Cleaning a scan basically means making the scans look good.
There are many steps in the process of cleaning a scan:
1. Colour-settings: Make sure the scan is in greyscale mode or, for colour images, RGB mode. [+] [-]
2. Rotating: Rotate the scan to have it aligned correctly. [+] [-]
3. Merging: Connecting two pages that are part of a double page spread. [+] [-]
4. Cropping: Crop out unneccessary parts of the scan. [+] [-]
5. Leveling and dusting: Level the image so the blacks are black and the whites are white without damaging the greys then clean any specks that were left. [+] [-]
This is more or less the core to cleaning; it's basically the real polishing of scans. As the headline says, we don't wanna loose any details here, so this will be a bit tricky for starters. Since up until now the screenshots have been taken from HQ raws, we will continue the classroom with working on those (which means we will also use the "exposure" tool). Usually low quality webraws are already more or less precleaned, so do not use exposure on them.
Let us begin with the HQ raws. Open the "image" dialogue's sub dialogue "adjust" and choose the option exposure.
Choose settings that fit (they depend on the raws you are working on), and make sure there is room left for leveling; exposure is not meant to completely clean pages. Actually the more you use exposure the higher the possibility for details to get lost, on the other hand you will need a shitload of time on your hand to compensate if you do not use exposure on non-precleaned raws.
Let us get to the actual leveling. To get to the leveling dialogue, open the "image" dialogue's sub dialogue "adjust" once again and choose the option "levels". Alternatively you can press Controll+L.
Just like with exposure, you will have to find fitting settings.
If you zoom (Controll-Mousewheel) in, it will look like this. On the left you can see an overleveled example, on the right it is correctly leveled (actually it is a bit underleveled, you will see). As you can see, the lines are much sharper on the left image, too sharp.
Another thing you should have seen is that there are still some specks left.
To get rid of those leftovers, there are various options, the most obvious (and actually worst) one being the brush tool (B). Another, better, one is using the dodge tool (O).
As you can see the colors are inverted here, that is because we needed to clean blacks. To invert, press Controll+i You could use the burn tool on this, too, but expirience has it, that the dodge tool handles details much more gently for some reason. Regarding the tool's settings, always set the aim to "lights". Anyway, now you can dodge the specks:
And in the end we got this result:
6. Redrawing: Complete any necessary redrawing, e.g. restoring the background behind offtexts. [+] [-]
7. Resizing: Resize your image to have a web-compatible size (depending on your group this may not be wanted) [+] [-]
8. Cleaning bubbles: Clear the text from the bubbles. [+] [-] [Action]
9. Saving: Save the image. [+] [-]
Other useful stuff pt.1: Adjustment layers. [+] [-]
Other useful stuff pt.2: Training Raws. [Low Quality]