Back to digital restoration.
If you prefer not to align your page by eye there is a more precise method with Photoshop
Let’s use an image that needs to be rotated (I exaggerate the misalignment on purpose).
We will use the Ruler tool (usually hidden underneath the Eyedropper tool).
With this tool draw a straight line using as a guide some element of the drawing that you think should be perfectly horizontal or vertical. In this case the top of the panel:
now activate the command Image -> Rotate Canvas -> Arbitrary (in newer versions of Photoshop is Image -> Image Rotation -> Arbitrary)
A box with a numerical value will appear. Magically that is the exact value of the angle, in degrees, you must use to align your page.
Hit OK and look at the final result.
Remember the splash page from Kamandi #1? It's not well aligned and needs a rotation
and here it is