This week’s challenge is a technical one, namely to simulate a B&W Pseudo- Solarization (also known as Sabattier Effect) by means of a considerable change of the gradation curve.

Now, some or many of you might not know what Solarisation and Pseudo-Solarisation are, what the difference is and why the challenge is to simulate and not to make a Pseudo-Solarisation.

The answer is quite simple, both Solarisation and Pseudo-Solarisation are photochemical effects, so these do not occur in digital photography but only in (what is falsely called) analog photography.

Here are links to Wikipedia articles describing these effects in detail:
https://en.wikipedia.org/wiki/Solarization_(photography)
https://en.wikipedia.org/wiki/Sabattier_effect


These two images are examples of a Pseudo-Solarisation (left) and of a (digitally) simulated one (right) and the result of your photo should have a similar look.

The left photo is a real Pseudo-Solarisation (original photo taken on B&W film and then processed in the darkroom to create the Pseudo- Solarisation (Sabatier) effect. The right one is a digital photo post-processed in GIMP to simulate a Pseudo-solarisation.

The choice of object is completely up to you, it can be a building, a flower, a vehicle or whatever but note you have to consider that the effect is quite drastic, so not every photo is suitable to be converted to a Pseudo-Solarisation and the aim is not only to get the effect but also to have a good looking image as result.

The best images for the effect are high contrast B&W photos (or B&W conversions) with simple outlines and preferably a lot of details having clearly delineated transitions from bright to dark.
Try different photos, not every photo is suitable for this effect, the goal should be an image in which the subject is presented mainly by white lines and a minimum of white areas.

How to create the effect in digital photography:

Start with a B&W photo [2] or convert a color photo to B&W [1] and open it in a program (Photoshop, GIMP, Lightroom etc.) which allows processing of color / gradation curves. If you don’t have such a program it can even be done in the free and easy to use app Snapseed which is available for iOs, Android and also for PC.

Open the curve dialog in which you see a straight line from the left lower to the upper right corner.
Note for Lightroom users: select Point curve (and not the Parabolic curve option)
Grab the center of the curve (red dot in [2]) and move it up vertically to the top, the curve will look like in [3] and the darker grey tones will get much brighter, the medium and brighter grey tones will become white. Grab the upper right corner (yellow dot) in [3] and drag it completely down. Your curve will now look like in [4].
Next step: move the lower left point (green dot) in [4] horizontally towards but not completely to the middle and then the lower right point (yellow dot in [5]) to the left. You will notice then the bright parts of the image getting darker, the more you drag the curve to the middle, the darker the former bright areas get [6] and [7].
If the left and right corner are too close together the image gets almost completely black and details get lost as demonstrated in [8], so you might need to move one or both of the points outwards again. It depends on the contrast and details of the original image how far from the center the left and right lower points (green and yellow dots) need to be to get the best result.

Note: if the left lower point (green dot) is moved too far to the middle, the image will look like the left picture below, if the right lower point (yellow dot) is moved too far to the middle it will look like the right one (which is just the negative image of the left one. In case both touch in the middle the image will turn either completely black or completely white (depending on the exact position of the topmost point of the curve:

Conversion of the same original photo to a Pseudo-solarisaton in Lightroom and Photoshop shows nearly idendical curves and result:

The next picture shows the same exercise repeated in Snapseed on a mobile phone. Open your image in Snapseed, select tools and in tool select curves and try to follow the procedure as described above. Controlling the curves on the small touchscreen with fingers is however not so easy, but you should be able to achieve similar curves to get end a similar result:

To recap this week’s challenge:

• Convert a photo to a simulated Pseudo-solarisation by means of changing the color / gradation curve.
• The choice of subject is up to you.
• Post your photo during the week of Sunday, Feb. 21 to Saturday, Feb. 27, 2021
• Please remember to comment on at least FIVE photo submissions this week by answering the question “why?” in your comments. In other words, “why do I like (or not like) this photo?” or “why did this photo catch my eye?” Thank you!

The friendly community guidelines are pretty simple:

• Take a new photo for the current weekly theme, not something from your back catalog or someone else’s image.
• Post your photo each week to our active communities on Facebook or Flickr (or both). Tag the photo:  #2021photochallenge #photochallenge #tempusaura
• Don’t leave home without your camera. Participating in the 2021 Trevor Carpenter Photo Challenge is fun and easy.