How to easily remove the white background from a scanned paper drawing | Photoshop tutorial

Step 1: Colour Range

Sample a range of background colours by holding shift & dragging the cursor 1cm.
Adjust the fuzziness till the background appears mostly white.

Step 2: Create Alpha Channel
Open the channels tab and load the selection as a channel & deselect the selection CMD+D.

Step 3: Select Background
Select the magic wand tool, roughly select the background area at a tolerance of 32 & contiguous checked.

Step 4: Expand Selection
Expand the selection by 20 pixels to move the selection over the image & clean up / simplify the selection of the background.

Step 5: Clean Up The Selection & Inverse
Add any areas left out of the selection with a selection tool of your choice.
I used the rectangular marquee too with 0 pixels of feathering. Inverse selection CMD+SHIFT+I

Step 6: Feather Selection & & Fill Image Area
Feather the selection by 10 pixels (half of step 4’s expansion). Fill the selection too black.

Step 7: Modify Selection & Fill Background Area
Expand the selection by 50 pixels (30 px from the image edge).
Inverse selection CMD+SHIFT+I. Fill the selected background area to white.

Step 8: Output Selection & Create Mask
Load the channel as a selection and switch to the layers tab. Select the image layer & add the layer mask. Select the mask and invert CMD+SHIFT+I.

Step 9: Refine Mask
Select the brush tool & adjust the hardness to 75%.
Mask out unwanted detail in the background with black and un-mask left out detail with white.