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-   -   SLR style control over N900 camera (https://talk.maemo.org/showthread.php?t=33216)

floffe 2009-12-17 14:59
Re: SLR style control over N900 camera
 
Quote:
Originally Posted by msa (Post 431955)
what camera has a rolling shutter? the n900-camera???
if so, how do you "use" it on purpose?

judging by the comments and tags this was shot with a n900...
Yes, the camera in the N900. As for how to "use" it, just take a picture of something moving really fast. See also http://en.wikipedia.org/wiki/Rolling_shutter

OrangeBox 2009-12-17 15:16
Re: SLR style control over N900 camera
 
Just out of curiosity: what would a file size of a RAW file be for a 5MP camera like the one on the N900? Anyone has an older DSLR with 5MP and can give some estimates?

abbra 2009-12-17 19:09
Re: SLR style control over N900 camera
 
Depends on RAW data format. First, it depends on BAYER pixel depth (8, 10, 12, ...), second -- on encoding used to represent pixel stream. Considering a simple case of BAYER8 and BAYER10 (8 bit per pixel and 10 bit per pixel) with no compression, it would be 1 byte per pixel or 2 bytes per pixel accordingly. So for 5MPix picture with BAYER8 image size, a size of RAW data would be 5000000 bytes, around 4.76MiB.

However, it is only a raw data from sensor, it does not include any metadata associated with the image. If you would save RAW file as many cameras do, in TIFF container, metadata would probably occupy another 2-4KiB. Not a big number compared to raw data itself.

For BAYER10 without any compression it would double the size of raw data, i.e. 10000000 bytes, around 9.54MiB.

If any compression technique is used, file size generally would be smaller.

go1dfish 2009-12-27 02:44
Re: SLR style control over N900 camera
 
Quote:
Originally Posted by attila77 (Post 355854)
Megahertzes mean nothing in this context. A specialized DSP/FPGA found in a midrange DSLR can easily outperform even a multi-gigahertz multi-core desktop processor at specific tasks. There was actually some talk about this at the summit - it was told the current time required to capture an image is a balance - if you would wait 10 minutes for an image, you would a lot better looking images. If you want quicker capture, quality will suffer.
I'm not intimately familiar with DSP's and FPGA's but the n900 does include a DSP, not sure if it would be usable to offload any of the processing here for image work.

It's a C64x+ DSP according to Wikipedia

http://en.wikipedia.org/wiki/Texas_I...0#C6000_Series

bgrigor 2009-12-28 06:39
Re: SLR style control over N900 camera
 
Quote:
Originally Posted by ohwut (Post 354973)
While I agree RAW would be great, I don't think we'll get manual control. I believe all camera phones have fixed apertures, focal lengths, and shutter speeds, generally around 4.7mm and f2.8. The only variable are the glass elements movement for the Auto Focus and ISO for different lighting conditions.

Though...I would love to see maybe a scroll bar, or a ring on the side of the screen to control focus distance.
Did some shooting this afternoon and evening with the N900 and one thing that seems to be missing is auto-exposure lock which is a feature of DSLR and better P&S cameras that I use ALL the time.

bgrigor 2009-12-28 06:55
Re: SLR style control over N900 camera
 
Quote:
Originally Posted by OrangeBox (Post 431982)
Just out of curiosity: what would a file size of a RAW file be for a 5MP camera like the one on the N900? Anyone has an older DSLR with 5MP and can give some estimates?
My Canon G2 is a 4 MP camera (2272 x 1704) and produces RAW files in Canon .CRW format ranging from 1.9 MB to 3.3 MB. The compression is lossless. One might expext a 5 MP camera to produce RAW files about 20% larger than that. The amount of compression depends on the "randomness" of the image, the less random the image, the more it can be compressed.

pta0007 2010-02-21 12:55
Re: SLR style control over N900 camera
 
Hi, I have a problem when trying to run the example_camera.c on n900.

I could compile the program correctly, but when I tried to run it on device, it showed "Failed to initialize pipeline ". The following is part of the code:
Code:
#ifdef __arm__
#define VIDEO_SRC "v4l2camsrc"
#define VIDEO_SINK "xvimagesink"
#else
#define VIDEO_SRC "videotestsrc"
#define VIDEO_SINK "ximagesink"
#endif
who can figure out what is the problem?


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