add image processing notes

Image.md

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+# Input Processing
+
+`Human` includes optional input pre-processing via `config.filter` configuration:
+- using `Canvas` features
+- using `WebGL` accelerated filters
+- using `TFJS` accelerated enhancements
+
+## Basic
+
+If both width and height are set to 0, there is no resizing  
+If just one is set, second one is scaled automatically  
+If both are set, values are used as-is  
+
+- `width`: resize input height
+- `height`: resize input width  
+
+Flip input as mirror image
+  
+- `flip`: boolean
+
+## Filters
+
+Global filters enabled/disabled is controlled via `config.filter.enabled`  
+Individual filters that can be set are:
+
+- `brightness`: -1 (darken) to 1 (lighten)
+- `contrast`: -1 (reduce contrast) to 1 (increase contrast)
+- `sharpness`: 0 (no sharpening) to 1 (maximum sharpening)
+- `blur`: 0 (no blur) to N (blur radius in pixels)
+- `saturation`: 1 (reduce saturation) to 1 (increase saturation)
+- `hue`: 0 (no change) to 360 (hue rotation in degrees)
+- `negative`: boolean
+- `sepia`: boolean
+- `vintage`: boolean
+- `kodachrome`: boolean
+- `technicolor`: boolean
+- `polaroid`: boolean
+- `pixelate`: 0 (no pixelate) to N (number of pixels to pixelate)
+
+## Enhancements
+
+If set, any input will be processed via histogram equalization to maximize color dynamic range to full spectrum
+
+- `equalization`: boolean