Develop Reference

Change alpha coefficient using Lockbits

I have written a function which changes the alpha coefficient of an image. I use setpixel and getpixel,which is very slow. I found out that Lockbits method is faster.How can I do it with Lockbits?
Here is my current code:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace WindowsFormsApplication2
{
public partial class Form1 : Form
{
private static Image Tran(Image s,int alpha)
{
int x = 0, y = 0;
Bitmap tImage = new Bitmap(s);
for (x = 0; x < tImage.Width; x++)
{
for (y = 0; y < tImage.Height; y++)
{
tImage.SetPixel(x, y, Color.FromArgb(alpha, tImage.GetPixel(x, y).R, tImage.GetPixel(x, y).G, tImage.GetPixel(x, y).B));
}
}
return tImage;
}
public Form1()
{
InitializeComponent();
trackBar1.TickStyle = TickStyle.Both;
trackBar1.Orientation = Orientation.Vertical;
trackBar1.Minimum = 0;
trackBar1.Maximum = 255;
trackBar1.Height = 101;
trackBar1.Value = 255;
pictureBox1.Image = Image.FromFile("C:\\Users\\rati\\Desktop\\water.jpg");
pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage;
}
private void trackBar1_Scroll(object sender, EventArgs e)
{
pictureBox1.Image = ChangeAlpha(pictureBox1.Image, trackBar1.Value);
textBox1.Text = trackBar1.Value.ToString();
}
}
}

You can change the opacity of your image by drawing it in a new bitmap using a new ColorMatrix and assigning a float value between 0 and 1 to its Matrix33 as its new alpha value:
public Image ChangeAlpha(Image img, int value)
{
if (value < 0 || value > 255)
throw new Exception("value must be between 0 and 255");
Bitmap bmp = new Bitmap(img.Width, img.Height); // Determining Width and Height of Source Image
Graphics graphics = Graphics.FromImage(bmp);
ColorMatrix colormatrix = new ColorMatrix();
colormatrix.Matrix33 = value / 255f;
ImageAttributes imgAttribute = new ImageAttributes();
imgAttribute.SetColorMatrix(colormatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
graphics.DrawImage(img, new Rectangle(0, 0, bmp.Width, bmp.Height), 0, 0, img.Width, img.Height, GraphicsUnit.Pixel, imgAttribute);
graphics.Dispose(); // Releasing all resource used by graphics
return bmp;
}
And here is a sample usage:
private void button1_Click(object sender, EventArgs e)
{
int opacityvalue = 127;
var img = ChangeAlpha(Image.FromFile(#"d:\1.png"), opacityvalue);
img.Save(#"d:\2.png");
}
Don't forget to add using System.Drawing; and using System.Drawing.Imaging;.
You can see before and after calling the function with value=127 below:
EDIT
If you want to see the result in a PictureBox you should pay attention to using 2 different picture boxes, one for original image, and one for changed image:
private void trackBar1_Scroll(object sender, EventArgs e)
{
this.pictureBox2.Image = ChangeAlpha(this.pictureBox1.Image, this.trackBar1.Value);
}
As I see in your code when you change the opacity, you set the result as image of your PictureBox1 again and apply opacity again on the result. In other word you apply opacity on an image that you applied opacity to it before over and over again.

public Form1()
{
...
originalImage = new Bitmap("C:\\Users\\rati\\Desktop\\water.jpg");
pictureBox1.Image = originalImage;
...
}
// Add an extra field to the Form class.
Bitmap originalImage;
void trackBar1_Scroll(object sender, EventArgs e)
{
pictureBox1.Image = ChangeAlpha((byte)trackBar1.Value);
textBox1.Text = trackBar1.Value.ToString();
}
Image ChangeAlpha(byte alpha)
{
Bitmap bmp = new Bitmap(originalImage);
Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);
BitmapData bmpData = bmp.LockBits(rect, ImageLockMode.ReadWrite, bmp.PixelFormat);
IntPtr ptr = bmpData.Scan0;
int bytes = Math.Abs(bmpData.Stride) * bmp.Height;
byte[] rgbValues = new byte[bytes];
Marshal.Copy(ptr, rgbValues, 0, bytes);
// Set every fourth value to alpha. A 32bpp bitmap will change transparency.
for (int counter = 3; counter < rgbValues.Length; counter += 4)
rgbValues[counter] = alpha;
// Also you can try parallelize loop.
//int length = rgbValues.Length / 4;
//Parallel.For(3, length, counter => rgbValues[counter * 4 - 1] = alpha);
Marshal.Copy(rgbValues, 0, ptr, bytes);
bmp.UnlockBits(bmpData);
return bmp;
}

Merge Several Picture Box Image and Save

I currently work on image processing application. I have 'Main' PictureBox as canvas. I want to insert some PictureBox into 'Main' PictureBox and merge all as one Image then save it to png. This is my code. Can anybody help me to acccomplish this task please?
Bitmap bmp = new Bitmap(pictureEdit.Width, pictureEdit.Height);
bmp = (Bitmap)pictureEdit.Image;
foreach (Control c in pictureEdit.Controls)
{
if (c is Functions.pictureEdit)
{
using (var bitmap = new Bitmap(pictureEdit.Image.Width, pictureEdit.Image.Height)) {
using (var canvas = Graphics.FromImage(bitmap)) {
canvas.DrawImage(bmp, new Rectangle(0, 0, pictureEdit.Image.Width, pictureEdit.Image.Height));
canvas.DrawImage(((Functions.pictureEdit)c).img, new Rectangle(0, 0, pictureEdit.Image.Width, pictureEdit.Image.Height));
canvas.Save();
}
bitmap.Save(#"D:\Test\new.png", System.Drawing.Imaging.ImageFormat.Png);
}
}
}

Hope you are okay with Combining images together
Following code does that
private Bitmap CombineBitmap(List lstImages, int width, int height)
{
int iTilesPerWidth = 5;
//create a bitmap to hold the combined image
Bitmap finalImage = new System.Drawing.Bitmap(width, height);
//get a graphics object from the image so we can draw on it
using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(finalImage))
{
PointF point1 = new PointF(0, 0);
int nCount = 1;
foreach (Bitmap BM in lstImages)
{
//512, 256
g.DrawImage(BM, point1);
point1.X += BM.Width;
if (nCount % iTilesPerWidth == 0)
{
point1.X = 0;
point1.Y += BM.Height;
}
nCount++;
}
}
return finalImage;
}

AForge net simple shape detection error

I try to write simple shape detection app. I'm using sample from Aforge.net library. But I always get same error:
cannot convert from 'AForge.Point[]' to 'System.Drawing.PointF[]'
I try to change some things in ImageProcess method as well as in ToPointsArray, but effect is always the same. What else can I try? What I do wrong?
Here is code:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
if (openFileDialog1.ShowDialog() == DialogResult.OK)
{
try
{
ProcessImage((Bitmap)Bitmap.FromFile(openFileDialog1.FileName));
}
catch
{
MessageBox.Show("Załadowanie obrazu niepowiodło się.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
}
private void ProcessImage(Bitmap bitmap)
{
//-------------------------------------
BitmapData bitmapData = bitmap.LockBits(
new Rectangle(0, 0, bitmap.Width, bitmap.Height),
ImageLockMode.ReadWrite, bitmap.PixelFormat);
//-------------------------------------
ColorFiltering colorFilter = new ColorFiltering();
colorFilter.Red = new IntRange(0, 64);
colorFilter.Green = new IntRange(0, 64);
colorFilter.Blue = new IntRange(0, 64);
colorFilter.FillOutsideRange = false;
colorFilter.ApplyInPlace(bitmapData);
//-------------------------------------
BlobCounter blobCounter = new BlobCounter();
blobCounter.FilterBlobs = true;
blobCounter.MinHeight = 5;
blobCounter.MinWidth = 5;
blobCounter.ProcessImage(bitmapData);
Blob[] blobs = blobCounter.GetObjectsInformation();
bitmap.UnlockBits(bitmapData);
//-------------------------------------
SimpleShapeChecker shapeChecker = new SimpleShapeChecker();
Graphics g = Graphics.FromImage(bitmap);
Pen redPen = new Pen(Color.Red, 2); // quadrilateral
Pen brownPen = new Pen(Color.Brown, 2); // quadrilateral with known sub-type
Pen greenPen = new Pen(Color.Green, 2); // known triangle
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.IsConvexPolygon(edgePoints, out corners))
{
// get sub-type
PolygonSubType subType = shapeChecker.CheckPolygonSubType(corners);
Pen pen;
if (subType == PolygonSubType.Unknown)
{
pen = (corners.Count == 4) ? redPen : bluePen;
}
else
{
pen = (corners.Count == 4) ? brownPen : greenPen;
}
g.DrawPolygon(pen, ToPointsArray(corners));
}
}
}
redPen.Dispose();
greenPen.Dispose();
bluePen.Dispose();
brownPen.Dispose();
g.Dispose();
// put new image to clipboard
Clipboard.SetDataObject(bitmap);
// and to picture box
pictureBox1.Image = bitmap;
UpdatePictureBoxPosition();
}
private Point[] ToPointsArray(List<IntPoint> points)
{
Point[] array = new Point[points.Count];
for (int i = 0, n = points.Count; i < n; i++)
{
array[i] = new Point(points[i].X, points[i].Y);
}
return array;
}

Your problem is that AForge have there own Point struct so your ToPointArray method actually returns an Aforge Points array rather than an array of the needed .net Point. The simplest solution is to fully qualify the type you want to use, so your method would become
private System.Drawing.Point[] ToPointsArray(List<IntPoint> points)
{
System.Drawing.Point[] array = new System.Drawing.Point[points.Count];
...
}
Alternatively, if you wanted to save a few characters you could alias the namespace with a using statement at the top of the class.
using NetPoint = System.Drawing.Point;
private NetPoint ToPointsArray(List<IntPoint> points)
{
NetPoint array = new NetPoint[points.Count];
...
}
As a side note this method could be shortened if linq is available to use. For example,
private System.Drawing.Point[] ToPointsArray(List<IntPoint> points)
{
return points.Select(p => new System.Drawing.Point(p.X, p.Y)).ToArray();
}

How to print panel in windows form?

I Have windows form but i want to print panel in windows form to hidden print button and it's my code :
private void printDoc_PrintPage(object sender, System.Drawing.Printing.PrintPageEventArgs e)
{
System.Drawing.Image image = System.Drawing.Image.FromStream(this.streamToPrint);
int x = e.MarginBounds.X;
int y = e.MarginBounds.Y;
int width = image.Width;
int height = image.Height;
if ((width / e.MarginBounds.Width) > (height / e.MarginBounds.Height))
{
width = e.MarginBounds.Width;
height = image.Height * e.MarginBounds.Width / image.Width;
}
else
{
height = e.MarginBounds.Height;
width = image.Width * e.MarginBounds.Height / image.Height;
}
System.Drawing.Rectangle destRect = new System.Drawing.Rectangle(x, y, width, height);
e.Graphics.DrawImage(image, destRect, 0, 0, image.Width, image.Height, System.Drawing.GraphicsUnit.Pixel);
}
public void StartPrint(Stream streamToPrint, string streamType)
{
this.printDoc.PrintPage += new PrintPageEventHandler(printDoc_PrintPage);
this.streamToPrint = streamToPrint;
this.streamType = streamType;
System.Windows.Forms.PrintDialog PrintDialog1 = new PrintDialog();
PrintDialog1.AllowSomePages = true;
PrintDialog1.ShowHelp = true;
PrintDialog1.Document = printDoc;
DialogResult result = PrintDialog1.ShowDialog();
if (result == DialogResult.OK)
{
printDoc.Print();
//docToPrint.Print();
}
}
private void button_Print_Certificate_Click(object sender, EventArgs e)
{
Graphics g1 = this.CreateGraphics();
Image MyImage = new Bitmap(this.ClientRectangle.Width, this.ClientRectangle.Height, g1);
Graphics g2 = Graphics.FromImage(MyImage);
IntPtr dc1 = g1.GetHdc();
IntPtr dc2 = g2.GetHdc();
BitBlt(dc2, 0, 0, this.ClientRectangle.Width, this.ClientRectangle.Height, dc1, 0, 0, 13369376);
g1.ReleaseHdc(dc1);
g2.ReleaseHdc(dc2);
MyImage.Save(#"D:\PrintPage.jpg", ImageFormat.Jpeg);
FileStream fileStream = new FileStream(#"D:\PrintPage.jpg", FileMode.Open, FileAccess.Read);
StartPrint(fileStream, "Image");
fileStream.Close();
if (System.IO.File.Exists(#"D:\PrintPage.jpg"))
{
System.IO.File.Delete(#"D:\PrintPage.jpg");
}
}

In order to print a particular control, you'll want to use that control as the source of your BitBlt operation.
So instead of this.CreateGraphics(), call panel.CreateGraphics(). Similarly, use panel.ClientRectangle to get the width and height of the image.
But take a look at https://stackoverflow.com/a/597088/103167 which gives you an easier way.

Merge two images to create a single image in C#.Net

I have a requirement wherein I need to merge two different png/jpeg images resulting into a single image using C#.Net. There will be a particular location defined on the source image wherein I need to insert another image. Can anybody suggest some links ?

This method merge two images one in the top of the other you can modify the code to meet for your needs:
public static Bitmap MergeTwoImages(Image firstImage, Image secondImage)
{
if (firstImage == null)
{
throw new ArgumentNullException("firstImage");
}
if (secondImage == null)
{
throw new ArgumentNullException("secondImage");
}
int outputImageWidth = firstImage.Width > secondImage.Width ? firstImage.Width : secondImage.Width;
int outputImageHeight = firstImage.Height + secondImage.Height + 1;
Bitmap outputImage = new Bitmap(outputImageWidth, outputImageHeight, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
using (Graphics graphics = Graphics.FromImage(outputImage))
{
graphics.DrawImage(firstImage, new Rectangle(new Point(), firstImage.Size),
new Rectangle(new Point(), firstImage.Size), GraphicsUnit.Pixel);
graphics.DrawImage(secondImage, new Rectangle(new Point(0, firstImage.Height + 1), secondImage.Size),
new Rectangle(new Point(), secondImage.Size), GraphicsUnit.Pixel);
}
return outputImage;
}

After all this, I found a new easier method try this ..
It can join multiple photos together:
public static System.Drawing.Bitmap CombineBitmap(string[] files)
{
//read all images into memory
List<System.Drawing.Bitmap> images = new List<System.Drawing.Bitmap>();
System.Drawing.Bitmap finalImage = null;
try
{
int width = 0;
int height = 0;
foreach (string image in files)
{
//create a Bitmap from the file and add it to the list
System.Drawing.Bitmap bitmap = new System.Drawing.Bitmap(image);
//update the size of the final bitmap
width += bitmap.Width;
height = bitmap.Height > height ? bitmap.Height : height;
images.Add(bitmap);
}
//create a bitmap to hold the combined image
finalImage = new System.Drawing.Bitmap(width, height);
//get a graphics object from the image so we can draw on it
using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(finalImage))
{
//set background color
g.Clear(System.Drawing.Color.Black);
//go through each image and draw it on the final image
int offset = 0;
foreach (System.Drawing.Bitmap image in images)
{
g.DrawImage(image,
new System.Drawing.Rectangle(offset, 0, image.Width, image.Height));
offset += image.Width;
}
}
return finalImage;
}
catch (Exception)
{
if (finalImage != null)
finalImage.Dispose();
//throw ex;
throw;
}
finally
{
//clean up memory
foreach (System.Drawing.Bitmap image in images)
{
image.Dispose();
}
}
}

Disclaimer: I work at Atalasoft
Our DotImage Photo SDK (which is free) can do this.
To open an image
AtalaImage botImage = new AtalaImage("bottomImage.png");
AtalaImage topImage = new AtalaImage("topImage.png");
To overlay one on top of another
Point pos = new Point(0,0); // or whatever you need
OverlayCommand cmd = new OverlayCommand(topImage, pos);
ImageResults res = cmd.Apply(botImage);
If you need the resulting image to be a different size, look at the CanvasCommand. You could also create an AtalaImage of the size you need, then overlay each image onto it.
To save
botImage.Save("newImage.png", new PngEncoder(), null);

String jpg1 = #"c:\images.jpeg";
String jpg2 = #"c:\images2.jpeg";
String jpg3 = #"c:\image3.jpg";
Image img1 = Image.FromFile(jpg1);
Image img2 = Image.FromFile(jpg2);
int width = img1.Width + img2.Width;
int height = Math.Max(img1.Height, img2.Height);
Bitmap img3 = new Bitmap(width, height);
Graphics g = Graphics.FromImage(img3);
g.Clear(Color.Black);
g.DrawImage(img1, new Point(0, 0));
g.DrawImage(img2, new Point(img1.Width, 0));
g.Dispose();
img1.Dispose();
img2.Dispose();
img3.Save(jpg3, System.Drawing.Imaging.ImageFormat.Jpeg);
img3.Dispose();

private void Merge _Click(object sender, EventArgs e)
{
}
DirectoryInfo directory=new DirectoryInfo("D:\\Images");
if(directory!=null)
{
FileInfo[]files = directory.GetFiles();
MergeImages(Image);
}
private void MergeImages(FileInfo[] Image)
{
//change the location to store the final image.
string FImage= #"D:\\Images\\FImage.jpg";
List imageHeights = new List();
int nIndex = 0;
int width = 0;
foreach (FileInfo file in files)
{
Image img = Image.FromFile(file.FullName);
imageHeights.Add(img.Height);
width += img.Width;
img.Dispose();
}
imageHeights.Sort();
int height = imageHeights[imageHeights.Count - 1];
Bitmap NewImg = new Bitmap(width, height);
Graphics Gr= Graphics.FromImage(NewImg);
Gr.Clear(SystemColors.AppWorkspace);
foreach (FileInfo file in files)
{
Image img = Image.FromFile(file.FullName);
if (nIndex == 0)
{
Gr.DrawImage(img, new Point(0, 0));
nIndex++;
width = img.Width;
}
else
{
Gr.DrawImage(img, new Point(width, 0));
width += img.Width;
}
img.Dispose();
}
Gr.Dispose();
NewImg .Save(FImage, System.Drawing.Imaging.ImageFormat.Jpeg);
NewImg .Dispose();
imageLocation.Image = Image.FromFile(FImage);
}