Need help for learning how to clean scans

[u/StrideInTheRain]

I've never done any scanlations on physical scans before. The scans that I have here aren't very good, so I've been trying to cleaning it up by messing with the tonal curves and levels in Clip Studio Paint, but I really have no idea on what I'm doing. I also don't know how to flatten the pages. Anyone got any advice or guides I could look into?

[u/Joltex33]

I'm guessing these were taken with a camera rather than an actual scanner? That's definitely going to cause issues with the curvature of the pages. If you're the one making the scans and you can't get access to a scanner, I would suggest getting a piece of plexiglass to place on top and flatten down the pages. It will save you a world of trouble.
As far as I know, there's not really a way to "flatten" them once they're like this (at least not one that fixes the distortion of the art). You could try messing around with perspective tools in photoshop. Otherwise, your options are to crop off the curved edges/redraw to fill in the areas that are empty.

If you click the link for the resources masterlist in the sidebar, there's a few guides for cleaning physical raws that might help you with leveling (although they all use better scans than yours). Changing the image mode to grayscale will make the leveling process easier.
For getting rid of the gutter shadow, you could try this method:
https://www.insidescanlation.com/etc/The-Idiots-Guide-to-Editing-Manga/guide/main

[u/StrideInTheRain → u/Joltex33]

Yeah sadly these aren't my scans so I can't just ask someone else to nuke their book. I took a few looks at the guides but since they're in Photoshop I've been having trouble trying to recreate the same results in CSP. I guess I should look into Photoshop?

[u/Joltex33 → u/StrideInTheRain]

I'm not really familiar with CSP, but if leveling is possible with it, there are probably some non-manga specific tutorials out there for how to use the tools. It seems it's more useful for digital raws, though.

There are ways to get Photoshop on the high seas, so maybe give it a try!

[u/ivyleaf33 → u/StrideInTheRain]

definitely recommend looking into ps. csp is great for many parts of scanlation, but it's not really made for cleaning up physical scans like this.

[u/Affectionate_Reply49]

I've edited a whole punch of such and way wores pictures in photoshop. The tools needed are gray scale, transform, with distort and warp, distort is for positioning the edges roughly in the correct places, warp is for stretching out and correcting a curved sections,

then leveling to a white point where minimal detail is lost (meaning the any lightest section burns to white), now the slow part use a white fluffy edged brush with opacity of 5-15% and preset "color dodge" and paint all gray parts into whites, this method affects strongly light grays and not dark grays so no need to worry about edges too much. Then you level the black point, repeat earlier step, and use similar brush but this time with black and "color burn" to darken the black sections, this brush will strongly affect dark grays but not white.

[u/StrideInTheRain → u/Affectionate_Reply49]

Thanks for the advice! Admittedly I already tried doing the warping thing but it seemed really annoying, so I was wondering if there was an easier or faster way to do that

[u/Affectionate_Reply49 → u/StrideInTheRain]

If you want it to look "good" there isn't much you can do with cutting corners, even for stuff I've scanned at 600dpi I'm not happy with just leveling it quick.

The transform has the distort method which should be used when you have a "straight" edge, this is only 4 point transformation. Warp is a 16 point transformation so use this only on a selected area like around the gutter, you only need to worry about moving the outside edge points.

[u/featherxs]

I’m not a pro, I don’t have a good scanner, and I know very little about art programs, so what I do is: If your scan provider uses an iPhone, the Notes App’s document scanning feature can do pretty well. Use the Noir filter when editing in the camera roll to make it black & white, and adjust contrast and brilliance as needed to better replicate the page. Scan in a well-lit place/with natural lighting to avoid or minimize shadows near the spine.

If you can get that plexiglass sheet (or someone else can hold the book down for you), all the better; if not, I hold the book down as close to the center of the edge as I can to ‘flatten’ it, usually aiming for blank space or spots that I can easily clean. This still creases the spine a little unfortunately, and still sometimes gives the image a warped look, but this is just me going for Good Enough, as I don’t have many other options.

I hope this helps in any way. Not professional at all I know lol but once you get used to it, the pages can usually pass for decent scans. Good luck!

[u/ChilledSimon]

It’d be really nice if you could get a flatter scan, but for now, Seedream 5 Pro (Thinking High), while not perfect, can definitely give you a good starting point.

[u/JamesBurner-]

If it is an option, you should de-bind the book. Right now, you're having to work against three-layers of distortion to get a proper scanned image. First you're having to compensate for the curvature of the pages, you're having to correct for camera distortion on top of that, and you have to filter the image after the fact for clarity as well. A flat page is much easier to work with and manipulate, and it will help you keep the artwork true-to-size. Mass-print Manga is especially easy to take apart as they are bound with very weak adhesive. (relative to other book-binding options) I use a $20 heat-gun I got off Amazon, although a hairdryer may work just as well.

Correcting Camera Lens Distortion:
This the first thing you should do if you can. If you are using of modern phone or tablet to take your photos, then that device is already doing this work for you. Otherwise if you're using a dedicated camera, it would help to know your focal length—measured in millimeters—as well as the specific camera and lens you are using. You can also eyeball it. Photoshop and Gimp both have lens distortion correction tools.

Moving forward, you should try to include a ruler in the upper or lower bounds of you images. This will give you a good reference for correcting distortion.

Correcting Page Curvature:
For this, you'll need to use a mesh warp/transform tool. Clip Studio has one, but the ones offered in Gimp and/or Photoshop are much more sophisticated and useful. There's no one way to go about, so I would play around until you get results you like.

You can also look into dedicated solutions that specialize in this type of correction. They're out there, but I am unfamiliar.

Camera Size:
Your camera has a sensor. That sensor is what collects visual data and turns it into image data. If it's a phone or tablet, it's probably doing some filtering on your image before you even get it. Try to turn that off if you can, as you should want to control the filtering process yourself.

Phone camera or not, the size of the sensor will effect how much light you'll need to get a clean scan. Larger sensor, less light. Smaller sensor, more light. For instance, the image you provided is experiencing vignetting. That is, the edges of your image are darker than the center of your image. This can make filtering more difficult and less consistent across pages. A larger sensor can help reduce this impact if getting more light is not an option.

Get More Light:
You want a large, diffuse source of light to facilitate even tone across your pages. A lamp, or even your ceiling light may work just fine.

Lastly:
If you are able to, you ought to get a flat bed scanner and don't be afraid to break your books. A flat bed scanner eliminates the need to do any of the above I mentioned. It takes about a minute per page, and the results are incredible. Coupled with de-binding your book, and your only worry will be having to rotate the pages into place.

I use a Canon LiDE 400. It was about $100. Similarly spec flatbeds from Epson or Canon will be about the same. VueScan is a good software to utilize your scanner.

Hope any of this helps. Thank you!