Eduardo,
Yes, here is one example which I found on YouTube:
https://www.youtube.com/watch?v=bWN-iR83Jj8"Simulated Process" is kind of a misnomer. Four-color (CMYK) "Process" uses four subtractive (transparent) inks to create the illusion of more colors. Spot colors (regular plastisol inks) are generally opaque, but not completely as some formulations and colors use varying quantities of other pigments such as transparent glass particles, titanium oxide, carbon and etc. With spot colors, the additional simulated colors are more a result of mixing as each ink as the squeegee applies them to the garment substrate on the pallet and is added rather than a subtraction of light spectrum.
Therefore, images with numerous integral color quantities can be simulated using very few colors.
You can experiment with this process yourself by taking a full-color image in Photoshop and converting the image mode to 'Indexed' color, except use a 'custom' palette of just a few colors which should be chosen as being the most prominant and useful within the image.
Sorry for the confusion, if any, as this can get a bit technical.