Have you ever seen relativly cheap or compelling cels from the same sequence?
Though I no longer own them, I once bought sixteen cels from two sequences at 200 or 300 yen a pop.
Have you ever bought a full cut of sketches because you loved the character or scene? And when you got the set, wondered what the heck you would do with twenty partial sketches of mouths and eyes?
I can't throw them away, that's terrible! That's discarding fantastic art like this:
What can we do? Use them as scrap paper for grocery lists? Fold them into elaborate origami animals?
No! We animate them! Once you've fully stepped into the world of animating your collection, those mouths you once considered recycling will become beautiful.
I'm going to start with the programs I know, the prehistoric Adobe Photoshop 5.5 with ImageReady. Despite its age, some of the principles should be the same as newer versions, or even other programs. You may find that I explain some things that you already know. This is because I tried to make as few assumptions as possible. I'll add information on other programs as people volunteer information or if I do some research and experimentation.
The example I am going to use below is a set of douga, however, please keep in mind that a similar process can be used on any sequence or partial sequence of cels, genga, roughs, and so on.
There are five main sections to this guide:
Step One: Scan (Or Photograph)
Step Two: Prep Work
Step Three: Animate
Step Four: Optimize
Other Programs
Now, before you start on my tutorial, please note the following advice:
1. Have plenty of food or drink at the ready.
2. Be prepared to take breaks...a lot of breaks, particularly if you've got a massive cut sequence on your hands.
3. Don't get frustrated....take a break and watch some anime! Then come here and post about how bloated my tutorial is and point out what part sounds like alien gobbledygock. Maybe I can clarify, or perhaps someone else can explain in two sentences what took me twenty paragraphs.
STEP ONE: SCAN (or Photograph)
Acquire pictures of all the artwork involved in the animation. This includes those formerly "worthless" sketches that were only of mouths, eyes, hair, etcetera.
Do whatever you can to scan your artwork instead of photographing. Buy, borrow, rob, steal, maim. Scan them as best as possible. I put a couple magazines or books on top my closed scanner lid, because when I close the scanner lid with no "weights", my scans tend to have more shadows to them.
If photographs are your only option, try to take the clearest photo possible, and remember that it will be harder to make a smooth animation and optimize (minimize) the size of the final animated image file.
On Registration Holes
When scanning (or photographing), try to make sure that at least part of the registration holes are visible. Registration holes are the best way of making sure everything is aligned. It's what the animators used, after all.
I can scan most of the image in one go, if I turn the sketch sideways. However, the registration holes are usually completely cut off. You might be able to make a decent animation without using the registration, so long as all of the sketches or cels are the same size.
Douga A-6: Sonsaku Hakufu of Ikki Tousen
I've always preferred to scan the entirety of a cel, sequence number and all. Unfortunately, virtually all of the reasonably priced scanners on the market today are 12x8.5 or 14x8.5 inches. Production sketches are 10.75x9.5 inches or larger (barring recent widescreen sketches, which are about 12x8.25 inches). This means double or triple the work to scan two halves of a cel/sketch and stitch them together. However, having the entirety of a sketch scanned is important to perfecting the animation.
+ 
+ Alignment of layers + Eraser used on the edge of the top layer =
On Saving Image Files to be Used in ImageReady
--Also about Resizing Images
Make sure to name the production files in order.
For example:
dougaA01.psd
dougaA02.psd
....
dougaA12end.psd
dougaB01.psd
dougaB02end.psd
....
The leading zeroes are important...otherwise you'll find that A10 comes after A1 and yet before A2 through A9.
You can use a different type of image file, but I recommend Photoshop files over jpegs and GIFs to maintain quality.
Check the size and number of your files! If you have fifty douga files scanned in at 300dpi, you probably need to resize each and every one of them. Save the resized images in a new, well-named, easy to find folder so as to keep the original scans. Think of your computer's feelings, because it will have to open all of these files at the same time!
Always resize using percent (with proportions constrained). This resizes all of the images in the same way (as opposed to picking a random pixel number). It keeps cel or sketch sizes consistent with one another, no matter how you cropped the images or whether any genga had registration holes realigned with scissors and tape.
I normally scan at 150 dpi and resize to 40%. If you want something larger, play around with what percent works for your images & computer system. For my example this time, I actually went for a slightly greater percentage that resulted in an image width of 795 pixels.
If your pictures seem blurry after resizing, try to sharpen the image. If you are using Photoshop go to the menu bar Filter > Sharpen > Unsharp Mask
Play around with the settings if necessary. I normally use a percent from 30% to 50%.
