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How to define picturebox coordinate

I am trying to draw an image on top of another image in a picturebox. They are the same size (125X150). When I paint the second picture at point[0,0] in the picturebox, the two pictures do not line up.Here is my code:
pictureBox1.Image = Image.FromFile("picture\\faces\\face3.png");
Bitmap bmp = new Bitmap(pictureBox1.Image);
Graphics g = Graphics.FromImage(bmp);
g.DrawImage(new Bitmap("picture\\faces\\eyebow1.png"), new Point(0, 0));
g.Dispose();
pictureBox1.Image = bmp;

I figured it out by myself. Although I do not know why:
pictureBox1.Image = Image.FromFile("picture\\faces\\face3.png");
Bitmap bmp = new Bitmap(pictureBox1.Image);
Console.WriteLine(bmp.Width);
Graphics g = Graphics.FromImage(bmp);
pictureBox1.Image = Image.FromFile("picture\\faces\\eyebow1.png");
g.DrawImage(new Bitmap(pictureBox1.Image), new Point(0, 0));
g.Dispose();
pictureBox1.Image = bmp;

Screenshot conversion into grayscale doesn't work. What causes this?

I have a Windows Forms application that takes a screenshot of a specific portion of the screen, then displays it in a picture box (pictureBox1). It works when I don't try to convert it, but I want to convert the image to grayscale or black and white. The problem is when I convert it to grayscale, it still shows the original picture in the picture box.
Here is the code when it works, without the conversion:
private void button1_Click(object sender, EventArgs e)
{
Rectangle rectangle = new Rectangle(660, 200, 600, 100);
pictureBox1.Height = rectangle.Height;
pictureBox1.Width = rectangle.Width;
imageUploader(rectangle);
}
public void imageUploader(Rectangle rectangle)
{
Bitmap bitmap = new Bitmap(rectangle.Width, rectangle.Height, PixelFormat.Format32bppArgb);
Graphics graphics = Graphics.FromImage(bitmap);
graphics.CopyFromScreen(rectangle.Left, rectangle.Top, 0, 0, bitmap.Size, CopyPixelOperation.SourceCopy);
bitmap.Save("proba.jpeg", ImageFormat.Jpeg);
pictureBox1.Image = bitmap;
}
Here is the conversion method, which I tried out:
public void toGrayscale(Bitmap bitmap)
{
Color c;
for (int y = 0; y < bitmap.Height; y++)
{
for (int x = 0; x < bitmap.Width; x++)
{
c = bitmap.GetPixel(x,y);
Color newColor = Color.FromArgb(c.R,0,0);
bitmap.SetPixel(x,y,newColor);
}
}
}
After I used this conversion (see below) the image showed up in the picture box, but it wasn't grayscale.
Here is the modified imageUploader void with the conversion:
public void imageUploader(Rectangle rectangle)
{
Bitmap bitmap = new Bitmap(rectangle.Width, rectangle.Height, PixelFormat.Format32bppArgb);
toGrayscale(bitmap);
Graphics graphics = Graphics.FromImage(bitmap);
graphics.CopyFromScreen(rectangle.Left, rectangle.Top, 0, 0, bitmap.Size, CopyPixelOperation.SourceCopy);
bitmap.Save("proba.jpeg", ImageFormat.Jpeg);
pictureBox1.Image = bitmap;
}

It appears that your issue is here:
public void imageUploader(Rectangle rectangle)
{
Bitmap bitmap = new Bitmap(rectangle.Width, rectangle.Height, PixelFormat.Format32bppArgb);
toGrayscale(bitmap);
Graphics graphics = Graphics.FromImage(bitmap);
graphics.CopyFromScreen(rectangle.Left, rectangle.Top, 0, 0, bitmap.Size, CopyPixelOperation.SourceCopy);
bitmap.Save("proba.jpeg", ImageFormat.Jpeg);
pictureBox1.Image = bitmap;
}
You're converting each pixel of the bitmap to greyscale (oddly it looks like you're only grabbing the red channel) then copying from the screen, which overwrites your conversion. To fix it, all you should need to do is move the toGreyscale after you copy from the screen, like this:
public void imageUploader(Rectangle rectangle)
{
Bitmap bitmap = new Bitmap(rectangle.Width, rectangle.Height, PixelFormat.Format32bppArgb);
Graphics graphics = Graphics.FromImage(bitmap);
graphics.CopyFromScreen(rectangle.Left, rectangle.Top, 0, 0, bitmap.Size, CopyPixelOperation.SourceCopy);
toGrayscale(bitmap); # Moved after the copy from screen
bitmap.Save("proba.jpeg", ImageFormat.Jpeg);
pictureBox1.Image = bitmap;
}
This should fix the issue.

You are converting an empty Bitmap to greyscale, then copying over the (nominally) greyscaled Bitmap with an image from the screen. Here is your code, annotated to describe what it is doing:
// This line creates an empty Bitmap.
Bitmap bitmap = new Bitmap(rectangle.Width, rectangle.Height, PixelFormat.Format32bppArgb);
// This line converts the empty Bitmap to grayscale.
toGrayscale(bitmap);
// This line creates a Graphics drawing surface from your bitmap.
Graphics graphics = Graphics.FromImage(bitmap);
// This line overwrites the image data from your bitmap with an image from the screen.
graphics.CopyFromScreen(rectangle.Left, rectangle.Top, 0, 0, bitmap.Size, CopyPixelOperation.SourceCopy);
You need to find some way to take the data you got from the screen and make it greyscale. You have not done this. You have made a greyscale image, but then you have thrown it away by writing other data on top of it. It happens that that replacement data is not greyscale.

Overlay bitmap on another bitmap

On a single bitmap I need to display graphs and text values. So what I did is create a bitmap with points and creating a another bitmap with the text and place on the large bitmap.
I tried using the brush to write the text, but I am not able to see the underlying graphics even though trasparency is set.
Instead I thought to set the transparency for the text bitmap, but the bitmap which I have created are 24 bit rgb. So can we set the transparency for the 24 bit map.
Bitmap textBitmap = null;
textBitmap = new Bitmap(10, 10, PixelFormat.Format24bppRgb);
using (Graphics memoryGrahics =
Graphics.FromImage(textBitmap))
{
memoryGrahics.FillRectangle(Brushes.Black, new Rectangle(0, 0, 100, 100));
memoryGrahics.DrawString(result, f, Brushes.White, x, y);
}
//placing the text bitmap on the graphbitmap
using (Graphics g = Graphics.FromImage(GraphBitmap))
{
g.CompositingMode = System.Drawing.Drawing2D.CompositingMode.SourceOver;
textBitmap.MakeTransparent();
g.DrawImage(textBitmap, 0, 0);
return GraphBitmap;
}

well.. it seems like you are using 2 different Graphical objects... although 1 Graphics objects with 1 bitmap can handle multiple layouts of custom drawings, like so:
int width = 800, height = 600;
var bit = new Bitmap(width, height);
var g = Graphics.FromImage(bit);
g.SmoothingMode = SmoothingMode.AntiAlias;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
var area = new Rectangle(0, 0, width, height);
g.FillRectangle(new LinearGradientBrush(area, Color.PaleGoldenrod, Color.OrangeRed, 45), area);
g.DrawImage(Image.FromFile(#"your image"), new Point(10, 10));
g.DrawString("sample", new System.Drawing.Font("Tahoma", 56), new SolidBrush(Color.Black), new PointF(50, 50));
pictureBox1.Image = bit;
note that g.DrawImage method can be used to load other bitmaps as well

How do I resize an image without stretching it?

I am trying to resize an image (bitmap) in C# without stretching the image.
Say the image is 100x100 pixels.
I am looking to make it 100x110 pixels, and leave a white gap at the bottom of the image where it added the extra pixels.
I have done this, but cannot find a way to specify the pixel format. I need it to be 8bppindexed. I've attached an example to show the before and after image.
Here is the code I have so far.
string visit2 = "C:\\users\\moorez\\desktop\\visit2.bmp";
Bitmap orig = new Bitmap(visit2);
int width = orig.Width;
int height = orig.Height;
int newHeight = height + 2;
Bitmap newImage = orig.Clone(new Rectangle(0, 0, width, height), System.Drawing.Imaging.PixelFormat.Format8bppIndexed);
newImage.Save("C:\\users\\moorez\\desktop\\visit3.bmp");
Bitmap test = new Bitmap(width, newHeight);
Graphics g = Graphics.FromImage(test);
g.DrawImage(newImage, new Point(0, 0));
test.Save("C:\\users\\moorez\\desktop\\visit4.bmp");

You can try this
Bitmap bmp = new Bitmap(newImage.Width, newHeight);
Graphics g = Graphics.FromImage(bmp);
g.Clear(Color.White);
g.DrawImageUnscaled(newImage, 0, 0, newImage.Width, newHeight);
bmp.Save(#"C:\\users\\moorez\\desktop\\visit3.bmp", ImageFormat.Jpeg);

C#: how to take a screenshot of a portion of screen

like
TakeScreenshot(new Rectangle(0,0,100,100), "output.jpg");

Use the following:
Rectangle rect = new Rectangle(0, 0, 100, 100);
Bitmap bmp = new Bitmap(rect.Width, rect.Height, PixelFormat.Format32bppArgb);
Graphics g = Graphics.FromImage(bmp);
g.CopyFromScreen(rect.Left, rect.Top, 0, 0, bmp.Size, CopyPixelOperation.SourceCopy);
bmp.Save(fileName, ImageFormat.Jpeg);

Here is the code to capture the screen. Change the values to the size you need.
Bitmap printscreen = new Bitmap(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height);
Graphics graphics = Graphics.FromImage(printscreen as Image);
graphics.CopyFromScreen(0, 0, 0, 0, printscreen.Size);
printscreen.Save(#"C:\printscreen.jpg", ImageFormat.Jpeg);
Or make method which will return you captured image like this :
Image CaptureScreen(int sourceX, int sourceY, int destX, int destY,
Size regionSize)
{
Bitmap bmp = new Bitmap(regionSize.Width, regionSize.Height);
Graphics g = Graphics.FromImage(bmp);
g.CopyFromScreen(sourceX, sourceY, destX, destY, regionSize);
return bmp;
}
......
// call
Image image = CaptureScreen(sourceX, sourceY, destX, destY, regionSize);
image.Save(#"C:\Somewhere\screen.jpg);

Use the Graphics.CopyFromScreen method. Google turns up this tutorial.

Have you checked the Graphics.CopyFromScreen method?