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Black and white photo that looks like colored photo illusion

Posted: 16 Aug 2019, 15:43
by tim
A friend shared this with me on facebook since he thought I'd be interested in this kind of stuff (Which I am).
https://petapixel.com/2019/07/31/this-b ... jXiT3IyZfc

Re: Black and white photo that looks like colored photo illusion

Posted: 16 Aug 2019, 18:14
by Wallace
We have amazing brains. :trampoline:

Re: Black and white photo that looks like colored photo illusion

Posted: 16 Aug 2019, 22:33
by Krikor
Interesting how our eyes can see what doesn't exist when the brain tries to standardize the information it receives.
I wanted to play a little with this information.

Re: Black and white photo that looks like colored photo illusion

Posted: 17 Aug 2019, 07:28
by neurolurker
Krikor, if you don't mind my asking, how were you able to apply the color grid over a desaturated image? I tried following Øyvind Kolås notes about entering text in Filters: Generic: GEGL Graph ... id=foo saturation scale=0.0 over aux=[ ref=foo saturation scale=2.5 opacity aux=[ color value="rgb(0.35,0.35,0.35)" newsprint period=23 pattern=cross color-model=white-on-black angle=45 ] crop aux=[ ref=foo ] ] ... but there seems to be no result after a variety of alternative layer attempts. And in Windows 10 GIMP 10.2.12 the GEGL Graph plugin itself seems to be inactive in some way, even though it is present in GIMP. I would be grateful for any guidance on what procedure sequence worked for you.

Re: Black and white photo that looks like colored photo illusion

Posted: 17 Aug 2019, 12:58
by tim
neurolurker wrote:
17 Aug 2019, 07:28
Krikor, if you don't mind my asking, how were you able to apply the color grid over a desaturated image? I tried following Øyvind Kolås notes about entering text in Filters: Generic: GEGL Graph ... id=foo saturation scale=0.0 over aux=[ ref=foo saturation scale=2.5 opacity aux=[ color value="rgb(0.35,0.35,0.35)" newsprint period=23 pattern=cross color-model=white-on-black angle=45 ] crop aux=[ ref=foo ] ] ... but there seems to be no result after a variety of alternative layer attempts. And in Windows 10 GIMP 10.2.12 the GEGL Graph plugin itself seems to be inactive in some way, even though it is present in GIMP. I would be grateful for any guidance on what procedure sequence worked for you.
Don't know how Krikor did it but this is how I did it.
1. Over saturate colors of an image (original layer).
2. Render a grid.
3. Rotate grid to about 45 degrees.
4. Alpha to selection grid, selection invert.
5. select original layer, desaturate.
6. Turn off visibility of grid.

Re: Black and white photo that looks like colored photo illusion

Posted: 17 Aug 2019, 19:19
by Krikor
neurolurker, basically I did as Tim described.
01.The original picture in layer 01.
02. New transparent layer over the original image
**03. Apply - Filter - Render - Pattern - Grid, on the transparent layer
04. In this layer, Alpha to Selection (Selecting the grid created)
05. Select - Invert (Ctrl + I)
*06. Select the original layer, duplicate this layer, and on the duplicate layer press delete.
07. select the original layer, duplicate it, desaturate.
08. Turn off the visibility of all layers but the desaturated one and that on step 06.

I may not have done it exactly in this sequence or this way, but it was basically the technique I used.

P.S:
* Ah, in the layer with the colored grid I suggest applying a saturation.

** ehhh, After step 03 and before step 04, I rotated the grid 30º (Rotate Toll - Shift+R )

Re: Black and white photo that looks like colored photo illusion

Posted: 17 Aug 2019, 21:48
by Pat625
Tin, that is another neat,interesting phenomenon that proves that the brain and eyes do not always interpret things the same, such as watching a car go by and the wheels look as they are spinning backwards!

Thank you for sharing with us.

Re: Black and white photo that looks like colored photo illusion

Posted: 18 Aug 2019, 01:58
by Pat625
I just had to play with this! I did make a mistake, but decided to leave it to show the difference between the outcome and the desaturated layer. When I rotated the grid, I forgot to check that the entire photo was covered. You can see this now that I have scaled the end result. Amazing! Look at the top right and bottom left for the difference.
Optical Illusion.jpg
Optical Illusion.jpg (135.09 KiB) Viewed 5453 times

Re: Black and white photo that looks like colored photo illusion

Posted: 18 Aug 2019, 02:01
by Pat625
Tin, this is posted in Anything goes, but shouldn't the procedure get posted in "Tutorials"?

Re: Black and white photo that looks like colored photo illusion

Posted: 18 Aug 2019, 03:12
by tim
It can I guess now that we have steps reproducing the effect.