Develop Reference

c# when crop an image black border appear

Sorry for my English. I'm trying to crop an image after dragging. It works but my problem is, black bold borders appears on cropped image. I don't know how to solve it.
Here is my code:
using (Bitmap sourceBitmap = new Bitmap(fullSizeImage))
{
Rectangle cropRect = new Rectangle(0, 0, sourceWidth, sourceHeight);
using (Bitmap newBitMap = new Bitmap(cropRect.Width, cropRect.Height))
{
using (Graphics g = Graphics.FromImage(newBitMap))
{
g.SmoothingMode = SmoothingMode.HighQuality;
g.PixelOffsetMode = PixelOffsetMode.HighQuality;
g.CompositingQuality = CompositingQuality.HighQuality;
g.CompositingMode = CompositingMode.SourceCopy;
g.DrawImage(sourceBitmap, new Rectangle(0, pp, sourceWidth, sourceHeight), cropRect, GraphicsUnit.Pixel);
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
ImageCodecInfo codec = ImageCodecInfo.GetImageEncoders()[4];
EncoderParameters parameters = new EncoderParameters(1);
parameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
newBitMap.Save(filePath);
}
}
}
And here is cropped image:

Your destination image is the same physical size, because you use the same physical dimensions to create it:
Rectangle cropRect = new Rectangle(0, 0, sourceWidth, sourceHeight);
When you draw the original image into this new bitmap, you draw it with an offset pp, but still with the same height and width (so you're only cropping the bottom and right). This offset "colours" the memory of the new bitmap only from that y-coordinate downwards, and hence you have the black border.

Why when cropping image i'm getting black image of the cropped image?

In form1 constructor
public Form1()
{
InitializeComponent();
BackColor = Color.LightGreen;
TransparencyKey = Color.LightGreen;
this.TopMost = true;
this.Location = new Point(0, 0);
timer1.Enabled = true;
}
Then:
private void Cap()
{
countImages++;
ScreenCapture sc = new ScreenCapture();
Image img = sc.CaptureScreen();
Bitmap bmp = new Bitmap(img);
Bitmap source = new Bitmap(this.Width, this.Height);
Rectangle section = new Rectangle(new Point(source.Width, source.Height), source.Size);
Bitmap CroppedImage = CropImage(source, section);
CroppedImage.Save("c:\\temp\\screens\\" + countImages + ".gif", ImageFormat.Gif);
source.Dispose();
}
And
public Bitmap CropImage(Bitmap source, Rectangle section)
{
// An empty bitmap which will hold the cropped image
Bitmap bmp = new Bitmap(section.Width, section.Height);
Graphics g = Graphics.FromImage(bmp);
// Draw the given area (section) of the source image
// at location 0,0 on the empty bitmap (bmp)
g.DrawImage(source, 0, 0, section, GraphicsUnit.Pixel);
return bmp;
}
The Bitmaps i save to the hard disk:
CroppedImage.Save("c:\\temp\\screens\\" + countImages + ".gif", ImageFormat.Gif);
They are all black.
I want to crop this part from the image and save it to the hard disk.
Example of screenshot and what i want to crop from it:
I marked with a red circle the transparent form1 and this is what i want to crop the part of the form1 and save this as cropped image the form1 part:
I tried this first:
private void CaptureDesktop()
{
countImages++;
ScreenCapture sc = new ScreenCapture();
Image img = sc.CaptureScreen();
Bitmap bmp = new Bitmap(img);
Bitmap source = new Bitmap(this.Width, this.Height);
Rectangle section = new Rectangle(new Point(source.Width, source.Height), source.Size);
Bitmap CroppedImage = CropImage(bmp, section);
CroppedImage.Save("c:\\temp\\desktopscreens\\" + countImages + ".gif", ImageFormat.Gif);
}
But i'm getting this cropped image as result: Strange picture in picture ?
Then i tried this code:
using (Bitmap bmpScreenCapture = new Bitmap(Screen.PrimaryScreen.Bounds.Width,
Screen.PrimaryScreen.Bounds.Height))
{
using (Graphics g = Graphics.FromImage(bmpScreenCapture))
{
g.CopyFromScreen(this.Location.X,
this.Location.Y,
0, 0,
this.Size,
CopyPixelOperation.SourceCopy);
}
Rectangle section = new Rectangle(new Point(this.Location.X, this.Location.Y), new Size(this.Width, this.Height));
Bitmap CroppedImage = CropImage(bmpScreenCapture, section);
CroppedImage.Save("c:\\temp\\desktopscreens\\1.bmp", ImageFormat.Bmp);
}
But the result is:
Not what i wanted. I want only to crop the form1 part from the whole image.

You do Bitmap source = new Bitmap(this.Width, this.Height); this creates a black image.
Then you proceed to crop it. That's still a black image.
Then you proceed to save it. That's still a black image.
Perhaps you meant to crop Bitmap bmp or Image img, not Bitmap source. I don't know what Bitmap source is meant to be.

Try this (some code from Capture the screen shot using .NET)
private void Cap()
{
using (Bitmap bmpScreenCapture = new Bitmap(Screen.PrimaryScreen.Bounds.Width,
Screen.PrimaryScreen.Bounds.Height))
{
using (Graphics g = Graphics.FromImage(bmpScreenCapture))
{
g.CopyFromScreen(this.Location.X,
this.Location.Y,
0, 0,
this.Size,
CopyPixelOperation.SourceCopy);
}
Rectangle section = new Rectangle(new Point(this.Location.X, this.Location.Y), new Size(this.Width, this.Height));
Bitmap CroppedImage = CropImage(bmpScreenCapture, section);
CroppedImage.Save("c:\\temp\\screens\1.bmp", ImageFormat.Bmp);
}
}
public Bitmap CropImage(Bitmap source, Rectangle section)
{
// An empty bitmap which will hold the cropped image
Bitmap bmp = new Bitmap(section.Width, section.Height);
Graphics g = Graphics.FromImage(bmp);
// Draw the given area (section) of the source image
// at location 0,0 on the empty bitmap (bmp)
g.DrawImage(source, 0, 0, section, GraphicsUnit.Pixel);
return bmp;
}

Watermark not drawing in image

I had an error come up:
A Graphics Object cannot be Created from an Image that has an Indexed Pixel Format
So I implemented this code into my method: Solution for "A Graphics Object cannot be Created from an Image that has an Indexed Pixel Format"
But now my watermark doesnt want to draw on my image.
Please can anyone assist.
Code:
private Image AddWaterMark(Image original)
{
Image waterMark = Image.FromFile(ConfigurationManager.AppSettings["GalleryFolder"] + #"\watermark.png");
Bitmap bm = (Bitmap)original;
Size waterMarkResize = ResizeFit(new Size(original.Width, original.Height));
using (Image watermarkImage = new Bitmap(waterMark, waterMarkResize))
using (Graphics imageGraphics = Graphics.FromImage(new Bitmap(bm.Width, bm.Height)))
{
imageGraphics.DrawImage(bm, new Rectangle(0, 0, bm.Width, bm.Height), 0, 0, bm.Width, bm.Height, GraphicsUnit.Pixel);
using (TextureBrush watermarkBrush = new TextureBrush(watermarkImage))
{
int x = (original.Width / 2 - watermarkImage.Width / 2);
int y = (original.Height / 2 - watermarkImage.Height / 2);
watermarkBrush.TranslateTransform(x, y);
imageGraphics.FillRectangle(watermarkBrush, new Rectangle(new Point(x, y), new Size(watermarkImage.Width + 1, watermarkImage.Height)));
}
}
return bm;
}

You're creating a new Bitmap to pass to Graphics.FromImage then returning the uneditted original Bitmap. Create the new Bitmap independently, pass it to FromImage then return the new Bitmap.
var edit = new Bitmap(bm.Width, bm.Height);
// ...
using (Graphics imagesGraphics = Graphics.FromImage(edit))
{
// draw original
// draw watermark
}
return edit;

Generated Bitmap Displays Weirdly in PictureBox

I cannot seem to programmatically create a colored bitmap to display in a PictureBox. The bitmap saves normally as a file, but is faded at the edges when displayed in a PictureBox. Here is simplified code used to create and display the Bitmap (in actual code, the bitmap generation is completely separate from the form, so forcing the bitmap size to match the picturebox size isn't possible):
Bitmap Bmp = new Bitmap(4, 4, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
using (Graphics gfx = Graphics.FromImage(Bmp))
using (SolidBrush brush = new SolidBrush(Color.BlueViolet))
{
gfx.FillRectangle(brush, 0, 0, 4, 4);
}
Then set the Image value on a PictureBox to the generated Bitmap:
pictureBox1.Image = Bmp;
Here is the resulting bitmap displayed in a 300x300 picturebox:
How do I set the Image on the PictureBox so that it displays the colored bitmap properly (full solid)?
EDIT: I am restricted to generating smaller source bitmaps, so upscaling into a PictureBox is unavoidable. The problem appears when the generated source bitmap is 4px or 100px square, so I believe these are relevant cases.
EDIT: The PictureBox scaling should be set to stretch or zoom for the issue to manifest. In this example case the 4x4 source bitmap is stretched to 300x300.
EDIT: The basic problem is PictureBox's inability to upscale small bitmaps into large controls. This is confusing because the Bitmap upscales nicely into a PictureBox.Background image. Unless you have a magic bullet that will fix the image upscaling problem, I think it might be best to go for clear and simple workarounds in your answer.

You are generating a 4x4 bitmap and it's being stretched. Specify the size to match the picture box instead:
int width = pictureBox1.Width;
int height = pictureBox1.Height;
var Bmp = new Bitmap(width, height, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
using (Graphics gfx = Graphics.FromImage(Bmp))
using (var brush = new SolidBrush(Color.BlueViolet))
{
gfx.FillRectangle(brush, 0, 0, width, height);
}
pictureBox1.Image = Bmp;

You will need to turn anti-aliasing off. Also, since you are using one color for the whole picturebox, why not make the bitmap 1x1? If you need it 4x4, change the int the top of the example from 1 to 4.
int hw = 1;
Bitmap Bmp = new Bitmap(hw, hw,
System.Drawing.Imaging.PixelFormat.Format24bppRgb);
using (Graphics gfx = Graphics.FromImage(Bmp))
{
// Turn off anti-aliasing and draw an exact copy
gfx.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.None;
gfx.CompositingMode = System.Drawing.Drawing2D.CompositingMode.SourceCopy;
using (SolidBrush brush = new SolidBrush(Color.BlueViolet))
{
gfx.FillRectangle(brush, 0, 0, hw, hw);
}
}
pictureBox1.Image = Bmp;
UPDATE
Since you are still having the same issue by setting the picturebox to the image, you will have to get the graphics object from the picturebox and draw directly on it.
The code is very similar.
using (Graphics gfx = Graphics.FromImage(pictureBox1.Image))
{
// Turn off anti-aliasing and draw an exact copy
gfx.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.None;
gfx.CompositingMode = System.Drawing.Drawing2D.CompositingMode.SourceCopy;
using (SolidBrush brush = new SolidBrush(Color.BlueViolet))
{
gfx.FillRectangle(brush, 0, 0,
pictureBox11.Width - 1,
pictureBox11.Height - 1);
}
}
// Force the picturebox to redraw with the new image.
// You could also use pictureBox11.Refresh() to do the redraw.
pictureBox11.Invalidate();

I tried to test your code and the image were properly displayed.
But when i used this code:
Rectangle srcRect = New Rectangle(0, 0, Bmp.Width, Bmp.Height);
Rectangle dstRect = New Rectangle(0, 0, PictureBox1.Width, PictureBox1.Height);
g = PictureBox1.CreateGraphics;
g.DrawImage(Bmp, dstRect, srcRect, GraphicsUnit.Pixel);
g.Dispose();
I did get exactly your result. In order to fix it:
Rectangle srcRect = New Rectangle(0, 0, Bmp.Width - 1, Bmp.Height - 1);
Rectangle dstRect = New Rectangle(0, 0, PictureBox1.Width, PictureBox1.Height);
g = PictureBox1.CreateGraphics;
g.DrawImage(Bmp, dstRect, srcRect, GraphicsUnit.Pixel);
g.Dispose();
Edit:
So you have the bitmap and you want to stretch it. And the bitmap has ane solid color. Do this insted:
Color pixelColor = Bmp.GetPixel(0, 0);
PictureBox1.BackColor = pixelColor;
valter

converting images to pixel formats - c#

I have a problem with the code below. I was able to convert the image into the pixel format I want. But the problem is that when I use the bitmap for my picturebox, its just black.
sourceImage = new Bitmap(sourceImage.Width, sourceImage.Height,
System.Drawing.Imaging.PixelFormat.Format24bppRgb);
pictureBoxCurrency.Image = sourceImage;

You have created the new bitmap, but you need to paint the image (transfer) from the original one to the new one.
Bitmap newBitmap = new Bitmap(sourceImage.Size.Width, sourceImage.Size.Height, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
Graphics g = Graphics.FromImage(newBitmap);
g.DrawImage(sourceImage, new Point(0, 0));
g.Dispose();
pictureBoxCurrency.Image = sourceImage;