Scans and How To Process Them

5 Nov

There’s no denying it. I am obsessed with scans. That is to say, I’m obsessed with collecting other people’s scans, as I haven’t got much of anything in my possession that someone else hasn’t already scanned and posted somewhere in cyberspace. My favorite thing of all to collect is artbooks, so it should come as no surprise that I also collect them in the form of high quality scans. All the kind words in the world wouldn’t be enough for me to thank icie, the people who run moe.imouto and other sites like it for their contributions to the scanning community. I’ll come right forward and admit that I am a firm believer in the theory that scanning something doesn’t make it yours. I think websites like AnimePaper and Minitokyo, which reward people scans on the basis of “in order to have a cookie you must first bake us 24 cookies, which we will probably throw out because your cookies suck and ours are awesome”, are run based on extremely hypocritical motives, as a great deal of the scans submitted to those sites are simply stolen from other scanners who share them freely with everyone. In fact, I’ve submitted my own scans to those sites, only to have them deleted and resubmitted by other users of the same site. In my opinion (and that is all it is – my opinion), the only person who really owns the image being scanned is the original artist… but I digress. I don’t intend for this post to be a rant on scanning ethics.

Everyone has felt the disappointment of downloading an image (especially on a site where you have to pay ‘credit’ to get a ‘high quality’ scan)  in all of it’s high resolution glory only to discover it is plagued by nasty moire . If you had plans to use this image in graphic design, your only hope is to find some way to fix the image without losing detail and quality. Despite being a graphic designer, I found myself sheepishly admitting I had no idea how to get rid of this devilish little pattern. I decided at last to do something about it, and went back to a thread I’ve found myself reading over and over for a long time over on moe.imouto. The time had come to decipher what all of those settings mean! Before I got to that, however, I opted to take the amateur’s approach and do a Google search on removing moire. In order for me to understand the more advanced techniques, I’d have to start with something simple. What I found was this post on About.com. Only five minutes to fix up an image? Right on! I opened up Photoshop CS3 and got crackin’.

 

I chose this scan of Kaworu as my victim. Rather, this section of a scan. (I figured it’d be easier this way to show you how everything works.) Notice the slight screening on the image? We want to get rid of it without losing too much detail or making it look like a Van Gogh.

 

Step #1 tells me to go to Filter > Noise > Median and to pick a setting between 1 and 3. The noise isn’t TOO terrible so I decide that “1” looks best. Setting it on “2” or “3” makes the image look over-filtered to my untrained eye. I’m actually pretty impressed how much better the image looks after only one step! I’m excited.

 

The next step directs me to the Unsharp Mask (Filter > Sharpen > Unsharp Mask) and suggests these settings: Amount 50-100%, Radius 1-3 pixels, Threshold 1-5. I play around with the settings and the only one that I can really see a difference with is Amount.  Ultimately, I go with 60%, 3 pixel radius and a threshold of 5. This brings back of the detail that we lost with that previous noise filter. Neat!

What next?! Oh, that’s it? That was really easy and only took a couple of minutes, and I think the image looks way better! Not perfect, but quite an improvement over the original. Why did I take so long to learn this? Let’s try out something a little more advanced now.

My friends over at moe.imouto are avid users of a free GIMP plugin called Greycstoration. I use Photoshop, but I really want to try Greyc out, so I download the most recent version of the PS plugin that petopeto whipped up. (Thanks, bro!) I open up the original Kaworu image again, go to Filter > Greycstoration > remove noise. I’m introduced to a UI with all kinds of funky settings. I don’t know where to start, so I go back to the what’s your processing thread and start scanning through various posts with recommended settings. I decide to go with one of midzki’s suggestions because midzki is a scan processing maniac. Seriously, this guy’s got mad skills. Many posts suggest doing two separate passes of Greyc with different settings and this one was no exception. Here’s the post I chose to use to try and fix up my image:

midzki said:
btw, I found filtering Greycstoration 2times with completely defferent parameters is really effective.

for example,
1st(-dt 10 -p 0.2 -a 0.6 -alpha 3 -sigma 0 -fast false)
2nd(-dt 30 -p 0.2 -a 1.0 -alpha 0 -sigma 3 -fast false)

1st setting is reducing moire, & 2nd setting is smoothing edges.
The point is setting -alpha and -sigma separately.


Here’s the result of the first pass. Holy cow! That’s different from the original for sure. It’s a lot less sharp than what I expected, but there’s really no loss of detail and it looks good. No moire to be found here, ladies and gents! The alpha setting knocked it right out.

 

Here’s the 2nd pass. Way smooooth. The sigma setting got rid of any remaining noise or paper texture on the image. Again, it looks really different, but it looks GOOD! Greycstoration is one heck of an awesome plugin!

You’ll notice that the result of my first set of filters versus the results of using Greycstoration are incredibly different. That’s not necessarily a bad thing. I find that in the end it almost turns out to be preferential. Greyc took a lot of the ‘organic’ feeling out by removing any sign of paper texture and making the rough pencil lines extremely smooth. (Granted I didn’t try a variety of settings, either.) Depending on what look you’re going for, you may or may not like it. For this particular image, which I believe Yoshiyuki Sadamoto used traditional media to create, I feel that the grainy paper look complements it, although others may see it as “just noise”. If I was editing, perhaps, a scan of a cel-shaded CG artwork, there’s no doubt in my mind that Greyc would be the only way to go. Ultimately, both methods of processing did their job of removing the moire pattern, so I’m quite satisfied with both. Here’s to learning something new!

p.s. – I’m fairly certain it goes without saying that you’re not going to see any difference in the images in this post without viewing them in full size, but just in case you’re a little slow… ;)

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