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Edited pi-pan-tilt part 3 a little; added raspistill note

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Chris Hodapp 2016-10-12 16:23:08 -04:00
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posts/2016-10-12-pi-pan-tilt-3.md
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@ -33,13 +33,10 @@ I may have mentioned in the first post that I'm using
[another][arducam_omx219] that uses the 8-megapixel Sony OMX 219, but [another][arducam_omx219] that uses the 8-megapixel Sony OMX 219, but
I haven't gotten my hands on one yet.) I haven't gotten my hands on one yet.)
If you are expecting the quality of sensors and exposure control that If you are expecting the quality of sensor even an old DSLR camera
even an old entry-level DSLR camera provides, this board will probably provides, this board's tiny, noisy sensor will probably disappoint
disappoint you. The sensor is tiny, it's noisy, and capturing still you. However, if you are accustomed to basically every other camera
images is quite slow (6-7 seconds, in my tests). that is within double the price and interfaces directly with a
However, if you are accustomed to basically every other camera that is
within 2-3 times the price and is meant to interface directly with a
computer of some kind (USB webcams and the like), I think you'll find computer of some kind (USB webcams and the like), I think you'll find
it quite impressive: it quite impressive:
@ -52,9 +49,9 @@ it quite impressive:
more detail on optics in a later post. more detail on optics in a later post.
- [raspistill][] will provide 10-bit raw images straight off the - [raspistill][] will provide 10-bit raw images straight off the
sensor (see its `--raw` option). Thus, we can bypass all of the sensor (see its `--raw` option). Thus, we can bypass all of the
automatic brightness, saturation, contrast, and whitebalance which automatic brightness, sharpness, saturation, contrast, and
are great for snapshots and video, but really annoying for composite whitebalance correction which are great for snapshots and video, but
images. really annoying for composite images.
- Likewise via [raspistill][], we may directly set the ISO speed and - Likewise via [raspistill][], we may directly set the ISO speed and
the shutter time in microseconds, bypassing all automatic exposure the shutter time in microseconds, bypassing all automatic exposure
control. control.
@ -71,6 +68,18 @@ to raspistill, and it will produce a JPEG file which contains a
normal, lossy image, followed by a binary dump of 10-bit raw Bayer normal, lossy image, followed by a binary dump of 10-bit raw Bayer
data from the sensor. data from the sensor.
Most of my image captures then are with something like:
raspistill --raw -t 1 -w 640 -h 480 -ss 1000 -ISO 100 -o filename.jpg
That `-t 1` is to remove the standard 5-second timeout; I'm not sure
if I can take it lower. `-w 640 -h 480 -q 75` applies to the JPEG
image, while the raw data with `--raw` is always full-resolution; I'm
saving only a much-reduced JPEG as a thumbnail of the raw data, rather
than wasting the disk space and I/O on larger JPEG data than I'll use.
`-ss 1000` is for a 1000 microsecond exposure (thus 1 millisecond),
and `-ISO 100` is for ISO 100 speed (the lowest this sensor will do).
# Converting Raw Images # Converting Raw Images
People have already put considerable work into converting these rather People have already put considerable work into converting these rather