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08-08-2007, 06:10 PM   #1
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Sensor Question

Hi,

I am trying to understand the relation of camera sensor and RAW. Since RAW is unprocessed image of what the sensor actually 'sees', does this mean that all camera regardless of brand but using the same sensor will output the same RAW quality image?

Thanks.

08-08-2007, 06:48 PM   #2
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No. The camera sensor is an electrical device only capable of delivering electrical signals. Each sensor manufacturer uses their own internal software algorithms to convert those electrical signals into binary, with each camera manufacturer then using their own internal software algorithms to convert that into RAW.

There are differences in the manufacturer's algorithms used with each sensor generation, and even within a single sensor generation. Likewise, there are differences in the camera manufacturer's algorithms used with each sensor in their various cameras (why, for example, one camera might be 8 megapixels, while another using the same sensor might be 10 megapixels). And, of course, each camera manufacturer using the same sensor also obviously use their own algorithms, each different from the algorithms used by other camera manufacturers using that same sensor (hence different RAW file formats between brands).

stewart

Last edited by stewart_photo; 08-08-2007 at 07:13 PM. Reason: clarification
08-08-2007, 07:02 PM   #3
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Thank you for the explaination.
08-08-2007, 08:25 PM   #4
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QuoteOriginally posted by stewart_photo Quote
No. The camera sensor is an electrical device only capable of delivering electrical signals. Each sensor manufacturer uses their own internal software algorithms to convert those electrical signals into binary, with each camera manufacturer then using their own internal software algorithms to convert that into RAW.

There are differences in the manufacturer's algorithms used with each sensor generation, and even within a single sensor generation. Likewise, there are differences in the camera manufacturer's algorithms used with each sensor in their various cameras (why, for example, one camera might be 8 megapixels, while another using the same sensor might be 10 megapixels). And, of course, each camera manufacturer using the same sensor also obviously use their own algorithms, each different from the algorithms used by other camera manufacturers using that same sensor (hence different RAW file formats between brands).

stewart
Also on the hardware side there is the A/D convertor and all the "glue" (noise cancellation, signal amplification etc...) hardware in between which needs to take into account from different manufacturers. The number of bits the A/D converts into and maybe even the speed of the conversion will make a different.

08-09-2007, 06:54 AM   #5
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QuoteOriginally posted by darthkir Quote
Hi,

I am trying to understand the relation of camera sensor and RAW. Since RAW is unprocessed image of what the sensor actually 'sees', does this mean that all camera regardless of brand but using the same sensor will output the same RAW quality image?

Thanks.
No.

Putting aside the difference in the file format of a RAW file (e.g. PEF, NEF or CRW etc.), the image data contained in the RAW file is not totally raw indeed.

The truly RAW data from the CCD sensors are analog one. Then it is digitalised from analog to digital via the A to D convertor. Moreover, various massage and processing, in both the analog and digital domain will be performed before you get the "RAW" file, for the image.

As an analog, the RAW file is just like the negative film. You can get the final picture with more adjustment but the negative film characteristic by itself will still vary differently from (different model of) film to film.
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