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Last Post:
16 Aug 26, 12:20
Last Post By: rcunnew
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Posts:
52
Registered:
23-Feb-2008
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Optimising image settings to avoid moiré effect
Posted:
12 Aug 26, 17:52
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A small number of my images suffer from a moiré effect (wave interference patterns) in jAlbum. The only way I've found to avoid this is to double image bounds (Settings>Images), which trebles file size. Is there any way you can increase image bounds for a particular image rather than the whole album? Or is there a different image setting which will avoid moiré without trebling album size?
For an example of the moiré effect in my live album (image bounds 2000 x 1125) see https://robertcunnew.uk/Digital/index.html#img=The%20Hertford%20Union%20at%20Bow%20No%201.jpg.
For the same image with bounds 5000 x 2250 see https://robertcunnew.uk/Test2/Digital/index.html#img=The%20Hertford%20Union%20at%20Bow%20No%201.jpg.
As you will see my images aren't photos; they're vector graphics exported to JPG from CorelDraw. I can increase the export size but this only has a small effect once it's gone through the jAlbum mill.
Any suggestions gratefully received. |
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Posts:
8,591
Registered:
31-Jan-2006
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Re: Optimising image settings to avoid moiré effect
Posted:
12 Aug 26, 18:02
in response to: rcunnew
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Just off the top of my head, I think for the "problem" image I would just tell jAlbum to use the original, instead of scaling it. Right-click the thumbnail for it in the Explore view to see that option - Use original (not just include the orignal). So, you'd take the size hit only for that image.
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Posts:
4,091
Registered:
4-Aug-2006
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Re: Optimising image settings to avoid moiré effect
Posted:
12 Aug 26, 18:03
in response to: rcunnew
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First try changing the output to AVIF, that should give smaller sizes and better results
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Posts:
4,091
Registered:
4-Aug-2006
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Re: Optimising image settings to avoid moiré effect
Posted:
12 Aug 26, 18:18
in response to: RobM
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The other thing to try is using NoPages skin to reduce the size in smaller steps, typically 10% at a time. Then use the final size you want as original, so it isn’t resized again after you have a moire free image.
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Posts:
52
Registered:
23-Feb-2008
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Re: Optimising image settings to avoid moiré effect
Posted:
12 Aug 26, 18:52
in response to: JeffTucker
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Thanks, that's seems a good fix if just a few images are involved. I'm slightly uneasy about having the full image online but with my settings you can't right click and save.
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Posts:
52
Registered:
23-Feb-2008
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Re: Optimising image settings to avoid moiré effect
Posted:
12 Aug 26, 18:53
in response to: RobM
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Ah, now I have a reason to upgrade my jAlbum version!
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Posts:
8,591
Registered:
31-Jan-2006
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Re: Optimising image settings to avoid moiré effect
Posted:
12 Aug 26, 18:59
in response to: rcunnew
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Ah, now I have a reason to upgrade my jAlbum version!
Once every five years, whether you need it, or not!  |
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Posts:
4,091
Registered:
4-Aug-2006
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Re: Optimising image settings to avoid moiré effect
Posted:
12 Aug 26, 19:45
in response to: rcunnew
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Thanks, that's seems a good fix if just a few images are involved. I'm slightly uneasy about having the full image online but with my settings you can't right click and save.
Easily bypassed, if you know what to do or know how to search the web and probably even easier if you use AI chat bots |
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Posts:
52
Registered:
23-Feb-2008
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Re: Optimising image settings to avoid moiré effect
Posted:
12 Aug 26, 20:43
in response to: RobM
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Yes I'd much prefer not to have the original online at all.
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Posts:
8,591
Registered:
31-Jan-2006
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Re: Optimising image settings to avoid moiré effect
Posted:
12 Aug 26, 21:12
in response to: rcunnew
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Yes I'd much prefer not to have the original online at all.
If the slide image is 2250x2250, like your HiDPI example above, anyone who's motivated to swipe it would probably be perfectly happy with that.
That's the tricky part of trying to protect your images. If they look good online, they're good enough to steal. To make them "not worth grabbing," you have to make them look lousy, either with low resolution or intrusive watermarking. |
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Posts:
52
Registered:
23-Feb-2008
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Re: Optimising image settings to avoid moiré effect
Posted:
13 Aug 26, 10:54
in response to: davidekholm
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Thanks for that suggestion. I've tried that and it does make a big improvement, possibly better than doubling the image bounds and safer. It's not perfect, I don't know if any of my other image settings could be improved:
Scaling method: smooth
Custom: standard
Sharpen: 25
JPEG quality: 85
WebP quality: 60
Image bounds: thumbnails 212x170, images 2000x1125
Other boxes unchecked
Advanced: I don't think I've changed any of these settings from the defaults.
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Posts:
4,028
Registered:
18-Oct-2002
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Re: Optimising image settings to avoid moiré effect
Posted:
13 Aug 26, 11:07
in response to: rcunnew
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If you go with the hardware accelerated scaling of recent jAlbum versions or use Blackman-Bessel, then you can set sharpening to 0 as well.
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Posts:
52
Registered:
23-Feb-2008
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Re: Optimising image settings to avoid moiré effect
Posted:
13 Aug 26, 11:31
in response to: davidekholm
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Thanks, I've now tried them and they all seem to give the same results with my problem image. So I'll go with Blackman-Bessel; the result is a lot better than standard. The alternative I think is to double image bounds; that gives the best results and is better anyway with the zoom button switched on but I'm concerned about the piracy risk if the image is too close to the original.
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