asked on topic [Forum, topic 16941] Histogramme

Coded in 5 hours, the plugin only does :
- histogram (with choice between Luminance, Average or Maxmimum methods)
- red, green, blue histogram (can be deactivated by setting no colors for graph)
- historgram is displayed with metadata
- when a picture is displayed :
     * if there is not histogram in cache, build it and load it through ajax call (allow to display the page quicky while histogram is rendered)
     * if there is an histogram in cache, if it was already rendered, display rendered graph
     * if there is an histogram in cache, if it was not already rendered, render and display graph on page load (this is quick)
     * when a render option is changed, all graph are purged but cache is kept, allowing to change render option at anytime


Other options will come later (manage transparency background, add graph informations like ticks, manage multi-display for histogram (actually, main, red, green and blue can be displayed on the same graph only)