Please help fix moire problem

Started Jun 8, 2004 | Discussions
greydarrah Forum Member • Posts: 88
Please help fix moire problem

I'm a working portrait photographer that has previously run a Nikon only (D1X bodies) studio. I recently purchased a new Kodak DCS Pro SLR/n body and upgraded the firmware to the latest 5.0.1. I only shoot with high end Nikon lenses (f 2.8 ED zooms) and use a Profoto 2400 power pack with D4 strobes/soft boxes and I always shoot in RAW mode. I used the Kodak for the first time the other day and was very disappointed at the moire problem. The shoot was a boy with his guitar and you can see color moire at the link below (the first picture) in both the blue jeans he's wearing as well as on areas of the guitar strings, and although you may not be able to see it, if zoomed in, you can see splotches in the hair. I also shot this same session on my D1X, for a comparison, and there is no moire in any of those shots, as you can see on the second image on this web page. I need to figure out how to fix this and ultimately, how to prevent it. While someone may be able to live with it (or a "mostly" corrected version of it) if used for there personal photographs, I cannot deliver this to a client that has spent $400 to $700 on a photo session and possible another $500 to $1200 on a large print. I tried someones advice of converting to LAB, selecting the A and B channel and then running dust and scratches filter, but I still see some moire. Again, the result has to be perfect as I'm charging quite the fees. I also tried the moire noise filter (on the high setting) in Kodak’s Photo Desk, and it helped, but the moire was still there. No amount of money for a plug in that works would be too much, but I don't think that I can use the Quantum Mechanics filter that some recommend, as I'm totally PC based (I think the moire filter is Mac only), using PhotoShop CS. I'm determined to try and make this work, so please don't take up any space here with "I told you so" replies. I LOVE the resolution of this camera as well as its rendition of color. It's the best

I've seen.

Thanks for any help,

Grey Darrah

http://www.darrahphoto.com \Moire.htm

Warren Sarle Veteran Member • Posts: 3,676
Re: Please help fix moire problem

greydarrah wrote:

... I tried someones advice of converting to
LAB, selecting the A and B channel and then running dust and
scratches filter, but I still see some moire.

That's what I usually do. You could try Gaussian blur instead of D&S. If you select the jeans, you can use a larger blur radius. If you can take the time to make an accurate selection, you can use any of a variety of methods to get rid of non-blue colors. As a last resort, you could hire a Photoshop expert.

To avoid the problem, you could shoot at apertures of f/22 or smaller, or buy cheaper lenses. We're still hoping that someone will report that Caprock filters work.

Ranjan Senior Member • Posts: 1,248
Re: Please help fix moire problem

I tested this camera recently & yes it does have the moire issue bcoz it does not have AA filter in front of sensor.

Have you tried noise reduction by choosing advance moire reduction option, this might help.

John Fulton Senior Member • Posts: 2,940
Re: Please help fix moire problem

JHF

Peter Humfryes Regular Member • Posts: 352
Re: Please help fix moire problem

Hi Grey

As Warren stated the only way to get rid of moire at the shooting stage is to shoot at small aperture. I find f16 or smaller will get rid of the moire completely. I've got the 14nx by the way.
Peter

Navdata Regular Member • Posts: 112
Re: Please help fix moire problem

John:
That looks great! How did you do it? Thanks!!

Gary

John Fulton wrote:

JHF

OP greydarrah Forum Member • Posts: 88
Re: Please help fix moire problem

OK John, what's your secret? Please tell me how to do whatever you did, and be gentle...you probably know MUCH more about PS than I do.

Thanks,

Grey

J_M2 Senior Member • Posts: 1,063
Re: Please help fix moire problem

I don't know what John did, but an easy and fast fix, if you don't want to convert to LAB and mess with channels, you can simply pick up a color from the sample and paint using the "color" mode. This is less of a help if there is a real luminance pattern. The "blue jeans" in this photo would be a good candidate for painting in color mode.

j

OP greydarrah Forum Member • Posts: 88
Re: Please help fix moire problem

I'm not a scientist, and maybe I'm over simplifying this subject, but if this is all about a missing AA filter over the sensor, isn't there some equivelant filter that can screwed onto the end of your lens?

Grey

Warren Sarle Veteran Member • Posts: 3,676
Re: Please help fix moire problem

greydarrah wrote:

I'm not a scientist, and maybe I'm over simplifying this subject,
but if this is all about a missing AA filter over the sensor, isn't
there some equivelant filter that can screwed onto the end of your
lens?

Caprock makes anti-aliasing filters, but they're expensive and we don't know whether they really work with the 14n, 14nx, SLR/n, and SLR/c.

DMillier Forum Pro • Posts: 19,943
Re: Please help fix moire problem

What you are trying to do with an AA filter is cut any detail from the image that is beyond the ability of the sensor to sample accurately without damaging detail at lower spatial resolutions.

There doesn't seem to be an optical equivalent of the 'brick wall' filters used in audio, so blurring the image by just the right amount seems to be the only trick.

Stopping down the lens to f22 will do this (diffraction softness) so I would image that in a studio situation any kind of softening trick should work (i.e. use a soft lens, add a soft focus filter, smear some vaseline on those expensive pro lenses...!).

Try it and see what happens...

greydarrah wrote:

I'm not a scientist, and maybe I'm over simplifying this subject,
but if this is all about a missing AA filter over the sensor, isn't
there some equivelant filter that can screwed onto the end of your
lens?

Grey

OP greydarrah Forum Member • Posts: 88
Re: Please help fix moire problem

I'm going to order the Caprock filter and see if it works. To complicate the matter, they offer it in 4 different strengths with a compromise of sharpness as your moire filter gets stronger. I'm going to go with the number 8 filter and see how it does. I'll keep you posted.

Grey

Clint Mers Junior Member • Posts: 46
I am testing a Caprock 5.6 filter

I have a Caprock filter now, ordered last week. I'm just waiting for the step up adapter from Adorama to arrive so I can test. I'm testing 5.6, so you may want to get a different "strength."

The filters are not expensive. $100 for a $4800 camera is not much. We'll see if they work though. I would guess that if it did work, most folks would need to get the square filter to use with the Lee filter system or something. I doubt I'll be able to use the 67mm filter permanently cause I'm sure it will vignette on my Canon lenses, but it should be fine for testing -- and it didn't require a filter system, just $10 for the adapter.

Caprock says you can return the filter if it does not work for you.

Will post results once the adapter arrives.

greydarrah wrote:

I'm going to order the Caprock filter and see if it works. To
complicate the matter, they offer it in 4 different strengths with
a compromise of sharpness as your moire filter gets stronger. I'm
going to go with the number 8 filter and see how it does. I'll
keep you posted.

Grey

J_M2 Senior Member • Posts: 1,063
Re: Please help fix moire problem

greydarrah wrote:

I'm not a scientist, and maybe I'm over simplifying this subject,
but if this is all about a missing AA filter over the sensor, isn't
there some equivelant filter that can screwed onto the end of your
lens?

Here are a couple useful links. The first is a link that details the Canon Low Pass filter and the second is a description of a Kodak "blur" filter, but it appears to be an OEM product. Although it does describe it as capable of use in front of the lens.

http://www.canon.com/technology/detail/digi_35mm/lo_filter/

download the "blur" filter PDF from the following page:

http://www.kodak.com/US/en/corp/optics/catalog.shtml

j

Muzz Forum Member • Posts: 79
Re: Please help fix moire problem

Here's a link to Johns secret from the Fuji Slr forum!

http://forums.dpreview.com/forums/read.asp?forum=1020&message=8917843

Cheers,

Muzz

greydarrah wrote:

OK John, what's your secret? Please tell me how to do whatever you
did, and be gentle...you probably know MUCH more about PS than I do.

Thanks,

Grey

John Fulton Senior Member • Posts: 2,940
Re: Please help fix moire problem

Hi,

This link will take you to a download of two moire reducer Photoshop plugins. Read instructions where to download and how to load. I use it on CS PS. You will be downloading to plugins. One called Moire reducer ( Walters method ) and Moire reducer 2 ( Hogan procedure ).
http://www.atris.it/temp/s2/S2ProMr.htm

I have found the Moire reducer ( Walters method ) most effective. On Grey's example ( Denim jeans ) I used the lasso tool to only surround/contain the moire effected area. Once selected I run the Moire reducer ( Walters method ). This did eliminate alot of moire but still left redish areas inside selected area. So I then reselected the reddish area's and used the Channel mixer in CS and used only the red source slider to eliminate the reddish area completely.

At this point in time this has been the most effective way for me to rid the moire from my images when present. I would say that Grey's example of moire has not been the worst I've seen but it comes near that.
I hope this will be helpful to you when needed as it has been for me.

Respectfully,

JHF

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