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| isp:white_balance [2018/06/04 09:10] – created Igor Yefmov | isp:white_balance [2019/05/09 00:54] – [Practical example] Igor Yefmov | ||
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| For the calibration purposes we have acquired a Philips "Hue White and Color Ambiance A19 LED Starter Kit" that allowed us to test various illumination scenarios for a range of color temperatures. For a given white color temperature setting we have dialed the red and blue gains to make the scene " | For the calibration purposes we have acquired a Philips "Hue White and Color Ambiance A19 LED Starter Kit" that allowed us to test various illumination scenarios for a range of color temperatures. For a given white color temperature setting we have dialed the red and blue gains to make the scene " | ||
| - | Corrections to the red channel were way more noticeable than those to the blue one so we approximated the blue gains' graph with a single line, described by the formula | + | Corrections to the red channel were way more noticeable than those to the blue one so we approximated the blue gains' graph with a single line, described by the formula |
| - | Red channel gains are approximated by two line segments, bordering the '' | + | Red channel gains are approximated by two line segments, bordering the \(3500°K\) mark: |
| - | + | ||
| - | below '' | + | |
| - | above '' | + | |
| + | \[ | ||
| + | R = | ||
| + | | ||
| + | 467.6 + T * 0.166 & \quad \text{if } T < 3500°K \\ | ||
| + | 82 + T * 0.277 & \quad \text{if } T >= 3500°K | ||
| + | | ||
| + | \] | ||
| {{: | {{: | ||
| ==== Experimental data and verification ==== | ==== Experimental data and verification ==== | ||
| Line 42: | Line 46: | ||
| ===== Practical example ===== | ===== Practical example ===== | ||
| - | What does all that mean in practice? Suppose you have set up your scene with " | + | What does all that mean in practice? Suppose you have set up your scene with " |
| See also [[Automatic white balance]] | See also [[Automatic white balance]] | ||