Step Eight: Scanning & Merging

Drawing on 11”x17” bristol board and trying to scan with only a legal-sized scanner may sound a little crazy, but there’s a trick to welding images together, so it’s not a problem.

First, I scan the page in three pieces, making sure I have the top, middle and bottom completely covered.

Because I’m a detail freak, I scan each in at 600dpi as line art (not grayscale), setting the cut-off point to 127 out of 255 (which is equivalent to 50% gray). This automatically cleans up all of the little blemishes in the paper and remnants leftover from the pencils, especially when erasing didn’t quite do the trick.

Squaring the Page
The tricky part of merging seperate scans is getting everything perfectly square. So, I fix this in each of the three pieces.

To fix the problem in Photoshop:

  1. Find the Ruler tool—click and hold the Eyedropper tool in the tool palette to find it.
  2. Measure the angle of the left edge the page—go to the top corner and drag the ruler down to the bottom corner.
  3. Use the measured angle to rotate the image—while still on the ruler tool, go to Image>Rotate Canvas>Arbitrary and the angle will automatically be entered into the number field. Just hit ‘Okay’ to fix the rotation.

Squaring the Page

Once the scans are ready, it’s time to merge these puppies together. I go to File>New and create a new 11”x17” grayscale document set to 600dpi. Then, I Cut and Paste the bottom section of the page into the new document and line up the bottom edge of the page with the bottom of the document. Next, I take the middle section and Cut and Paste it into the new document.

Now, to line it up with the bottom section, I go over to the Layers Palette and change the Blending from Normal to Multiply so I can see where the two sections are overlapping.* I zoom in to line up the bottom corner of the rightmost panels. With any luck they match up more or less correctly, but if it seems they’re a little off, no problem:

  1. Pull up Free Transform—Cmd-T (Mac) or Ctrl-T (Win).
  2. Drag the center point to the bottom corner of the aligned panel.
  3. Adjust the rotation until it looks about right—in Photoshop 6 and above you can actually type in numeric degrees. Usually it’s less than +/-.1 degree off.

Lining up scans

Once that’s done, I switch the Blending back to Normal. On the off chance things don’t look quite right along the edge, I create a Transparency Mask for the layer and erase a few lines until it looks good. Then I repeat the process for the top section. Luckily, when there are only three rows of panels, I cut the edges in the gutters between panels so the alignment usually goes pretty quickly.

*Another way to do this is to set layer opacity to 75%. That way the faded scan can be seen below.

NextStep Seven