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Weird effect with stripes?

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Elaine Pack

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Had an interesting effect show up in a photo from my FZ4. Happened to take two photos recently of different people wearing clothing that had very narrow stripes, approximately 1/4 inch wide, one vertical, the other horizontal. The stripes were all the same color, well, one color and one white or they wouldn't be stripes :)

Anyway, the resulting photos came out with the garments having what looked like stripes on LSD! They were jagged, almost like a moire effect, and appeared to be a lot wider than they were in reality.

Is this some kind of weird optical illusion that the camera somehow caught? Something else? Is it fixable? The camera is set to a simple 640 res, nothing fancy anywhere else I'm aware of (being still something of a novice in all this, I haven't deliberately set any other params).

TIA

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Elaine Pack
Charlottesville, VA
Use http://www.xinbox.com/elaine to email me
 
first thought is the problem is a result of shooting at such a low resolution. Is there a reason you have the camera set at the lowest res? If you need the images that size, you would be better to shoot at the highest resolution and resize the pictures in your computer.
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Trevor

 
No reason at all, frankly, other than to maximize the number of photos on the card. That said, your point is very well taken, and that would produce a better image--I have Photoshop so it's easy enough to resize them. Initially I thought I'd need more room, but reality showed me that I'm not taking all THAT many, so I think I will bump it. Thanks for the tip!

elaine
cdsgraphic said:
first thought is the problem is a result of shooting at such a low
resolution. Is there a reason you have the camera set at the
lowest res? If you need the images that size, you would be better
to shoot at the highest resolution and resize the pictures in your
computer.
--
Trevor

Click to expand...
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Elaine Pack
Charlottesville, VA
Use http://www.xinbox.com/elaine to email me
 
Looks like moire' to me. When Phil does a resolution test... the stripes eventually merge so close together that they sometimes create moire' patterns.
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Regards,
Kirwin
http://timebandit.smugmug.com
 
Sounds like it, they definitely merged. I will check out references mentioned in this thread and get back here if I have any further questions.

Thanks so much!

elaine
Kirwin said:
Looks like moire' to me. When Phil does a resolution test... the
stripes eventually merge so close together that they sometimes
create moire' patterns.
--



Regards,
Kirwin
http://timebandit.smugmug.com
Click to expand...
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Elaine Pack
Charlottesville, VA
Use http://www.xinbox.com/elaine to email me
 
OK, I've reviewed the Russell Brown movie, which was extremely interesting and I learned a LOT, no doubt about it. The fix, however, seems to work best when the underlying image is a solid color, more or less. In my case, the garment is actually striped, and I don't think it will fix it. I think one of you kind folks mentioned (or it was on one of the references) that a higher res to start with might eliminate the problem from the get go. I can try that. Probably can't hurt anyway :)

elaine
korsair said:
Moire & colorshift fix
http://forums.dpreview.com/forums/read.asp?forum=1006&message=20153002--

Korsair
Fluzi 1v2 and 5
'If it's true that we are here to help others, then what exactly
are the others here for ?'
Click to expand...
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Elaine Pack
Charlottesville, VA
Use http://www.xinbox.com/elaine to email me
 
Along with shooting at a higher resolution- have you looked at the image on-screen at 100 percent? Many moire effects come from the screen pixel pattern and the image pixel pattern interacting. I often see strange effects that disappear when I go to 100% (double click the zoom tool on the Photoshop tool bar to get 100%). And when printed, does it show up?
Dan Daniel
 
Oh, also the effect might come from shooting at a reduced resolution in the downsampling from the original pixels on the CCD to the final file size. Like looking at it on-screen where the screen pixels and image 'pixels' don't match. This can be a good reason to not shoot in anything other than the native CCD's resolution.
Dan Daniel
 
Your photo on Shutterfly is 344 by 229 pixels. If the original was 640 by 480, then it has been distorted while being reduced, or possibly it was cropped. Can you post the original 640 by 480?
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MJD
 
I believe Shutterfly reduces the images when it posts them, but my original photo looks exactly like this, tho, regardless of the size.

elaine
Mike Dumas said:
Your photo on Shutterfly is 344 by 229 pixels. If the original was
640 by 480, then it has been distorted while being reduced, or
possibly it was cropped. Can you post the original 640 by 480?
--
MJD
Click to expand...
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Elaine Pack
Charlottesville, VA
Use http://www.xinbox.com/elaine to email me
 
Oh yes, I always view images at 100% to verify stuff. I haven't tried printing it, tho, as I rarely do that, but I will (the original is at home, sorry, so will have to wait until later)

elaine
ddan daniel said:
Along with shooting at a higher resolution- have you looked at the
image on-screen at 100 percent? Many moire effects come from the
screen pixel pattern and the image pixel pattern interacting. I
often see strange effects that disappear when I go to 100% (double
click the zoom tool on the Photoshop tool bar to get 100%). And
when printed, does it show up?
Dan Daniel
Click to expand...
--
Elaine Pack
Charlottesville, VA
Use http://www.xinbox.com/elaine to email me
 
Um, sorry--CCD? I'm still pretty much a novice :) That said, I did note another recommendation to up the res, and will try it again at 1280, and go from there. This was the first time I'd shot such a photo, hence my question.

elaine
ddan daniel said:
Oh, also the effect might come from shooting at a reduced
resolution in the downsampling from the original pixels on the CCD
to the final file size. Like looking at it on-screen where the
screen pixels and image 'pixels' don't match. This can be a good
reason to not shoot in anything other than the native CCD's
resolution.
Dan Daniel
Click to expand...
--
Elaine Pack
Charlottesville, VA
Use http://www.xinbox.com/elaine to email me
 
If you are concerned about the number of photos, have you considered buying a higher capacity card? The price of SD cards has dropped to such an extent that cost should not be a problem.

Folks on the forum often reduce and display their photos for viewing at minimum 800 by 600. That size fills the screen on my computer and retains a fair amount of detail. The resulting file size is suitable for downloading via a dial-up connection.

--
MJD
 
Elaine Pack said:
Um, sorry--CCD? I'm still pretty much a novice :) That said, I did
note another recommendation to up the res, and will try it again at
1280, and go from there. This was the first time I'd shot such a
photo, hence my question.
Click to expand...
CCD is common shorthand for the electronic imaging device- the equivelant of 'film' for the digital world. A basic overview-
http://www.shortcourses.com/how/sensors/sensors.htm

Moire patterns come from different patterns overlayed on each other creating various interferences, etc. So in your case, the original grid pattern of the CCD would lead to an image file of the same grid pattern (well, for all intents although not technically accurate). But when you save the file at a lower resolution, the original grid pattern needs to be converted by software to a new grid pattern. This translation might lead to moire patterns, especially if the converted grid pattern isn't a clean multiple of the original grid pattern: e.g. it could be a 1:2 ratio (clean), or it could be, say, a 14:23 ratio (messy?).
Dan Daniel
 
Naw, I've got a 512 which is PLENTY for my needs. I was just ignorant of how it all worked :)

elaine
Mike Dumas said:
If you are concerned about the number of photos, have you
considered buying a higher capacity card? The price of SD cards has
dropped to such an extent that cost should not be a problem.

Folks on the forum often reduce and display their photos for
viewing at minimum 800 by 600. That size fills the screen on my
computer and retains a fair amount of detail. The resulting file
size is suitable for downloading via a dial-up connection.

--
MJD
Click to expand...
--
Elaine Pack
Charlottesville, VA
Use http://www.xinbox.com/elaine to email me
 
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