C＃WIA设置的分辨率不会增加分辨率，而是会增加图像的宽度和高度。 在C＃中

Question

i am trying to scan a document/photo using WIA (Windows Image Acquisition Library v2.0) in C#, but when i increase resolution it doesn't increase the resolution instead increases width and height of the image, but the resolution stays the same. (Default dpi of the scanner is 75 dpi) ImageFile variable always has 96 dpi.

eg. if at default dpi 75, image has width and height of 100 then if i set dpi to 150, image will have width and height of 200. but the resulting ImageFile always has 96 dpi regardless of dpi i have set.

            WIA.ImageFile img = null;
            WIA.Item Item = WiaDev.Items[1] as WIA.Item;


            try
            {
                Item.Properties.get_Item("4104").set_Value(24);
                Item.Properties.get_Item("6146").set_Value(1);


                double OrigResolution = Convert.ToDouble(Item.Properties["6147"].get_Value().ToString());
                double ResDiff = 0.0;
                int width = 0, height = 0;
                if (OrigResolution < dpi)
                {
                    ResDiff = 150 / OrigResolution;
                    width = (int)Math.Floor((Convert.ToDouble(Item.Properties["6151"].get_Value().ToString()) * ResDiff));
                    height = (int)Math.Floor((Convert.ToDouble(Item.Properties["6152"].get_Value().ToString()) * ResDiff));

                    Item.Properties["6149"].set_Value(0);
                    Item.Properties["6150"].set_Value(0);

                    Item.Properties.get_Item("6147").set_Value(dpi.ToString("0.0"));
                    Item.Properties.get_Item("6148").set_Value(dpi.ToString("0.0"));

                    Item.Properties["6151"].set_Value(width);
                    Item.Properties["6152"].set_Value(height);
                }

                img = (ImageFile)WiaCommonDialog.ShowTransfer(Item, WIA.FormatID.wiaFormatJPEG, false);
                img.SaveFile("D:\\Test.jpg");

Answer 1

Here is the sample example , you can try according to it

private void setItem(IItem item, object property, object value)
   {
       WIA.Property aProperty = item.Properties.get_Item(ref property);
       aProperty.set_Value(ref value);
   }



   internal bool Scan(bool flatBed)
   {

       WIA.DeviceManager manager = new DeviceManager();
       bool result = false;
       object something = 1;
       object somethingElse;
       WIA.Device scanner = manager.DeviceInfos.get_Item(ref something).Connect();
       IItem item = scanner.Items[1];
      setItem(item, "6146", 4);
       setItem(item, "6147", 200);
       setItem(item, "6148", 200);
       setItem(item, "6151", 200 * 8.5);
       setItem(item, "6152", 200 * 11);
   }

The first setItem is the color [4 black and white, 2 grayscale, 1 color, 0 unspecified] The second is horizontal resolution. The third is veritcal resolution. The fourth is horizontal scanning area. The fifth is vertical scanning area.