How can I remove moire patterns from a cover with GIMP?

[arny91]

Hi everyone
I unsuccessfully tried to remove the moire pattern of a cover with gimp following the steps described in this post:

 http://www.thecoverproject.net/forums/index.php?topic=1305.msg29355#msg29355 .

When I use " difference of gaussians " filter an error appears saying that there was no image on which apply the filter or image type was "rgb" while it expected "gray". Moreover, in another version of gimp (2.7.2 unstable), when i try to use "difference of gaussians" after anchoring the floating selection of the copied background layer to the mask it exits with another error: "difference of gaussians can't be applied to masks or channel but only to layers".
 
Seems that there are technical errors in this tutorial. I know there aren't a lot of people using gimp in this forum, but I ask this anyway: has anyone succeeded to remove moire pattern using this guide? Can you explain me the right procedure? I also tried a script-fu called "descreen", but it doesn't work well by itself. (maybe using it on another layer with multiplier it does something but i think the tutorial is better).

Thanks

P.S: I am getting mad trying repeatedly to do that thing following the guide and hope that the author will reply.

[noclass_nick]

Remove moire during the scanning process not after?

[Arseen]

Remove moire during the scanning process not after?

Yes, it's easier to remove the moire when scanning.

That tutorial is meant as last effort way to save scans with moire effect if the scans are otherwise good quality, and the original box or cover is not availble anymore for re-scan.

[arny91]

Yes, probably the best way to remove the moire is during the scan, but this time i hadn't acquired them directly with a scanner, i received the covers by email from a person who did the work (maybe the software was without this function). I don't have the original covers, so the only way to remove the moire effect is the use of external programs.

P.S: I was thinking to upload the covers here after i finish the restore.

[Arseen]

P.S: I was thinking to upload the covers here after i finish the restore.

Please do.

And you can of course just upload the unaltered scans for someone else to have crack at them.
There are few great scan fixing wizards here.

[BadChad]

If you have Photo Shop, try using Despeckle or Dust and Scratches under Noise in the Filters tab.

[tiktektak]

This really should only be a last resort because most of this filtering blurs the image.

[arny91]

Well, seems there's no way to remove moire effect without the scanner software. Meanwhile, i have other games whose cover is not in the archive. I have an hp scanjet 3400c, is that good for scanning covers? I noticed that there isn't a tutorial explaining how to adjust colors. Do i need to set gamma, brightness and contrast in the scanning software or later in the image editor? In XSANE there is a median filter,  which seems to remove most of noise without blurring too much the image. Should i use it?

I uploaded on imageshack the cover of "Hybrid" scanned with the default settings: gamma 1,09; brightness -0,4; contrast 0,4.
This is without the median filter:



Uploaded with ImageShack.us

This is with median filter enabled (radius 2)



Uploaded with ImageShack.us

I know that the colors of the other raw covers are more brilliant, but which of the two is better?

[noclass_nick]

Some covers the moire effect wont be removed no matter what, some of my pal ps1 covers are moired before i even put them in the scanner

[Arseen]

Well, seems there's no way to remove moire effect without the scanner software. Meanwhile, i have other games whose cover is not in the archive. I have an hp scanjet 3400c, is that good for scanning covers? I noticed that there isn't a tutorial explaining how to adjust colors. Do i need to set gamma, brightness and contrast in the scanning software or later in the image editor? In XSANE there is a median filter,  which seems to remove most of noise without blurring too much the image. Should i use it?

I uploaded on imageshack the cover of "Hybrid" scanned with the default settings: gamma 1,09; brightness -0,4; contrast 0,4.
This is without the median filter:



Uploaded with ImageShack.us

This is with median filter enabled (radius 2)



Uploaded with ImageShack.us

I know that the colors of the other raw covers are more brilliant, but which of the two is better?

Would you make either Mediafire or Box.net account, upload there and then link here.
Imasgeshack screws the image resolution.
Thank you!

[arny91]

Here you are:
http://www.mediafire.com/file/itzlal62tghecun/hybrid-front.tiff
http://www.mediafire.com/file/zp16pwht2eb23p9/hybrid-front-median.tiff

[ShoothimNow]

Sorry for posting this... but I JUST made this guide YESTERDAY stating NO IMAGESHACK like 50 times.
http://www.thecoverproject.net/forums/index.php?topic=5754.0

Meh dudes, no one reads anymore

[Arseen]

Thanks.

After checking the scans I'd say the first is marginally better, as the second has moire AND is blurry.  

I don't think the color correcting is necessary as the artist making the cover can adjust them when making the covers.
Most important is to do the best to scan withouit moire.

Moire is also known as rasterization -> when scanning choose de-rasterization or de-screen.
I know in reality those are bit different things, but in this case close enough.

[Arseen]

Sorry for posting this... but I JUST made this guide YESTERDAY stating NO IMAGESHACK like 50 times.
http://www.thecoverproject.net/forums/index.php?topic=5754.0

Meh dudes, no one reads anymore

What never realized taht! 
As yours is better than mine, it is important and there are not that many pinned topics I pin yours, if other mod disagree with that they can unpin it.

[arny91]

I'm sorry for using imageshack, didn't read that thread.
I'm not using median filter anymore, as it blurs the image.
Here's the back cover:

http://www.mediafire.com/file/gn7gbla9zcfqu1e/hybrid-back.tiff

Let me know if it's good.