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Possibilities CHDK

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2_05

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
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Offline Microfunguy

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

Quote from: 2_05 on 24 / February / 2010, 09:25:47
I want to program the device to:
  • take a picture

No problem.

Quote
  • 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.
Quote
  • then do some basic image processing on them

Yes.

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

Quote
  • 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.

Quote
  • repeat this process after a minute

Yes.

Quote
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).

Quote
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.

Quote
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.

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

Need more information.

Quote
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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