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README.md

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+
+# Crate `plot_icon`
+
+## Overview
+
+This is a lib crate for generating standard 19-circle icons in png and in svg format.  
+
+Output could be in form of .png or .svg files, or the Vec<u8> with png data, or svg::Document with svg data.  
+
+The code is following the published javascript code for icon generation from `https://github.com/paritytech/oo7/blob/master/packages/polkadot-identicon/src/index.jsx`.  
+
+
+
+## Input needed to generate data (to be used in Signer)  
+
+Input requires:  
+
+1. actual input data:  
+    - `Vec<u8>` to be used with `png_data_from_vec` and `svg_from_vec` functions  
+    - or hex format string to be used with `png_data_from_hex` and `svg_from_hex` functions  
+    - or base58 format string to be used with `png_data_from_base58` and `svg_from_base58` functions  
+2. size parameter `halfsize` of final file (created image is square, with ``halfsize`*2+1`` pixels side for png and ``halfsize`*2`` for svg)  
+
+
+## Input needed to make files (at the moment, mainly for test pics)  
+
+Input requires:  
+
+1. actual input data:  
+    - `Vec<u8>` to be used with `plot_png_from_vec` and `plot_svg_from_vec` functions  
+    - or hex format string to be used with `plot_png_from_hex` and `plot_svg_from_hex` functions  
+    - or base58 format string to be used with `plot_png_from_base58` and `plot_svg_from_base58` functions  
+2. size parameter `halfsize` of final file (created image is square, with ``halfsize`*2+1`` pixels side for png and ``halfsize`*2`` for svg)  
+3. output file name  
+
+
+## Tests and Examples
+
+Currently there are tests to check if the color sets calculated for Alice and Bob are identical to the colors in the corresponding well-known icons.  
+
+Examples are plotting both .png and .svg icons for base58 westend Alice address, and hex westend genesis hash.
+
+
+## Notes
+
+There are several uncertainties about how the original published code was designed to work, those should be clarified.  
+
+For example, calculated HSL color saturation could range 30..109, and is processed as percents. Crate `palette` (currently used here) processes saturation values over 100 as percents over 100, and gives some results (slightly different from results for 100% saturation), but it is necessary to check if the calculations in js and here are matching.  
+
+See details in code comments.  
+