Human Vision & Our Perception of Visual Art, 2

Impressionist painting techniques – Carry over to photography?

The previous post introduced a vision phenomena called equiluminance and discussed its effect on human vision –

Specifically, that our determination of where something is located is based entirely on the object’s lightness values (i.e., depends 100% on B&W data and 0% on color)
Thus, if the object in question’s luminance is the same as its surroundings (no contrast), our “Where System” may be “confused” and objects may appear to move or shimmer

This phenomena was illustrated with the example of this Monet painting where the luminance (lower image) of the sun is virtually identical to that of its background –

Before going further, note that not everyone’s vision is affected the same way – nor is any single individual’s vision affected the same way 100% of the time. If you don’t see any shimmer|movement in Monet’s painting you’re not alone – nor do I. Maybe we need to see the original painting.
In the previous post, I speculated that the technique leading to the above phenomena could be reproduced easily in photos by the following steps in Photoshop –

  1. Start with a color image
  2. Convert the image to B&W in a separate layer and modify the B&W image’s luminance to create areas of equiluminance in appropriate areas of the image
  3. Change the blending mode of the B&W image created in step #2 to Luminosity
  4. This will result in an image that –
    1. Takes its color (hue & saturation) from the original image
    2. Takes its luminance (lightness) from this new B&W layer

This, in theory, replicates the equiluminance color technique used by Monet in the above painting (and others like this next one) –

The next several screen shots illustrate my proposed technique to create an “impressionist painting film” in Photoshop.
Step 1 – open original color in PS (elements)

Step 2 – Convert color to B&W (this is Silver Efex Pro 2’s neutral B&W conversion)

Step 3 – Create an area of equiluminance around the sun; done using SEP2’s Selective Adjustments

Step 4 – save the new equiluminant image as a new layer

Step 5 – change the blending mode for the new layer from Normal to Luminosity

Step 6 – The new resulting image picks up color (hue & saturation) from the original color image and lightness values from the luminosity layer. Since the luminosity layer has new lightness values only in the vicinity of the sun where we made selective adjustments, colors change only in this same changed area.

And here are some example results. The bottom row is the result of Luminosity blending with the luminance layer from SEP 2 immediately above it. The first result (left) is identical to our original since its B&W layer is the default luminance associated with the original (recall how Luminosity blending works – hue & saturation are taken from the lower layer and luminance is taken from the top layer; since neither has changed in the left most image, the result is identical to the original. The center and right luminance layers are two attempts at creating an area of equiluminance around the sun.
The results are definitely not “Monet-ish” and a bit disappointing (but not sure what I was expecting). Click to enlarge.

Trying the same approach on a different image gave the same disappointing results. I tried to “equiluminate” the berries and water lily pads. Original on left & “Monet” on right.

I’ll continue my experiments now that I have the procedure down pat. If nothing else I’m gaining a better appreciation for the HSL color model (there’s life after RGB ;-)). Even more importantly to me, I see all sorts of potential in Photoshop’s Luminosity blending mode. Let me illustrate the latter with a few examples.
First, just a fun version of the above image made by creating a “luminance layer” in Silver Efex Pro 2, as illustrated above, using one of SEP 2’s Film Noir presets and then blending it with the color original using the Luminosity blend mode – click to enlarge.

And a final set of Luminosity blending examples. The left image in each set is the same – it’s the original color and its associated luminance image. The right image in each set shows the change in the original color version due to changes in luminance values. Note how the blended result, in general, has increased contrast and details. If this is something that you’re often looking for in your images – look no further, as this technique shows you the way. In the first set, note how the mountains “pop” from the clouds, 3-D! You need to click on the following sets for a better appreciation of the before|after changes.

This next one uses the above right for a starting point and greatly reduced the contrast which brings us toward equiluminance (which started all of this to begin with). In theory this should make the clouds more “interesting” since your “where system” has more difficulty nailing down their location.

I’m learning – even for an old dog – but it’s not exactly what I was looking|hoping for when I started this human vision & perception experiment. 😉

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