javascript - OpenLayers 3 how to keep original image extent

I'm new at ol3, I'm trying to display my GIS view by updating my ol2 code.

I created the projection and I can display my static image but I'm obliged to use local extent [0, 0, 1024, 968] instead of my image extent [44823.715846278064, 66102.38217556383, 49823.715846278064, 71102.38217556383] otherwise I get a blank screen. In ol2 I made my bounds with the original datas and everything worked fine :/

here the new code :

    var extent = [0, 0, 1024, 968];
    var projection = new ol.proj.Projection({
                       units: 'pixels',
                       extent: extent
                     });

    MAP = new ol.Map({
              target: target,
              view: new ol.View({

                  projection: projection,
                  center: ol.extent.getCenter(extent),
                  zoom: 2
              })
          );

   var imageProjection = new ol.proj.Projection({ 
                            units: 'pixels',
                            extent: [0, 0, 1024, 968]
                         });


   var graphic = new ol.layer.Image({
                        source: new ol.source.ImageStatic({
                            url: layerData,
                            projection: imageProjection,
                            imageExtent: [0, 0, 1024, 968]
                        })
                 });

   MAP.addLayer(graphic);

I need to keep the original extent to communicate with my server to generate the good image when moveend happens. I tried to use an EPSG:4326 projection but it doesn't work. I'm missing something but I don't know where.