Viz: client-side JS for colormapping

[JohnTigue]

A Jupyter widget which reads grayscale intensity image data and performs colormapping client-side (maybe as webgl shaders). This is also a way to get a similar effect as described in #59. Pro: more user control of dynamic color mapping, con does not generate a static file (PNG, or animated GIF).

[JohnTigue]

How about a mouse/trackpad interface of up-down for z-indexing, and left-right for various smoothly transitioning colormaps. Basically play with that little viewer that jus does up-down for EM data.

Meh. More valuable is probably just having a slider alongside neuroglancer that does "left-right for various smoothly transitioning colormaps." Leave this out of the UI for 3D navigation.

[JohnTigue]

MDN: Pixel manipulation with canvas

https://discourse.processing.org/t/color-map-from-grayscale/10656

[JohnTigue]

Transmitting grayscale images is more efficient (single channel vs triple channel is 1:3) In this way clientside colormapping is a form of data compression. It also makes for a more dynamic UX. Of course is requires client-side javascript.

Or maybe CSS/SVG can do it:
https://stackoverflow.com/a/38625471

 <filter id="redselect" color-interpolation-filters="linearRGB">
    <feColorMatrix in="SourceGraphic" result="BigRed"type="matrix" values="0 0 0 0 0
                        0 0 0 0 0
                        0 0 0 0 0
                        3.8 -4 -4 0 -0.5" >
    </feColorMatrix>

    <feColorMatrix type="saturate" values="0" in="SourceGraphic" result="GreySource"/>
    <feComposite operator="in" in="SourceGraphic" in2="BigRed" result="RedOriginal"/>
    <feComposite operator="atop" in="RedOriginal" in2="GreySource" result="final"/>
</filter>

[JohnTigue]

https://github.com/timothygebhard/js-colormaps

[JohnTigue]

The switching should be like a header image carousel. A horizontal row of dot/circles that has current image corresponding dot/circle highlighted. Happens on a timer. Transition: some sequential colormap interpolation.

[JohnTigue]

http://camanjs.com/examples/