Trichromy - RGB color separation

Brian Atherton said:
Isn't this the technique that the Hubble telescope and other interplanetary cameras on probes use?
Click to expand...

Dwig said:
Yes, though very often astronomical images will actually be "false color", using an infrared channel as one of the color channels.
Click to expand...

I think you're both technically correct, and I learned something new today! These two videos do a great job of explaining. The second one actually shows the post-processing in Lightroom, which I find fascinating:
https://www.youtube.com/watch?v=WSG0MnmUsEY
https://www.youtube.com/watch?v=fDwkDZ5dx-c

So... since I've done the same thing as Hubble scientists, does that make me an intergalactic astrophysicist? :D
 
The individual B&W frames aren't quite as well aligned on these two, so they show a bit more (tri)chromatic aberration. :D Spotted a few blocks from the Chevy C10 in Post #1.

1965 Buick LeSabre 400.

Nikon FM2n, AI Nikkor 50mm f/1.8S, Ultrafine Xtreme 400, developed in LegacyPro L110 at 1:31 for 5.5 minutes. Three individual black and white frames shot through Tiffen #25 Red, #58 Green, and #47 Blue filters, respectively, then combined using GIMP to create a trichrome color image.


2020.05.09 Roll #244-04717-positive-trichrome.jpg by dourbalistar, on Flickr



2020.05.09 Roll #244-04720-positive-trichrome.jpg by dourbalistar, on Flickr
 
Abbazz said:
Henri Gaud is a French photographer who has been exploring trichromy since 2005. He uses a 8x10 view camera and Trix-X film. Here's an article he wrote for the French site Galerie-Photo (courtesy Google Translate):

https://galerie-photo.com/test-trichromie.html

His photostream:

https://www.flickr.com/photos/23493377@N04/

You can also download his paper about trichromy (in French) : http://cours.education/dufacilitateur/wp-content/uploads/2017/01/Trichromie.pdf

Cheers!

Abbazz
Click to expand...

Thanks for sharing, Abbazz! Monsieur Gaud is much more technical than me in his approach. But what I lack in skill and expertise I make up for with enthusiasm! :D

Although he doesn't seem to have any recent work on Flickr (last upload circa 2009), I see his photos are in the trichromy Flickr groups that I also found. I'll have to study more of his work for inspiration.
 
David Hughes said:
Years ago we explored some of the early experimenters work; try this:-
https://www.rangefinderforum.com/forums/showthread.php?t=155159&highlight=Prokudin-Gorskii

Regards, David
Click to expand...

Thanks for the reminder and link for the old thread. There's a lot of good discussion in that thread.

Three color separations for creating color images what first proposed in 1855, and demonstrated in a somewhat flawed presentation in 1861, by the Scotsman James Clerk Maxwell. This was largely forgotten and separation processes were "re-invented" by others later in the century.

Frederic Ives was a major contributor to color photography and reproduction. He invented half-tone printing, both basic B&W and color, and developed his Kromskop (pronounced "chrome-scope") process for 3-color separation process.
 
The reds surprised me on this one. Some color correction to remove the magenta cast, but that's it.

Nikon FM2n, AI Nikkor 50mm f/1.8S, Ultrafine Xtreme 400, developed in LegacyPro L110 at 1:31 for 5.5 minutes. Three individual black and white frames shot through Tiffen #25 Red, #58 Green, and #47 Blue filters, respectively, then combined using GIMP to create a trichrome color image.


2020.05.09 Roll #244-04723-positive-trichrome.jpg by dourbalistar, on Flickr
 
Very cool! I never got around to trying this outside for real.

I briefly played around with this once about 10 years ago. Some with Tri-X and a few with TMZ. Cool thing about it is if each of the three exposures are properly exposed, images will come out with the proper balance for different color temperatures (like tungsten). I combined mine in Photoshop after scanning.

https://www.flickr.com/photos/tgray1/albums/72157613514418888
 
Very Nice, reverse dye transfer ;-p

Back in the mid-90s the first Leaf digital camera was a Hasselblad with a monochrome sensor and a RGB "color wheel" that spun the filters in front of the lens.

Some scanners do the same sort of thing, in a dark room you can see each R, G, and B pass.
 
dourbalistar said:
The reds surprised me on this one. Some color correction to remove the magenta cast, but that's it.

Nikon FM2n, AI Nikkor 50mm f/1.8S, Ultrafine Xtreme 400, developed in LegacyPro L110 at 1:31 for 5.5 minutes.* Three individual black and white frames shot through Tiffen #25 Red, #58 Green, and #47 Blue filters, respectively, then combined using GIMP to create a trichrome color image.
Click to expand...


Superb, @dourbalistar. Those reds are incredible.

I've seen similar before (somewhere:confused:), from the same process. I still can't understand why this process produces reds which are SO much more appealing than the results from simply turning up the saturation in PS. There's seems to be a kind of 'density' (can't think of a better way to put it) of colour, rather than just saturation.

Very interesting stuff - I'd like to see some more, if/when you do any!
 
How wonderful! I've been missing colour of late, but have no desire to develop it at home, so this has a lot of appeal!

Thank you so much Dourbalister!
 
Red poppies and roses are always difficult to photograph; luckily they are not impossible but I've always wondered why.


Regards, David
 
Tim Gray said:
Very cool! I never got around to trying this outside for real.

I briefly played around with this once about 10 years ago. Some with Tri-X and a few with TMZ. Cool thing about it is if each of the three exposures are properly exposed, images will come out with the proper balance for different color temperatures (like tungsten). I combined mine in Photoshop after scanning.

https://www.flickr.com/photos/tgray1/albums/72157613514418888
Click to expand...

Thanks, Tim! Looks like I'm using the same exact Tiffen filters as you did. Using Photoshop to combine the images is probably a lot easier, but I don't have Photoshop and GIMP is free. It is a bit, well, gimpy, but it works. :)

Bart Bart said:
Very Nice, reverse dye transfer ;-p

Back in the mid-90s the first Leaf digital camera was a Hasselblad with a monochrome sensor and a RGB "color wheel" that spun the filters in front of the lens.

Some scanners do the same sort of thing, in a dark room you can see each R, G, and B pass.
Click to expand...

Thanks, Bart Bart. This is a bit less technical than Technicolor, that seemed like a hugely complex process.

tbhv55 said:
Superb, @dourbalistar. Those reds are incredible.

I've seen similar before (somewhere:confused:), from the same process. I still can't understand why this process produces reds which are SO much more appealing than the results from simply turning up the saturation in PS. There's seems to be a kind of 'density' (can't think of a better way to put it) of colour, rather than just saturation.

Very interesting stuff - I'd like to see some more, if/when you do any!
Click to expand...

Thank you, tbhv55! My guess is the effect of the red filter. In the B&W image taken with the red filter, reds render as white tones, so that might increase its "density" in the final color image. Or something like that, I have no idea. :eek: In any case, I'm enjoying the process a lot, so I'll definitely share more results.

CharlesDAMorgan said:
How wonderful! I've been missing colour of late, but have no desire to develop it at home, so this has a lot of appeal!

Thank you so much Dourbalister!
Click to expand...

Glad you enjoy the images, Charles. It's a relatively cheap experiment if you're already doing your own B&W development. Would love to see your results if you do end up trying it!
 
You must log in or register to reply here.
Back
Top Bottom