Develop Reference

Cropping an image from file and resaving in C#

Never really worked with Graphics before. I have looked around on this and pieced together a few solutions from answers which address small parts of my question. but none have worked.
I want to load an image from a file, which will always be 320x240 in size. I then want to crop it to obtain a 240x240 image, with the outer 40px on each side trimmed. After this is done I want to save as a new image.
private void croptoSquare(string date)
{
//Location of 320x240 image
string fileName = Server.MapPath("~/Content/images/" + date + "contactimage.jpg");
//New rectangle of final size (I think maybe Point is where I would eventually specify where the crop square site i.e. (40, 0))
Rectangle cropRect = new Rectangle(new Point(0, 0), new Size(240, 240));
//Create a Bitmap with correct height/width.
Bitmap target = new Bitmap(cropRect.Width, cropRect.Height);
//Load image from file
using (Image image = Image.FromFile(fileName))
{
//Create Graphics object from image
using (Graphics graphic = Graphics.FromImage(image))
{
//Not sure what this does, I found it on a post.
graphic.DrawImage(image,
cropRect,
new Rectangle(0, 0, target.Width, target.Height),
GraphicsUnit.Pixel);
fileName = Server.MapPath("~/Content/images/" + date + "contactimagecropped.jpg");
image.Save(fileName);
}
}
}
Currently it is simply resaving the same image and I'm not sure why. I have specified a destination rectangle as 240x240 and a src rectangle as 320x240.
As I say I know basically nothing about working with graphics objects so I imagine this is blatant.
Can anybody tell me how to achieve what I want?

private void croptoSquare(string date)
{
//Location of 320x240 image
string fileName = Server.MapPath("~/Content/images/" + date + "contactimage.jpg");
// Create a new image at the cropped size
Bitmap cropped = new Bitmap(240,240);
//Load image from file
using (Image image = Image.FromFile(fileName))
{
// Create a Graphics object to do the drawing, *with the new bitmap as the target*
using (Graphics g = Graphics.FromImage(cropped) )
{
// Draw the desired area of the original into the graphics object
g.DrawImage(image, new Rectangle(0, 0, 240, 240), new Rectangle(40, 0, 240, 240), GraphicsUnit.Pixel);
fileName = Server.MapPath("~/Content/images/" + date + "contactimagecropped.jpg");
// Save the result
cropped.Save(fileName);
}
}
}

Why don't you use JCrop instead? http://www.programmerclubhouse.com/index.php/crop-image-using-jcrop-in-asp-net-c-shar/

Find Black Squares/Rectangles in Image with C#

I want to find small black squares/rectangles in scanned sheet to:
deskewing image if needed.
remove white page margin.
Input image:
sample image 1 http://us.cdn.persiangig.com/preview/ii2jf6/2.jpg
Output image:
sample image 2 http://us.cdn.persiangig.com/preview/9ntpnc/1.jpg
My code to find square is:
Bitmap pic =(Bitmap) pictureBox1.Image;
// create filter
AForge.Imaging.Filters.Median Medianfilter = new AForge.Imaging.Filters.Median();
// apply the filter
Medianfilter.ApplyInPlace(pic);
Bitmap grayImage;
if (pic.PixelFormat != PixelFormat.Format16bppGrayScale && pic.PixelFormat != PixelFormat.Format8bppIndexed)
{
AForge.Imaging.Filters.Grayscale grayscalefilter = new AForge.Imaging.Filters.Grayscale(0.2125, 0.7154, 0.0721);
grayImage = grayscalefilter.Apply((Bitmap)pictureBox1.Image);
}
else
{
grayImage = pic;
}
// black & white:
Threshold(ref grayImage, Convert.ToInt32(textBox1.Text), Convert.ToInt32(textBox1.Text));
// invert filter
Invert invertfilter = new Invert();
// apply the filter
invertfilter.ApplyInPlace(grayImage);
// Edge Detector filter
DifferenceEdgeDetector EdgeDetectorfilter = new DifferenceEdgeDetector();
// apply the filter
EdgeDetectorfilter.ApplyInPlace(grayImage);
// create filter
Dilatation Dilatationfilter = new Dilatation();
// apply the filter
Dilatationfilter.ApplyInPlace(grayImage);
Finding object(square/rectangle) in image:
// lock image
BitmapData bitmapData = grayImage.LockBits(new Rectangle(0, 0, grayImage.Width, grayImage.Height),
ImageLockMode.ReadWrite, grayImage.PixelFormat);
// step 2 - locating objects
BlobCounter blobCounter = new BlobCounter();
blobCounter.FilterBlobs = true;
blobCounter.MinHeight = 10; //*-*-*-*-
blobCounter.MinWidth = 10;
blobCounter.MaxHeight = 50;
blobCounter.MaxWidth = 50;
blobCounter.ProcessImage(bitmapData);
Blob[] blobs = blobCounter.GetObjectsInformation();
grayImage.UnlockBits(bitmapData);
// step 3 - check objects' type and highlight
SimpleShapeChecker shapeChecker = new SimpleShapeChecker();
Graphics g = Graphics.FromImage(pic);
Pen redPen = new Pen(Color.Red, 2); // quadrilateral
Pen bluePen = new Pen(Color.Blue, 2); // triangle
for (int i = 0, n = blobs.Length; i < n; i++)
{
List<IntPoint> edgePoints = blobCounter.GetBlobsEdgePoints(blobs[i]);
List<IntPoint> corners;
// is triangle or quadrilateral
if (shapeChecker.IsQuadrilateral(edgePoints, out corners))
{
// get sub-type
PolygonSubType subType = shapeChecker.CheckPolygonSubType(corners);
Pen pen;
if (subType == PolygonSubType.Square)
{
pen = (corners.Count == 4) ? bluePen : redPen;
g.DrawPolygon(pen, ToPointsArray(corners));
}
}
}
redPen.Dispose();
bluePen.Dispose();
g.Dispose();
pictureBox1.Image = pic;
Problem is low accuracy on detecting squares and rectangles!!!
How can I solve this problem?

If you can use OpenCV this is quite easy. Use the Hough transform and find peaks in the output. Those correspond to straight lines in your input.
If you can't use OpenCV, you'll need to implement it yourself. Here's something to get you started.
https://en.wikipedia.org/?title=Hough_transform
EDIT
As Anders Gustafsson points out in the comment below, the Hough Transform is available in AForge for .NET so implementing it yourself isn't a necessity.
http://www.aforgenet.com/framework/features/hough_transformation.html

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;
}

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 */);

C# redaction drawing on Image

Whats going on is i need to draw a black rectangle over the image. I have to load a tif and then show a blackbox over it. I was helped with some code but i continously got the error: A Graphics object cannot be created from an image that has an indexed pixel format.
So i had to read it in to bit format, but when i display the box it resizes the box wierd. And completly displays the the picture box in all black nothing of the original image. if someone could help me where i'm going wrong that would be awesome.
Bitmap original = (Bitmap)System.Drawing.Image.FromFile(coveted, true);
Bitmap newImage = new Bitmap(original.Width, original.Height);
pictureBox1.Image = newImage;
using (Graphics g = Graphics.FromImage(pictureBox1.Image))
{
using (SolidBrush brush = new SolidBrush(Color.Black))
{
g.FillRectangle(brush, new Rectangle(x1value, y1value, x3value, y3value));
}
}
I'm not sure how I can make this clearer. Whats happening is I have a tif in a unsupported format. So I have to change it to a Bitmap so I can actually draw a rectangle on it. Then I need to display this redacted image (the original with the redaction) in a picturebox. Whats going on with the code above, is once it's completed, all it displays is a blackbox with no original image.
I believe i ran something about using a Bitmap from stream and then closing the stream. Anybody familiar with this?
Thanks to all the help from STO members!! heres the correct code for redacting images if you encounter the error "A Graphics object cannot be created from an image that has an indexed pixel format.".
if you're given the redacted starting points (obviously you have to make the Regex work to your situation):
//Regex for pulling points from a file
string x1 = x1 = Regex.Match(l, #"\r\n(\d+)\r\n(\d+)").Groups[2].Value;
string y1 = y1 = Regex.Match(l, #"\r\n(\d+)\r\n(\d+)\r\n(\d+)").Groups[3].Value;
string x2 = x2 = Regex.Match(l, #"\r\n(\d+)\r\n(\d+)\r\n(\d+)\r\n(\d+)").Groups[4].Value;
string y2 = y2 = Regex.Match(l, #"\r\n(\d+)\r\n(\d+)\r\n(\d+)\r\n(\d+)\r\n(\d+)").Groups[5].Value;
string x3 = x3 = Regex.Match(l, #"\r\n(\d+)\r\n(\d+)\r\n(\d+)\r\n(\d+)\r\n(\d+)\r\n(\d+)").Groups[6].Value;
string y3 = y3 = Regex.Match(l, #"\r\n(\d+)\r\n(\d+)\r\n(\d+)\r\n(\d+)\r\n(\d+)\r\n(\d+)\r\n(\d+)").Groups[7].Value;
{
//convert string to int for redacted points
int x1value = Convert.ToInt32(x1);
int y1value = Convert.ToInt32(y1);
int x3value = Convert.ToInt32(x3);
int y3value = Convert.ToInt32(y3);
{
//BEGIN Workaround for indexed pixels
Bitmap original = (Bitmap)System.Drawing.Image.FromFile(YOURFILE, true);
Bitmap newImage = new Bitmap(original);
pictureBox1.Image = newImage; //END Workaround for indexed pixels
using (Graphics g = Graphics.FromImage(pictureBox1.Image)) //start redaction
{
using (SolidBrush brush = new SolidBrush(Color.Black))
{
g.DrawImageUnscaled(newImage, 0,0);
g.FillRectangle(brush, new Rectangle(x1value, y1value, x3value, y3value));
}
} //End Redaction
pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage; //Resized to fit into a static picturebox
}
}

Instead of
Bitmap newImage = new Bitmap(original.Width, original.Height);
you want
Bitmap newImage = new Bitmap(original);
This will make your newImage start with the contents of original.
The difference will be that you will end up with newImage.PixelFormat == PixelFormat.Format32bppArgb, while I'm assuming original.PixelFormat == PixelFormat.Format1bppIndexed.
With PixelFormat.Format32bppArgb, you can create a Graphics object; you cannot with PixelFormat.Format1bppIndexed.

This should work for you:
original = (Bitmap)System.Drawing.Image.FromFile(coveted, true);
using (Graphics g = Graphics.FromImage(original))
{
using (SolidBrush brush = new SolidBrush(Color.Black))
{
g.FillRectangle(brush, new Rectangle(x1value, y1value, x3value, y3value));
}
}
pictureBox1.Image = original;

You aren't drawing the original image on the newImage.
To do so :
g.DrawImageUnscaled(original, 0, 0);
Also, I would do it as follows, I think it works better drawing in RAM, and then showing it to screen. Perhaps I'm wrong though.
using (Graphics g = Graphics.FromImage(newImage))
{
g.DrawImageUnscaled(original, 0, 0);
using (SolidBrush brush = new SolidBrush(Color.Black))
{
g.FillRectangle(brush, new Rectangle(x1value, y1value, x3value, y3value));
}
}
pictureBox1.Image = newImage;
I haven't tested the code above.. good luck though.