[lapiovra]

in my memory,prime II is a 12-bit engine, but in the pentax office website, it says the raw file of k-5 is 14 bits
this is K-5 specification in official website
How the 12-bit prime II image engine get 14-bit raw file?

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Last edited by lapiovra; 12-25-2011 at 01:45 AM. Reason: more easy to understand

[Adam]

I think it's thanks to the better sensor and firmware- it's not like a processor would use a 12-bit architecture these days

[Anvh]

Processor is an ARM processor (roughly the same as in phone and tablets for example), it's the software that's making the difference.

It might now sound that 12-bit shooter are missing something but the K5 is the first to actually go over 12-bit of information with the sensor.

[owl]

I haven't looked into this specific question regarding Pentax but I am an engineer who designs video cameras and here is how you can get there in my experience:

The "RAW" data is the computational result of the camera's image processing algorithms. These processes might include median noise filtering, applying gain and offset correction (for example to reduce vignetting and reduce speckle) and white balance scaling, gamma correction and the like. When you run these calculations, you end up with more bits than you started with, 14 sounds about right. It would be silly to throw away these additional bits since they contain useful information.

Good question.

[Anvh]

I haven't looked into this specific question regarding Pentax but I am an engineer who designs video cameras and here is how you can get there in my experience:

The "RAW" data is the computational result of the camera's image processing algorithms. These processes might include median noise filtering, applying gain and offset correction (for example to reduce vignetting and reduce speckle) and white balance scaling, gamma correction and the like. When you run these calculations, you end up with more bits than you started with, 14 sounds about right. It would be silly to throw away these additional bits since they contain useful information.

Good question.

These are differnt kind of bits
These are bits that correspond with colour.
It's like you can have a 8bit TIFF and a 16bit TIFF, it has nothing to do with processing or extra information squeeze in, its just colour.

Bit Depth

Digital cameras actually record each color channel with more precision than the 8-bits (256 levels) per channel used for JPEG images (see "Understanding Bit Depth"). Most current cameras capture each color with 12-bits of precision (212 = 4096 levels) per color channel, providing several times more levels than could be achieved by using an in-camera JPEG. Higher bit depth decreases the susceptibility to posterization, and increases your flexibility when choosing a color space and in post-processing.

Normally 12bit is more then enough but because of the huge dynamic range of the K5 at lower ISO it goes past 12bit of information.

[Gimbal]

How the 12-bit prime II image engine get 14-bit raw file?

Probably by reading the 14bit output from the A/D converters embedded in the sony sensor.

(IIRCC the A/D is 14 bit)

[zapp]

in my memory,prime II is a 12-bit engine, but in the pentax office website, it says the raw file of k-5 is 14 bits
this is K-5 specification in official website
How the 12-bit prime II image engine get 14-bit raw file?

You can save any bit value from any given source... If your input is 12 bit, a 14 bit raw file will not add information. Sometimres files get "upscaled" with no-information to fulfill 8 or 16 bit formats.

[owl]

Different kind of bits...

"color bits" is just a magnitude of one of the red, green (usually two of these) and blue detectors; they are monochrome until you tell them that they are supposed to be something else. If we are all guessing what is happening inside firmware/hardware, that is my guess based on 15 years of camera design experience. I could be wrong. They could just be reading 14 bits off of the A//D, but usually one or two bits are noise and are truncated but additional bits are picked up further down the processing chain for the reasons that I stated.

[dosdan]

Owl, I see from your profile that you design thermal imaging cameras. Do you think Peltier-effect cooling, applied to the back of the sensor, will ever be used in consumer DSLRs? I presume the thermal inertia will be too much for it to be used in standard modes, due to an unacceptable shutter lag, but what about Bulb mode (to reduce dark current) and in Movie mode (to increase max. recording time)?

Dan.

[owl]

Off topic to OP. Withdrawn.