How to adjust a color image like a scanned image

Question

I want to make a effect that a colored normal image to a scanned image.

like 2 pictures below, first image is the original image, second image is the adjusted image,

Answer 1

I believe in order to manually implement Photoshop-like level adjustment feature, you'll need to understand some of the core knowledge on the field of Image Processing.

You may want to read this Core Image Programming Guide as a starting point:

https://developer.apple.com/library/content/documentation/GraphicsImaging/Conceptual/CoreImaging/ci_intro/ci_intro.html

Or, you may simply end up using a third party framework, though you have already stated that you don't want to use 3rd party libraries. If this is the case, I would like to recommend GPUImage2, just in case:

https://github.com/BradLarson/GPUImage2

Finally, I found a similar question to this so you may want to take a look:

How can I map Photoshop's level adjustment to a Core Image filter?

Good luck.