Develop Reference

Bitmap image - Decrease the number of pixels

I am using the following code
Bitmap bitmap = new Bitmap(Screen.PrimaryScreen.Bounds.Width,Screen.PrimaryScreen.Bounds.Height);
Graphics graphics = Graphics.FromImage(bitmap as Image);
graphics.CopyFromScreen(0, 0, 0, 0, bitmap.Size);
bitmap.Save(#"C:\test\2560.png", ImageFormat.Png);
The code works. I take a screenshot of the screen with graphics.CopyFromScreen() and save the bitmap with bitmap.Save().
The image consists of 2560x1440 pixels. Basically I want to step through the pixels looking for a color value.
3,686,400 queries is too much for me and I would like to reduce the number of pixels, which means the image quality will deteriorate. Is there a possibility of
Image processing to reduce the number of pixels? So that some pixels blur together and result in an average value?
I set it with bitmap.SetResolution(800, 600); but unfortunately it didn't work.

This should do the trick.
Bitmap bitmap = new Bitmap(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height);
Graphics graphics = Graphics.FromImage(bitmap as Image);
graphics.CopyFromScreen(0, 0, 0, 0, bitmap.Size);
Bitmap smallBmp = new Bitmap(bitmap, new Size(800, 600));
smallBmp.Save(#"C:\test\2560.png", ImageFormat.Png);

Take screenshot and show it in form

I try to create a screenshot like described here:
private Graphics takeScreenshot()
{
//Create a new bitmap.
var bmpScreenshot = new Bitmap(Screen.PrimaryScreen.Bounds.Width,
Screen.PrimaryScreen.Bounds.Height,
System.Drawing.Imaging.PixelFormat.Format32bppArgb);
// Create a graphics object from the bitmap.
var gfxScreenshot = Graphics.FromImage(bmpScreenshot);
// Take the screenshot from the upper left corner to the right bottom corner.
gfxScreenshot.CopyFromScreen(Screen.PrimaryScreen.Bounds.X,
Screen.PrimaryScreen.Bounds.Y,
0,
0,
Screen.PrimaryScreen.Bounds.Size,
CopyPixelOperation.SourceCopy);
return gfxScreenshot;
}
How can I show it in my form after it is taken?
I tried to display it inside a pictureBox:
Graphics screenshot = takeScreenshot();
pictureBox1.Image = screenshot;
But I get:
Severity Code Description Project File Line Suppression State
Error CS0029 Cannot implicitly convert type 'System.Drawing.Graphics'
to 'System.Drawing.Image' SRAT C:\Users\Edd\documents\visual studio
2017\Projects\SRAT\SRAT\Form1.cs 20 Active
and this answer says that it is not possible to convert it

A Graphics object is a sort of wrapper around an image that lets you draw on the image. They are usually temporary, and don't actually own the pixels that you're drawing.
In your case, gfxScreenshot is just providing the ability to draw onto bmpScreenshot, which is where the image actually lives in memory.
You should throw away the Graphics and return the Bitmap:
private Bitmap TakeScreenshot()
{
//Create a new bitmap.
var bmpScreenshot = new Bitmap(Screen.PrimaryScreen.Bounds.Width,
Screen.PrimaryScreen.Bounds.Height,
System.Drawing.Imaging.PixelFormat.Format32bppArgb);
// Create a graphics object from the bitmap.
using (var gfxScreenshot = Graphics.FromImage(bmpScreenshot))
{
// Take the screenshot from the upper left corner to the right bottom corner.
gfxScreenshot.CopyFromScreen(Screen.PrimaryScreen.Bounds.X,
Screen.PrimaryScreen.Bounds.Y,
0,
0,
Screen.PrimaryScreen.Bounds.Size,
CopyPixelOperation.SourceCopy);
}
return bmpScreenshot;
}
Then you can assign the bitmap to a PictureBox:
Bitmap screenshot = TakeScreenshot();
pictureBox1.Image = screenshot;

Apply Curl effect to a static Image C#

Anyone ever wrote a C# GDI+ function to curl the corner of a BITMAP. I need to be able to take a static image and apply the peel effect to it on the bottom right corner. And I need to do it with C# all my searching leads to CSS3/FLASH/SilverLight virtual book type examples. I just want to create a static image that has a curled up corner and save the file.
Any Ideas?
Ok so I made the image with photo shop so that I can show you what I am trying to achieve
I start this image
and I want to write some C# code that would yield this image
The end result is just an image that is not animated, and does nothing. Any thoughts.

There are some good tools to do this, such as Fred's ImageMagick plugin script, but here is a C# version as requested.
using System.Drawing.Imaging;
public partial class ImagePeelEffect : Form
{
string WorkingDirectory = #"C:\temp\";
public ImagePeelEffect()
{
InitializeComponent();
}
private void ImagePeelEffect_Load(object sender, EventArgs e)
{
picBefore.Image = Image.FromFile(WorkingDirectory + "\\before.jpg");
}
private void button1_Click(object sender, EventArgs e)
{
//create a image object containing the photograph to add page peel effect
Image imgPhoto = Image.FromFile(WorkingDirectory + "\\before.jpg");
int phWidth = imgPhoto.Width;
int phHeight = imgPhoto.Height;
//create a Bitmap the Size of the original photograph
Bitmap bmPhoto = new Bitmap(phWidth, phHeight, PixelFormat.Format24bppRgb);
bmPhoto.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution);
//load the Bitmap into a Graphics object
Graphics grPhoto = Graphics.FromImage(bmPhoto);
//create a image object containing the PagePeel
Image imgPagePeel = new Bitmap(WorkingDirectory + "\\PagePeel.bmp");
int ppWidth = imgPagePeel.Width;
int ppHeight = imgPagePeel.Height;
//Set the rendering quality for this Graphics object
grPhoto.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
//Draws the photo Image object at original size to the graphics object.
grPhoto.DrawImage(
imgPhoto, // Photo Image object
new Rectangle(0, 0, phWidth, phHeight), // Rectangle structure
0, // x-coordinate of the portion of the source image to draw.
0, // y-coordinate of the portion of the source image to draw.
phWidth, // Width of the portion of the source image to draw.
phHeight, // Height of the portion of the source image to draw.
GraphicsUnit.Pixel); // Units of measure
//The first step in manipulating the PagePeel image is to replace
//the background color with one that is transparent (Alpha=0, R=0, G=0, B=0)
//to do this we will use a Colormap and define ImageAttributes with a RemapTable
ImageAttributes imageAttributes = new ImageAttributes();
ColorMap colorMap = new ColorMap();
//My PagePeel was defined with a background of 100% Green this will
//be the color we search for and replace with transparency
colorMap.OldColor = Color.FromArgb(255, 0, 255, 0);
colorMap.NewColor = Color.FromArgb(0, 0, 0, 0);
//Set the Remap Table with the old and new color map
ColorMap[] remapTable = { colorMap };
imageAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap);
//For this example we will place the PagePeel in the bottom right
//hand corner of the photograph
int xPosOfPp = phWidth - ppWidth;
int yPosOfPp = phHeight - ppHeight + 1;
grPhoto.DrawImage(imgPagePeel,
new Rectangle(xPosOfPp, yPosOfPp, ppWidth, ppHeight), //Set the detination Position
0, // x-coordinate of the portion of the source image to draw.
0, // y-coordinate of the portion of the source image to draw.
ppWidth, // PagePeel Width
ppHeight, // PagePeel Height
GraphicsUnit.Pixel, // Unit of measurment
imageAttributes); //ImageAttributes Object
//Replace the original photgraphs bitmap with the new Bitmap
imgPhoto = bmPhoto;
grPhoto.Dispose();
//save new image to file system.
imgPhoto.Save(WorkingDirectory + "\\after.jpg", ImageFormat.Jpeg);
imgPhoto.Dispose();
imgPagePeel.Dispose();
//Show the After image
picAfter.Image = Image.FromFile(WorkingDirectory + "\\after.jpg");
}
The PagePeel.bmp:
The Before and After result:
Update
Here's a version that uses a Transparent Page Peel overlay so you dont neet to convert the "green screen" to invisible. The advantage of this method is when the original photograph contains the colour green RGB(0,255,0) it wont be turned into transparent:
TransparentPagePeel.png:
private void button2_Click(object sender, EventArgs e)
{
//create a image object containing the photograph to add page peel effect
Image imgPhoto = Image.FromFile(WorkingDirectory + "\\before.jpg");
int phWidth = imgPhoto.Width;
int phHeight = imgPhoto.Height;
//create a Bitmap the Size of the original photograph
Bitmap bmPhoto = new Bitmap(phWidth, phHeight, PixelFormat.Format24bppRgb);
bmPhoto.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution);
//load the Bitmap into a Graphics object
Graphics grPhoto = Graphics.FromImage(bmPhoto);
//create a image object containing the PagePeel
Image imgPagePeel = new Bitmap(WorkingDirectory + "\\transparentPagePeel.png");
int ppWidth = imgPagePeel.Width;
int ppHeight = imgPagePeel.Height;
//Set the rendering quality for this Graphics object
grPhoto.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
//Draws the photo Image object at original size to the graphics object.
grPhoto.DrawImage(
imgPhoto, // Photo Image object
new Rectangle(0, 0, phWidth, phHeight), // Rectangle structure
0, // x-coordinate of the portion of the source image to draw.
0, // y-coordinate of the portion of the source image to draw.
phWidth, // Width of the portion of the source image to draw.
phHeight, // Height of the portion of the source image to draw.
GraphicsUnit.Pixel); // Units of measure
//For this example we will place the PagePeel in the bottom right
//hand corner of the photograph
int xPosOfPp = phWidth - ppWidth;
int yPosOfPp = phHeight - ppHeight + 1;
grPhoto.DrawImage(imgPagePeel,
new Rectangle(xPosOfPp, yPosOfPp, ppWidth, ppHeight), //Set the detination Position
0, // x-coordinate of the portion of the source image to draw.
0, // y-coordinate of the portion of the source image to draw.
ppWidth, // PagePeel Width
ppHeight, // PagePeel Height
GraphicsUnit.Pixel, // Unit of measurment
null); //ImageAttributes Object
//Replace the original photgraphs bitmap with the new Bitmap
imgPhoto = bmPhoto;
grPhoto.Dispose();
//save new image to file system.
imgPhoto.Save(WorkingDirectory + "\\after1.jpg", ImageFormat.Jpeg);
imgPhoto.Dispose();
imgPagePeel.Dispose();
picAfter.Image = Image.FromFile(WorkingDirectory + "\\after1.jpg");
}

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

Convert Bitmap to unindexed pixelformat without compression/qualityloss

Is it possible to convert a indexed Bitmap to a unindexed without losing any quality?
I currently use this code to convert:
public Bitmap CreateNonIndexedImage(Image src)
{
Bitmap newBmp = new Bitmap(src.Width, src.Height, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
using (Graphics gfx = Graphics.FromImage(newBmp))
{
gfx.DrawImage(src, 0, 0);
}
return newBmp;
}
Here is the indexed bitmap: http://puu.sh/6VO1N.png
And this is the converted image: http://puu.sh/6VO2Q.png
I need the unindexed to be exactly the same as the indexed but I don´t know what to do.

The image was resampled. That's normally a Good Thing, it helps to get rid of the dithering artifacts in the original image. But you don't like it so you have to turn interpolation off. You also should use the DrawImage() overload that prevents rescaling due to the resolution of the original image. Not actually a problem with the image you've got but it could be one with another. Thus:
public static Bitmap CreateNonIndexedImage(Image src) {
Bitmap newBmp = new Bitmap(src.Width, src.Height, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
using (Graphics gfx = Graphics.FromImage(newBmp)) {
gfx.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.None;
gfx.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.NearestNeighbor;
gfx.DrawImage(src, new Rectangle(0, 0, src.Width, src.Height));
}
return newBmp;
}