JAI Mosaic from URL

Question

Hello,
I create some RenderedImages from URLs (JAI.create("url", new URL(url))) and I mosaic them using the code bellow. The input files are RGB JPEGs. The result mosaic has unfortunatelly wrong colors. But if I save first the images on the disk ( JAI.create("filestore", ri, imageLocation, "JPEG", null), then reopen them and create the mosaic the mosaic is corect.
I am wondering if someone has an idea how I could create the mosaic directly from URLs. I would like to spare some time, avoiding saving the files on the disk.
Thank you.
          ParameterBlock pbMosaic = new ParameterBlock();
          pbMosaic.add(MosaicDescriptor.MOSAIC_TYPE_OVERLAY);
          RenderedImage translated =null;
          for(Tile tile:tiles){
               if (tile.x==0 && tile.y==0){
                    translated=tile.filename;
                    pbMosaic.addSource(tile.filename);
               else{
                    ParameterBlock pbTranslate = new ParameterBlock();
                    pbTranslate.addSource(tile.filename);
                    pbTranslate.add((float)tile.x*256);
                    pbTranslate.add((float)tile.y*256);
                    pbTranslate.add(new InterpolationNearest());
                    translated = JAI.create("translate", pbTranslate, null);
                    pbMosaic.addSource(translated);
          ImageLayout imageLayout = new ImageLayout(0, 0, width*256, height*256);
          imageLayout.setTileWidth(256);
          imageLayout.setTileHeight(256);
          imageLayout.setColorModel(translated.getColorModel());
          imageLayout.setSampleModel(translated.getSampleModel());
          RenderedImage mosaic = JAI.create("mosaic", pbMosaic, new RenderingHints(JAI.KEY_IMAGE_LAYOUT, imageLayout));

Answer 1

Actually, 540x540 IS correct for getImage(1). But I also get 540x540 if I call getImage(2) or getImage(3), etc.
The correct result should be:
0: 600x600
1:540x540
2:486x486
etc.
Jean-Robert