Capturing a Light

Illum Reader is a function to analyse the light.The purpose is to check the quality of your light into a viewing booths or in your viewing conditions.

1. Prerequisites

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

2. How to use Illum Reader

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

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

A new window will appear to calibrate your spectrophotometer.

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

Then click on the Start calibration button.

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

Be aware, you have to use the cap to read the light with the Konica Minolta MYIRO, I1 Pro 1, 2 & 3.

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

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

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

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.

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, Ra, Brithness, Lab and x,y

The CIE 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.

The color temperature of a light source is the temperature of an ideal black-body radiator that radiates light of a color comparable to that of the light source. Color temperature is a characteristic of visible light that has important applications in lighting, photography, videography, publishing, manufacturing, astrophysics, 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 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, using the symbol K, a 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 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]

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.

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

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

Create a profile from a standard reference

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

Spectral viewer

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Last updated 5 years ago

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