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Twin raw buffers without jpeg creation would permit twin hdr exposure

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Offline Lebeau

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When we capture raw image, it uses one raw buffer that get "corrupted" by the jpeg creation process.

If we annihilate the jpeg creation process, on twin raw buffer apparatus, we would be able to rapidly catch a second capture (with different exposure) and then save both buffers. The twin capture would create an hdr compound.

That could motivate jpeg creation process hacking !!

Some ideas how-to ?

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Offline philmoz

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Re: Twin raw buffers without jpeg creation would permit twin hdr exposure
« Reply #1 on: 15 / September / 2011, 22:43:48 »
When we capture raw image, it uses one raw buffer that get "corrupted" by the jpeg creation process.

If we annihilate the jpeg creation process, on twin raw buffer apparatus, we would be able to rapidly catch a second capture (with different exposure) and then save both buffers. The twin capture would create an hdr compound.

That could motivate jpeg creation process hacking !!

Some ideas how-to ?

From what I've seen the camera firmware does not always switch buffers between shots.

In addition to disabling the jpeg conversion (which I don't think anyone has figure out how to do), you will also need to find a way to make sure that the camera alternates between the two raw buffers.

Phil.
CHDK ports:
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Offline Lebeau

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Re: Twin raw buffers without jpeg creation would permit twin hdr exposure
« Reply #2 on: 16 / September / 2011, 17:16:15 »
Didn't know about the buffer switching. I will get a look to before exploring jpeg trap. Thks.

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Offline Lebeau

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Re: Twin raw buffers without jpeg creation would permit twin hdr exposure
« Reply #3 on: 13 / November / 2011, 11:11:24 »
I made some tests:
 - rawadr and altrawadr are swapping for each exposure
 - moving raw data to altrawadr and moving it back to rawadr in postprocess didn't work since it seams that jpg process use altrawadr :(

The only way, imho, is to trap jpg process.


 

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