Engravings

greyscale scan, at 300 dpi, of a page from Webster's (1911)
New International Dictionary of the English Language (see reference)

In working with an engraving I suggest the following:

1. scan in greyscale at 300 dpi (higher if detail is extraordinarily crisp, and/or, if the printer belongs to you -- it will take longer).

2. bring the images into Photoshop running on a machine with some RAM -- a few score of megabytes for the operating system (more in Washington state) and a few score more for the application ought to suffice.

3. rotate the page to conform to your preferred viewing angle (typically upright) --use Image/Rotate Canvas.

4. grab one pretty picture at a time, using the marquis tool and CTRL-C. Paste the single pic into a new document:

1.select; copy; new file

2.paste

5. Flatten the image and resize it to 72 dpi, without shrinking the filesize (shown under pixel dimesions):

300 dpi

72 dpi - no resampling

6. Examine flaws in several "typical" images:

7. Define (through experimentation) a standard process for cleaning the background of the image (if appropriate): consider enhancing contrast, reducing page discoloration, tears, and paper irregularities, etc. But it should be a standard, non-intrusive, and replicable process. Keep notes, if possible. Is hand-retouching allowed? If so, under what circumstances?

8. Build a macro (Photoshop action) which repeats standardized parts of the above process. Here's something I've used from time-to-time; feel free to try it out.

1. set wand tolerance to allow selection of proper background shades Double-click on the tool to reset its default values.

2. make a new action/button Show actions from window menu; uncheck button mode; choose new action.

3.record maco a. contract selection this helps ensure that fine details around the edge of the image are not included as part of the background b. select similar -- this gathers any white areas inside the image c. contract selection by radius 2 -- again this is to ensure that "real" details will not be obliterated by what happens next d. fill selected region using 50% white e. select inverse -- getting the good stuff this time f. Image/adjust/auto levels -- to enhance contrast of the foreground image g. face auto levels (from filters menu) -- to about 35% -- prevents contrast from becoming too strong h. select all then select border of about 8 pixels -- fill with 100% white i. select entire image and posterize to 16 colors -- 4 bits per pixel -- will reduce image size by 50%

9. Run the macro once or twice per image.

10. Give some thought to consistency of filenames -- recall that spaces in filenames can cause troubles, but that they may be meaningful.

11. Save in lossless format (e.g. gif) -- for 4-bit images, this works just fine and should take less space and do better preservation than .jpg. SagoPalm.gif. Consider, however, the emergence of other formats.

12. Think about issues of how to show data about the magnification factor(s) -- on a per image, or per page basis, in an errata field in the database, etc. etc.