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I started using chdk recently to take pictures with my Canon Powershot sx280hs. When I started saving high ISO pictures in the DNG format, a few pictures would come out with a purple/pink/blue tint to them. Nothing I've done has really changed the frequency.

A compressed jpg of what it would normally look like: enter image description here

What it sometimes looks like: enter image description here

According to what I've found, it might be because the original canon firmware changes the way the colors are saved in the DNG, which causes the image to take on a tint. It didn't say anything about how to fix it, though.

Why is this happening, and is there any way to prevent it? If there isn't, could I edit the image afterwards to get rid of the tint?

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  • \$\begingroup\$ How do you wave with this camera as DNG? Do you check only preview or you open a image in RAW editor? \$\endgroup\$ Aug 19, 2022 at 4:51
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    \$\begingroup\$ HOW are you converting to DNG? In other words, who wrote the implementation of the DNG converter? I highly doubt it was Canon. \$\endgroup\$
    – Michael C
    Aug 22, 2022 at 10:39
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    \$\begingroup\$ How are you viewing the DNG files? Different applications will render the same raw data contained in the same DNG file differently, especially if they are Adobe products that ignore almost all of the information in the maker notes section of the EXIF info. \$\endgroup\$
    – Michael C
    Aug 22, 2022 at 10:41

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Typically a color cast is due to a lack of, or improper, demosaicing of the original raw data.

When raw data is not demosaiced the color cast is overall green, due to there being 2x as many green filtered photosites. When the demosaicing is done wrong the color cast is often magenta/purple, due to the incorrect interpretation of the blue and red photosites influence/importance.

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