A discussion on "why" this is happening:<p>"""<p>The reason older photocopiers don't copy blue is very simply that the
drum was activated by reflected light from the scanner. The chemical
process that creates the "semiconductor" on the drum surface is
sensitive to a fair proportion of the light spectrum, but frequently
lost sensitivity t the blue portion of the range. Organic
photoconductors had a better response to blues but still cut off a
portion of the spectrum. Newer Photocopiers (Digital) operate
differently and are dependent on the frequency range of the CCD in the
scanner, they are usually pretty good at the blues, and frequently
have settings that enable Text enhancement, enabling a setting of a
contrast point, anything darker than that point is registered as black
anything lighter as white.<p>"""<p><a href="http://answers.google.com/answers/threadview/id/536535.html" rel="nofollow">http://answers.google.com/answers/threadview/id/536535.html</a>
Back in the late 70's, early 80's, Dungeons and Dragons modules (self contained adventures) used to print all their dungeon maps in light blue because photocopy machines would not pick them up. This was effectively a poor mans protection against piracy.
Any art or writing instrument store will have gobs or pens and pencils (or lead inserts for mechanical pencils) in this shade of blue if you're interested. As the article states, it's good for sketches that you'll ink or pencil over later, since they will disappear if you scan or photocopy them in high-contrast B&W.<p>It sort of reminds me of the old graphics method of using RGB(255,0,255) for sections of a sprite that should be transparent, since an alpha channel wasn't an option, because it's such a hot pink and such a precise color it would never naturally appear in artwork.
And my engineering notebooks from the EurekaLabNotebook company use this color for the grid which is a bit disconcerting if you make a copy of the page and the grid disappears and you have only your writing and diagrams.
As long as we're talking about shades of blue:<p><a href="https://en.wikipedia.org/wiki/Prussian_blue" rel="nofollow">https://en.wikipedia.org/wiki/Prussian_blue</a>
When the article refers to 'graphics-arts cameras', what do they mean?<p>Is there a spectral notch filter applied to the CCD, or is the article a troll?<p>"Scanning in black-and-white makes it possible for the non-photo blue still to serve its original purpose, as notes and rough sketching lines can be placed throughout the image being scanned and remain undetected by the scan head."<p>Any black-and-white scanner should have a spectrally-flat response, picking up blue just as black and white photographs see the sky as darker than white.<p>It's entirely possible that older lithographic film didn't have much response in the blue, but there's really no way that a modern imaging system won't pick it up.<p>What am I missing?<p>Edit: Experiment is the arbiter of truth: I took a picture of the screen with my digital SLR. As expected, every color swatch in the article is blue. Desaturated the RAW image. Looks grey.
When I was younger I worked at a small newspaper which had only recently made the transition from self-publishing the old-fashioned way to laying out the paper with software and sending it off to a publishing company.<p>The old printing press easily took up half of our little room, and old supplies still littered the shelves and floor. I loved digging through papers (we had copies dating back to the first half of the 20th century) and learning tidbits about the old way of doing things. The rest of the workers had been there 30+ years and would reminisce about late nights spent pasting strips of paper with text and images onto a board, annotating it with a pen that wouldn't show up, taking and developing the photographs, and running the press.<p>I don't really have anything to contribute, but it's cool to see this pop up on here and learn a little more about it.
There are certain variety of blue flowers that, when photographed, always come out as pink. Back in the film days (with the delay to process film), it was often the source of a mind trick. "Could've sworn that these flowers were blue…" :)