Idea: CCD colour conversion to tube B&W cameras

[Aussie Bloke]

G'day all.

A little while ago I posted an experiment of mine which was to take two video stills of a subject using a vidicon B&W camera and CCD colour camera and superimpose them over each other to create a colour image with vidicon luminance and CCD chroma which can be viewed here http://videokarma.org/showthread.php?t=251215 . And I briefly talked about this being fron the idea of converting a B&W tube camera to colour using this method.

I have now expanded this tube/CCD colour camera idea of mine and have made a page on my site illustrating it in greater detail http://www.troysvintagevideo.741.com/tubeccdcolour.html .

I also have been thinking it would also be good to make the converted tube camera be interswitchable between 3 modes for versatility of use which are:
1: tube on, CCD on (luminance attenuated) for tube/CCD colour
2: tube on, CCD off for original tube B&W
3: tube off, CCD on (with normal luminance) for modern CCD colour

Anyways I have followed it up the tube/CCD idea with some diagram layouts of 3 general tube type cameras, the iconoscope, the image orthicon and the vidicon. The layout consists of a B&W tube, a colour CCD, a prism beam splitter to split the light to both image pickup devices and lenses and mirrors in between. I basically took the diagram of Fernseh's colour camera design consiting of a 3" IO and a colour striped vidicon from this page http://www.fernsehmuseum.info/fese-kc-33.html and have adapted the design as a basic platform to work off for my tube/CCD camera idea. I am not sure of what optical setup would be needed for the CCD so I left the the optic layout the same as the original, same thing for the colour matrixing method even though I think the green won't be accurately derived from the YRB when Y is a tube and RB is CCD.

I admit I don't know how practical or impractical this idea is but thought I'd put it out anyhow. I hope to somehow get the knowhow to put it into practice and either build a tube/CCD camera or modify a B&W tube camera with CCD and make it work! If anyone wants to put this idea into practice they are welcome and I totally encourage it!

Anyways here attached is a few diagrams of a tube/CCD colour layout which are for iconoscope, image orthicon and vidicon, these are featured on my page.

[old_tv_nut]

I think this is basically doable. The major stumbling block seems to be the distance from the lens to the imaging devices, which I think will probably require some sort of relay optics like that used in the TK-41.

[site123a]

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[site123a]

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[Aussie Bloke]

Originally Posted by site123a

I just saw this post and I think it's a great idea, one change I would make though.

A beam splitter is not a good idea because pickup tubes typically need a lot of light, and you would lose 50% of it after the split. It would be better to send light from the lens through a color prism and split green light to the pickup tube, and red & blue to there own CCDs, however your #3 example wouldn't work under this setup.

BTW, your image combinations shown on your site was not done correctly. I re-did your images by spitting your CCD photo into component YCrCb, then replaced the Y luminance with the pickup tubes and re-combin...

Your welcome to use those photos on your site, just give credit to site123a

Thanks for sharing your knowledge and ideas, I will definitely keep them in mind when I one day put this tube/CCD idea into practice. Yep the way I did my colour combinations does not follow the given diagrams of the YRB colour combination method and I actually did mention it too, correct me if I'm wrong but I figured if I were to use the YRB method, the green would be derived from the luminance of the tube and the red/blue of the CCD and would probably be rather different and to the red and blue primaries which purely come from the CCD in which the greens may look more softer and along the lines of the tube used. So I chose to go the EMI 2001 4 tube colour camera method and basically have the 3 chroma primaries come from the CCD and have the luminance come from the tube and add the luminance on top of the chroma, this is so all three chroma channels are purely CCD and the luminance is purely tube. Anyhow looked at your YRB combinations, have to say they look very good and I don't seem to see any real smear on the greens like I thought I would, however have to see how it goes in practice.

[old_tv_nut]

I would caution against using only R and B from the CCD. The reason is that any imbalance between G (derived from the tube) and R and B (from the CCD) will result in a green or magenta cast, which is the most objectionable of color shifts. If you develop only Y from the tube, and color difference signals from the CCD RGB, then mismatches will show only as an error in color saturation - much more tolerable.

[site123a]

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