Question

I’m using ImageTools for Silverlight to load a JPG image, but the decoded image quality is BAD (no anti-aliasing, see the second image in the red square).

Here is my code:

OpenFileDialog dlg = new OpenFileDialog();

if (dlg.ShowDialog() == true)
{
    var stream = dlg.File.OpenRead();
    var newImg = new ExtendedImage(); // ExtendedImage is a ImageTools Api class
    var d= new ImageTools.IO.Jpeg.JpegDecoder();
    d.Decode(newImg, stream);
    image1.Source = newImg.ToBitmap(); //image1 is a System.Windows.Controls.Image
}

Source image

Bad result

Observations

If I set image1.source directly to a URL from the original image, the image is rendered correctly!

Is this a bug in the ImageTools API?

The problem is posted on Codeplex, but it doesn’t have any answers.

If I rewrite my code, I get the same result.

XAML

<UserControl x:Class="JPGDecoder.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="400">

<Grid x:Name="LayoutRoot" Background="White">
    <Image Height="120" HorizontalAlignment="Left" Margin="46,75,0,0" Name="image1" Stretch="Fill" VerticalAlignment="Top" Width="160" Source="/JPGDecoder;component/Images/org.jpg" />
    <Image Height="120" HorizontalAlignment="Left" Margin="212,75,0,0" Name="image2" Stretch="Fill" VerticalAlignment="Top" Width="160" />
    <Button Content="Decode JPG from File Stream" Height="23" HorizontalAlignment="Left" Margin="44,25,0,0" Name="button1" VerticalAlignment="Top" Width="192" Click="button1_Click" />
</Grid>

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using ImageTools;

namespace JPGDecoder
{
public partial class MainPage : UserControl
{
    public MainPage()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, RoutedEventArgs e)
    {
        var dlg = new OpenFileDialog();

        if (dlg.ShowDialog()==true)
        {
            var stream = dlg.File.OpenRead();
            var newImg = new ExtendedImage();
            var d = new ImageTools.IO.Jpeg.JpegDecoder();
            d.Decode(newImg, stream);
            image2.Source = newImg.ToBitmap();
        }
    }
}
}

Result

Answer 1

ImageTools does not support antialising, so I got FJCore from Subversion and ran the sample app.

1. First test same result, bad quality.

2. Looking at the source code, I found this code block:

   // Resize
   DecodedJpeg jpegOut = new DecodedJpeg(
       new ImageResizer(jpegIn.Image).Resize(320, ResamplingFilters.NearestNeighbor),
       jpegIn.MetaHeaders); // Retain EXIF details
   

   and changed it to this:

   //Resize
   DecodedJpeg jpegOut = new DecodedJpeg(
       new ImageResizer(jpegIn.Image).Resize(320, ResamplingFilters.LowpassAntiAlias),
       jpegIn.MetaHeaders); // Retain EXIF details
   

This is the solution: ResamplingFilters.LowpassAntiAlias

Thanks everyone!!