Scrolling gui texture up and down, Android

I am making some android prototypes and I need help from community for an issue. I have a long image(1280p wide and 2534p height). I want the user to scroll with finger this image up and down to read it’s content. Can someone point me to some resources or solutions.
Below is the image that I created to tell the storyline of the game. Sorry that I blurred it.

[14994-in+ap.jpg|14994]

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[14995-storyline+2.jpg|14995]

An approach would be to get the touch position in word space, calculate a velocity (previous - current) and move the camera down or a container up.

Touch touch = Input.touches[0];
touchPosition = touch.position;
touchPosition.z = -camera.transform.position.z;
touchPosition = camera.ScreenToWorldPoint(touchPosition);

...

velocityY = touchPosition.y - previousTouchPosition.y;

...

//apply velocity
newPositionY += velocityY;
camPosition.y = newPositionY;
camera.transform.position = camPosition;

previousTouchPosition = touchPosition;

I didn’t test the code and some features are missing e.g. decrement the velocity when there is no touch and check for top and bottom bounds.