How to make a nymph’s heart beat

Or more prosaically: “Tutorial: How to add (subtle) heartbeats to people in photos and pictures”. First of all I have to explain what is a “Movement and Color Changes Microscope”.
Here is the TED talk for those who want:  Michael Rubinstein – See invisible motion, hear silent sounds.

Summing up what is related with this post: they have developed a technique to amplify color changes and movements. It’s software and although it doesn’t function as a microscope, both of them allow our eyes to see something tiny. In this case it’s not the size what is tiny, it’s the object’s movement or color change.

It’s easier to understand through an example: the blood moves inside our bodies by pulses, pushed by the beatings of the heart. That makes our faces more red when blood comes in, and little less red when blood goes back to the heart. These changes are so subtle (tiny) we are not able to notice them. But if we use the “Color Changes Microscope” (taken from previous video):

With this video you can do inverse engineering and get the same effect from an static photo o picture. The last option also allows you to justify a title as naïf as the title of this post. The nymph in question comes from a detail from the picture Nymphs and satyr of William-Adolphe Bouguereau. This is the original static picture:


First of all we are going to make the effect just like the previous example, with huge color changes. On the left it has the effect with maximum opacity and on the left with less opacity:


Now you only have to do the opposite of what the “Microscope” does, you have to continue to make the effect more subtle until it’s almost unnoticeable but you still can perceive it subliminally. This is the final version, very subtle. Indeed it is the same picture than the first one. Did you notice that it is animated? It will depend on the screen and your visual acuity (I’m squinting a little bit right now because so many GIFs). Anyway, the color still changes with every heartbeat:

Next, I want to try to do in a picture with two or more people. And one of them very nervous, o scared, and the other more relaxed. Playing with the animation timing you can set different hear rate for each one. If this effect does really something, it should amplify the contrast of the moods.


Anyone who uses image edition software (GIMP or similar) has already guesses how to do it. My steps have been:

  1. Make a mask for the nymph’s skin

    Make a mask selecting only the nymph’s skin and blur it:


    We’ll apply this mask to both color layers (green and red). I have also used the brightness of the source image in the mask, blurring it too. I think this will be no noticed.


  2. Make the more red image

    Enhance the red color in the original image with a color correction layer. Applying the mask from the step 1. I changed the fusion mode to “Multiply”, I liked and there it is:


  3. Make the more green image

    Do the same with green/yellow color but without changing the fusion mode.

  4. Anmiate the heartbeting

    The timing for the animation depends on the hear rate of the character. For this example I took the same hear rate I have measured in the Michael Rubinstein’s video. Each heartbeat takes 1.17 seconds which corresponds to 51 beats per minute. The animation has 9 frames with this timing and opacity:

       frame timing (length in sec) 0.25 0.16 0.16 0.1 0.1 0.1 0.1 0.1 0.1
       red layer opacity 100 90 75 55 25 0 25 50 75
       green layer opacity 0 20 40 60 80 100 75 50 25

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