDiP%2FMesure%20lumiere%20I1Pro%202.jpg?alt=media\&token=9df00a42-0707-4643-8217-e49d51b9efb3)
{% endtab %}

{% tab title="XRite I1 Pro 3" %}
![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-MF5-R0DzoN6k0ioEGbf%2F-MF5Jkh5c4fFMGprSj3l%2FIMG_0099.JPG?alt=media\&token=e952f689-9101-42c5-a47a-2a701ba6ccd9)
{% endtab %}
{% endtabs %}

To capture the light, it is now sufficient to measure directly with the spectrophotometer. \
Successive measurements will be displayed one below the other.

![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-MF5-R0DzoN6k0ioEGbf%2F-MF5IrbJW0ts_Id72sk1%2FLight%205.png?alt=media\&token=93499c1c-1584-4ab4-b7d8-d8cdc48236db)

You can make multiple measurements and rename them as you like.

![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-MF5MKs2k0E0M2W9jd2s%2F-MF5Ms_MKdCkxsgcviCq%2FLight%206.png?alt=media\&token=3d711c2f-2dfa-4694-bd9c-eadfb6ad927e)

When your measurements are finished, click on **Save and quit**.\
Yours lights samples will be add into the left column.

![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-MF5MKs2k0E0M2W9jd2s%2F-MF5NDRrB-j0wuPC7UdL%2FLight%207.png?alt=media\&token=2a1b3d4b-240b-403f-829c-6322643f95f3)

### 3. How to manage yours Lights samples

Click right on the color to **Rename**, **Duplicate** and **Delete**.\
**Export** option allow saving the color as a .sp file with spectral data.\
These .sp files are useful to share and backup yours light samples.

![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-MF5MKs2k0E0M2W9jd2s%2F-MF5Ojgl4w_j1Ww7aUs8%2FLight%208.png?alt=media\&token=7d171d68-6960-4cb4-98e7-001051ed224d)

Measures can be export as a .sp file, to be saved on your hard drive.

### 4. What are the values associated with the measured sample?

When we read a light, we can get information like [CCT, CRI, ](https://en.wikipedia.org/wiki/Color_temperature)Ra, Brithness, Lab and x,y

![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-MF5PBJ8egZ5Si0qVanZ%2F-MF5TQO5IvFcXzSwcr-w%2FLight%209.png?alt=media\&token=11e575bc-5d4c-4099-af7d-e12f9bd34453)

{% hint style="info" %}
The [CIE](https://en.wikipedia.org/wiki/International_Commission_on_Illumination) [color rendering index](https://en.wikipedia.org/wiki/Color_rendering_index) (**CRI**) is a method to determine how well a light source's illumination of eight sample patches compares to the illumination provided by a reference source. Cited together, the CRI and CCT give a numerical estimate of what reference (ideal) light source best approximates a particular artificial light, and what the difference is.\
\
**CRI is a quality index for evaluating an illuminant. It is expressed as a percentage. the higher the value, the better the quality of the illuminant.**
{% endhint %}

{% hint style="info" %}
The **color temperature** of a light source is the [temperature](https://en.wikipedia.org/wiki/Temperature) of an ideal [black-body radiator](https://en.wikipedia.org/wiki/Black-body_radiation) that radiates light of a color comparable to that of the light source. Color temperature is a characteristic of [visible light](https://en.wikipedia.org/wiki/Visible_light) that has important applications in [lighting](https://en.wikipedia.org/wiki/Lighting), [photography](https://en.wikipedia.org/wiki/Photography), [videography](https://en.wikipedia.org/wiki/Videography), [publishing](https://en.wikipedia.org/wiki/Publishing), [manufacturing](https://en.wikipedia.org/wiki/Manufacturing), [astrophysics](https://en.wikipedia.org/wiki/Astrophysics), [horticulture](https://en.wikipedia.org/wiki/Horticulture), and other fields. In practice, color temperature is meaningful only for light sources that do in fact correspond somewhat closely to the radiation of some black body, i.e., light in a range going from red to orange to yellow to [white](https://en.wikipedia.org/wiki/White) to blueish white; it does not make sense to speak of the color temperature of, e.g., a green or a purple light. Color temperature is conventionally expressed in [kelvins](https://en.wikipedia.org/wiki/Kelvin), using the symbol K, a [unit of measure](https://en.wikipedia.org/wiki/Unit_of_measure) for absolute temperature.

Color temperatures over 5000 K are called "cool colors" (bluish), while lower color temperatures (2700–3000 K) are called "warm colors" (yellowish). "Warm" in this context is an analogy to radiated heat flux of traditional [incandescent lighting](https://en.wikipedia.org/wiki/Incandescent_light) rather than temperature. The spectral peak of warm-coloured light is closer to infrared, and most natural warm-coloured light sources emit significant infrared radiation. The fact that "warm" lighting in this sense actually has a "cooler" color temperature often leads to confusion.[\[1\]](https://en.wikipedia.org/wiki/Color_temperature#cite_note-1)
{% endhint %}

![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-LmsEuEewniDFop1omFP%2F-LmsIAQPj61iwyT_gosv%2F1280px-PlanckianLocus.png?alt=media\&token=b8aa2a73-ec03-4f85-85e0-57a8076f954c)

To save your measure, click right on the measured light into the left bar, and select **Export** to save as a .sp file.\
As you see, you can also Rename, Duplicate or Delete the file when you click left on it.

### 5. Control your booth or your viewing condition

IllumReader can be useful to check uniformity, the color temperature and the light intensity into a booth, to check the conditions for viewing proofs, objects and prints. \
\
In the field of graphic arts, ISO standards have been defined to standardize the visualization conditions of prints.\
\
Knowing how to master one's light knows how to master one's color.

{% tabs %}
{% tab title="Viewing condition" %}
![](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-LmoMe6kZsc6wMQk1bY3%2F-LmofTkvXFPoBw20MPny%2FI1Pro-Light.jpg?alt=media\&token=1ae364e3-a617-4c11-8bd7-ce743ef9baf3)
{% endtab %}

{% tab title="P1 Critical Comparison" %}
![Standard viewing condition ISO 3664: 2009 P1](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-LjCcnNw2pNMdonyMjU9%2F-LjCd7c8rcQdm_sxPFsO%2FViewing-device.jpg?alt=media\&token=154094e0-f573-421c-ae25-c8c354212781)
{% endtab %}

{% tab title="P2 Practical Appraisal" %}
![Standard viewing condition ISO 3664: 2009 P2](https://817532847-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LjCNvq-KDdSRn96lZIz%2F-LmsEuEewniDFop1omFP%2F-LmsW8Kgsb1hbe_FtuiP%2FCabine.jpeg?alt=media\&token=f41bda3d-4d2e-4522-896d-3558f0d1fc56)
{% endtab %}
{% endtabs %}

{% hint style="info" %}
ISO 3664:2009 – VIEWING CONDITIONS\
\
 **Light source**\
 • Relative spectral power distribution must match CIE illuminant D50\
 • UV energy must meet CIE illuminant D50 (correlates to M1 within ISO 13655)\
\
**Two levels of light intensity conditions**\
 • P1 Critical Comparison: e.g. two prints: **illuminance 2000 ± 500 Lux**\
 • P2 Practical Appraisal: less critical comparisons e.g. hardcopy to softproof: **500 ± 125 Lux** or exact illuminance adjustment of light booth to monitor \
\
**Further definitions**\
 • **Homogenity (Control over 9 zones in your booth)**\
 • Surrounding: neutral gray diffuse surface\
 • Viewing angle to avoid glare
{% endhint %}

### 6. Light measurement can be use to calculate an Icc profile.

{% content-ref url="../printer-management/how-to-create-a-media-profile" %}
[how-to-create-a-media-profile](https://docs.coraye.com/printer-management/how-to-create-a-media-profile)
{% endcontent-ref %}

### 7. Show yours reflectance curves in the Spectral Viewer.

It could be useful to compare reflectance curves of your color sample with a spectral curve of a specific light to understand the metamerism effect.

If you need to display the spectral curve of your measured light, you can use the [Spectral Viewer](https://docs.coraye.com/visualization-modules/spectral-viewer)

{% content-ref url="../visualization-modules/spectral-viewer" %}
[spectral-viewer](https://docs.coraye.com/visualization-modules/spectral-viewer)
{% endcontent-ref %}