As long as we're talking about shades of blue:
Non-photo blue
21–30 of 44 posts
Re: Non-photo blue
#22There 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…" :)
Re: Non-photo blue
#23When the article refers to 'graphics-arts cameras', what do they mean? Is there a spectral notch filter applied to the CCD, or is the article a troll? "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." Any black-and-white scanner should ha…
I believe they are referring to a technology of the ancients where they made thin films of photosensitive chemicals, exposed them to light, then processed them to make images. The chemicals varied in which wavelengths would activate them. For instance, red would not activate the paper commonly used for black and white prints, hence the red lights in dark rooms. It is also possible the cameras illuminated the artwork…
The magic word here is "orthochromatic". Orthochromatic photo emulsions (the light-sensitive part of film or photo paper) are only sensitive to short wavelengths of light. The first photo emulsions were all orthochromatic, which makes skin look weird. Later we developed Panchromatic film which is equally sensitive to all colors. It replaced ortho in the camera, but ortho continued to be very useful in the darkroom and in compositing because it allows the red safelight and tricks like non-photo blue.
Re: Non-photo blue
#24When the article refers to 'graphics-arts cameras', what do they mean? Is there a spectral notch filter applied to the CCD, or is the article a troll? "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." Any black-and-white scanner should ha…
The "graphics arts cameras" they are referring to are pre-digital. They looked like this: http://www.forgottenartsupplies.com/?what=artifacts&image_id... The goal was to compose a layout into a single image. You created a layout by literally cutting and pasting things onto a board. Then you placed that board in the area at the bottom and took a picture of it that was transferred to film loaded in the top. You're righ…
And just to add a couple things to your answer:
-- Litho film was also very high contrast so everything pretty much came out black or white. (Photos weren't actually reproduced as greyscale but rather as a set of larger or smaller black dots using a halftone screen. This still applies when things are printed.)
-- Because litho film was sensitive to blue, the non-repro blue writing on the white paper would, like the white itself, be an exposed part of the image. This results in a black area of the negative where silver halide has been turned into metallic silver. This black area would then become white again when the negative was used to create a printing plate.
Re: Non-photo blue
#25totally off topic, but also a lovely song by the band pinback.
came here to say this. going to go off and listen to it now
Re: Non-photo blue
#26There 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…" :)
It apparently has to do with infrared reflectivity and even has a name: Ageratum effect.
Re: Non-photo blue
#27Ah, this is why some government documents need to be signed using blue ink!
Re: Non-photo blue
#28Earlier quoted context omitted.
Kind of strange for the info box to specify a color used in the pre-digital era using a digital sRGB triplet.
Yeah, I expect that's just someone with a mania for Wiki-standardization. It's not a precise shade; any cyan-ish color would do. In practice non-repro pencils and markers varied from sky blue to a rich turquoise. The article seems confused - it's implying that there is some magic shade of blue that cameras can't see (even today), which is totally wrong. I think that's why someone found it interesting to post here.
Graphic arts film wasn't at all fussy about the shade of blue (as you note) and so while there were expensive non-repro blue markers and pencils, everyone I knew (at the very end of the era of graphic arts cameras) used blue highlighters, so design studios were full of them.
I've stuck with blue as the only highlighter colour I'll ever use, more than 20 years since the original rationale.
Also, used to freak people out scribbling (non-repro) obscenities on a flat that was going to be sent to photo and turned into a newspaper the next day.
Re: Non-photo blue
#29Ah, this is why some government documents need to be signed using blue ink!
It's more likely that they require blue ink so they can distinguish the original from a photocopy.
Re: Non-photo blue
#30Any 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.
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.