How do you image the REALLY big items? Or the items that won’t fit in a normal scanner?
The largest (and most exciting!) image-processing machine we have here at DI is definitely the TTI.
The TTI is used to scan large, fragile, or otherwise oddly shaped items. You may have caught glimpses of it here.
To show you how it works we are scanning a few delicate maps from the Chung Collection. The maps are foldouts from a book by Sir George Simpson that are still attached, so we couldn’t use THIS machine.
To start, we boot up Capture Flow. Capture Flow is an image-processing program with settings for the exposure time and color adjustment. We also turn on the camera back (Sinarback Evolution 86 H with a Sinaron Digital HR 5.6/90 CMV lens) pointed at the TTI flatbed, and two banks of LED lights that evenly illuminate any item being imaged.
Laying the map on the large TTI bed (40” by 60”) the color corrector, a QPcard 101, and a Better Light focus card are used. They help color correct the image in the editing phase and focus the image properly, respectively, so the picture comes out as true to life as possible.
Test images are taken. They are viewed on the attached screen to check everything is working properly. The color sometimes looks off in the image, but we will correct that later.
Then the real fun begins! To flatten the map we turn on a vacuum built in to the flatbed of the TTI. It will draw the scanned item gently flat. A clean glass plate is set over the map to smooth it out even more.
The camera’s CCD sensor’s pixel matrix is shifted three times laterally or vertically by exactly one pixel width from one exposure to the next, so that every image point is covered by every primary color (red, blue, 2x green).. Captureflow receives the images as a single unit for a more color-realistic and detailed image.
This particular map is too big to image all at once. The map gets flipped and moved to image additional sections.
Later the images are stitched together in the post processing step, using Adobe Photoshop. The final product you end up with is a beauty that looks like this: