How inkjet printer uses subtractive color mixing method by CYM color at molecular level?

The subtractive method in CMY color

As seen in an Inkjet printer video, We had understood how the subtractive method works by examining the RGB ink at a molecular level. Physics becomes more interesting and complex when we go for an analysis of CMY ink at a molecular level. In this article, we will understand how orange color is produced using yellow and magenta ink and study it at the molecular level.

So how do we produce orange color? Just mix 2 droplets of yellow ink and 1 droplet of magenta ink. Let’s go to the molecular level, Since one layer of molecules cannot completely fill a surface, we should consider at least two layers for this study. Here, we are assuming that the yellow and magenta color molecules are arranged as shown in the image for understanding.

Fig: Molecular arrangement of yellow and magenta molecules
Fig: Molecular arrangement of yellow and magenta molecules

First, we will clarify the basics, The yellow molecule will reflect red and green color and absorbs blue color, similarly, the magenta molecule will reflect red and blue color and absorbs the green color. Let’s start with the bottom layer and do the analysis of light reflected by the molecules one by one.

Color reflection and abortion analysis

The left side bottom yellow molecule will reflect red and green color light. However, light has to pass through the upper molecular layer. You can see this top yellow molecule will allow both colors of light to pass. Let’s go to the next molecule, The magenta will reflect red and blue color light but the above yellow molecule will just allow the red color light to pass and absorb the blue color. Nevertheless, the above magenta molecule will allow both lights to pass. Again the next yellow molecule will reflect red and green color light but the above magenta molecule will only allow the red color to pass and absorbs the green light. Similarly, the above yellow molecule will allow both color lights to pass from a bottom yellow molecule.

Fig: 2 - Light reflected by top layer
Fig: 2 - Light reflected by top layer

The above patterns repeat as we go further right side and also a downside. Let’s analyze the final output of all the lights which reflects from the top layer as follows.

1.Red + Green

2.Red

3.Red + Blue

4.Red

5.Red + Green

So the final output contains 5 Red+2 Green+1 Blue light rays, Let’s see the output with the color mixer website. First, we have to convert this color mixing proportion into an 8-bit color depth for analyis. The mixing proportion is in integer form so it is quite easy to calculate. The maximum value of 8-bit color depth is 255 so let’s divide it into 5 equal parts. 255/5=51.

So the value we have to put into a website will become:-

1.Red = 255

Green = 102

Blue= 51

Fig:3 - Output from the color mixer website
Fig:3 - Output from the color mixer website

Verifying output from websites:- 

After adding the values to the website, we end up with this color, which looks very similar to the actual orange color. The above patterns repeat as we go further to the right and down.

Now, let’s visit another website( trycolor.com) to compare our output with the precise color which we will be getting by mixing yellow and magenta colors. You will notice, that the dissimilarity between those two colors, it’s minor. But why do we get it? The exact reason for the difference is quite obvious, we have taken the simplest molecular arrangement feasible for illustration purposes. Also, the molecular structure of ink molecules is quite complicated according to dye chemistry, and it’s quite challenging to find the exact resultant color outcome of each molecular interaction.

Fig:4a- The final output
Fig:4a- The final output

You can try yourself various color combination on following website :- check here  and one more

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