RGB Inkjet Print , possible ?

Is it possible to inkjet print with RGB inks ? I posted a Autochrome thread about dye potato starch at APUG . I am asking to ink jet print with these dyes ?

Best regards ,

Mustafa Umut Sarac

Istanbul

Yeah, why not?

Mustafa Umut Sarac said:

Is it possible to inkjet print with RGB inks ? I posted a Autochrome thread about dye potato starch at APUG . I am asking to ink jet print with these dyes ?

Best regards ,

Mustafa Umut Sarac

Istanbul

Click to expand...

Yes and no. I am now assuming you really mean inks coloured red, green and blue.

Yes, of course, if you have a continuous ink system with refillable cartridges, you could simply throw in something else than CMYK ink.

The "No" is, that you will not be able to achieve any realistic colours, because CMYK and RGB are two different colour systems (additive and subtractive). A good explanation of the difference can be found here:

http://www.cambridgeincolour.com/tutorials/color-perception.htm

Where "mixing" maximum 255,255,255 RGB values on a computer screen results in white light, mixing RGB coloured inks on paper would probably result in some very dark muddy brown...

That's the clash between a subtractive (CMYK) and additive (RGB) colour system.

Marco

Marco B said:

http://www.cambridgeincolour.com/tutorials/color-perception.htm

Where "mixing" maximum 255,255,255 RGB values on a computer screen results in white light, mixing RGB coloured inks on paper would probably result in some very dark muddy brown...

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Apples to apples.......


By your cited reference, you would get brown because RGB should be printed on BLACK paper to be additive.

An interesting thought though...

mrred said:

Apples to apples.......


By your cited reference, you would get brown because RGB should be printed on BLACK paper to be additive.

An interesting thought though...

Click to expand...

Hehehe

Next time I start oil painting again, I will try to mix white paint from red, green and blue paints

Of course, as far as the printing paper and inks is concerned, there only exists a subtractive colour system, where the colours red, green and blue are just part of the entire spectrum of potential colours you could buy and mix as paints on paper or canvas. In fact, Pantone developed the Hexachrome offset printing system also using an additional Orange and Green inks next to CMYK, see my lingering thread here:

http://www.hybridphoto.com/forums/showthread.php?t=1745

The clash is only virtual, with the printer driver expecting an RGB image that needs to be converted to CMYK for printing.

Mustafa Umut Sarac said:

Is it possible to inkjet print with RGB inks? I posted a Autochrome thread about dye potato starch at APUG. I am asking to ink jet print with these dyes?

Click to expand...

You can surely print inkjets using RGB inks. No one does this at this time however, because the roots of fine art inkjet printers were in CMYK proofers for magazines and newspapers. And once this was done, suddenly we had "we've always done it this way" syndrome set in. IOW, it was easier to use the same ink technology on new printers, as opposed to developing an entirely new ink technology.

Now there will be some who will bring up the additive/subtractive paint vs. light argument. I don't think this applies. Inkjet printers aren't mixing paint. Indeed, most dots laid down with an inkjet printer are isolated -- surrounded by paper white. The same human visual mechanisms that allow tiny isolated dots of CMY inks to make a "visual" gray will also work to allow tiny isolated dots of RGB inks to make that same visual gray color. Nothing about the ink colors themselves changes the laws of physics.

OTOH, I doubt you'll ever get dyes from the autochrome process to run successfully through an inkjet printer. There are too many variables in the interaction between the inks, print heads (and ink feeds), and papers. You'll have to use an ink designed for the printer/substrate you want to print with.

Then you'll have the problems of how to control the printer. It's internals will undoubtedly expect CMY inks and won't know how to make the colors you want with RGB inks. The answer to that is a RIP that does.

I don't know of any inkjet inks available as RGB sets, nor any RIPS that are designed to use RGB ink sets. They may be out there somewhere, but if they are they certainly aren't common.

So in the end, the answer to your query is probably "no".

Bruce Watson said:

Now there will be some who will bring up the additive/subtractive paint vs. light argument. I don't think this applies. Inkjet printers aren't mixing paint. Indeed, most dots laid down with an inkjet printer are isolated -- surrounded by paper white. The same human visual mechanisms that allow tiny isolated dots of CMY inks to make a "visual" gray will also work to allow tiny isolated dots of RGB inks to make that same visual gray color. Nothing about the ink colors themselves changes the laws of physics.
....
Then you'll have the problems of how to control the printer. It's internals will undoubtedly expect CMY inks and won't know how to make the colors you want with RGB inks. The answer to that is a RIP that does.

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Bruce, this is to some extent what I have been trying to say in other words, although I have a bit doubt if your remark

"The same human visual mechanisms that allow tiny isolated dots of CMY inks to make a "visual" gray will also work to allow tiny isolated dots of RGB inks to make that same visual gray color."

holds up, see my next remarks about color gamut. My reference to the additive vs. substructive is just to make people aware that the main issue is in the printer driver (which actually is a RIP, as it determines the color separation).

My reference to Pantones CMYKOG with additional Orange and Green colors, and the accompanying implementations in offset printers software to support the six color color separation, already shows that there are other possibilities than CMYK for printing if a RIP supports it.

However, one important question remains, even if we do assume an RGB RIP existed:

Can RGB colors replicate or simulate the full spectrum of human visible colors to the extent the CMYK colors can when mixed on paper. :confused:

I doubt it. There are physical limitations here that may severely limit the resulting printing gamut. You can't just say: oh, let's pix three colors, write RIP software, and we will be able to print an acceptably big color gamut as to be useful in the printing of photographic color images.

Just like how you can't just pick any three colors of oil paint, and expect to be able to mix any other possible color the human eye can see.

The problems with the colors used in printing and the gamut they can reproduce, is also nicely illustrated in these articles:

http://en.wikipedia.org/wiki/Subtractive_color
http://en.wikipedia.org/wiki/RYB_color_model

As this last referenced article shows, maybe a more viable option would be the combination of Red, Yellow and Blue, as in the RYB color model shown there, as this can replicate quite a set of colors when mixed.

Some colors may therefore prove impossible to reproduce with an RGB color set. I think this is also nicely described in this paragraph of the link below:

"Many historical “color theorists” have assumed that three “pure” primary colors can mix all possible colors, and that any failure of specific paints or inks to match this ideal performance is due to the impurity or imperfection of the colorants. In reality, only imaginary “primary colors” used in colorimetry can "mix" or quantify all visible (perceptually possible) colors; but to do this the colors are defined as lying outside the range of visible colors: they cannot be seen. Any three real “primary” colors of light, paint or ink can mix only a limited range of colors, called a gamut, which is always smaller (contains fewer colors) than the full range of colors humans can perceive."

http://en.wikipedia.org/wiki/Color_theory

Also interesting in that same article, explaining partly why we use CMYK instead of RYB:

"Across the same period, industrial chemistry radically expanded the color range of lightfast synthetic pigments, allowing for substantially improved saturation in color mixtures of dyes, paints and inks. It also created the dyes and chemical processes necessary for color photography. As a result three-color printing became aesthetically and economically feasible in mass printed media, and the artists' color theory was adapted to primary colors most effective in inks or photographic dyes: cyan, magenta, and yellow (CMY). (In printing, dark colors are supplemented by a black ink, known as the CMYK system; in both printing and photography, white is provided by the color of the paper.)"

Marco

Marco B said:

Bruce, this is to some extent what I have been trying to say in other words, although I have a bit doubt if your remark

"The same human visual mechanisms that allow tiny isolated dots of CMY inks to make a "visual" gray will also work to allow tiny isolated dots of RGB inks to make that same visual gray color."

holds up...

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You can doubt it if you want. But I've seen it done in a lab. I have no doubt that it works.

Will it produce the same gamut as CMY? No, it's a different gamut, obviously. Does it have problems with yellow? Of course. CMY has it's own weaknesses, notably greens and oranges, hence the hexachromes.

But nobody said you had to limit a base inkset to three or four colors. If I were going to build a better inkset to replace CMYK for fine art, it would be at least RGBYK.

Interestingly enough, one of the TV makers (Sharp) released a new TV at the last CES that uses RGBY instead of RGB.

But all of this is seriously far afield. The OP wanted to know if he could use autochrome dyes in an inkjet printer to make inkjet prints. The answer is that it's possible, but highly unlikely to be successful without bringing lots of resources to bear on the problem, which no one is likely to do. Because when you get down to it, CMYK is good enough. Besides, "we've always done it that way." :rolleyes:

Bruce, I think we basically fully agree on all points, we just put it in slightly different words.

And your remark about visual grey with RGB is OK, according to the theories in the articles I myself referenced and have now fully read myself, so forget that part in the last posts I made.

Bruce Watson said:

Because when you get down to it, CMYK is good enough. Besides, "we've always done it that way." :rolleyes:

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Actually, as shown in the articles, CMYK is exactly that, simply offering one of the most suitable gamuts based on a limited set of colors (good for printing economy!) and probably better than most other possible color combination options (except for the ones adding additional colors into the color system as we both suggested), and they probably simply recognized this notion when "full" :rolleyes: color printing really took off (a century ago maybe?)

In this respect, the 1877 color photo by Louis Ducos referenced in the link here utilizing Yellow, Cyan and Red is also a very nice historical example of the limitations or possibilities of some of the other possible color systems and separations.

Marco

I have now been reading up a bit on Autochromes, which I should have done before... Interestingly, it seems the original autochromes didn't use RGB, see the quote below:

"The 1906 U.S. patent describes the process more generally: the grains can be orange, violet, and green, or red, yellow, and blue (or "any number of colors"), optionally with black powder filling the gaps."

Bruce Watson said:

Then you'll have the problems of how to control the printer. It's internals will undoubtedly expect CMY inks and won't know how to make the colors you want with RGB inks. The answer to that is a RIP that does.

I don't know of any inkjet inks available as RGB sets, nor any RIPS that are designed to use RGB ink sets. They may be out there somewhere, but if they are they certainly aren't common.

Click to expand...

I have now been thinking about this, but besides the (possible) difficulties of a true autochrome dye being passed through an inkjet printers nozzle, do you really need an RGB based RIP? :confused:

With QuadTone RIP, (which I admittedly only had a brief look at, and have never used in practice besides a two prints on default settings), I have understood you have full control over all colors that your printer can lay down.

What about this strategy:

- Replace the CMY inks with RYB in the printer.
- In Photoshop, create 3 separate greyscale images for the RYB (or OVG - Orange, Violet, Green) color separation. So each greyscale image represents what needs to be printed in Red, Yellow or Blue.
- Open one of the images in QtR, e.g. the one representing Red.
- Set Quadtone RIP to supress completely the usage of the light cyan, light magenta, llk, lk and k ink (assuming an EPSON R24000/R2880 here). In addition, set it to supress the non-used RYB colors (Y and B) , so the printer is essentially turned into a single monochrome color printer (Red).
- Print the image, you now have a monochrome Red image using just the Red autochrome ink
- Reinsert the paper (or whatever you are printing onto...), now go through the same process for the second color (Y), suppressing the usage of all others using QtR.

Wouldn't such a scenario be feasible? :confused:

Exact alignment might be another possible issue here... but theoretically?

Marco

Hi,

Most all talk above color, do you know the latest innovation are capable to press in digital print and offset. All these just the software preparation need. I think spot color combination on the images printing should be more up to date in this century. see in Graphic Republik - Innovative solutions for Packaging Professionals

Leon

As someone else has pointed out the only reason colours additional to CMY are used is to address shortcomings in reproducing those colours from CMY. This applies equally to commercial printing as it does to inkjet. It is illuminating to look at the colour swatches that can often be found printed on the flaps of many packing cartons for products like beer, biscuits, breakfast cereals etc where one can see the custom inks that are used to accurately reproduce things like corporate livery.

I'm pretty sure that CMY will not be superceded any time soon simply because it works. A few years ago Canon did produce a printer that used RGB dyes in addition to CMYK but I don't think it survived very long. The measure of how good any three colour process is the ability to produce black and it is a tribute to the technology behind traditional photography that chemically processed colour paper like Kodak's Endura or Fuji's CA (and the now discontinued Ilfochrome) is about the only process that comes remotely close to producing a true dead black from the three subtractive colours. Some dye sub materials can get close but no inkjet or printing press can. OzJohn

RGB possible still not an ending yet at this moment, maybe or because in the market the software/hardware development with their know how still a limited to find a better solution. I should said the hardware technology is updated, just the device to drive out brightness future....earlier or soon issue. I still believe software with well separation in front end preparation, will taking important part combination to drive this out no matter CMYKRGB or CMYKOG with today hardware technologies.

Leon