Ice Bear SoftHow Important Is Correct Setting of White Balance?

1. Introduction
2. Making the test of white balance setting
3. Results of the test
4. Conclusion

1. Introduction

White light is in fact a balanced combination of many colours of light. An eye is sensitive to three colours, namely red, green, and blue. The whole imaging technology is therefore oriented to the same colours. The ration of colours differ in different light sources but an eye always perceives white as white. This is not incapability. A human being does not need to know physical characteristics of a particular light source but must see the object in the same way no matter what the light source is. The sensing chip does not have this capability, therefore white must be balanced in some way.

If a colour of a light source changes, the signals going from the cone cells to the brain change as well. White is balanced in the brain. The same is done in digital photography. The sensing chip delivers the signal corresponding to the light source. White is balanced by software. We will test how the changes of settings will be reflectad in the image data.

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2. Making the test of white balance setting

The photos of standard colour tables were taken at natural light. Sensitivity was set to ISO 64. Exposition mode was set to P and autofocus was used. For comparison, the colour tables were also scanned by a scanner calibrated using the Q60 target. The images were stored as raw.

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3. Results of the test

The table below shows the scanned tables and Preview Images. The white balance setting was obtained from the EXIF metadata by:

exiftool -FileName -WhiteBalance -FileOrder FileName -ext nef .

The results are here:

Scanned
Scanned
Auto0
White Balance: Auto0
Natural Auto
White Balance: Natural Auto
Incandescent
White Balance: Incandescent
Cool WHT FL
White Balance: Cool WHT FL
Sunny
White Balance: Sunny
Flash
White Balance: Flash
Cloudy
White Balance: Cloudy
Shade
White Balance: Shade
10000K
White Balance: 10000K
9090K
White Balance: 9090K
9090K
White Balance: 9090K
8330K
White Balance: 8330K
7690K
White Balance: 7690K
7140K
White Balance: 7140K
6670K
White Balance: 6670K
6250K
White Balance: 6250K
5880K
White Balance: 5880K
5560K
White Balance: 5560K
5260K
White Balance: 5260K
5000K
White Balance: 5000K
4760K
White Balance: 4760K
4550K
White Balance: 4550K
4350K
White Balance: 4350K
4170K
White Balance: 4170K
4000K
White Balance: 4000K
3850K
White Balance: 3850K
3700K
White Balance: 3700K
3570K
White Balance: 3570K
3450K
White Balance: 3450K
3330K
White Balance: 3330K
3230K
White Balance: 3230K
3130K
White Balance: 3130K
3030K
White Balance: 3030K
2940K
White Balance: 2940K
2860K
White Balance: 2860K
2780K
White Balance: 2780K
2700K
White Balance: 2700K
2630K
White Balance: 2630K
2560K
White Balance: 2560K
2500K
White Balance: 2500K
Auto0
White Balance: Auto0
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4. Conclusion

The test showed that raw files contain exactly the data acquired from the chip, white balance setting is only stored in the EXIF metadata from which the graphical software can read them. It has real effect in included previews and images stored in the JPG and TIFF formats. Thus if you plan to use rawimages, the correct setting is not important in many cases and automatic white balance can be used. Correct setting can be important if you use studio flashes because the automat can be confused by a different colour of pilot lights. Precise white balance setting is necessary for technical photography.

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