One problem I've had with my DIY book scanner has been that the right hand doesn't know what the left hand is doing. I try to line up the book for the camera on the right, and try to match the size and alignment with the camera on the left, but there always seem to be differences which detract from the final product. Anything which helps me match the right and left views should improve the ultimate quality, or maybe just take less time to achieve the same quality.
Here's a possible aid. CHDK allows me to create my own grid, and this is what I've come up with: Now, when I'm lining up the book and the camera, I have more than just the edge of the viewfinder to use as a guide. In addition, I can be more accurate with the zoom and distance, and really match the size of the left image and the right image. That "Z:52/x2.7" bar is the zoom information for my camera (the DIGIC III series offers zoom from 0 to 127, and the precise level of zoom can also be controlled thru CHDK). If I put each camera the same distance from the platen, and set the zoom the same (52 in this case), I should get matching page sizes. The grid helps me line up the book, and get lots of nice rectilinear edges. Sure, I'll have to be careful to keep the book from moving as I scan (which I have some ideas about also), but as long as the sizes are the same and they're more or less straight, post-processing software should have an easier time making the pages match.
Here's the code for the custom grid itself:
Code: Select all
@title DIY Bookscanner Grid
@line 0, 10, 359, 10, 0x55
@line 0, 20, 359, 20, 0x66
@line 0, 30, 359, 30, 0x77
@line 0, 40, 359, 40, 0x88
@line 0, 50, 359, 50, 0xAA
@line 0, 60, 359, 60, 0xFF
@line 10, 0, 10, 239, 0x55
@line 350, 0, 350, 239, 0x55
@line 20, 0, 20, 239, 0x66
@line 340, 0, 340, 239, 0x66
@line 30, 0, 30, 239, 0x77
@line 330, 0, 330, 239, 0x77
@line 40, 0, 40, 239, 0x88
@line 320, 0, 320, 239, 0x88
@line 50, 0, 50, 239, 0xAA
@line 310, 0, 310, 239, 0xAA
@line 60, 0, 60, 239, 0xFF
@line 300, 0, 300, 239, 0xFF
If you want the zoom information as well, click through OSD parameters -> "Show Miscellaneous Values" to set the zoom. I position the zoom banner where it won't interfere with my grid using the OSD parameters -> OSD layout editor, but that's not strictly necessary.
Almost dark here in L.A.; keeping my fingers crossed for the motion detector script. If it works, I'll make that another CHDK goodie...