Pi-Camera pink tinted center

[Dave Liquorice]

I have "daylight" Pi camera as a webcam at capturing images every 30
seconds at 960 x 540 using python script and the picamera python
module.

There is subtle red tinted area in the central area of the image.
Normally visible on clouds:

http://www.howhill.com/weather/webcam/camera-1.jpg

It's not the LED as I've turned that off and at night with it on the
reflection is quite obvious on the left hand side.

Is a subtle central red tint a known problem with PiCameras?

Is it a function of only capturing a 960x540 image rather than full
Pi Camera resolution? I can resize later when I add the text.

--
Cheers
Dave.

[bcw...@gmail.com]

Looking around the net with Google purple/red/pink tints to such cameras are common. You'll see a number of posts about HTC phones, Android devices and such with the same basic camera and tint problems. You could recolor things with software but your problem seems to be only in part of the image, which will make that more difficult. If the whole picture was tinted that's much easier to correct, but it still could be done. It would just take very specialized software setup for that one camera ;(

[Dave Liquorice]

On Mon, 30 Jun 2014 07:45:07 -0700 (PDT), bcw...@gmail.com wrote:

> Looking around the net with Google purple/red/pink tints to such cameras
> are common. You'll see a number of posts about HTC phones, Android
> devices and such with the same basic camera and tint problems.

Thanks for that, not surprised it is after all a cheap comodity
camera module.

> You could recolor things with software but your problem seems to be only
> in part of the image, which will make that more difficult.

The patch is more or less consistent in area but it doesn't always
appear to be there. On the 30 sec frame interval time lapse movies
it's sometimes obvious other times not. Maybe it's an exposure
function, I'm currently using "matrix".

--
Cheers
Dave.

[Rob Morley]

Might it be internal reflection? I'd try fitting a hood to the lens.

[Dave Liquorice]

On Tue, 1 Jul 2014 01:02:24 +0100, Rob Morley wrote:

>> The patch is more or less consistent in area but it doesn't always
>> appear to be there. On the 30 sec frame interval time lapse movies
>> it's sometimes obvious other times not. Maybe it's an exposure
>> function, I'm currently using "matrix".
>
> Might it be internal reflection? I'd try fitting a hood to the lens.

It looks far too diffuse. I'm caputuring 960 x 540 and the affected
patch is more or less full height, circular and centred.

It's not a refracted highlight, not well enough defined and it's
visible when there is no point source (aka the sun) shining into the
lens. It doesn't move either. It could be a more general lens flare
but they tend
to just lift the whole image uniformally and without a colour tint.

The module is tapped to the glass of a double glazed window so it
could be an out of focus reflection of the lens, the tint coming from
some interaction of glass/lens coatings.

--
Cheers
Dave.

[Jasen Betts]

Could it be ligt leaking into the camera? see if shining light on the
camera or shading it has any effect.




--
umop apisdn

[Dave Liquorice]

On 1 Jul 2014 07:10:23 GMT, Jasen Betts wrote:

> Could it be ligt leaking into the camera? see if shining light on the
> camera or shading it has any effect.

I'd expect that to be a streak from a small source or a broad streak
from a more linear source. This a diffuse pinkish tinted circular
area centerd in the frame.

--
Cheers
Dave.

[Dave]

"Dave Liquorice" <allsortsn...@howhill.com> wrote in message
news:nyyfbegfubjuvyypb...@srv1.howhill.co.uk...

I would say it's a function of cheap plastic lenses at curtain angles within
the lens and wave lengths of light. Try another lens - if you can ?

Another Dave ...

[Johny B Good]

On Wed, 2 Jul 2014 10:05:12 +0100, "Dave" <m...@me.com> wrote:

>
>
>"Dave Liquorice" <allsortsn...@howhill.com> wrote in message
>news:nyyfbegfubjuvyypb...@srv1.howhill.co.uk...
>> On 1 Jul 2014 07:10:23 GMT, Jasen Betts wrote:
>>
>>> Could it be ligt leaking into the camera? see if shining light on the
>>> camera or shading it has any effect.
>>
>> I'd expect that to be a streak from a small source or a broad streak
>> from a more linear source. This a diffuse pinkish tinted circular
>> area centerd in the frame.
>>
>> --
>> Cheers
>> Dave.
>>
>>
>>
>I would say it's a function of cheap plastic lenses at curtain angles within

"curtain angles" seems to be a misspelling for "certain angles". My
search for this term, to make sure it wasn't simply one I was unfamiar
with rather than the misspeling I suspected it was, led me to a wiki
article on the subject of cameras which held my attention for an
enjoyable 20 minutes or so.

>the lens and wave lengths of light. Try another lens - if you can ?
>

Good idea, but as you pointed out, only if it's possible to fit
another lens that can be adjusted to compensate for varaition in focal
length.

Such cheap miniature cameras use a lens mounted in a small tube that
is threaded onto the body, typically with thick silicone grease so it
can be screwed in the required amount to satisfy the focussing
condition with the silicone grease acting as 'locking compound' to
hold the adjustment.

I'm not sure but there's probably a limited number of standard thread
mounting sizes used in this class of camera so it might not be quite
so hard to find another lens (usually canabalised from a scrapped
miniature camera or else borrowed off another working camera) If the
camera manufacturer offers a choice between wide angle and 'Fish Eye'
lenses you may even be able to opt for a higher spec lens.
--
J B Good

[Rob Morley]

I wonder if it might be worth trying a polarising filter.

[Dave]

"Johny B Good" <johnny...@invalid.ntlworld.com> wrote in message
news:s378r958i2tih7fl7...@4ax.com...

Yes, I should pay attention to auto spell check !. One thing that would
almost certainly check to see if it's the lens, is to remove the lens and
place a piece of white paper over the hole and eliminate it from behind and
see then if is it still has a pink tinge in the centre then.

[The Natural Philosopher]

On 04/07/14 09:38, Dave wrote:
> Yes, I should pay attention to auto spell check !.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

One thing that would
> almost certainly check to see if it's the lens, is to remove the lens
> and place a piece of white paper over the hole and eliminate it from

^^^^^^^^^^^^^

> behind and see then if is it still has a pink tinge in the centre then.

Yep shoot the fucker in the back! Or ram a red hot poker up its back
passage. Eliminating from behind is the only answer!



--
Ineptocracy

(in-ep-toc’-ra-cy) – a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

[Johny B Good]

On Fri, 04 Jul 2014 10:00:36 +0100, The Natural Philosopher
<t...@invalid.invalid> wrote:

>On 04/07/14 09:38, Dave wrote:
>> Yes, I should pay attention to auto spell check !.
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> One thing that would
>> almost certainly check to see if it's the lens, is to remove the lens
>> and place a piece of white paper over the hole and eliminate it from
> ^^^^^^^^^^^^^
>> behind and see then if is it still has a pink tinge in the centre then.
>
>Yep shoot the fucker in the back! Or ram a red hot poker up its back

>passage. Eliminating from behind is the only answer! :-)

Fixed your post._______________________________^
--
J B Good

[Johny B Good]

Disable that damn spell checker[1] :-\ _______^^^^^^

>see then if is it still has a pink tinge in the centre then.

An excellent idea! (why didn't _I_ think of that?). At least you'll
know whether a replacement lens will be worth trying or not _before_
spending any more money and/or time on a more permanent fix.

[1] I figured you meant to type 'illuminate'. I'll happily accept
another 'auto spell check cockup' excuse for this one ("Once is an
accident, twice is a coincidence...") :-)
--
J B Good

[Dave Liquorice]

On Fri, 4 Jul 2014 09:38:02 +0100, Dave wrote:


> One thing that would almost certainly check to see if it's the lens, is

> to remove the lens and ...

Probably bugger the camera. This a Pi camera module, if you are
really careful it might be possible to unstick the lens but it's a
bit risky.

--
Cheers
Dave.

[Martin Gregorie]

Might be worth attaching a (small) piece of paper so its sitting on the
front of the lens, putting it where its lit by bright, diffuse daylight
and seeing it it still shows the pink patch. At least that should tell
you if the problem is external or internal to the camera.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[Mike]

In article <lp5p5a$95b$1...@dont-email.me>, Dave <m...@me.com> wrote:

>place a piece of white paper over the hole and eliminate it from behind and
>see then if is it still has a pink tinge in the centre then.

And if you do find a pink tinge on the white paper when you eliminate
from behind, do see a doctor. It could be something serious.

--
--------------------------------------+------------------------------------
Mike Brown: mjb[-at-]signal11.org.uk | http://www.signal11.org.uk

[Dave]

"Johny B Good" <johnny...@invalid.ntlworld.com> wrote in message

news:ve3dr9dgjt4t4lumc...@4ax.com...

Also now being more sober, I've turned OFF auto spell check - It's really
funny to look back ... Did I really type that - don't really remember that
well !.....