I started with this image from the Rijksmuseum website, which provides high-resolution images free to use and modify for any purpose, in their Rijksstudio.

In iColorama, I cropped and processed for smoothness using Effect/Denoise and for tone in Adjust/Tonelab and Levels.

I used Form/Warp to get a different shape for the face of the geisha, which to me seems more open.

In Adjust/Exposure, I moved the brightness slider all the way to the left to create a white canvas, and saved. Then in Effect/Blend, I brought in the warped image, and I painted a brush mask to get rid of the man. I used a large hard square basic brush to paint the mask.

I removed the yellow color case in Tone.

In Effect/Blend, I blended the image with itself in Normal mode at 100% opacity, resizing the top layer and using a brush mask to reveal part of the lower layer. When blending like this it is helpful to reduce opacity while you resize and position the top layer, then bring back 100% opacity to paint the mask.

In Effect/Blend, I blended the image with an earlier version.

I again blended the image with an earlier version, this time flipping the top image on its x-axis, and using a brush mask.

I did some additional blending of the image with itself and used an inverted brush mask to clean up some details. Then I applied Style/Flow with an inverted brush mask to smooth some jagged edges particularly where some of the blend edges came together.

I made several different versions with slightly different colors, created using Tone. Then in Effect/Blend, I blended two of those versions together in Normal mode, and used the gray slider, which produced the color splashes in the areas between and below the faces.

At Ann Lamb's suggestion, I removed some details from the top of the image. To do this, in Effect/Blend I blended the image with itself, slightly offset, and used an inverted brush mask in to paint those details away. This took several blend steps. Then to smooth out those areas, I used Effect/Blur and an inverted brush mask to apply a bit of blur just to those areas.

Using Texture/Vintage, I applied several different vintage textures to the different areas of the image, using a brush mask each time to apply to just the desired area. The result is that each area looks different, and each has multiple textures applied at low opacity.

Now I blended this image with itself at medium opacity, using a brush mask to mask out some areas that would have looked too confusing.

I applied Adjust/Levels for increased contrast and Effect/Raise for definition, for the final result.

I went crazy and made another version.