Once the original blueprints were scanned at 400 DPI by Draftech, we experimented to find the best way to convert them back into positives, better to view them as originally drawn by architect Brainerd Jones. With Candice's extensive knowledge of image processing theory, we developed a seven step Photoshop "recipe" to filter and enhance the images. The results can be downloaded from the blueprints page of our regular website.
All blueprints are unique, but we believe these directions yielded the best possible results for our data. Despeckling twice, for example, removed just the right amount of "dirt" from the image without harming significant fine details in these drawings, including evidence of erasures. Your mileage may vary; only by experimenting with the settings on your own blueprints can you find the optimal tweaks. (We urge you to follow the exact sequence indicated below, however.) The final step -- reducing the image down to 200 DPI -- is optional, but practical; it makes a great difference in the file size with no appreciable degradation of quality.
Each step includes the menu path where that particular tool can be found in the Mac OS X version of Photoshop 7. (This post has nothing to do with old house restoration, of course, but we didn't have a better place for this topic, which is certainly "obscura.")
ERRATUM, APR. 26: a typo in the custom filter was fixed.
Custom filter: | ||||
0 | 0 | -1 | 0 | 0 |
0 | 1 | 1 | 1 | 0 |
-1 | 1 | 8 | 1 | -1 |
0 | 1 | 1 | 1 | 0 |
0 | 0 | -1 | 0 | 0 |
scale 8 | ||||
2) invert (Image > Adjustments > Invert)
3) apply custom filter shown at right (Filter > Other > Custom)
4) set levels 0 1.55 155 (Image > Adjustments > Levels)
5) despeckle twice (Filter > Noise > Despeckle)
6) set threshold to 237 (Image > Adjustments > Threshold)
7 optional) set to 200 DPI (Image > Image Size)
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