Develop Reference

c# how to deskew an image

I'm currently working with an OCR program. I'm using tesseract and i need to deskew images to improve the quality of the detected characters. The problem is that the deskew property given by tesseract doesn't produce enough attractive results. So i tried to deskew the image with AForge and Atalasoft, but every time, no matter what, the image is not in the format they require. What am i doing wrong? Or there is a better solution?
This is AForge implementation
System.Drawing.Bitmap imageToBitmap = AForge.Imaging.Image.FromFile(imagePath);
Console.WriteLine("before " + imageToBitmap.PixelFormat);
System.Drawing.Bitmap NewPicture = imageToBitmap.Clone(new System.Drawing.Rectangle(0, 0, imageToBitmap.Width, imageToBitmap.Height), System.Drawing.Imaging.PixelFormat.Format24bppRgb);
var dop = AForge.Imaging.Image.Clone(imageToBitmap, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
Console.WriteLine("after " + dop.PixelFormat);
AForge.Imaging.DocumentSkewChecker skewChecker = new AForge.Imaging.DocumentSkewChecker();
// get documents skew angle
double angle = skewChecker.GetSkewAngle(dop);
// create rotation filter
AForge.Imaging.Filters.RotateBilinear rotationFilter = new AForge.Imaging.Filters.RotateBilinear(-angle);
rotationFilter.FillColor = System.Drawing.Color.White;
// rotate image applying the filter
System.Drawing.Bitmap rotatedImage = rotationFilter.Apply(imageToBitmap);
rotatedImage.Save("deskewedImage");
This is Atalasoft implementation
AtalaImage img = new AtalaImage(imagePath);
AutoDeskewCommand cmd = new AutoDeskewCommand();
AtalaImage resultImage = cmd.Apply(img).Image;
resultImage.Save("result.tif", new TiffEncoder(), null);

I finally managed to understand why it wasn't working: the image should be converted to Format8bppIndexed or the method skewChecker.GetSkewAngle(image) will throw an exception
Bitmap tempImage = AForge.Imaging.Image.FromFile(imagePath);
Bitmap image;
if (tempImage.PixelFormat.ToString().Equals("Format8bppIndexed"))
{
image = tempImage;
}
else
{
image = AForge.Imaging.Filters.Grayscale.CommonAlgorithms.BT709.Apply(tempImage);
}
tempImage.Dispose();
AForge.Imaging.DocumentSkewChecker skewChecker = new AForge.Imaging.DocumentSkewChecker();
// get documents skew angle
double angle = skewChecker.GetSkewAngle(image);
// create rotation filter
AForge.Imaging.Filters.RotateBilinear rotationFilter = new AForge.Imaging.Filters.RotateBilinear(-angle);
rotationFilter.FillColor = Color.Black;
// rotate image applying the filter
Bitmap rotatedImage = rotationFilter.Apply(image);
var deskewedImagePath = folderSavePath + filename + "_deskewed.tiff";
rotatedImage.Save(deskewedImagePath, System.Drawing.Imaging.ImageFormat.Tiff);
image.Dispose();
rotatedImage.Dispose();

Aforge fill holes filter result in black image

I'm trying use Aforge library for filling holes in the resulting binary image, the problem is I'm getting a BLACK image as a result instead of the filled image.
Your assistance is highly appreciated.
Bitmap bitImage = (Bitmap)pic.Image;
Bitmap bm = Convert(bitImage);
FillHoles filter = new FillHoles();
filter.CoupledSizeFiltering = true;
// apply the filter
pictureBox1.Image = filter.Apply(bm);
public Bitmap Convert(Bitmap bit)
{
Grayscale filter = new Grayscale(0.2125, 0.7154, 0.0721);
// apply the filter
Bitmap bm = filter.Apply(bit);
return bm;
}

Saving writeablebitmap to a JPG in silverlight

I have a writeablebitmap object that I would like to save to JPG in silverlight , how can I do that?

I am also converting writeablebitmap object into image as
WriteableBitmap bitmap = new WriteableBitmap(Width,Height);
//Some operation of drawing on bitmap
and then
Image imageFHR = new Image();
imageFHR.Source = bitmap;
imageFHR.Height = Height;
imageFHR.Width = Width;
myCanvas.Children.Add(imageFHR);

Change image size with C# in MVC3?

[HttpPost]
public ActionResult AddImage(Image model)
{
if (model.ImageData != null && model.ImageData.ContentLength > 0)
{
var fileName = Path.GetFileName(model.ImageData.FileName);
var pathBig = Path.Combine(Server.MapPath("~/UploadedImages"), fileName);
var pathSmall = Path.Combine(Server.MapPath("~/UploadedImages"), "small_" + fileName);
// --> How to change image size to big(800 x 600)
// and small (100x80) and save them?
model.ImageData.SaveAs(pathBig);
model.ImageData.SaveAs(pathSmall);
}
}
How do I change the image size to big(800 x 600) to small (100x80) and save them?

You could try this library:
http://nuget.org/packages/ImageResizer
It does support asp.net-mvc:
http://imageresizing.net/
Or you could get a pure C# lib and use it on your app. See these posts:
Resize an Image C#
https://stackoverflow.com/a/2861813/368070
And this snippet I found : http://snippets.dzone.com/posts/show/4336

The simplest way of doing it from the framework methods itself will be to use the DrawImage() method of the Graphics Class.
The example code could be like:
//For first scale
Bitmap bmp = new Bitmap(800, 600);
Graphics gf = Graphics.FromImage(bmp);
Image userpic = Image.FromStream(/*pass here the image byte stream*/)
gf.DrawImage(userpic, new Rectangle(0,0,800,600))
gf.Save(/* the save path */);
//For second scale
Bitmap bmp = new Bitmap(100, 80);
Graphics gf = Graphics.FromImage(bmp);
Image userpic = Image.FromStream(/*pass here the image byte stream*/)
gf.DrawImage(userpic, new Rectangle(0,0,100,80))
gf.Save(/* the save path */);

How do I print an Image from a Uri?

I am attempting to print a JPEG file that I reference using a Uri object and am having some difficulties. I found that while the image was printing, it was cropped slightly and was flipped and mirrored. I'm guessing that the crop was caused by a size not being set properly but have no idea why it's being flipped and rotated. Assuming that this was a natural oddity, I attempted to resolve the issue by applying a transform to the drawingContext object but this results a blank page being printed. Here is my code:
public void Print(List<Uri> ListToBePrinted)
{
XpsDocumentWriter writer =
PrintQueue.CreateXpsDocumentWriter(this.SelectedPrinter.PrintQueue);
PrintCapabilities printerCapabilities =
this.SelectedPrinter.PrintQueue.GetPrintCapabilities();
Size PageSize =
new Size(printerCapabilities.PageImageableArea.ExtentWidth,
printerCapabilities.PageImageableArea.ExtentHeight);
foreach (Uri aUri in ListToBePrinted)
{
BitmapImage anImage = new BitmapImage(aUri);
//create new visual which would be initialized by image
DrawingVisual drawingVisual = new DrawingVisual();
//create a drawing context so that image can be rendered to print
DrawingContext drawingContext = drawingVisual.RenderOpen();
// Flips along X and Y axis (flips and mirrors)
drawingContext.PushTransform(new ScaleTransform(-1, -1));
drawingContext.DrawImage(anImage, new Rect(PageSize));
drawingContext.Close();
writer.Write(drawingVisual);
}
}
Any help would be greatly appreciated - thank you!

Here's what I ended up with:
public void Print(List<Uri> ListToBePrinted)
{
XpsDocumentWriter writer =
PrintQueue.CreateXpsDocumentWriter(this.SelectedPrinter.PrintQueue);
PrintCapabilities printerCapabilities =
this.SelectedPrinter.PrintQueue.GetPrintCapabilities();
Size PrintableImageSize =
new Size(printerCapabilities.PageImageableArea.ExtentWidth,
printerCapabilities.PageImageableArea.ExtentHeight);
foreach (Uri aUri in ListToBePrinted)
{
DrawingVisual drawVisual = new DrawingVisual();
ImageBrush imageBrush = new ImageBrush();
imageBrush.ImageSource = new BitmapImage(aUri);
imageBrush.Stretch = Stretch.Fill;
imageBrush.TileMode = TileMode.None;
imageBrush.AlignmentX = AlignmentX.Center;
imageBrush.AlignmentY = AlignmentY.Center;
using (DrawingContext drawingContext = drawVisual.RenderOpen())
{
// Flips along X and Y axis (flips and mirrors)
drawingContext.PushTransform(new ScaleTransform(-1, 1, PrintableImageSize.Width / 2, PrintableImageSize.Height / 2));
drawingContext.PushTransform(new RotateTransform(180, PrintableImageSize.Width / 2, PrintableImageSize.Height / 2)); // Rotates 180 degree
drawingContext.DrawRectangle(imageBrush, null, new Rect(25, -25, PrintableImageSize.Width, PrintableImageSize.Height));
}
writer.Write(drawVisual);
}
}
The image is a little fuzzy but is certainly acceptable. I'm still not sure why my image needed to be flipped or mirrored.

Could you do something like:
BitmapImage anImage = new BitmapImage(aUri);
Image image = new Image();
image.BeginInit();
image.Source = anImage;
image.EndInit();
image.Measure(PageSize);
image.InvalidateVisual();
Then just print the Image object since it derives from Visual...
You need to call InvalidateVisual so that OnRender will be called, if you didn't it would result in a blank image...