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Is there any way to fix the wavy lines that appear when photographing a striped dress? enter image description here

It's not just in viewing online: when it was printed at wallet size, the wavy lines showed up.

mattdm
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stacy sims
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    Wow thats intense!!!!! it makes my brain hurt!! – Digital Lightcraft Sep 29 '15 at 20:03
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    Depending on magnification, i don't see any moire in that image, or a lot of it at small size. Ie., the moire isn't in the image, but a result of displaying it. – ths Sep 29 '15 at 22:12
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    Could it be that this artifact is purely due to pixelation from the display? For what its worth, when viewed at 100% on my Macbook Pro Retina display, it renders just fine. However if I shrink it down to 50% or less, then the wavy lines become very apparent. – Digital Trauma Sep 30 '15 at 00:09
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    When it was printed in wallet size, the wavy lines showed up – stacy sims Sep 30 '15 at 02:22
  • Blame image viewers and printing programs. – Euri Pinhollow Nov 01 '17 at 13:05

3 Answers3

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There doesn't appear to be any moire in the image itself. What you are seeing are scaling errors when the image is resized by a particular application for display on a particular size screen or print.

To solve this you can create, optimize, and export different resolutions of the image for different display environments.

For instance the display on a MacBook Pro (3rd gen) 15" is 2880x1800 pixels. Assuming you wish to view the image in portrait mode you would create a version of the image that is 1800 pixels tall by 1200 pixels wide.

For printing those wallet sized photos, you would take the native resolution of the printer in ppi (pixels per inch, not to be confused with dpi - dots per inch) and multiply by the 2.5 x 3.5 inch size of each picture on the sheet. If the printer's native resolution is 300 ppi, you would need a version of the image that is 1050 x 750. Note that you will need to crop about 7% off the height of the photo from the top, bottom, or a combination of both to fit your 1.5:1 aspect ratio photo to the 1.4:1 aspect ratio print size.

Michael C
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    This is correct though there is one additional step needed when resizing. Resizing should be done in a gamma=1 colorspace. Standard colorspaces can introduce moire not previously present and this most often occurs when the stripes transition sharply. See this example of an image with no moire that had moire when printed and just from downsizing without changing to a gamma=1 colorspace. https://www.dpreview.com/forums/post/60087890 – doug Nov 01 '17 at 21:33
  • @Doug Yeah. I don't usually downsize a processed image using PS. I generally go back and export another image at the lower resolution (and sometimes with altered sharpening) from the original raw file using a non-Adobe raw processing tool. It seems doing it this way I've managed to fly under the radar with regard to the issue identified in the link. Hey, and even though I wasn't aware of it, it does kind of fall under the umbrella in the second paragraph that mentions creating, optimizing, and then exporting specific resolutions for specific uses. – Michael C Nov 01 '17 at 22:00
  • Adobe has been doing it this way forever and it usually doesn't create problems but every now and then people pull their hair out over it. BTW, it can show up when upsizing as well but it's much rarer. Easy solution is to create a custom working space in Photoshop as outlined at the link. The problem more often shows up when blending colors that sharply transition, say blue->red. Especially on synthetic images like vector artwork that has been rasterized. Most, but not all, photo images aren't a problem. The newer ones from camera's w/o AA filters can be more of an issue. – doug Nov 01 '17 at 22:23
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    @doug one of the nice things about working with Raw images is that they're naturally at gamma=1, it's not until you export them to a colorspace that a gamma is applied. – Mark Ransom Nov 02 '17 at 22:15
  • @MarkRansom Exactly! – Michael C Nov 03 '17 at 02:43
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This is known as Moire and generally occurs in patterns outside of nature. When the fine patterns in the image intersect with the camera sensor, these moire effects occur.

If you are using Lightroom, then it is very easily corrected.

Open your image in Lightroom and go to the Developer Module

Then click on the Adjustment brush.

When the sliders for the Adjustment Brush open, ensure they are all at Zero. You can double click on each line to do this.

Increase the Size of the Brush and feather accordingly.

I tend to keep the Auto Mask off as I prefer to cover the area manually rather than let the computer do it, but it is a personal choice.

Paint over the effected area.

Finally, Adjust the Moire slider until the desired effect has been reached. In most cases, this will solve majority of the problem without having to resort to further Cloning!

Abdul N Quraishi
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    HUm... THat is not morie. That pattern is not small enough. That is an optical ilusion onthe retina, not on the photo. – Rafael Sep 29 '15 at 22:55
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If you are noticing this while you are photographing, the easiest fix is to move forward or back, or zoom in or out. Changing the magnification of the subject will change how the pattern interacts with the sensor. If you're dealing with it after the fact, the previous answer regarding the moire brush is your best bet.

Matt Owen
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    When photographing, how can you tell that the moire is in the recorded image and not an artifact of playback or EVF display? – mattdm Sep 29 '15 at 18:43
  • Zooming to 100% in playback would give you an indication, but you're right that it's not certain due to screen differences. – Matt Owen Sep 29 '15 at 19:23