Sigma X3F raw data


Most of the Sigma Camera Model's raw data, especially pre-Merrill, can exceed the theoretical ADC max value of 4095 by a lot - but without indicating any sensor saturation. For example, the SD14 is quite OK at values around 6,700 and indeed various numbers in the meta-data show nothing wrong with that.

So Sigma clearly does something to the ADC data before writing it as "raw" to the X3F file. That doesn't bother me too much - after all, the saturation level is easy enough to estimate from a simple over-exposed image.

But one irritating oddity to me is the DP2s compact model.

According to RawDigger, this camera saturates at about 2,400 - much less than the theoretical 4,095. As far as know the camera has 12-bit ADCs and, unlike other Sigmas (SD15, DP2x,Quattro), it has no AFE.

I always shoot at ISO 100, FWIW. RD black level is manual 0.

In this post I am seeking confirmation that, for the Sigma DP2s, RawDigger is displaying the X3F raw data as written to the camera's memory card with no additional scaling done by RawDigger.

best regards,


RawDigger uses LibRaw library

RawDigger uses LibRaw library to decode raw data. LibRaw uses Kalpanica x3f tools ( )

RawDigger do not scale raw data for histogram/stats/under-mouse-values display (scaling is used for raw display and raw export and it is possible to turn it off via settings).

LibRaw passes data received from x3f tools unmodified.

I do not have DP2s sample on hand (could you please provide one?), for Sigma DP2 (w/o s) 'x3f tools' decoding path does not use any scaling, just Huffman-like decoding.


We use only decoder part of

We use only decoder part of X3F tools, but not any additional processing (flat fields, etc)

No additional processing

"We use only decoder part of X3F tools, but not any additional processing (flat fields, etc)"

Understood and fine for my purposes!



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