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Why are you using 6*.../10 as green component factor in DNG thumbnail creation?

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Offline Lebeau

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Why are you using 6*.../10 as green component factor in DNG thumbnail creation?
« on: 15 / November / 2010, 16:17:36 »
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At line 81 of raw.c, you are using 6*.../10 as green component factor when creating a thumbnail for the DHG format.

Why 6 and 10 ?

And are you using both green component of the Bayer cross?
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Offline fudgey

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Re: Why are you using 6*.../10 as green component factor in DNG thumbnail creation?
« Reply #1 on: 15 / November / 2010, 17:56:17 »
Quote from: Lebeau on 15 / November / 2010, 16:17:36
At line 81 of raw.c, you are using 6*.../10 as green component factor when creating a thumbnail for the DHG format.

Why 6 and 10 ?

DNG... A forum search might reveal details, that code has evolved, it wasn't always 0.6. There is no color matrix or white balance applied to the thumbnail, so I suppose it's just an attempt to adjust the colors so that they're reasonably tolerable on most cameras.

Quote from: Lebeau on 15 / November / 2010, 16:17:36
And are you using both green component of the Bayer cross?

No. It's supposed to be very simple and fast. It just gets a few pixels here and there and scales them around a bit according to a common gamma curve to cook up rgb pixels that are close enough.
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