Why do my home-scanned color negatives look purple or blue after inversion?
Asked 7/26/2021
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I’m new to developing color film at home. Lab-processed rolls looked normal, but when I develop and scan at home, the images often come out with a strong purple/blue cast after inversion. I kept the chemistry and water at about 38°C, so I first suspected development. However, these files are the raw scans from a cheap home scanner. Could this color cast be caused by scanning or inversion rather than the film development itself? How should color negative film be scanned and corrected properly?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
4y ago
2 Answers
3
Your blueish tinted image looks like a case of "direct color inversion of scan". Most color negative films have an orange mask (see this question for more detail) to them, which when you invert the colors would yield a blueish tint like yours. Because of this mask, you need to to adjust the "white balance" (although it's more complicated than a simple white balance) of the scanned negative. One common way to deal with the orange mask is to adjust the color curves of the negative image, such that the piece of the film outside the exposed frame renders white. (The unexposed part only have the negative of black, which should be white).
For more information, see for instance this this page or this (which also shows an example of a direct inversion). Because of the somewhat complex nature of correctly "removing" the orange mask, it's generally recommended to get a dedicated software for negative inversion (often included with scanners made for scanning negatives). Negative lab pro is a popular Lightroom plugin, but comes at a cost of ~$100. For the Linux users out there, negative2positive is an open-source alternative for converting negative scans to positive.
Originally by user100021. Source · Licensed CC BY-SA 4.0
user100021
4y ago
0
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This is most likely a scanning/inversion issue, not a development-temperature issue.
Color negative film has an orange mask. If you simply invert the scan’s colors, that orange base turns into a strong blue/cyan/purple cast. That matches what you’re seeing.
What to do:
- Don’t rely on a straight color inversion alone.
- Correct for the orange mask when scanning or in post.
- A common approach is to adjust the RGB curves so the unexposed film base (the area outside the image frame) becomes neutral/white after inversion.
- Better scanner software or a better scanner can help, especially if it has proper color-negative handling/profiles.
So the likely problem is that your scanner/raw workflow is not compensating correctly for the film base mask. The negatives themselves may be fine.
In short: if lab scans looked good but your home “raw” scans look blue, the scanner setup and negative-conversion process are the first things to fix.
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AI4y ago
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