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  4. What causes 'red eye' in photographs?
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What causes 'red eye' in photographs?

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Offline rosalind dna

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What causes 'red eye' in photographs?
« Reply #20 on: 30/04/2008 21:11:32 »
I have just looked at the Help bit of JASC's Paintshop Pro 7
and it does have the cloning tools. I still have to work them out but I will have fun discovering that, originally I got redeyes and removed them from some family photos. Easier than I'd thought possible.
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Offline DoctorBeaver

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What causes 'red eye' in photographs?
« Reply #21 on: 01/05/2008 07:57:16 »
Quote from: rosalind dna on 30/04/2008 11:07:25
...and I don't want to keep on clicking my camera as I'll lose the photos which I don't want to do.

I'm not sure what you mean by that.
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Offline rosalind dna

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What causes 'red eye' in photographs?
« Reply #22 on: 01/05/2008 10:32:39 »
Quote from: DoctorBeaver on 29/04/2008 22:28:39
The software analyses the colour of the pixels and reduces the amount of red. In photoshop, you position a circular cursor over the red part of the eye and click. If you click repeatedly the iris will go grey.
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author=DoctorBeaver link=topic=14159.msg170913#msg170913 date=1209625036]
Quote from: rosalind dna on 30/04/2008 11:07:25
...and I don't want to keep on clicking my camera as I'll lose the photos which I don't want to do.

I'm not sure what you mean by that.

Quote from: DoctorBeaver on 29/04/2008 22:28:39
The software analyses the colour of the pixels and reduces the amount of red. In photoshop, you position a circular cursor over the red part of the eye and click. If you click repeatedly the iris will go grey.
Dr Beaver that is what you had said yesterday and maybe I'd misunderstood you. I thought that you had meant that if the camera is clicked repeatedly then the redeye problems would go. oops?
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lyner

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What causes 'red eye' in photographs?
« Reply #23 on: 01/05/2008 11:15:58 »
Clicking whilst using the software - not while using the camera, I think dr beaver means.
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Offline techmind

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What causes 'red eye' in photographs?
« Reply #24 on: 02/05/2008 20:47:20 »
Quote from: another_someone on 29/04/2008 17:07:48
The software solution is the next answer.  This merely looks for an area of red in the photograph that looks like 'red-eye', and assumes that this should be the pupil of the eye, and so that area is merely painted black.


Hmmm - I saw a photo recently where it looked like the subject had a missing tooth. We figured that the anti-red-eye software had mistaken a reflection off the tooth or a bit of spittle for red-eye ... and blacked it out!
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What causes 'red eye' in photographs?
« Reply #25 on: 02/05/2008 20:59:16 »
Quote from: sophiecentaur on 01/05/2008 11:15:58
Clicking whilst using the software - not while using the camera, I think dr beaver means.

Precisely.
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What causes 'red eye' in photographs?
« Reply #26 on: 02/05/2008 20:59:58 »
Quote from: techmind on 02/05/2008 20:47:20
Quote from: another_someone on 29/04/2008 17:07:48
The software solution is the next answer.  This merely looks for an area of red in the photograph that looks like 'red-eye', and assumes that this should be the pupil of the eye, and so that area is merely painted black.


Hmmm - I saw a photo recently where it looked like the subject had a missing tooth. We figured that the anti-red-eye software had mistaken a reflection off the tooth or a bit of spittle for red-eye ... and blacked it out!

 [:D]
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Offline rosalind dna

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What causes 'red eye' in photographs?
« Reply #27 on: 02/05/2008 21:12:37 »
Thanks
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Rosalind Franklin was my first cousin and one my life's main regrets is that I never met this brilliant and beautiful lady.
She discovered the Single DNA Helix in 1953, then it was taken by Wilkins without her knowledge or agreeement.
 

another_someone

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What causes 'red eye' in photographs?
« Reply #28 on: 02/05/2008 22:10:36 »
Quote from: techmind on 02/05/2008 20:47:20
Quote from: another_someone on 29/04/2008 17:07:48
The software solution is the next answer.  This merely looks for an area of red in the photograph that looks like 'red-eye', and assumes that this should be the pupil of the eye, and so that area is merely painted black.


Hmmm - I saw a photo recently where it looked like the subject had a missing tooth. We figured that the anti-red-eye software had mistaken a reflection off the tooth or a bit of spittle for red-eye ... and blacked it out!

This is why I prefer to take out red-eye manually, selecting the area myself, and painting or cloning over it myself, rather than let a dumb piece of software get it wrong.
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Offline neilep

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What causes 'red eye' in photographs?
« Reply #29 on: 02/05/2008 22:37:38 »
Removing red-eye from photos is ace !....
I've use red eye reduction in a number of programs and they all seem rather good. Unless you're going to do a close up portrait then they are all pretty good.

....Though some cameras now flash a light for a few seconds first to inhibit the red eye phenomena......Does it work ?...and how does it work ?

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lyner

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What causes 'red eye' in photographs?
« Reply #30 on: 02/05/2008 22:47:07 »
It just causes your irises to close down because of the burst of bright light. In the sort of dark conditions where you need flash, they are open wide and make the effect much worse.
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another_someone

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What causes 'red eye' in photographs?
« Reply #31 on: 02/05/2008 23:28:37 »
Quote from: sophiecentaur on 02/05/2008 22:47:07
It just causes your irises to close down because of the burst of bright light. In the sort of dark conditions where you need flash, they are open wide and make the effect much worse.

I've usually found the effect of pre-flash to be marginal.

Ofcourse, if you really want to avoid red-eye, then get a decent camera and use bounce flash, or at least off-camera flash (used to do that with my old film cameras, but alas, no longer have kit as good as that).

Anyway, as I pointed out before, having the pupils close down makes the eyes less attractive (hence, in the past, the use of belladonna to dilate the pupils, and make them look more sexy - although it must be remembered belladonna is also known as deadly nightshade, so not something I would recommend as a cosmetic, no matter how effective it is).
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