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#ImageJJS

Dr. Juande Santander-Velajuandesant@astrodon.social
2023-12-18

TIL about ImageJ.JS [1], a JS transcompiled version of ImageJ.

[1]: ij.imjoy.io

I did it because I was looking for a way to illustrate today’s APOD [2] image, and I thought that a profile would illustrate it very clearly.

[2]: apod.nasa.gov/apod/ap231218.ht

Below you can find some screenshots of ImageJ.JS in action running on iPadOS 17. The Alt-text includes proper descriptions and captions for them.

#ImageJ #ImageJJS #OpticalIllusions #ImageProfile

Astronomy Picture of the Day for December 18th, 2023. It shows a 3D checkerboard with dark and clear patches on a completely white background, and a green cylinder on the top right corner casting a shadow. The brain interprets the patternnas the square marked as A as being much darker than the one marked B, but they have the same brightness.Screenshot of ImageJ.JS running on an iPad. Inside the white canvas there is an ImageJ.JS logo (with the classic microscope brand of ImageJ to the left of the logo), and the text “Powered by ImJoy”. On the top of the canvas there is a toolbar with several menu options (File, Edit, Image, Process, Analyze, Plugins, Window, Help), and several buttons.Snapshot of ImageJ.JS with the optic illusion image open, and the Analyze menú open. There are several options… Measure Analyze Particles... Summarize Distribution... Label Clear Results Set Measurements... Set Scale... Calibrate... Histogram Plot Profile Surface Plot... Gels > (submenu available) Tools > (submenu available)Snapshot of ImageJ.JS with the illusion image open, a line selection across the A and B marked squares, and a window with the intensity profile at the bottom. The line starts in the white part, and the profile starts at 255. It then lowers towards a value of 128 for the background of the A square, and even lower when the line crosses the leg of the A. It then goes up to around 205, with a taper down to 150, and then sharply to a darker colour in the shadows, before recovering in square B to the same 128 level, with several dips caused by crossing different parts of the letter B. It comes back down to around 16 to the parts of a dark square in the shadow with a bit of taper up to ~32, then sharply up to ~150 again, and finally with a taper back to the same level of around 205… to drop sharply to 128, and then darker for the part of the image that is in the 3D border. It finally returns to 255 when it reaches the white again.

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