In color? No. In monochrome? Mayyybe... According to Wikipedia, the wet-collodion process was sensitive only to blue and ultraviolet light. The tattoos reflect

In color? No. In monochrome? Mayyybe... According to Wikipedia, the wet-collodion process was sensitive only to blue and ultraviolet light. The tattoos reflect mainly blue, whereas skin tone has very little blue; this has the effect of lightening the tattoo and darkening the skin, so it's hard to distinguish them in monochrome. But there's likely no wavelength of "red" you can select where the skin reflects the same amount as the blue tattoo - the tattoo will always look darker. Or to put it another way - there's no stage lighting you could come up with that will make blue tattoos look skin colored, let alone while also making skin look skin colored. The best you could do is to use the blue channel only, or even light the scene only with the deepest blue light the camera can pick up (and convert the photo to monochrome). Generally speaking you can't make things look very different to cameras than the human eye, as they have similar frequency response. Moreover, you can't distort the appearance of objects very much by picking specific narrow frequencies to light them with, or objects would look incredibly strange under narrowband LED lighting (they don't look perfect, but it's not a heavy distortion). Spectral response of objects isn't totally flat, but it's usually not very "spiky" either, so RGB captures a pretty good approximation of the spectral response in most situations. Interestingly, this question has direct application in the field of holography, where the scene must be lit by RGB laser. You only get 3 wavelengths to work with (and you don't have a huge amount of latitude as to which 3) and the entire rest of the spectrum is discarded, and yet full color holograms usually look impressively accurate. [edit] I've played around in GIMP a bit, and you can indeed remove most of the tattoo simply by taking the blue channel. You can further reduce it by shifting the response even more towards blue by subtracting the red and green, albeit with increasing amounts of color banding and other aliasing. I'm pretty sure you could decently approximate this effect entirely in software, with the correct coefficients.