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Possibilities CHDK

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Possibilities CHDK
« on: 24 / February / 2010, 09:25:47 »
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How endless are the possibilities of the CHDK. I'd like to do some stand-alone logging in a room and I am considering the use of a Canon camera.

I understand that after taking a picture, a raw picture is available from the camera buffer. I want to program the device to:
  • take a picture, or maybe a serie of 10 pictures in one second
  • then do some basic image processing on them
  • then write the resulting numbers (not a picture) to the memory?
  • display a modified picture on the screen when requested by pressing some camera button
  • repeat this process after a minute

I understand that the motion detector now available in the CHDK uses thumbnail images from the memory. My program has to make use of the more detaild, full MP picture.
I also understand from the zebra script that it is possible to alter the display immage.

Can you give me some advise on if I could make such a thing work and what the sidenotes are. Or is it easier to take a simple ARM processor and a webcam?

What steps do the cameras go through when taking a picture and where can you interrupt? Something like this?
  • Recording a preview for the display
  • Recording the full image and write it RAW to a buffer
  • Converting the RAW image to JPEG and write it to the memory (or to the buffer first?)
  • Again start recording a preview for the display

Re: Possibilities CHDK
« Reply #1 on: 24 / February / 2010, 11:50:29 »
    Hello and welcome.

I want to program the device to:
  • take a picture

No problem.

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  • or maybe a serie of 10 pictures in one second
Cannot be done.
A minor speed-up from the camera's native continuous-shooting mode may be possible.
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  • then do some basic image processing on them

Yes.

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  • then write the resulting numbers (not a picture) to the memory?
Yes.

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  • display a modified picture on the screen when requested by pressing some camera button
In Record mode you are limited to an overlay of eight-bit colours/pixel
Any changes made to the image in the raw buffer will also be in the JPG image.
An example is time/date code.

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  • repeat this process after a minute

Yes.

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I understand that the motion detector now available in the CHDK uses thumbnail images from the memory.
The so-called live-viewport area of memory.
(don't know where this word 'viewport' came from).

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My program has to make use of the more detaild, full MP picture.
That is the raw image and functions are available for reading and setting pixels.
It is six bytes/four pixels in YUV 4:1:1 format.

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I also understand from the zebra script that it is possible to alter the display immage.
That is just an eight-bit bitmap overlay, not a YUV image.

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Can you give me some advise on if I could make such a thing work

Need more information.

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is it easier to take a simple ARM processor and a webcam?
Not for me  ;)

The Canon firmware will save the raw image as JPG whether you want it to or not.

That will include any changes you have made to the raw image.
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« Last Edit: 24 / February / 2010, 11:52:15 by Microfunguy »

 

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