This page collects images I've made of ATF Bodoni Book, to study the optical scaling more carefully. I'm using an averaging technique discussed in more detail on this typophile thread, and have also posted a thread advertising this page. Please follow up feedback and discussion there.
The 6pt sample was taken from p. 72 of the 1912 ATF specimen book. The original 2400 dpi scans can be downloaded from the TUG mirror.
Here is one sample impression of a 6pt 'a'. 2400 dpi scan, enlarged
3x using cubic interpolation.
And here's an average image of 199 impressions, using blend script (grayscale is normalized, so contrast is enhanced.
It's a little blurry, so I apply sharpening (Gimp Enhance/Sharpen set to 80).
You can see some effects involving ink spread when the gamma of that image is lightened.
For optical scaling comparison, here is a composite image of the 18pt 'a', scanned from p. 75. These images are 2400 dpi without any further scaling. If there were no optical scaling, it would be identical to the previous one.
I've traced the outline into vector form. I plan to make more images using this outline, showing how I can use anamorphic scaling and stroke offset (convolution with circular pen) to match the ATF results fairly closely.
This image shows something about how the optical scaling works. It's the sharp 6pt 'a' above, superimposed with the 18pt outline, scaled by 0.37 horizontally and 0.327 vertically (the ratio is 1.13).
And the same outline superimposed on the lightened image:
Raph Levien, 24 Feb 2006